sS^t

,*a

THE BOOK OF THE
ROTHAMSTED EXPERIMENTS

The Book of the
Rothamsted Experiments

BY A. I). HA LI., M.A. (Oxon.)

DIRECTOR OK THE HOTHAMSTKD EXI'KRIMEXTAI. STATION, URSI I'llISlIl'AI OI I II K SOTTII
EASTERN AC.UICl.i;iX-RAL COLI.W.E

ISSUED WITH THE AUTHORITY OF THE LAWES AGRIClETrRAL
TRUST COMMITTEE

LONDON

JOHN Ml'iniAV, ALBEMAKLK bTliKKT. W
1005

.>

'^■^'b'

k<?»<A

PREFACE

In' writing' this account of the Rothamsted Experiments — tlie
v^ixty years" work of two men, Lawes and Gilhei't, wliose names
liave become famihar in every part of tlie world where a«;ri-
cuUnre is something more than a matter of tradition and
onstom — I am of necessity acting as an external demonstrator,
descril)ing from the outside, as it were, what seem to he the
chief lessons conveyed by the experiments wliich I have now
the honour to conduct. Lawes and Gill^ert are dead, and with
them passed away many observations of value and many notable
generalisations Avhich they had found no oppoi-tunity of giving to
the world, nor had I the personal contact with either which
would enable me to report even such portions of their exi)eri-
ences as might have been conveyed by conversati(jn. ]>ut
though these losses cannot be repaired, and though nothing
can replace the instinctive knowledge that comes of having
seen a thing grow year after year, yet the position of an t)Ut-
sider has some advantages, especially when drawing up an
account which, like the present, is addressed to the L'-eneral
student of the subject.

In the first place, the outsider approaches the consideration
of each experiment without any of the prepossessions arising
from too exclusive a recollection of the purpose with which th<'
experiment was originally framed. Headers of the Jioth'ini-
,<-fr(i Mciiio'tr.t will know how certain ideas, r.//., the source and
function of the nitrogen in vegetation, occupied the ninid> n|
Lawes and Gilbert from the very beginning of their experiments
until the end. Tn consequence, the i)apers on .specific invest i-

viii PEEFACE

gations often tend to be less accounts of the experiment as a
whole than discussions of such of its results as bear upon
the dominant idea with which Lawes and Gilbert were then
engrossed.

The outsider, again, who has any knowledge of his subject
cannot fail to bring some ideas of his own which he can find
illustrated and elucidated in the work done at Eothamsted.
For here comes the jDarticular distinction of the Eothamsted
Experiments ; the plots exist to-day as they have been for the
last fifty years or so, and records of the most astonishing
completeness remain of their past history, so that as soon as
one looks closely into the material there is hardly any j^art of
the science of the nutrition of the plant on which it cannot
be made to throw light Indeed only a portion of the story
of the Eothamsted Experiments has yet been told, for new
matter will be discovered in them as our knowledge grows
and fresh lines of investigation are opened up. Accordingly,
in planning this account I have tried to look at each experiment
from as general a point of view as possible, and to set out
what information it can afford both to the student of agri-
cultural science and to the man more occupied with practical
problems. I have endeavoured to summarise under the head
of each crop the mass of information that has already been
published in the long series of Rothamsted Memoirs, and to
add other facts and deductions arising out of the experiments
which the original investigators had not hitherto been able to
publish.

As to the purpose of the book, that is best dealt with by
discussing the purpose of the Eothamsted Experiments them-
selves. They are, above all, attempts to obtain knowledge —
to ascertain the conditions under which the plant grows and
the soil supplies it with nutriment And as the attainment of
knowledge is the prime object, practical considerations are put
on one side in framing the scheme of the experiments. For
example, on one of the Eothamsted fields wheat has been grown
for the last sixty years, year after year, on the same plots of

PKKFACE ix

land with the same manures. As tlie liritish farmer never
grows wheat continuously on the same land, and rarely uses any
kind of manure for it. the wliole experiment is tVom one point
of view hopelessly unpractical ; indeed many men might con-
sider that to grow wheat at all nowadays is unpractical. lUit
the aim of the experiments is to find out lioir tin' irln'nt phinf
prows, and the scheme of manuring and management adopted
is the most practical method of solving that proMem. Experi-
ments which only aim at ascertaining how to derive the
greatest monetary return from a given crop, however necessary
they may be, are only of value for a short time and for the
particular soil and locahty where they are carried out. During
the period the Eothamsted wheat field has been under experi-
ment the price of wheat has been as high as 75s. and as low as
23s. ; any conckisions reached as to the most paying system at
the former price would have to be akogether revised at the
lower rates. There is, of course, every probaliility that price
and other economic conditions may fluctuate just as nuich in
the future as they have done in the past, but the one thing
that will for ever remain unchanged is the manner in which the
crop draws its nutrition from the air, the water, and the soil.
Hence the farmer who best knows how this process takes
place will, other conditions being equal, be the one best fitted
to continue to derive a profit under the changing conditions.

The great object, then, of the Rotham.sted Experiments is
to obtain knowledge that is true everywhere, and to arrive
at principles of general application, leaving the fiirmer himself,
through his more immediate advisers, to adapt these princijiles
to his own practical conditions and translate them into pounds,
shillings, and pence. Thus the farmer who visits Eothamsted
nmst not expect to see demonstrations of the most profitable
means of growing this or that crop, but rather to obtain
information as to its habits and requirements which on
reflection he can make useful under his own conditions.
vSome of the work also that is going on may seem to deal \\\\\\
problems little connected with practice ; so remote, in fact, that

X PREFACE

they never can have any bearing upon the business of farming.
There are, however, many matters in which the actual farmer
will always have to rely upon the advice of scientific experts,
and as a rule the unpractical-looking experiments are devised
to settle this or that point on which the scientific man must
have information in order to form a correct judgment for the
guidance of the practical man.

Agricultural science involves some of the most complex
and difficult problems the world is ever likely to have to solve,
and if it is to continue to be of benefit to the working farmer,
the investigations, as far as their actual conduct goes, must
very quickly pass into regions where only the professional
scientific man can hope to follow them. However, it is not
with such research that the present volume deals ; here, I
trust, there is nothing that the farmer with an intelligent
interest in his profession cannot appreciate and find useful.
The book is intended, firstly, for any man concerned with the
management of land, whether farmer or market gardener, land-
owner or agent, who wants to learn something of the processes
going on in the growing crop and in the soil, as they have been
elucidated by the most complete set of field experiments the
world has yet seen. Secondly, the book is intended for the
agricultural student ; it will furnish a running commentary on
a very large portion of the information he finds in his text-
books on agriculture and agricultural chemistry. It is of great
importance to the student that he should from time to time get
in touch with the sources of the statements and conclusions he
reads in his text-books or hears in lecture, since he obtains
thereby some idea of the extent to which these statements can
be trusted to apply to working conditions. Lastly, the book is
intended for the agricultural teacher and expert, for whom it
will provide a certain amount of unpublished matter con-
cerning Rothamsted, and will also serve as a guide to the
very extensive series of reports issued by Lawes and Gilbert.
To this end references have been added at the close of each
chapter to the original papers dealing with the subject.

PREFACE xi

Throughont I liave kept the teacher in view, and have
endeavoured to supply him with tlie sunmiarjes and iUus-
trations wliich will be useful in his elass wi)i"k.

Of course, in many respects the book covers tlie same
ground as the summary of the Kothamsted Experiments <lrawn
up by Gilbert for his lectures in America, whieh weri' published
both by the United States Department of Agriculture and liy
the Highland and Agricultural Society of Scotland in ISO.").
The American lectures were, however, in the main intended
for the reader who was already eipiipped with a considerabk"
knowledge of agricultural science; on the one hand, they did
not deal with all the Rothamsted work, and on the other, they
went into much greater detail than is here attempted. In the
present book I have endeavoured to make matters })lain to
the non-technical reader and to elucidate the subject by
diagrams and simplified tables, leaving the specialist to ccjnsult
the original papers for fuller information.

By the kind permission of ]Mr R. Warington and the
Council of the Royal Society, I have been permitted to reprint
Mr \yarington's account of Law^es and Gilbert from the Ol)ituary
Notices of the Royal Society, and this forms the best intro-
duction to the history of the Rothamsted Experiments and the
personality of their founders.

In the Appendix will be found a bil)liograi)liy of all the
more important papers issued by Lawes and Gilbert, together
with others which deal with Rothamsted material by inde-
pendent investigators. A list will also be found of previous
books which have given a general account of the experiments,
including Dr Fream's little book published in 1888, which,
though dealing only with wdieat, barley, and grass, has formed
for so many readers their introduction and guide to the
Rothamsted investigations.

A hst is given of the men who have worked in the Koihani-
sted Laboratory, either as members of the stall", or as voluntary
workers for a long or short period. Although by the terni>
of the trust deed no teaching may be done at the Station,

Xll

PEEFACE

accommodation may be provided for men capable of assisting in
research ; such men are welcomed and are given all facilities for
carrying out special investigations with the material in which
the Station is so rich.

In this book little has been said of the work now in progress ;
speaking generally, the old plots as described are being continued
without essential change, but the current investigations deal
chiefly with the composition of the crops produced and with the
soil. The bacterial life of the soil forms indeed the unknown
territory which promises the greatest reward to the explorations
of the agricultural chemist of to-day.

In the preparation of the book, I have to thank Dr N. H. J.
Miller for most of Chapter II., and both him and Mr J. J.
WilHs for much detailed information and many facts that have
never been recorded. Dr H. T. Brown, F.R.S., and Dr J. A.
Voelcker have been good enough to read the proof-sheets and
make many suggestions. Particularly I have to thank Mr G.
T. Dunkley for the great trouble and care he has taken over
the preparation of the tables and diagrams ; without the help
of his knowledge of the past history and his familiarity with the
records, I should have found it impossible to prepare this account
of the Pothamsted Experiments.

A. D. Hall.

The Rothamsted Experimental Station,
Harpenden, March 1905.

CONTENTS

Biographical In'trodictiox

xxi

CHAPTER I
The Sources of the Nitrogen of Vegetation

CHAPTER II

Meteorological Observations

15

CHAPTER III

The Composition of the Rothamsted Soil

24

II.
III.

CHAPTER IV

E.XPERIMENTS UPON WhEAT

The Continuous Growth of Wheat, Broadbalk Field . . ."^l

A. Maintenance of the Yield under Continuous Wheat Grow-

ing on the same Land ..... 36

B. Effect of Nitrogenous Manures .... 42

C. Effect of the Mineral Constituents . . . . 4S

D. Retention of Manures by the Soil .... bO

E. Character of the Crop as affected by Manuring and Season 54
Wheat after Fallow, and in Rotation .... IL'
Trials of Varieties of Wheat . . . . .66
Practical Conclusions and References . . . . 6S

CHAPTER V
Experiments upon Barley
I. The Continuous Growth of Barley upon the same Land, Hoos Field

A. Maintenance of Yield under the Continuous (irowth of

Barley on the same Land

B. Effect of Nitrogenous Manures

C. Effect of Mineral Manures .

D. Character of the Crop as affected by Manuring
II. Barley Grown in Rotation, Agdell Field .

Practical Conclusions and References

76
.SO
i<3
88
90

xiv CONTENTS

CHAPTER VI

Experiments upon Oats

PAGE

Experiments upon Oats Grown Continuously upon the same Land,

Geescroft Field . . . . . .92

CHAPTER VII

Experiments upon Root-Crops Grown Continuously on the
SAME Land.

I. Experiments upon Mangels, Barnfield, 1876-1904 . . 96

A. Effect of Nitrogenous Manures .... 99

B. Effect of Mineral Manures . . . . .103

C. Comparison of Nitrate of Soda and Ammonium-salts as

sources of Nitrogen . . . . .107

D. Effect of Nitrogenous and Mineral Manures when used in

conjunction with Dung . . . . .108

E. Proportion of Root to Leaf . . . .112

F. Proportion of the Nitrogen recovered in Crop to that

supplied in Manure . . . . .112

G. The Composition of the Mangel Crop as affected by

Manuring . . . . .11-5

Practical Conclusions . . . . . .119

II. Experiments upon Turnips, Barn Field, 1843-1870 . . 119

Practical Conclusions . . . . . . 1J2

III Experiments on the Continuous Growth of Potatoes on the same

Land, Hoos Field, 1876-1901 . . . . .122

Practical Conclusions . . . . . .126

IV. Experiments on the Growth of Sugar Beet, Barn Field . . 127

A. First Series, 1871-75 ..... 127

B. Second Series, 1898-1901 ..... 130
Practical Conclusions and References . . . .132

CHAPTER VIII

Experiments upon the Continuous Growth of Leguminous
Crops

I. The Continuous Growth of Beans on the same Land, Geescroft

Field 133

II. The Continuous Growth of Red Clover on ordinary Arable Land,

Hoos Field ....... 141

III. The Continuous Growth of Clover on rich Garden Soil . . 144

References . . . . . . . .149

CONTENTS

XV

CHArrKH IX
Experiments ii'on (Juass Land Mown von Hay eveio Ykah

I. The Unnianurt'd Plots ....
II. L'se of Nitrogeimus Maniu-fs alone

III. Mineral Manures used alone

IV. Complete Manures — Nitrogen and AMinerals
\ . The Action of Organic Matter

VI. Effects of Lime .....

\TI. Changes in Herbage following Changes in Manuring

MIL The Effect of Season ....

Practical Conclusions ....

References .....

mi

157
15S
160
165

107
IGS
ls;i
1^5
KH9

CHAPTER X

Experiments upon Chops (.rown in Rotation, Aodei.i, Fiei.

I. The Unmanured Plots .....

II. Effect of the Manures .....

III. The Effect of the (irowth of Clover or Beans on the succeedin^

Crops .......

IV. Effect of Manorial Residues on subsequent Crops .
y. Gain or Loss of Manurial Constituents to the Land

Practical Conclusions .....

References .......

192
19.-.

2(M)

204
2<il)
211
2 If,

Nitrification and

CHAPTER XI

ME Composition ok Draina(;k U'atk.r.-

I. The Process of Nitrification
II. Denitrification
III. Nitrates in Cultivated Soils
I\'. Nitrates in Manured and Cropped Soils

\'. The Nitrates in Drainage Waters .
\T. Other Constituents of Drainage Waters
References ....

217
2 1 !>
221
22.1
229
2 .{7
239

XVI

CONTENTS

CHAPTER XII

The Feeding Experiments

I. Relative Value of Nitrogenous and Non -nitrogenous Constituents
of Food .......

II. Relation of Nitrogenous Food to Work

III. The Source of Fat in the Animal Body

IV. Relation of Food Consumed to Live Weight Increase
V. The Composition of Oxen, Sheep, and Pigs, and of their Increase

during Fattening .....

VI. The Manure Value of Foods ....

VII. Miscellaneous Feeding Experiments

References .......

240

24.5
246

248

250
254
258
259

CHAPTER XIII

Miscellaneous Enquiries

I. Experiments upon Sewage Irrigation
II. Experiments upon Malt and Barley

III. Experiments upon Ensilage

IV. The Composition of Wheat Grain and its Mill Products
References . .

260
261

266
268

•779

Appendix I : —

I. List of Publications issued from the Rotharasted Experi-
mental Station, 1843-1905 .... 273
II. Publications by other Investigators, dealing with Material

from Rothamsted ..... 283

III. Other Publications dealing with the Rothamsted Experi-
ments ....... 284

Appendix II : —

Officials 286

Appendix III : —

List of Past and Present W'orkers at the Rothamsted Experi-
mental Station . . . . . .287

Index

289

LIST OF ILLUSTRA'lIONS

FULL-PAGE PLATLS

Sir John Bkxnkt Lawks, Baut.

Sir Joseph Henuv Gilueut

Fig. 17.— Turf from Plot 3. Without Manure

'I'o face

18.-

ly.-

20.-

26.

27_

»

Plot 4-i

30.—

j»

Plot 6

31.—

Plot ir,

Plot 5. Amnioniuni-salts alone

Plot 17. Nitrate Soda alone .

Plot 7. Full Minerals

Plot 8. Minerals without Pota.sh

Plot 4-1 . Superphosphate alone

Plot 9. Full Minerals and Am
monium-salts = 86 lb. N.

Plot 11. Full Minerals and Am - I
monium-salts = 147 lb. N. I

Plot 14. Full Minerals and Nitrate,
of Soda . . .|

Superphosphate and Am- I
monium-salts . . '

Full Minerals after .\m- i
monium . . '

Full .Minerals after Nitrite I

page XXI
xxxij

1.-.6

58

160

hvi

164

170

DIAGIIAMS I \ TM K T K .\ T

Fig. 1. — Uainfall, Sunshine, and Mean 'I'emper.iture .

l>._Broadbalk Wheat. Maintenanee of yield during' lO-year

periods ...■■•••'

„ 3. — IJroadbalk Wheat. EHeet of iiiereasinj,' amounts of Nitroj^en
on the production of \N heat ((irain and Straw)

xvii I,

i.i

xviii LIST OF ILLUSTRATIONS

DIAGRAMS IN THE TEXT— conti7iue(l .

Fig. 4. — Comparison of Nitrate of Soda and Ammonium-salts on
Wheat ......

„ 5. — Relation between Cost of Production and Returns with
varying quantities of Manure

„ 6. — Production of Wheat with varying Mineral Manures

„ 7. — Loss of Nitrogen as Nitrates in the Drainage Water, lb
per aci'e ......

„ 8. — Comfjarative Effects on Wheat of Ammonium-salts applied
at different times .....

^^ 9. — Effect of Wet or Dry Autumns on continuous Wheat, and
Wheat alternated with Fallow

,, 10. — Yield of Barley during successive 10-year periods (1852
1901)

,, 11. — Yield of Bai'ley (Grain and Straw) with different sources
of Nitrogen .....

„ 12. — Bai'ley. Total Produce, showing residual effect of Dung and
no Manure in relation to the Dung Plot = 100 .

„ 13. — Effect of Mineral Manures on the yield of Barley (Grain and
Straw) ......

J. 14. — Mangel Wurzel. Effect of increasing amounts of Nitrogen

J, 1.5. — Mangel Wurzel. Effect of various Mineral Manures

,j 16. — Mangel Wurzel. Effect of addition of Mineral Manure to
Dung, with various Nitrogenous Cross-dressings .

„ 21. — Effect of the various Ash constituents with and without
Nitrogen on the produce of Hay per acre

J, 28. — Effect of Nitrogenous Manures on the produce of Hay pe

acre . . •

^^ 29. — Progressive Effect of Changes in the Manuring on the Com

position of the Hay Crop ....

„ .32. — Percentage of Anthoxanthum odoratum in the Herbage of the
Grass Plots .....

„ 33. — Percentage of Festuca ovina in the Herbage of the Grass
Plots . .

^^ 34. — Percentage of Alopecimis prafensis in the Herbage of the
Grass Plots .....

^, 3.5. — Percentage of Arrhenatherum aveiiaceimi in the Herbage of
the Grass Plots .....

^^ 36. — Percentage of Holms lanatus in the Herbage of the Grass
Plots ......

TJST ol- ll.l.rsii;.vn()NS xix

DIACKAMS IN IIIK I'l: XT -.,•„«/„„/,•,/.

Fk;. -U. — IV-rcenlagf i>f I'ri to/mm icjh-iis, Tril'oHiiiii pralrnsr, aiul htlns

coniini/aliix (toi^i'thor) in tht- Htrlm<jo «tf tin- (Jrass Plots . IS2

., 38. — I'eriH-nt.ific of I.at/n/nix /nulnixix in tin- Hcrh.t-^c of Ihr

(irass Plots . |SJ

."59. — PtTCi'iitajjc of (riiliinrcii ni;^ni in llic I lirl)aL,M- of' the (Jrass

Plots ....... 18G

to. — Percenfafif of lumn-.r arclosit in tin- I IcihaLCr of tlit- (Irass

Plots ....... 1S8

n. — Crops (Irowii in Hot.itioii. .M.iiiittiiaiut' of virld without

Manure ....... I'.Ct

.,, 1-. — Eft'ect of .Manure upon Crops drown in Hotation . I'.O

,. 43. — Comparative Effect of Clover or Hart- fallow on the suit eed-

ing Crops in the Rotation . . L'Ol

., \\. — Effect of Eeedin<r or Carting the Koot Crop on the succeed-
ing Crops in the Rotation ..... 208

^, 15. — Rainfall, Percolation, and Nitrogen as Nitrate in Dr.ainage

through 20 inches of Soil ..... l':{(»

„ 4G. — Dry Matter and Nitrogenous Substance consumed per loo Ih.

Live-weight per week. Pigs . . . iM.'?

„ 47. — Nitrogenous and Non-nitrogenous Matter in I'ood rccpiircd

to produce 100 lb. Live-weight Increase. Pigs L' J I

„ 48. — Percentage Composition of the Whole Bodies of 0.\en, Shctp.

and Pigs ....... L'50

^, 19. — Oxen, Sheej), and Pig'^- Composition of increase in

Fattening ....... 'I'uS

Sir John Bennet Lawes, Bart., D.C.L. , LL. D. , F.R.S.

Face page xxi.]

BIOGRAPHICAL INTRODlK/l ION*

Sir J(MIN Bknnki' Lawks, IVvirr., IslMKoo

The manor-house of Rothamsted, situatcil in ilic jiarisli of
Harpenden, Herts, was tlie birtliplace of John Bcnnct Lawes,
and the Rothamsted farm became, in subsequent years, tlie
scene of the great work of his long life. So far-reach in. l: have
been the results wdiich he achieved, that the name of Kotham-
sted is now a household word wherever the science of
Agriculture is studied.

The ancestors of Sir John Lawes had occupied Rotliamsted
for many generations. Jaques Wittewronge came to England
from Flanders in 1564, owing to the religious persecution then
prevaihng. The manor of llothamsted was purchase<l in l»)*j:i
for his grandson, John Wittewronge, who was then a minor.
John Wittewronge was knighted by Charles I., and afterwards
created a baronet by Charles II. In consequence of the faihnc
of male heirs, the manor passed to the Bennet family by ihv
marriage of Elizabeth Wittewronge with Thomas Bennet, and
finally to the Lawes family by the marriage of Mary l^ennct
(great-granddaughter of James Wittewronge) with Thomas
Lawes. His son, John Bennet Lawes, was the father of the
John Bennet Lawes of whom we have to speak, who was born
at Itothamsted on December '2x, 1^14.

John Bennet Lawes was an only son. He lost his father
when eight years old, and owed much to his nujthcr's bringing;
up. He seems to have led the life of a country boy, and his

* Ueprinted from the Obituary Notirt-s of the Royal Society.

xxii BIOGRAPHICAL INTRODUCTION

studies he afterwards described as being " of a most desultory
character." Experiments in chemistry, made at home, seem ta
have been one of his favourite occupations. He was sent
successively to Eton, and to Brasenose College, Oxford, which
he entered in 1832. While at Oxford he attended some of the
lectures of Dr Daubeny, the professor of chemistry. He left
the University without taking a degree.

In 1834 Mr Lawes entered on the personal management of
the home farm at Rothamsted, then of about 250 acres ; he at
the same time threw himself heartily into chemical investiga-
tions. He tells us : "At the age of twenty I gave an order to a
London firm to fit up a complete laboratory, and I am afraid it
sadly disturl^ed the peace of mind of my mother to see one of
the best bedrooms in the house fitted up with stoves, retorts,^
and all the apparatus and reagents necessary for chemical
research. At the time my attention was very much directed to
the composition of drugs ; I almost knew the Pharmacopoeia
by heart, and I was not satisfied until I had made the acquaint-
ance of the author, Dr A. T. Thomson. The active principle
of a number of substances was being discovered at this time^
and, in order to make these substances, I sowed on my farm
poppies, hemlock, henbane, colchicum, belladonna, etc. Some
of these are still growing about the place. Dr Thomson had
suggested a process for making calomel and corrosive sublimate
by burning quicksilver in chlorine gas. I undertook to carry
out the process on a large scale, and wasted a good deal of
time and money on a process which was, in fact, no improve-
ment on the process then in use." At this time Dr Anthony
Todd Thomson, Professor of Materia Medica at University
College, London, was his chief instructor and adviser. An old
barn at Rothamsted was transformed into a laboratory, and
here the calomel was afterwards made ; this laboratory
remained in active use till 1855.

The researches of De Saussure, on the nutrition of plants,
seem to have first called Mr Lawes' attention to the relations
between chemistry and agriculture. In 1837 he commenced

BIOriKAIMUCAl, INTKODrCTroX

xxm

experiments in pots with agricultural plants, the manures made
use of supplying various elements of plant food. These cxpci-i-
ments were continued on a larger scale in 1^:N .md l^:;i».
Spent animal charcoal was then a waste product , and Mr
Lawes was asked by a London friend if it coulil I»e turned tu
any use. He therefore employed it as a mannre in his pot
experiments, and discovered that if previously treate<l witli
sulphuric acid its efficacy as a manure was greatly increased.
-Vpatite and other mineral phosphates were soon treatecl in a
similar manner, and the "superphosphate of lime," thus
prepared, was found to be most effective as a manure, especially
for turnips. The new superphosphate was employed on a
large scale for crops on the Eothamsted farm in ls4() and
1841, and the results were so satisfactory that in ls4*2 Mr
Lawes took out a patent for the manufacture of super-
phosphate.

The application of sulphuric acid to bones had been
practised before the date of Mr Lawes' patent ; the novelty of
his patented invention consisted in the treatment of mineral
phosphates in this manner. The supply of lione available for
farmers is but small, but the supply of apatite, coprolite, and
of the various rock phosphates discovered in recent years, is
almost unHmited. These mineral phosphates are usually too
insoluble to have any practical value as manure, but by treat-
ment with a limited quantity of sulphuric acid, a mixture of
monocalcic phosphate, phosphoric acid, and gypsum is produced.
The phosphates in this compound are almost entirely soluble
in water, and far more efficacious as manure than the phos-
phates of raw bone. The enormous influence which the
introduction of superphosphate has had on the development of
agriculture may be gathered from the (juantity now aininall\
employed by farmers. The annual mamifaclure of >nper
phosphate in Great Britain amounts at present to about
1,000,000 tons, while the total manufacture in the world is
about six times this amount. If Sir John Lawes had done
nothing more than introduce the manufacture of artificial

xxiv BIOGRAPHICAL INTRODUCTION

manures, he would still rank among the greatest benefactors
to agriculture.

The life of Sir John Lawes divides at this point into two
parts. He became from the date of his patent a chemical
manufactm-er, carrying on an extensive London business, and
as prosperity increased he embarked in a variety of enterprises.
While, however, obliged to spend two days of every week in
London, his devotion to agricultural research continued to
increase, and the profits yielded by commerce were employed
for the creation and maintenance of a large experiment station
at Eothamsted. The experiments in the fields had already, at
the date of his patent, reached a stage at which the continuous
services of a trained chemist were urgently needed. On the
recommendation of Dr A. T. Thomson, Mr Lawes engaged a
young chemist who had studied under Liebig — Dr J. H.
Gilbert. Dr Gilbert entered upon his work at Eothamsted in
June 1843, and continued actively occupied in the scientific
superintendence of the agricultural experiments during the
whole of his long life. For fifty-seven years Lawes and
Gilbert worked together on a great variety of agricultural
problems ; of these labours and their results we shall give a
brief account, after completing our sketch of the life of each
worker.

Mr Lawes married, in 1842, Caroline Fountaine, daughter
of Andrew Fountaine, Esq., of Narford Hall, Norfolk. He
enjoyed her society for more than fifty years, and her artistic
power was not unfrequently employed in providing illustrations
of the investigations in progress. As the commencement of
manufacturing operations made great demands on his capital,
Mr Lawes at this period let Eothamsted House, and for some
years resided either in London or Devonshire.

His first factory for the manufactm^e of superphosphate was
erected at Deptford Creek in 1843. The business rapidly
extended, and in 1857 about 100 acres of land were purchased
at Barking Creek, and a larger factory erected, including an
extensive plant for the manufacture of sulphuric acid. In 1866

BIOGKAPHKWl. INTKM )l)r(Tl( )N wv

Mr Lawes purchased the tartaric and citric acid lactnrv at
jNIillwall. The purchase was unwillinudy uuulv, lait the new
work w^as taken up with his accustomed eneri,^ and enterprise,
many economies and improvements were intnxhiced. and the
factory became the most important of its kind in this eoinitrv.
In 1872 he sokl the whole of his manure luisiness for £:)()(l,(i()() ;
he retained the tartaric and citric acid factory till liis death.
Mr Lawes had also a large sugar estate in Queensland : the
low^ price of sugar and the lack of cheap labour prevente(l, in
this instance, a commercial success.

The investigations at Rothamsted made rapid progress. In
1843 were commenced the systematic field experiments on
turnips and wheat ; the wheat field has grown wheat witliout
intermission ever since. In 1847 the field experiments on
beans commenced, and in 1848 those on clover, and on a four-
course rotation. In 1851 the rotations of wheat and fallow
and w^heat and beans were started. In 1852 the field experi-
ments on barley commenced. In 1856 those on f^rass land.
In all about 40 acres were l)rought under experiment. Of all
these crops complete chemical statistics were (»btained.
Experiments on sheep-feeding w^ith various foods conunenced
in 1848. The whole bodies of ten animals — oxen, slieej). aii<l
pigs — of various ages and conditions as to fatness, were analysed
between 1848 and 1850. In 1850 an extensive series of pig-
feeding experiments was made.

The extent of the work undertaken, its thoroughnes.s, and
the practical value of the results obtained, gained the a(hnira-
tion of both scientific and practical men. At a meeting of
Hertfordshire farmers at 8t Albans, on J3eceml)cr 24, ]xy.]. it
was resolved to present Mr Lawes with a testinionial. The
circular issued states : " It was considered that .Mr Lawes lias
for many years been engaged in a series of scientifii- and
disinterested investigations for the improvement of agriculture
generally, which have been carried out to an e.xtciit. wiili a!i
attention to accuracy and <letail, and at a cost, never before
undertaken by any individual, or even by any public institu-

xxvi BIOGRAPHICAL INTRODUCTION

tion." The proposal was soon enlarged, and became national
in its character. The subscriptions received amounted to about
£1160. At Mr Lawes' desire, the greater part of this sum
was spent in the erection of a new laboratory, which was
opened at a gathering of distinguished agriculturists on July
19, 1855, the Earl of Chichester presiding on the occasion.
The speeches made by Mr Lawes, Dr Gilbert, and others, have
fortunately been preserved. Mr Lawes, on this occasion, paid
a warm tribute to the work done by Dr Gilljert. Besides the
gift of the laboratory, Mr Lawes received a handsome silver
candelabrum, bearing a suitable inscription. In later years the
lal^oratory was found too small for the preparation and storage
of the numerous samples, and additional buildings were
erected.

Mr Lawes was elected a Fellow of the Royal Society in
1854, and in 1867 one of the Royal medals was awarded to him
and Dr Gilbert for their systematic researches upon agricul-
tural chemistry. Seven papers by Lawes and Gilbert have
been published in the Society's Philosophical Transactions.

The connection of Mr Lawes with the Royal Agricultural
Society was naturally a close one. He became a member of
the Council in 1848, and was afterwards a vice-president and
trustee. In 1893 the presidency of the Society was offered to
him, but declined on account of his advancing years. In the
Journal of the Society the greater number of the reports on
the Rothamsted agricultural investigations have been published ;
forty-six reports had thus appeared before the year 1900. In
1876 he took an active part in arranging for the commencement
of the field experiments conducted by the Society at Woburn,
in Bedfordshire. These experiments consisted in repetitions^
of the experiments at Rothamsted upon the continuous growth
of wheat and barley with known manures, the experiments in
this case being made upon a purely sandy soil ; they also
included rotation experiments designed to test the manurial
value of cattle foods. These experiments were conducted on
the Duke of Bedford's estate, and at his expense.

BIOGLWIMIICAL 1 XTLM)! Ul "IK )N xxvii

The relations of Mr l.nwes witli the Chemical Society wci-o
also intimate. He l)ecame a Fellow in ls.')(), and was ek'cted
to the Council in lS()-2. The chief part of the chemical work
done in the Kothamsted lahoratory was conununicated to this
Society, and ahout twenty-two lectures and pa{)ers ]»y Lawes
and (lill)ert, and other Kothamsted workers, appear in the
Jonnial and Transactions.

Mr Lawes was a member of the Royal Conunission
appointed in 1857 "To inquire into the best mode of distri-
buting the sewage of towns, and applying it to l^eneficial and
profitable uses." Two meml)ers of this Conunission, Lawes
and Way, conducted for several years important experiments
on sewage irrigation at Rugby. The investigation dealt with
the quantity and comjDosition of the grass receiving varyin.^-
amoimts of sewage, and its value as food for fattening oxen and
milking cows, including the composition of the milk obtained.
The etiiuent waters from the irrigated fields were also analysed,
and the formation of nitrates in large quantities was demon-
strated. The final report was published in 1865.

The aid of Rothamsted was again sought l)y the Govern-
ment in 1863, the object in this case being to ascertain
whether the malting of barley resulted in any increase of its
value as a food. A considerable bulk of barley was divided
into two lots, one of which w^as malted, and the loss in dry
matter ascertained; feeding experiments were then nia(h', in
which the nutritive effect of a given weight of barley was com-
pared with that sliown by the quantity of malt which could have
been produced from it. The trials with oxen, sheep, and pigs,
were made at Rothamsted, and those with milking cows at
Rugby. The full report w^as presented to Parliament in 1S()6.

While the formal reports on the Rothamsted investigations
were to a large extent the work of Dr Giil)ert, IMr Lawes was
himself an active writer on agricultural .subjects. In midcUe
life he was a frequent contributor of .short papers to agricul-
tiu-al newspapers and periodicals, l)oth Knghsh and American ;
he also lectured from time to time to a'M'icultural associations.

xxviii BIOGRAPHICAL INTRODUCTIOX

His writings were always marked by great originality, they
were also very practical in character. When bringing forward
the results of recent scientific enquiries, he would avoid as far
as possible the use of scientific language, and speak as a farmer
to farmers. The fertihty of the land and its relation to
landlord and tenant, and the manure value of foods, with the
compensation due to an outgoing tenant for unexhausted
manures, were subjects which he made peculiarly his own.
For many years he sent annually to the Times newspaper, in
the early autumn, an estimate of the quantity of wheat yielded
by the preceding harvest in this country. This estimate was
based on the produce of the standard plots in the experimental
wheat field at Rothamsted ; as the produce here was over or
under the average, so it was assumed would be the general
produce of the country. The estimates thus made proved
generally to be near the truth.

For his great services to agriculture Mr Lawes was created
a baronet by the Queen in 1882. The degree of LL.D. was
conferred on him by the University of Edinburgh in 1877;
D.C.L. by Oxford in 1893; and Sc.D. by Cambridge in 1894.
He received the Legion of Honour from Napoleon III. ; he
was also a Chevalier du Merite Agricole. He was elected a
corresponding member of the Institute of France in 1879. In
1863, he received a Gold Medal from the Russian Government.
In 1881, the German Emperor awarded a Gold Medal for
Agricultural Merit to Lawes and Gilbert.

Sir John Lawes early conceived the idea of perpetuating
the Rothamsted investigations by placing the laboratory and
fields in the hands of trustees with a permanent endowment
for their maintenance. He first spoke of this in his speech at
the opening of the new laboratory in 1855. In 1872 he
publicly announced that he had set aside £100,000 for this
purpose. By deeds executed by him in February 1889, the
laboratory and experimental fields were leased to Sir John
Lubbock, William Wells, Esq., and Sir John Evans, as
trustees, for ninety-nine years at a peppercorn rent. To the same

BIOGRAPHICAL INTEODUCTION xxix

trustees he covenanted to pay the sum of £100,000, the interest
on which was to lie applied to the maintenance of agricultural
investigations under the direction of a Committee of nine
persons, of whom four were to be nominated by the Koyal
Society, two by the Koyal Agricultural Society, one by the
Linnean Society, and one by the Chemical Society, the owner
of Rothamsted being always a member of the Committee.
The appointment of new trustees when required was vested in
the Royal Society. The Managing Committee were at once
appointed. They consisted of Sir John Evans, Dr Hugo
Mtiller, Sir Michael Foster, and Sir W. T. Thiselton Dyer,
nominated ])y the Royal Society ; Sir John H. Thorold, and
Charles Whitehead, Esq., nominated by the Royal Agriculim-al
Society ; William Carruthers, Esq., nominated l:»y the Linnean
Society ; Prof. H. E. Armstrong, nominated ])y the Chemical
Society ; with Sir John Bennet Lawes. Under this Committee,
with but few alterations in their constitution, the direction of
the work at Rothamsted has since proceeded. One provision
of the trust deed directs the Committee to send a lecturer from
time to time to the United States of America to lecture upon
the results of the Rothamsted investigations.

The Jubilee of the Rothamsted Experiments was celebrated
on July 29, 1893. The organisation of this celebration
originated with the Royal Agricultural Society. At a meeting
on March 1, presided over by H.R.H. the Prince of Wales, it
was resolved : "That some public recognition should be made
of the invaluable services rendered to Agriculture ])y Sir John
Lawes and Dr Gilbert." A subscription hst was opened, and
with the contributions received a large Ijoulder of Shap granite
was erected in front of the laboratory, bearing the following
inscription : — "To connnemorate the completion of Fifty Years
of continuous experiments (the first of their kind) in agriculture,
conducted at Rothamsted l)y vSir John Bennet Lawes and
Joseph Henry Gilbert. a.d. Mi)rc("xciii." A large and
distinguislied gathering was held in front of the ]al)oratory
on the afternoon of July 29, the Rt. Hon. Herbert Gardner,

XXX BIOGRAPHICAL INTRODUCTION

M.P., President of the Board of Agriculture, presided. The
Duke of Westminster, as President of the Royal Agricultural
Society, presented to Sir John Lawes his portrait, painted by
H. Herkomer, R.A., and to Dr J. H. Gilbert, a silver salver.
He also presented congratulatory addresses to both Lawes and
Gilbert from the subscribers to the fund, each address being
signed by H.R.H. the Prince of Wales. The presentation of a
large number of addresses from English and Foreign Societies
then followed, including one from the Royal Society. Sir
John Lawes and Dr Gilbert then replied. A few of the
words spoken l^y Sir John Lawes nmst be quoted. " That
afternoon he had to return thanks to that distinguished and
briUiant assembly for their kind congratulations to himself and
Dr Gilbert upon the work that they had been carrying on for
the last fifty years. When two people were joined together in
marriage they could not part, because they were liound
together by very solemn ties. But with regard to himself and
Dr Gilbert the case was quite different, Dr Gilbert could have
left him, or he could have left Dr Gilbert. Tiieir connection,
however, had lasted for more than fifty years. What was the
cause ? Nothing less than mutual love of the work they had
been engaged in. He (Sir John) had dehghted in the work
from the beginning. All the time he could spare in the midst
of many other responsibilities and duties he had given to the
work. But with Dr Gilbert it had been the work of his life.
If it had not been for Dr Gilbert's collaboration their investiga-
tions would have been in a very different state to what they
were then."

Shortly after the Jubilee celel3ration Dr Gilbert received
the honour of knighthood. In September of the same year
the Liebig Silver Medal was awarded to Sir John Lawes and
Sir Henry Gilbert by the curators of the Liebig Foundation of
the Royal Bavarian Academy of Sciences. In the following
year, 1894, the Albert Gold Medal of the Society of Arts was
presented to Lawes and Gilbert by H.R.H. the Prince of
Wales, "for their joint services to scientific agriculture, and

BIOGKAIMIICAI, IN riJoDrc'l ION \x\i

notably for the researches whicli, tlirou^hout a prriud of titty
years, have been carried on by them at tlu' b'xpcriiiKMital I'arni,
Ivothamsted."

Something must now be said as to tlio personality of tlie
remarkable man whose life's work we have attempted to
<lescribe. He possessed an extremely vigorous constitution,
and when past 85, exhibited but few of the inhrmities of old
age. His holiday was always spent in Scotland, and deer
stalking and salmon fishing were then his chief occupations.
At home, all his leisure time was spent on the farm. He was
a keen observer, and knew the experimental iields l)etter than
anyone else. His interest in agricultural problems never
tired, he was continually finding fresh subjects for in(|niry.
While gifted with a full share of the scientific imagination, he
was thoroughly practical in his conclusions. His long
experience as a farmer, and the careful attention to economy
learnt in business, were of great use to him when he brought
the results of scientific investigation before the agricultural
world. He took a broad, statesman-like view of all agricultural
questions, and was looked up to by the English farm(>r as his
safest guide and his highest authority.

Sir John Lawes seldom took part in public functicjns, he
was not seen at meetings of scientific societies, and took no
active part in politics ; excepting the hours unavoidably spent
on his London business, he lived as far as possible a country
life. It was, however, in no sense a secluded lite : his
correspondence was very large, and the visitors to tlie
Kothamsted experiments were extremely numerous and of all
nationalities. They found at Kothamsted a genial host and
a ready guide to the fields, where the lessons taught l)y the
experimental crops were described in lirief and pithy sentences
by one who knew thoroughly the whole history of each plot.

Sir John Lawes by no means confined his attention to
science, agriculture, and business; lie was a man of active
benevolence. The agricultural labourers of Ilarpendcn found
in him their best Iriend. He began to provide allotment

xxxii BIOGRAPHICAL INTRODUCTION

gardens in 1852, and before his death the number had reached
334. In 1857 he built a club room in the gardens. Various
co-operative schemes were started for the labourer's benefit ;
one of these has been immortahsed by Charles Dickens, who
visited the club room in April 1859, and afterwards gave an
account of what he saw in the first number of All the Year
Round. The welfare of his workmen at his various factories
was equally considered. He exercised a wide private benevo-
lence, and in his own parish was never appealed to in vain for
any good work.

Sir John Lawes' life was prolonged to an unusual period ;
he lived and worked and taught through two successive
generations. His health remained very good till within about
a week of his death. He died at Rothamsted on August 31,
1900, in his 86tli year, and was buried at Harpenden. His
only son. Sir Charles Bennet Lawes, who has assumed the
additional name of Wittewronge, succeeds to the Rothamsted
estate.

Sir Joseph Henry Gilbert, 1817-1901

Joseph Henry Gilbert was born at Hull on August 1,
1817. He was the second son of the Rev. Joseph Gilbert, a
Congregational Minister, who had previously held the position
of Professor of Classics at the Divinity College, Rotherham.
His mother belonged to a well-known literary family, and
under her maiden name of Ann Taylor, was a popular authoress
of poems for children. The family removed in 1825 to
Nottingham, and it vvas here that the boyhood of Joseph Henry
Gilbert was spent. He was first sent to an elementary school
taught by a blind lady of great intelligence, and afterwards to a
school kept by Mr Long at Mansfield. In 1832, while at Scar-
borough, he met with a serious gunshot accident, which per-
manently deprived him of the sight of one eye, and considerably
damaged the other ; his general health suffered much from the

SiK JosEiMi Henuv GiLHKKT, M.A., Ph.D., LL.D., r.li.S.

[Fact page xxrll.

•^N/vepg

OF

BIOGRAPHICAL INTEODUC TIOX xxxiii

shock, tand it was some years before he was able to resume
his studies. Dm-iiig this interval he in 1838 paid a visit to St
Petersbm-g. In the autumn of 1838 he became a student at the
University of Glasgow; here he devoted nearly a year to the
study of analytical chemistry in the laboratory of Prof. Thomas
Thomson. Materia-Medica was studied under Dr J. Couper,
and botany under Sir W. J. Hooker. He came to London in
the autumn of 1839, and continued his studies at University
College, where he attended the chemical lectures and practical
classes of Prof. T. Graham, and worked for a short time in the
laboratory of Prof. Anthony Todd Thomson. He also studied
natural philosophy under J. Sylvester, anatomy under Dr
Grant, and botany under Lindley at Chiswick, and made some
progress in the German language. In 1840 he went to
Germany, and spent a summer session at Giessen, in the
laboratory of Prof. Liebig. Here he took the degree of Ph.D. ;
two other Enghsh students, J. Stenhouse and L. Playfair, after-
wards to become celebrated as chemists, took their degrees
at the same time. On returning to England, Dr Gilbert
renewed his studies at University College, and became class
and laboratory assistant to Prof. A. T. Thomson during the
winter and summer sessions of 1840-41. In 1842 he left
London and became consulting chemist to Mr Burd, a calico-
printer in the neighbourhood of Manchester. The turning
point of his life soon arrived. Mr Lawes had already made
his acquaintance in the laboratory of Prof. A. T. Thomson, and
being in want of a trained chemist to assist in the agricultural
investigations he had commenced at Rothamsted, he, on the
recommendation of Prof. Thomson, engaged the services of Dr
Gilbert. On June 1, 1843, Dr Gilbert entered on his work at
Rothamsted. The connection between Lawes and Gilbert thus
commenced continued till the death of Sir John Lawes in 1900,
a period of fifty-seven years.

The rapid development of the agricultural investigations at
Rothamsted after the year 1843 has been already noticed in the
preceding account of the life of Sir John Lawes. The value of

xxxiv BIOGEAPHICAL INTRODUCTION

the work done was largely due to the unremitted labours of Dr
Gilbert. At the opening of the new laboratory in 1855, Mr
Lawes said, " I should be most ungrateful were I to omit this
opportunity of stating how greatly I am indebted to those
gentlemen whose lives are devoted to the conduct and manage-
ment of my experiments. To Dr. Gilbert more especially, I
consider a debt of gratitude is due from myself and from every
agriculturist in Great Britain. It is not every gentleman of
his attainments who would subject himself to the caprice of an
individual, or risk his reputation by following the pursuits of a
science which has hardly a recognised existence. For twelve
years our acquaintance has existed, and I hope twelve years
more will find it continuing." The testimony borne by Sir John
Lawes to his colleague at the end of fifty years of their joint
work has been already quoted in the preceding account of Sir
John Lawes.

We must now attempt to give some idea of the special part
taken by Sir Henry Gilbert in the Rothamsted investigations.
The two leaders of the work were in almost daily consultation,
Sir H. Gilbert spending, as a rule, an hour at Rothamsted
every day that Sir John Lawes was at home. The plans for
new experiments, the results obtained from day to day, and
the drafts of the reports in preparation, were thus all discussed
by them together. Sir John Lawes directed the agricultural
operations in the experimental fields ; the execution of the
remainder of the work was in the hands of Sir Henry Gilbert.
Sir John Lawes contributed to the joint work a thorough
knowledge of practical agriculture. His original mind was
stored with facts learnt by keen observation and study in the
field. A born investigator, he seemed to be continually
occupied in the study of agricultural problems. His enterpris-
ing and practical spirit impressed its character on the whole of
the Rothamsted work. Sir Henry Gilbert supplemented in a
remarkable manner the qualities of his chief. His training as
an analytical chemist, and his acquaintance with foreign
languages and literature, were naturally of great value in

BIOGRAPHICAL INTRODUCTION xxxv

research work. His knowledge of collociiiial (Jcnnan enal>K'<i
him in after years to (lescril)e the resuUs of the Rotlianisted
investigations to many foreign visitors. His .s])ecial mental
characteristics also eminently fitted him for the work sub-
sequently carried out. He was both cautious and painstaking
to a remarkable extent, desiring to accumulate a great mass of
facts before coming to any certain conclusion upon them. His
mode of work was also extremely methodical, and the method
once adopted, after full consideration, was continued through
many subsequent years, thus giving rise to long series of results
obtained in a perfectly similar manner. The continuation of
the same field experiments for more than fifty years, and the
important results which subsequently followed from an examina-
tion of the soils so long under definite cultivation, may be cited
as examples of Gilbert's method. Under his care, samples of
the grain and straw from each experimental plot, in each year
were preserved in the laboratory, and also samples of the ash
yielded by each. In later years, when samples of the soils and
subsoils of each plot were repeatedly taken, large portions of
each sample were also preserved. At his death the number of
samples stored for future reference in the laboratory and in the
adjoining building exceeded 50,000. The bulk of tabulated
records prepared by the clerks at the laboratory was corre-
spondingly large. He thus laid the foundation of nuich solid
work. The same characteristics appeared in his reports.
These usually contained a great bulk of numerical statements,
set forth in an orderly manner, with not unfrequently only a
small proportion of illuminating theory. The recording of
observed facts seemed often to satisfy his object as an investi-
gator. When, however, a definite conclusion had been arrived
at it was tenaciously held, and if attacked was vigorously
defended. Sir Henry Gilbert was an antagonist who never
tired. His controversies with Liebig, on the subject of his
mineral theory, and, in later years, with other (Icrnian investi-
gators, on the source of fat in tlic animal Ixxly. will be well
remembered by his contemporaries.

xxxvi BIOGRAPHICAL INTRODUCTION

The life work of Sir Henry Gilbert will chiefly be found in
the published reports of the Rothamsted investigations, which,
at the time of his death, had reached ten volumes ; the subjects
of these investigations will be briefly noticed at the close of
this biography. His work, however, frequently extended beyond
the sphere of the Rothamsted Experiments. He was Mr
Lawes' scientific adviser, and as such he played an active part
in the trials wdiich took place in the Law Courts respecting the
alleged infringement of Mr Lawes' patent. He made reports
on deposits of phosphates at home and abroad. He
superintended the experiments relating to the disposal of
sewage at the time when Mr Lawes was a member of the
Royal Commission of 1857. Other important undertakings will
be mentioned presently.

Dr Gilbert was married in 1850 to Eliza Laurie, daughter
of the Rev. G. Laurie. His wife died in 1853. He married a
second time, in 1855, Maria Smith, who survives him. Sir
Henry Gilbert owed much to his second wife's untiring assist-
ance. The feeble condition of his eyesight obliged him to rely
a good deal on clerical help. Both foreign and English papers
were read to him by Lady Gilbert, while the greater [Mvt of his
own work was dictated to an amanuensis. His great pluck
and determination, with the assistance thus rendered, enabled
him to accompHsh a very large amount of work notwithstanding
the serious difficulties under which he laboured.

Sir Henry Gilbert was an active member of many scientific
societies, a regular attendant at their meetings, and a member
of many scientific committees. The Rothamsted investigations
undoubtedly gained by the intercourse thus obtained with other
investigators, though the time occupied by visits to London
was often considerable. Sir Henry Gilbert was elected a
Fellow of the Royal Society in 1860. He was the author, with
Sir John Lawes, of seven papers in the Philosophical Trans-
actions. In 1867 he received, with Sir John Lawes, one of
the Royal medals for the work done at Rothamsted. He
served on the Council in 1886-8. Sir Henry Gilbert joined the

BIOGRAPHICAL INTKODICTION xxwii

Chemical Society in 1841, a few weeks after its formation,
became a member of the Council in 1850, and a \'ic('-l'ivsi(h'iit
in 1868. In 1882 he was elected President of the Society.
Sir Henry Gilbert delivered fom* lectures before {\\v Socit'ty,
and was the part author of several other papers. In isos a
memorable dinner was given by the Society to six Past-
Presidents, all of whom had been members of the Society foi*
more than fifty years : of these Past-Presidents Gilbert was the
eldest. The President concluded his address to him by saying :
" The Rothamsted results will be for ever memorable : they are
unique, and characteristic of the indomitable perseverance and
energy of our venerated President, Sir Henry Gilbert."

Of the Linnean and Meteorological Societies Sir Henry
Gilbert was also a Fellow, and occasionally read papers at
their meetings. He was also a member of the Society of Arts.
He became a member of the Scientific Committee of tlie
Horticultural Society in 1868, and for many years regularly
attended its meetings.

In his summer hohdays the meeting of the British Associa-
tion for the Advancement of Science was generally attended ;
his attendance commenced in 1842, and during many years he
scarcely missed a meeting, and frequently read a paper
describing some of the Rothamsted results. In 1880 he was
President of the Chemical Section, and gave as his address,
"A Sketch of the Progress of Agricultural Chemistry." A
tour on the Continent generally formed part of the sunnner
holiday; agricultural laboratories and experimental stations
were then visited, and the Naturforscher Versammlung, and
other scientific gatherings, were often attended and papers
read before them. In 1871, and the following year, the
details of sugar-beet culture were studied in Germany, Austria,
and France, preparatory to the commencement of cxpcrimcnls
on this subject at Rothamsted.

Three visits were paid to the United States and Canada.
In 1882 he attended the meeting of the xVmerican Association
for the Advancement of Science, at Montreal, and brought.

xxxviii BIOGRAPHICAL INTRODUCTION

before them the recent determinations of nitrogen in the
experimental soils at Rothamsted. A tom* of nearly three
months was afterwards made in the United States. In 1884
he was again at Montreal, at the meeting of the British
Association, and afterwards made a second extensive tom*
through North America.' The last visit was paid in 1893,
after the celebration of the Rothamsted jubilee, for the
purpose of delivering a course of lectures on the Rothamsted
experiments, in accordance with a provision of Sir John Lawes'
trust deed. Sir Henry Gilbert first attended the Agricultural
Congress held in connection with the World's Fair at Chicago ;
here he had a splendid reception, all present rising and
cheering for some time. To this Exhibition at Chicago a large
collection of diagrams had been sent from Rothamsted, and
for these a medal was afterwards awarded. Sir Henry Gilbert
then gave a course of seven lectures at the State Agricultural
College at Amherst, Mass., taking as his subject the chief
results relating to the crops ordinarily grown in rotation, with
those relating to the feeding of animals, obtained at Rothamsted
during the previous fifty years. These lectures, in an enlarged
form, were afterwards published by the United States Depart-
ment of Agriculture, and were reprinted, with an introductory
account of the Rothamsted Experiments, in the Transactions
of the Highland and Agricultural Society of Scotland for
1895.

In 1884 Dr Gilbert was elected Sibthorpian Professor of
Rural Economy in the University of Oxford, and held this
office for six years, the full term allowed by the statute. He
delivered during this time over seventy lectures on the results-
of the Rothamsted investigations ; these lectures he hoped to
publish, but the intention has remained unfulfilled.

In 1885 Dr Gilbert became an Honorary Professor of the
Royal Agricultural College at Cirencester, and delivered an
annual lecture during six years ; the lectures were published in
the Agricultural Studeiits Gazette. They treat in a condensed
form of some of the subjects previously discussed at Oxford.

BIOGRAPHICAL INTIJODTI TION wxix

The transfer of the hiboratory and expiM-inuMital liclds to
the management of a committee appointed under Sii- dolm
Lawes' trust deed of 1889 has been ah-eady mentionc'd. After
this date the virtual direction of the experiments contiiuied Id
remain in the hands of Lawes and Gilbert during tlieir joint
lives. For the information of the new committee Sir Henry
Gilbert drew up a brief report on the investigations hitherto
conducted, showing to what extent the results obtained had
been already published, and making suggestions as to future
work. This report was printed in 1891 foi- the use of tlie
committee.

The celebration of the jubilee of the Kothamsted Exi)eri-
ments in 1893 has been already described in the notice
of Sir John Lawes, with the numerous honours sul)sequenlly
conferred on both Lawes and Gill^ert. Dr Gilbert re-
ceived knighthood from the Queen on August 11 of tliat
year.

Sir Henry Gilbert was a memljer of the committee
appointed by the Government in 1896 to take evidence
and report on the materials used in the manufcicture of beer.
The committee presented their report to the Treasury in
1899.

He received many honorary degrees. The University of
Glasgow made him LL.D. in 1883; Oxford, M.A. in 1884;
Edinburgh, LL.D. in 1890; Cambridge, Sc.D. in 1894. He
was a life governor of University College, London; a Corre-
sponding Member of the Institute of France; a Chevalier du
Merite Agricole ; and an honorary memljer of many auiicul-
tural societies at home and aljroad.

With a life so filled with many lal)ours it need liardly be
said that Sir Henry Gilbert was possessed of a robust constitu-
tion. He, however, suffered at times from over-braiiiwoik.
and his fre(i[uent excursions al)road were really ni-eded to
maintain a healthy tone. In later years he suffere<l mueli at
times from internal i)ain, the precursor, pr(jl»ably, of hi.-. la>t
illness. The death of Sir John Lawes in 1900 was naturally a

xl BIOGRAPHICAL INTRODUCTION

great shock to him. He was fairly vigorous, however,
during the next summer, but was taken seriously ill during
a visit to Scotland, and returned home with difficulty. He
died at Harpenden on December 23, 1901, in his 85th
year.

R. Warington.

CHAPTER I

THE SOURCES OF THE NITROGEN OF VEGETATION

To arrive at a proper understanding of the scheme of the
Kothamsted Experiments it is necessary to reconstruct a
little the state of the knowledge of agricultural science at the
time they were begun in 1843. In many respects it was a
period of considerable activity in matters agricultural ; the whole
landed interest were making great efforts towards the improve-
ment of land and stock and of methods of cultivation ; great
areas of the country were being tile-drained and rendered for
the first time suitable for arable cultivation, other poor sandy
land was being reclaimed by marling and claying. A sign of
the times was the establishment of the Eoyal Agricultm'al
Society in 1838, and in its earlier volumes, particularly in the
writings of Dr Daubeny on the scientific side, and those of
Philip Pusey on the practical side, a good idea may be
formed of the point of view of the intelligent farmer of that
date. The science of the time had just reached a point which
enabled a general theory of the nutrition of both plant and
animal to be formed. In the latter part of the eighteenth
century the researches of Priestley, followed up l)y Ingenhousz
and Senebier, had settled the fundamental fact that green
plants in sunlight decompose the carbonic acid of the atmos-
phere, setting free the oxygen and retaining the carbon, this
being the source of the carbon which makes up the bulk uf the
dry matter of plants. A little later De Saussure, who pul)lished

2 SOUECES OF THE NITROGEN OF VEGETATION

his Recherches Chimiques sur la Vegetation in 1804, confirmed
the above-mentioned discoveries and gave them a coherent
shape. He then proceeded to discuss the mineral or ash
constituents of plants, made a series of analyses of the ashes
of various plants, and pointed out the importance of these
substances in the nutrition of the plant. Davy, whose lectures
on Agricultural Chemistry to the Board of Agriculture
were published in 1813, though he did not advance the
subject much by his own investigations, yet did much service
in presenting to the agricultural public the science that
was then available. He laid more stress than before on
the importance of the ash constituents and the use of
manures to supply them, but he appears still to have con-
sidered that much of the carbonaceous matter of plants
was directly derived from the humus of the soil, and that
the assimilation of carbon from the atmosphere was of minor
importance.

Boussingault's memorable work began in 1834, and in 1838
he published the result of the enquiries he had been making on
his farm into the principles underlying the rotation of crops.
He analysed both the manures applied and the crops removed
from the land, and thus demonstrated statistically that the
source of the enormous quantities of carbon removed annually
can only be the carbonic acid of the atmospliere, not the soil
nor the manures applied. In 1840 appeared Liebig's famous
report to the British Association on *' Organic Chemistry in its
applications to Agriculture and Physiology." Here, building
upon the foundations laid by De Saussure and by Boussingault
(for in this direction Liebig was not an original investigator),
and illuminating these facts by the light of his own recent
discoveries in organic chemistry, Liebig drew out a convincing
scheme of the nutrition of the plant. Green plants by the aid
of sunlight derive their whole substance from carbonic acid,
water, ammonia present in the atmosphere and produced
by decaying matter in the soil, and the simple inorganic
salts which are afterwards found in the ash when the plant

EARLY THEORIES 3

is burned. From these simple sul)stances the plant elaborates
those compounds of carbon and nitrogen, such as starcli,
sugar, fat, and the proteids, which the animal requires for
its food, and thereby reconverts into the original simpler
materials. Liebig's brilliant essay excited universal attention
and roused the interest of both the scientific and practical
men of all civilised countries in the subject, so that to
a very large extent we can date modern agricultural science
from this stimulating publication. Henceforwai'd we may
take it that the som'ce of the carbon of vegetation was no
longer regarded as doubtful; it came from the atmosphere,
and the humus of the soil practically contributed nothing
to it.

The origin of the nitrogen was however by no means so
settled : De Saussure had concluded that plants were unable to
assimilate the free nitrogen of the atmosphere, but obtained it
from the nitrogenous compounds in the soil and from the small
amount of ammonia which he showed to be present in ordinary
air. Boussingault took out statistics of the nitrogen as well as
the carbon supplied in manures and recovered in the crops ; in
1838 he also published an account of experiments in which
plants were grown in pots and supplied with known amounts
of combined nitrogen, so as to ascertain if the growing plant did
assimilate atmospheric nitrogen. While the crop statistics
seemed to show in certain cases a considerable surplus of
nitrogen removed in the crops during a rotation over that
supplied in the manure, his direct experiments, made as
accurately as the chemistry of the time would permit, indi-
cated that plants drew only nitrogen from the soil or
manure.

The arguments of De Saussure and of Boussingault were
adopted by Liebig in his first publication ; he considered the
source of the nitrogen of vegetation was ammonia derived from
the decay of the previous generation of plants or brought down
from the atmosphere by the rain. In his later editions Liebig
somewhat shifted from this point of view and began to minimise

4 SOUECES OF THE NITROGEN OF VEGETATION

the importance of any supply of combined nitrogen to the
plant ; provided that the soil were supplied with the mineral
constituents removed by the crop, he argued that it would be
able to grow luxuriantly and obtain for itself all the nitrogen
necessary. It is difficult now to estimate exactly the positions
held by controversialists of more than half a century ago,
but there can be little doubt that Liebig overestimated
the amount of ammonia which could be obtained from the
atmosphere, and that he and his followers, arguing from
general grounds as to the origin of the original stock of
combined nitrogen in the world, were disposed to believe
that some, if not all, leafy plants could assimilate and fix
free atmospheric nitrogen.

Some little time before the publication of Liebig's re-
port, Lawes had begun his experiments on a small scale ;
as early as 1835 he was making trials in pots at Roth-
amsted, and these were year by year extended to the fields
on the home farm, until in 1843 the scale had so far in-
creased that he secured the co-operation of Gilbert and
the Rothamsted Experiments as we now know them
began.

Curiously enough, at this very time (1842) Dr Daubeny,
some of whose lectures Lawes had attended at Oxford, was
writing in the new Journal of the Royal Agricultural Society
about the necessity of systematic experiments to ascertain the
value of manures : "I know not how such experiments can
well be instituted, except it be on an experimental farm,
established for the purpose, and placed under scientific hands.
Productive of no immediate advantage to the land on which
they are tried beyond what could be equally well attained by
a much inferior expenditure of labour, they are not likely to be
taken up by any private individual who combines practical
experience and pecuniary resources with the requisite scientific
skill ; and even if such a person were to present himself, what
guarantee can we offer to the world that he possesses the
requisite qualifications ? " For it should be remembered that

EAKLY EXPERIINLEN'rs Ol' I.AAVES

this was the period of the first iiitroihietioii of \vliat we now
call artificial inaiuires ; the virtue of bones liad k^ng l)een
known, and at Liebig's instigation their phosphoric acid was
being made soluble by acid, and dissolved bones were becoming
an article of commerce. Lawes had followed up ITenshnv's
discovery of coprolites by converting them into mineral super-
phosphate, and setting up the earliest manufactory of artiiicial
manures. The first importations of Peruvian guano hatl l.)een
made, and nitrate of soda w^as also beginning to find its way
into the countiy.

With these and many other substances Lawes had been
experimenting on a small scale, and the results of his trials
and all his farming experience w^ent to show that a supply
of combined nitrogen in some form or other was not only
necessary to the crop, but on the whole determined its
yield to a far greater extent than the supply of ash
constituents. Yet Liebig's argument in the second (1843)
edition of his report all inclined to represent the mineral
manures as fundamental, and a supply of combined
nitrogen as unnecessary, or at least of secondary import-
ance. This question of the value or otherwise of nitrogenous
manures supplied the main guiding principle in the design of
all the earlier field experiments at Rothamsted, as will be
evident when the individual fields come to be considered, and
the controversy which arose with Liebig on the publication of
the first reports from Rothamsted endured for more than a
generation. Indeed the source and fjxte of the nitrogen of
vegetation remained in one form or another the dominant
interest in the Rothamsted Experiments up to the death of
Lawes and Gilbert.

The evidence from the field experiments that farm crops
require a supply of combined nitrogen will be considered else-
where, as also the results of the determinations made of the
amounts of ammonia and other nitrogenous compounds
brought down by the rain ; in neither case was thei-e evidence
that a normal vegetation could supply itself with the necessary

6 SOURCES OF THE NITROGEN OF VEGETATION

nitrogen from atmospheric som-ces only. Attempts had also
been made to grow plants in artificial media with a known
supply of nitrogen, which could be compared with the amount
of nitrogen found later in the fully grown plant. Boussingault,
to whom the first experiments of this nature were due, soon
found that very elaborate precautions must be taken to obviate
the influx of nitrogen either in dust or as ammonia in the
atmosjDhere and in the water employed, hence in all his later
experiments the plants were grown in closed cases fed with air
from which all ammonia had been withdrawn by acid. Bous-
singault's conclusions were against the fixation of any nitrogen,
but they were not accepted universally ; in particular, Ville
brought forward other similar experiments, in which the plant
showed a distinct gain of combined nitrogen. In 1857 the
subject was taken up at Rothamsted, and a most elaborate
series of experiments were carried out by Dr Evan Pugh,
at that time working in the Rothamsted laboratory. The
experimental plants were grown under glass shades, and
every precaution was taken to ensure the freedom from
ammonia of the air entering the shades, and also of the other
materials — the burnt earth, the pots, the water, the manures —
employed in the experiment.

The experiments were made with wheat, barley, oats, clover,
beans, peas, and buckwheat, and the trials were repeated, in the
one case with no manm^e in the pots, and in the other with the
supply of a small quantity of sulphate of ammonia. The soils
employed were made up from either ignited pumice or ignited
soil, and the glass shades under which the plants were grown
rested in the groove of a stoneware vessel, mercury being used
as a lute. The air, previously passed through sulphuric acid
and sodium carbonate solution and washed, was forced into
the apparatus, so as to always maintain a greater pressure
inside than out, thus minimising all danger of unwashed air
leaking in ; carbonic acid was also introduced as required.
Under these rigorous conditions the following results were
obtained : —

PLANTS DO NOT FIX FIJKK MTIJOdKN

Table I. — Summanj of fhc Iic.'<iilt^ of Experimcnls made at liolhavistrd lo
drtermine whethei' Plants aaaimilate Free Nitrogen.

N-ltrogon-Oram.

Ratio or
Nitrogen
rccovt«n«l to
Nitrogpn
suppllpcl.

1.

Ill Sft'il

and Mamirp

If any.

III Plants,

rot, aiKl

Soil.

Oaln or I.om.

With no combined Nitrogen supplied beyond that in the Seed sowi

r

1857 -

Wlieat
Barley
Barley

0-0080
0-0056
0-0056

0-0072
0-0072
0-0082

-0-OOOS
+ 0-0016
+ 0-0026

0-90
1-29
1-46

Gramineae . -

1858 -

Wheat
Barley
Oats .

0-0078
0-0057
0-0063

0-0081
0-0058
0-0056

+ 0-0003
+ 0-0001
-0-0007

1-04
1-02
0-89

1858 1

Wheat
Oats .

0-0078
0-0064

0-0078
0-0063

- 0-0001

1-00
0-98

Legiiminosae . -!

1857

Beans

0-0796

0-0791

-0-0005

0-99

1858 1

Beans
Peas .

0-0750
0-0188

0-07.-.7
0-0167

+ 0-0007
-0-0021

1-01 -
0-89

Other Plants .

1858

Buckwheat

0-0200

0-0182

-0-0018

0-91

Wi

til combined J

Nitrogen si

pplied.

-1

Wheat
Wheat
Barley
Barley

0-0329
0 0329
0-0326
0-0268

0-0383
0-0331
0-0328
0-0337

+ 0-0054
+ 0-0002
+ 0-0002
+ 0-0069

1-16
1-01
1-01
1-25

Gramineae . -^

1858 j

Wheat
Barley
Oats .

0-0548
0-0496
0-0312

0-0536
0-0464
0-0216

-0-0012
-0-0032
-0-0096

0-98
0-94
0-69

1858 •

Wheat
Barley
Oats .

0-0268
0-0257
0-0260

0-0274
0-0242
0-0198

+ 0-0006
-0-0015
- 0-0062

1-02
0-94
0-76

Leguminosae . -

1858 1

Peas .
Clover

0-0227
0-0712

0-0211
0-0665

-0-0016
-0-0047

0-93
0-93

1858

Beans

0-0711

0-0655

-0-0056

0-92

Other Plants .

1858

Buckwheat

0-0308

0-0292

-0-0016

0-95

These results seem to exclude ilie possiliilily of any
fixation of nitrogen by living plants, and as tli(>y had heen
obtained with plants of tlu-ee different natural orders, and lioth
without and with manure to induce an initial vigorous growtli,
for many years the whole trend of scientific oiiinion was against
the possibility of the fixation of nitrogen l)y living plants.

8 SOURCES OF THE NITROGEN OF VEGETATION

There remained, however, a number of facts difficult to
account for : although laboratory experiments similar to those
just described, but resulting in a gain of nitrogen, could be dis-
missed as vitiated by the many possible sources of error, yet
the statistics of the nitrogen collected by various crops could
not be explained in any such fashion. It has already been
mentioned that Boussingault made out a balance-sheet of
nitrogen supplied in manure and removed in crop during
different rotations ; he found that while in a rotation of wheat
and fallow alone the wheat contained rather less nitrogen than
was applied as manure, yet other rotations in which clover was
included, and particularly a five years' continuous cropping
with lucerne, gave a large surplus of nitrogen removed over
that supplied. Similar evidence was accumulated at Rotham-
sted and was made more cogent by the analysis of the soils,
which showed not only no decrease but an actual gain of
nitrogen during the period when the leguminous crop was
producing such large quantities of nitrogenous matter above
ground. Thus when the various crops were grown con-
tinuously with mineral manures* but without any supply of
combined nitrogen, the following average amounts of nitrogen
per acre were taken away : —

Table II. — Average Removal of Nitrogen per acre hy Crops
grown continuously vnth Mineral Ifanures only.

Nitrogen removed
per acre.

Wheat .
Barley .
Root 'Crops .
Beans .•
Clover .

'24 years

24 years .....

30 years

24 years, of which 2 fallow .
22 years, 6 crops only .

Lb.
22-1
22-4
16-4
45-5
39-8

In a comparison of the alternate wheat and fallow plots
with the adjacent plots continually under leguminous plants,

* The term mineral manures will be used throughout for mixtures of the
constituents found in the ash of plants, i.e., phosphates, sulphates and chlorides
of sodium, potassium, calcium and magnesium, but always excluding nitrogen
in any form.

FIELD EXPERIMENTS INDICATINC FIXATION l»

the following comparative figures were obtained ath>r l)()tli had
been under a similar treatment for many years.

Table III. — Nitrogen in Crop and Soil. Leguminous PhniU compared
until Mlieat and Falloic. Hoos Field.

Unmanured

Mineral Manures only, 80 ynars.

Wheat

and

Fallow

alternately.

Trifolium
repcns.

Metllotos
Icucantlia.

Me<llcago
Mtiva.

Average Annual Removal of Nitrogen, S years
(1878-S5) .......

Nitrogen per cent, in Surface Soil in 1SS5
Nitrogen as Nitric Acid in Soil and Subsoil to
the depth of 9 feet, lb. per acre, 1885

Lb.

12

0-1021

42

Lb.

33

0-1269

101

Lb.

71

0-ll.')l

79

Lb.

110

0-1219

17

In another experiment in Little Hoos Field, after five years'
cropping by cereals without any nitrogenous manure, in 1872 a
portion of the field in barley was sown with clover; in 1873
this portion carried a clover crop which was cut three times,
the other 23ortion which had not been sown with clover was
again cropped with barley. Determinations of the nitrogen
removed in 1873 showed 151 lb. in the clover crop and 37 lb.
per acre in the barley crop respectively. In the following
year (1874) barley was again sown over the whole area, but the
barley crop which followed clover took away nearly twice as
much nitrogen as that which followed barley, although this
had contained less than the corresponding clover. Yet an
analysis of the soil immediately after the 1873 crop had been
removed showed more nitrogen in the land where clover Iiad
been growing than where the barley had been growing, as
shown in Table IV. (p. 10), where all the results are summarised.

In yet another experiment, land which had previously
grown beans and then been fallow for five years was sown
with barley and clover in 1883, the clover being allowed to
stand in 1884 and 1885. At starting, the soil was analysed ;
the surface 9 inches contained on an average 2657 lb. per acre
of nitrogen, while of nitrogen as nitric acid the soil only con-

10 SOUECES OF THE NITROGEN OF VEGETATION

tained 25*7 lb. per acre down to a depth of 6 feet. As a
result of the three years' cropping with barley and clover, and
then with clover only, an average amount of 319*5 lb. of

Table IV. — Nitrogen accumulated hy Clover Crop.
Little Hoos Field.

Year, etc.

Lb. of Nitrogen per acre in
Crop removed.

Plot A.

Plot B.

1873

1874

Nitrogen per cent, in Soil at end of 1873 .

Barley, 37-3
Barley, 39-1

0-1416

Clover, 1.51 -3
Barley, 69-4

0-1566

nitrogen was removed, yet the soil contained, on analysis at
the end of the experiment, 2832 lb. of nitrogen per acre in the
top 9 inches, or a gain of 175 lb. per acre in the three years ;
making a total, with the crop removed, of nearly 500 lb. of
nitrogen per acre to be accounted for.

Experiments like these, coupled with the long experience of
practical farmers^' of the beneficial effects of the growth of
clover and other leguminous plants on the succeeding crops
in a rotation, led many men to think that there still might
be fixation of nitrogen by leguminous plants, in spite of the
apparent exclusion of any such hypothesis by Pugh's experi-
ments at Rothamsted. Voelcker, in England, when discussing
the power of a clover crop to accumulate nitrogen, expressed
the opinion that the atmosphere furnishes nitrogenous food to
that plant ; in France it was maintained by Ville ; Berthelot
also brought evidence to show that the soil itself, by the aid
of microscopic vegetation, assimilated some free nitrogen.

* Vergil, Georgics I., 73 : —

"Aut ibi flava seres, mutato sidere, farra

Unde pi-ius laetum siliqua quassante legumen
Aut tenuis foetus viciae, tristisque lupini

Sustuleris fragiles ealamos, sylvamque sonantem."
" Or, under a changed star, you will then sow the golden wheat, whence
earlier you took away the bean, luxuriant M'ith quivering pod, or the growth of
the slender vetch, and the fragile stalks and rustling grove of the bitter
lupin."

EXPERIMENTS OF HELLIUEGEI. AM ) \\ I l.I- Ainil 1 1

Lawes and Gilbert themselves were disposed to look t.. tlir
subsoil as the source of this excessive amount of nitro^^en, and
were conducting experiments to ascertain whether the widely
ranging roots of the leguminous plants, in virtue of their hij^^hly
acid sap, did not possess some special power of attackinLi the
dormant nitrogenous compounds in the subsoil, wlicn the
clearing up of the whole subject came with the publication, in
1886, of the researches of Hellriegel and Wilfarth. 'IMnvsc;
investigators found that when plants w^ere grown in sand and
. were fed with nutrient solutions, the Graminea\ the Crucifera'.
the Chenopodiacea3, the Polygoneoe, grew almost proportionally
to the amount of combined nitrogen supplied ; and, if this were
absent, nitrogen starvation set in as soon as the nitrogen of the
seed was exhausted. With the Leguminosai, however, a plant
was observed sometimes to recover from the stage of nitrogen
starvation and begin a luxurious grow^th which lasted until
maturity, though no combined nitrogen was supplied. In such
cases the root of the plant was always found to be set with the
little nodules characteristic of the roots of leguminous plants
when growing under natural conditions. Further experiments
were made in which the plants w^ere grown in sterile sand, Itut
as soon as the stage of nitrogen hunger was reached, a small
portion of a watery extract of ordinary cultivated soil was
added ; whereupon the plants receiving the extract recovered
from their nitrogen starvation and grew to maturity, assimilat-
ing consideraljle quantities of nitrogen. The renewed growth and
the assimilation of nitrogen were always found to be attendant
upon the production of nodules on the roots. The nodules
were found to be full of bacteria, to which the name of
Bacilhis radicicola has been given; they could only l)e pro-
duced ])y previous infection, either ])y an extract of the
crushed nodules or of a cultivated soil, in some cases
(lupins, serradella) only by soil which had i)reviously carried
the same crop.

Gilbert had been present at themceting of th(> Naturforsclicr
Versamndung at Halle when Hellriegel and AVilfarlh read tlu-ir

12 SOURCES OF THE NITEOGEN OF VEGETATION

paper, and on his return to England experiments were
immediately begun at Rothamsted to check their results.

A series of small pits were built up of slate slabs out of
doors, and these were filled with either soil or washed sand and
then sown with various leguminous plants, which were after-
wards inoculated or not as desired. The growth was cut away
for the determination of dry matter produced, and the nitrogen
collected ; afterwards the roots were washed out from the soil
or sand for the examination of the development of the nodules.

A more rigorous set of experiments were carried out in
glazed stoneware pots in the glasshouse, and some of the
results obtained are set out in Table V. (p. 13).

The table consists of a balance-sheet for the nitrogen only,
in which the nitrogen supplied, either in the seed, in the sand
or soil used, in the extract employed for inoculation, or in a
few cases in the manure, is compared with that recovered in the
soil or the plant. The first horizontal line for each plant shows
the results obtained when there was no inoculation and the
plant grew with simply the store of nitrogen present in the seed
and what it could obtain from the soil ; the second and third
lines show the results of inoculation, both seed and soil being
otherwise similar ; the fourth line shows the result when
the seeds were sown in ordinary soil.

It is needless to elaborate the results thus obtained ; they
confirmed, as has repeatedly been done since, the conclusions
of Hellriegel and Wilfarth, and showed that the leguminous
plants possess the power of " fixing " nitrogen under ordinary
conditions of field culture by the agency of the bacteria living
in the nodules on their roots.

The very rigour with which the earlier laboratory experi-
ments, like those at Rothamsted on peas and beans in 1857-8,
had been carried out, had prevented any fixation of nitrogen
by excluding all possibility of inoculation.

The interpretation of the increased stock of nitrogen
obtained with leguminous crops, which, as instanced above,
had hitherto been so difficult of explanation, at once became

FIXATION BY T.EGr:\ir\OT\^ IM.ANTS

i:;

apparent, and tlie long controversy as to the somri's of
nitrogen in vegetation was thus closed by a vindication of
both schools of opinion.

Table V.

Plant.

d
in

1

"5^
§1

Nitrogen.

At Beginning.

At End.

H

5 .

C3 J4_

In Soil,
Soil-

In Sand

In

Extract,

Total.

or

Pro-

Total.

on

and

Soil.

duce.

Z 8 —

Seeds.

o

U

Annuals.

Wks.

Grams.

Grams.

Grams.

Grams.

Grams.

Grams.

Peas . 1

1

15

0-0265

0-0265

0-0090

0-01-25

0-0215

-0-0050

2

15

0-0273

0-0273

0-0108

0-1475

0-1583

+ 0-1310

ii-8

3

15

0-0270

0-0270

0-0162

0-1S-J5

0-1987

+ 0-1717

14-6

4

15

6-9422

6-9422

6-8817

0-2075

7-0892

+ 0-1470

Vetches . \

9

15

0-0137

0-0137

0-0184

0-0065

0-0249

+ 0-0112

10

15

0-0141

0-0141

0-0260

0-1651

0-1911

+ 0-1770

25-4

11

15

0-0139

0-0139

0-0230

0-1868

0--2098

+ 0-1959

28-7

12

15

7-5966

7-5966

7-3052

0-2087

7-5139

-0-0827

f

17

21

0-0375

0-0375

0-0551

0-0153

0-0704

+ 0-0329

YeUow J

]8

21

0-0378

0-0378

0-0523

0-4980

0-5503

+ 0-5125

32-5

Lupins 1

19

21

0-0380

0-0380

0-0594

0-4fil4

0-5508

+ 0-5128

32-1

I

20

21

fi-0408

6-0408

6-7883

0-2146

7-0029

+ 0-9621

...

P

lants of I

..onger Life.

r

5

77

0-0082

0-0082

0-0273

0-2094

0-2367:

+ 0-2285

Red Clover -

6

77

0 0089

0-0089

0-0312

0-2885

0-3197

+ 0-3108

7

77

0-0083

0-2381*

0-0323

0-2986

0-3309t

+ 0-0930

I

8

77

6-4274

6-4274

6-3198

1-7288

8-0486

+ 1-6212

r

21

68

0-0231

0-0231

0-0-200

0-0030

0-0230

-0-0001

Lucerne . -

22

75

0-0247

0-0247

00514

0-3589

0-4103

+ 0-3856

119-6

23

76

0-02.36

0-3278*

0-0371

0-4307

0-49l7t

+ 0-1639

143-5

24

76

17-4983

17-4983

16-8141

1-2345

18-0486

+ 0-5503

33

131

0-0110

0-0110

0-0148

0-0016

0-0164

+ 0 0054

White
Clover

34

131

0-0119

0-0119

0-0575

0-7098

0-7673

+ 0-7554

443-6

35

131

0-0120

0-0120

0-0482

0-54()5

0-5947

+ 0-5827

341 -C

36

131

5-3423

3-4726

8-8149

37

131

0-0081

0-6746*

0-0459

0-4430

0-6754t

+ 0-0008

• Including Calcium Nitrate, added as follows :— Pot 7, 0"2298 gram. ; Pot 23, 0-8042 gram. ; and Pot 87,

0-66C5 gram.
t Including also the following amounts of Nitrate recovered :— Pot 7, nono ; Pot 23, 00-239 gram. ; and

Pot 37, 01865 gram. t Accidentally inoculated.

Lawes and Gilbert were perfectly correct in maintaining:
that the ordinary green plant has no power of fixing nitrogen,
but the whole class of leguminous plants form an exception

14 SOURCES OF THE NITROGEN OF VEGETATION

when grown under ordinary field conditions, for then they
become collectors of atmospheric nitrogen in virtue of the
nodule bacteria with which they are associated.

Without doubt, Hellriegel and Wilfarth's discovery came as
somewhat of a disappointment to the Rothamsted investi-
gators ; although the statistics they had accumulated form to
this day the best demonstration of its truth on a field scale,
still they had so long and so rightly upheld the necessity of
combined nitrogen to the nutrition of the plant, that to have
to concede the point in issue, as far even as the leguminous
plants were concerned, could not have been welcome. Indeed,
Liebig's idea having thus triumphed in the one special case,
his most sweeping generalisation was justified — that it is the
function of plants to manufacture the complex nitrogen com-
pounds from elementary nitrogen, just as they do the carbon
compounds from the carbon dioxide in the atmosphere. These
complex nitrogen and carbon compounds are necessary to
animals, which derive their vital heat and energy by breaking
them down again into the simpler materials used by the
plant. In this eternal cycle Liebig had placed nitrogen
alongside of carbon, and though the statement may be true
only of the particular leguminous plants, it is true, in a
general sense, in that these plants (or rather the bacteria
with which they are associated) are probably the original
sources of the world's stock of combined nitrogen.

References
" Agricultural Chemistry, especially in relation to the Mineral Theory of

Baron Liebig." J.R.A.S., 12 (1851), 1. R. Mem., Vol. I., No. 5.
"On the Sources of the Nitrogen of Vegetation." Phil. Trans., 151 (1861),

431. B. Mem., Vol. I. (4to), No. 1.
"On the Sources of the Nitrogen of Vegetation." Jour. Chem. Soc, 16

(1863), 100. R Mem., Vol. III., No. 1.
"Sketch of the Progress of Agricultural Chemistry." Rep. Brit. Assn. for

1880. R. Mem., Vol. V., No. 13.
" On the Present Position of the Question of the Sources of Nitrogen of Vege-
tation." Phil. Trans., 180, B (1889), 1. R. Mem., Vol. I. (4to), No. 2.
" Results of Experiments at Rothamsted on the Question of the Fixation

of Free Nitrogen." Agricultural Students' Gazette, New Series, 5,

1890-91. R. Mem., Vol. VII., No. 1.

CHAPTER II

METEOROLOGICAL OBSERVATIONS

The rainfall has been measured at Eotliamsted since Fel)ruary
1853 in a 5-inch funnel gauge and in a rectangular gauge
(7 feet 3'12 inches by 6 feet), having an area of one-thousandth
acre.

In addition to these gauges, an 8-inch Board of Trade
gauge has been employed since January 1881.

The ground on which the gauges are situated is 420 feet
above the sea-level ; it adjoins the Barn Field (continuous
root crops), and is at a slightly lower level than the l^roadbalk
and Hoos fields.

The amount of water percolating through bare soil has
been measured since 1870 by means of three drain-gauges,
each having an area of one-thousandth acre. These were
constructed by undermining the soil at the desired depths — 20,
40, and 60 inches respectively — and inserting perforated iron
plates to support the soil. When this was completed, trenches
were cut round the blocks of soil, and these were then
isolated by means of brick and cement walls. The external
soil was then returned. The percolating water falls on to
zinc funnels, from which it passes to the measuring cylinders.

Barometric and temperature records have been kept since
1873, and since July 1891 daily observations of tlie ])right
sunshine have been made by means of a Campbell-Stokes
recorder.

The average yearly rainfall as measured at Kothamsted
during the last fifty-one years, 1853-1903, is 28-Jl inches.
This is higher than the average in Hertfordshire (26'33).

16

METEOEOLOGICAL OBSERVATIONS

As regards years of exceptional rainfall, either low or high,
the records show five years in which the rainfall was less than
21 inches — the lowest was 18-56 in 1864 — and three years in
which it was more than 35 inches — the highest recorded being
38-69 inches in 1903. More prolonged periods of wet occurred
in 1875 and 1876, and in 1879 and 1880, when 69-34 and 70-0
inches fell in two consecutive years. The nine-year period,
1875 to 1883 inclusive, was an exceptionally wet one, each

Ram
Inches

Jan. Feb. Mar. April May June July Au_

Fig. 1.— Rainfall : Average of 51 years (1853-1903).

Sun.shine : Average of 11 years (1892, 1893, and 1895-1903).
Mean Temperature : Average of 26 years (1878-1903).

individual year giving a fail of more than 30 inches, and
averaging 33-54 inches over the nine years. Exceptional
periods of drought extending over two years are less frequent,
and the lowest averages of two consecutive years are 21-7 in
1863 and 1864, 221 in 1901 and 1902, and 23-2 in 1870 and
1871. The longest consecutive period of years showing under
average rainfall was the five years 1867-1871, when the falls
ranged from 21-3 to 26-9 inches, and averaged over the five
years 24-84 inches.

In Fig. 1 curves are set out showing the average rainfall,

KAINFALL AND SUNSHINE IJKCOIM)

mean teiiiperatinv, niid duralion of sii!isliim> tVom monili to
montli.

The greatest average rainfall (see Table \'[.) is in October,
3*16 inches, followed by '2\u in November, while in December
and Jannary the amonnts decline to 231 and '21]') inclies
respectively. From February to August inclusive there is a
gradual rise from 178 to 2'G7 inches, but it declines to 2')\
inches in September.

Table VL—

Meteorological Summary.

Rainfall.

Bright Si

.nshiiie.
11 years

Temperature.

Average, 51 3

•ears

Average,

Average, 20 years

(1853-1903).

(1892

1893, and 1895-1903).

(1878-1908).

Total
Fall.

Rainy Days.

Per

cent.

Days with 01
hour, or more.

Means.

1-1

Actual.

Per
cent.

Total.

Actual.

Per

cent.

Mini-
mum.

Maxi-
mum.

m

Inches.

Xo.

Iluurs.

Xo.

F.

'F.

'F.

January .

2-3.'5

16

52

46-4

19

16

51

31-5

41-6

36-6

February

1-78

13

47

69-2

25

19

60

32-5

43-9

38-2

March .

1-81

13

42

114-6

32

26

85

33-5

48-3

40-9

AprU .
May .

1-86

13

43

170-3

42

27

91

36-8

54-2

45-5

2-22

13

42

199-9

41

29

93

-12-2

60-2

51-2

June

2-39

12

41

201-9

41

27

91

48-4

66-6

57-5

July .

2-58

13

43

217-5

44

29

95

51-7

69-7

60-7

August .

2-67

14

44

201-1

45

30

96

51-4

68-5

59-9

September

2-51

13

44

158-3

43

27

02

47-6

64-1

55-9

October .

3-16

18

57

106-1

32

25

79

41-1

54-8

48-0

November

2-57

17

55

57-0

22

18

58

36-8

48-3

42-6

December
Whole year

2-31

16

52

43-2

18

16

51

32-4

42-9

37-7

28-21

171

47

1585-5

36

289

79

40-5

55-3

47-9

The average number of rainy days (with 0*01 incli or more)
does not vary very much ; the greatest is, like the rainftill,
in October, and the lowest in June. The total number of
rainy days in an average year amounts to less than 50 per cent.

The maximum amount of sunshine occurs in July (217")
hours, or 44 per cent.). There is a slight decrease in August
followed by a very rapid decrease until November. The
minimum (43'2 hours, or 18 per cent.) is reached in December,
after which there is a continuous increase until the maxinuun in
July. As regards percentages of possilJe sunshine, the highest

18 METEOROLOGICAL OBSERVATIONS

(45 per cent.) occurs in August, which is closely followed by
July, September, and April, with 44, 43, and 42 per cent,
respectively, and May and June with 41 per cent. Of the
remaining months, March and October (32 per cent.) have the
highest, and January and December the lowest percentages
(19 and 18) of possible sunshine. In the whole year we have
an average amount of 1586 hours, or not much more than a
third of the actual sunshine above the level of the clouds.

The Amounts of Nitrogen as Ammonia and Nitrates, Chlorine,
and Sulphuric Acid, in the Rain-ivater at Rothamsted.

At the time of the commencement of the Rothamsted
Experiments very little was known as to the amounts of com-
bined nitrogen and other substances present in rain-water.

The presence of ammonia, both in the atmosphere and in
rain-water, was well known, but, owing to the imperfections of
the methods of analysis then available, somewhat exaggerated
ideas prevailed as to the amount. Liebig considered that the
atmosphere was able to furnish the average crop with sufficient
ammonia for its development, hence followed his celebrated
" mineral " theory that to add to the soil the ash constituents
of a crop would be a sufficient manuring. As this opinion of
Liebig's was strongly contested by the Rothamsted investi-
gators it was necessary to make accurate measures of the
combined nitrogen brought by the rain.

The earliest analyses of Rothamsted rain were made in
1853-4, and were restricted to determinations of the nitrogen
present as ammonia. These were followed in 1855-6 by
determinations of ammonia and nitric nitrogen made by
Professor Way. No further analyses were made until 1877,
when monthly determinations of ammonia were recommenced.
These were continued with some interruptions until December
1885, and again resumed in December 1887 and February
1888, since which time ammonia has been regularly determined
each month. Nitric acid has been determined uninterruptedly

COMBINED NITROCxEN IN KAIN 1<»

since September 188G (for the first few montlis by Scliloesing's
method, antl subsequently by Williams' zinc-copper couple
method).

In addition to the analyses of monthly samples of rain, a
large number of single samples have been analysed at
Rothamsted, as well as about eighty samples by the late Sir
E. Frankland.*

Table VI I. — Nitrogen and Chlorine in Ilothamstcd Rain. Munfhly
Averages, 15 years (1889-1903).

1

1

Nitrogen.

Chlorine.

Per million.

Per acre.

Per cent, of
Total.

.1
1

1

.2

S

<

1,1

< S
1

111

3
^

4

< E

E
•«3

111

<

j .

January.
February
March .
April .
:May
June

July . .
August .
September
October .
November
! December

Inches.
1-951
1-710
2-036
1-516
2-028
2-185
2-631
2-959
2-098
3-407
2-505
2-590

0-401
0-424
0-410
0-571
0-516
0-520
0-464
0-476
0-535
0-335
0-411
0-379

0-168
0-209
0-204
0-227
0-200
0-216
0-175
0-170
0-213
0-160
0-189
0-195

Lb.

0-177
0-164
0-189
0-196
0-237
0-257
0-276
0-319
0-254
0-258
0-233
0-222

Lb.
0-074
0-081
0-094
0-078
0-092
0-107
0-104
0-114
0-101
0-123
0-107
0-114

Lb.
0-251
0-245
0-283
0-274
0-329
0-364
0-380
0-433
0-.3.55
0-381
0-340
0-336

70-5
66-9
66-8
71-5
72-0
70-6
72-6
73-7
71-5
67-7
68-5
66-1

29-5
33-1
33-2
28-5
28-0
29-4
27-4
26-3
28-5
32-3
31-5
33-9

4-17
3-33
3-47
2-71
2-05
1-46
1-09
1-33
1-92
2-32
3-00
3-60

Lb.
1-84
1-29
1-60
0-93
0-94
0-72
0-65
0-89
0-91
1-79
1-70
2-11

Jan. to April .
May to Aug. .
Sept to Dec.

7-213

9-803

10-600

0-445
0-491
0-403

0-200
0-188
0-186

0-726
1089
0-967

0-327
0-417
0-445

1-053
1-506
1-412

68-9
72-3
68-5

31-1
27-7
31-5

3-47
1-44

2-71

5-66
3-20
6-51

Whole year

27-616

0-445

0-190

2-782

1-189

3-971

70-1

29-9

2-46 15-37

It will be convenient, for the purpose of sunimari.sing the
results relating to nitrogen, to confine attention to the fifteen
years 1889-1003, as during that period regular determinations
both of ammonia and nitrates are availa])le.

In Table VII. will 1)0 found the average monthly I'ainfall
for the period in question, the amount of nitrogen as ammonia
and as nitrate (or nitrite), also the chlorine, all expressed both

* See the Sixth Report of the Rivers Pollution Commission, 1874.

20 METEOROLOGICAL OBSERVATIONS

as parts per million and as lb. per acre. Other columns show
the relative proportions of the two combinations of nitrogen.

Reference to the table will show that the average amomit
of nitrogen in the two forms is 3 "97 lb. per acre per annum,
and that most of the nitrogen is in the form of ammonia,
the nitric nitrogen representing only three-tenths of the whole.
The monthly variations show little regularity either in the
total nitrogen or in the relation of ammonia to nitrates. It is,
however, of interest to note that in the period April to
September, during which the rainfall is less than half the total
for the year, the rain contains more nitrogen than in the six
months October to March, and that the amount of nitric
nitrogen is nearly the same in both periods, the excess in the
warmer periods being mainly due to ammonia.

When we compare the yearly amounts of nitrogen
in the rain, the variations are not found to be great, and
seem to have little if any relation to the rainfall. The highest
result corresponds with the highest rainfall (4-84 lb. in
1903); but the minimum result (3-30 lb.) was obtained
in 1890, when the rainfall amounted to 2478 inches. With
one of the lowest rainfalls of the period, however (20 '967 inches
in 1902), we get nearly the maximum amount of nitrogen, viz.,
4-673 lb.

It must be borne in mind that the nitrogen in the forms of
ammonia and nitrates does not represent the whole amount
suppHed to the soil. Frankland's results showed that the
rain contains besides the nitrogen in these forms a certain
amount of organic nitrogen, equal to about one-third of the
nitrogen as ammonia and nitrates. So that we may consider
that the average annual rainfall at Rothamsted contains 3 "97
plus 1 "3, or about 5 lb. of total nitrogen per acre.

The amount of chlorine in the monthly samples of rain has
been determined at Rothamsted since 1877. The average
amount over the whole year is 2 '46 per million. The minimum
amount is in the July rain (1'09 per million), and the
maximum (417 per milHon) in the January rain. The

CHLORIDES IX IJATX

21

amount falls and rises in the intermediate months with
considerable regularity, the only l)reak occurring in tlie
March rain, which contains more c^hlorinc than the rain
ftilling in February. The total chlorine is equivalent to 2;')-:} lb
of common salt per acre per annum. Of this amount, 170 11).
is contributed by the rain falling from October to March, and

Table VJ II. — Comparison of Maxiynum and Minimum
Precipitation of Rain and Chlorine.

Rainfall.

Chlorine.

Maximum Rainfall (1903)
Minimum Rainfall (1S9S)

Maximum Chlorine (1903)
Minimum Chlorine (1890)

Inches.
38-69
20-49

38-69
24-78

Lb. per acre.
19-99
16-33

19-99
10-21

the rest (8-3 lb.) by the spring and summer rains (April to
September). This difference is all the more striking as
the rainfall of the two six-monthly periods is almost the same.

The yearly amounts of chlorine per acre vary considerably,
and the variations depend more on the distribution of the
rainfall during the year than on the total fall.

No recent determinations of sulphuric acid in rain-water

Table IX. — Sulphuric Acid and Chlorine in Rain-water <ollertcd at
Rothamsted.

1881-7.

Rainfall.

Per million.

Per

acre.

BO,

to lb.

CI.

SO,.

CI.

SO,.

April-September .
October-March .

Whole year .

Inches. .

13-90

16-05

1-31
2-89

2-77
2-39

Lb.

4-11

10-51

Lb.
S-71
8-70

2-12
0-.S3

29-95

2-16

2-57

14-62

17-41

1-19

have been made at Rothamsted, but a summary of the results
obtained in 1881-7 is given here to complete the record.

Keference to the Table {IX. ) will show that the rain

22 METEOROLOGICAL OBSERVATIONS

contains on the average 2*57 per million of sulphuric acid
(as SO3), and that the total annual amount per acre is
17*41 lb. The most noteworthy result is the close agreement
between the amounts furnished by the summer and winter
rain, especially in view of the great variations in the chlorine.

In conclusion, it may be pointed out that the rain falling
at Rothamsted contributes to the soil enough chlorine and
sulphimc acid to meet the requirements of most crops.

Proportion of Rainfall 'percolating through Bare Soil.

Alongside the large rain gauge, three percolation or drain
gauges were constructed in 1870. Portions of the undisturbed
soil, each one-thousandth of an acre in area, were isolated
from the surrounding soil by digging trenches and building
brick and cement walls round the blocks of soil thus exposed.
The blocks were then undermined, and eventually carried
upon bars and plates of iron perforated to enable the percolat-
ing water to find its way into the collecting funnel beneath.
Thus in the end three blocks of undisturbed soil were
obtained, each one-thousandth acre in area, 20, 40, and 60
inches in thickness respectively, entirely isolated from the
surrounding soil, and the rain-water percolating through each
block is collected separately and measured like the rainfall.

Table X. shows the average results obtained during the
thirty-four years 1871-1904.

It will be seen that the three different thicknesses of soil
yield practically the same results, it being difficult to account for
the small but constant differences which occur. On the average,
about half the annual rainfall percolates through the gauges,
and about one-half is evaporated. It should be borne in mind,
however, that the surface of the soil in these gauges is kept
free from vegetation of all kinds, so that there is no drying
effect due to the crop. Again, as communication between
the subsoil and the soil of the gauges is cut off, all capillary
movements of water, both downwards during rain and back
again during periods of drought, are stopped at a certain point.

rEoroirrroN ov kaixfai.i

23

thus affecting botli percolation and eva|)orati(>n Ity unknown
amounts.

TaI?LK X. — IxainfaU and Dr((i)iai/c at Ilothnmstril.

Percolation through

Diflerence Bvaporatod

Rainfall

Soil.

(orlloUinodbySoll).

(iTsWth
Acre

20 in.

40 in.

00 in.

20 in. 40 in.

60 In.

deep.

deep.

deep.

deep. deep.

de«.p.

Average for each

Month, 34 years

(1871 to 1904).

Inches.

Inches.

Inches.

Inches.

Inches.

Inches.

Inchoa.

January ....

2-32

1-82

2-0-.

1-96

0-50

0-27

0-3G

Febniarv

1-97

1-42

1-57

1-48

0-55

0-40

0-49

March

1-S3

0-87

1-02

0-95

0-96

0-81

0-88

April

1-89

0-50

0-57

0-53

1-39

1-32

1-36

May

2-11

0-49

0-55

0-50

1-62

1-56

1-61

June

2-36

0-63

0-65

0-62

1-73

1-71

1-74

July

2-73

0-69

0-70

0-65

2-04

2-03

2-08

August .

2-67

0-62

0-62

0-58

2-05

2-05

2-09

September

2-52

0*88

0-83

0-76

1-64

1-69

1-76

October .

3-20

1-85

1-84

1-68

1-35

1-36

1-52

November

2-86

2-11

2-18

2-04

0-75

0-68

0-82

December

2-52

2-02

2-15

2-04

0-50

0-37

0-48

Mean Total per year .

28-98

13-90

14-73

13-79

15-08

14-25

15-19

Results for Ma

xiraum and Minimum llainfall.

Maximum (1903) . . 38-69

23-48

23-60

24-23

15-21 15-09

14-46

Minimum (1S98) . . 20-49

7-32

7-90

7-69

13-17 12-59

12-80

References

45 (1870).
A'. Mi;,,.,

" On the Amounts of and Methods of Estimating Ammonia and Nitric .Veld

in Rain-water." Rep. Brit. Assn., 1851. R. Mem., Vol. I., No. 6.
•'Effects of the Drought of 1870 on some of the Experimental Crops at

Rothamsted." J.R.A.S., 32 (1871), 91. U. Mn„., Vol. III., No. 11.
"On Rainfall, Evaporation, and Percolation." I'roc. In.sl. Civ. Kn^

R. Mem., Vol. V., No. .5.
"Our Climate and our Wheat Crops." ././.'.. /..S'., 41 (ISSO), 17;?.

Vol. v.. No. 11.
" On the Amount and Composition of the Hain and Drainage Waters."

42 (1881), 241 and 311 ; 43 (1882), 1. R. Mem., Vol. V., N(
-' New Determinations of Ammonia, Chlorine, and Sulphuric Acid in

water." J.R.A.S., 44 (188.3), 313. R. Me,,,., Vol. V., No. 21.
"The Amount of Nitric Acid in the Rain-water at Rothamsted." 7V«;/.s

C/iem. Soc., 55 (1889), .^37.
" Observatitms on Rainfall, Percolation, and Kvajxn-atiun ;it R.ithamsted.'

Proc. I„st. Civ. Eng., 105 (1891). R. Mem., WA. Nil., No. 2.

J.R
18.
the R;

.i.!S.

CHAPTER III

THE COMPOSITION OF THE ROTHAMSTED SOIL

The Rothamsted soil was described by Lawes in the first paper
he contributed to the Journal of the Royal Agricultural Society
in 1847, as follows : — " The soil upon which my experiments
were tried consists of rather a heavy loam resting upon chalk,
capable of producing good wheat when well manured ; not
sufficiently heavy for beans, but too heavy for good turnips or
barley. The average produce of wheat in the neighbourhood
is said to be less than 22 bushels per acre, vdieat being grown
once in five years. The rent varies from 20s. to 26s. per acre,
tithe free."

The geological character of the Rothamsted soils has been
thus described by Mr H. B. Woodward, F.R.S. : "The geology
of the Rothamsted estate is comparatively simple. Chalk
forms the foundation of the entire area, but it is exposed only
on the slopes. The plateau ground is covered with a very
mixed deposit of clay-with-flints, with remnants of the mottled
clays, sands, and pebble-beds of the Reading series, and also of
remnants of drift gravel. The low grounds are occupied by
valley gravel."

" The experimenta^l fields belonging to the Lawes Agricul-
tural Trust are entirely on the mixed deposit of clay-with-
flints, etc."

"The chalk, which is extensively 'piped,' appears here and
there in irregular pinnacles near the surface. It is usually hned
with stiff red or dark brown clay-with-flints, the joints in

ORIGIN OF ROTHAMSTET) SOU.

the clay, and also the Hints, being l)la('laMR'(l liy manganese-
oxide. Masses of this stift'clay-with-llints form the sn))soil in
places; elsewhere light sands or red loamy sands witli or
withont black Hint pebbles, or masses of pebbles alone, foi-ni
the immediate subsoil ; again, grey or mottled clay or loam
with occasional pebbles or free from stones, or with a gravelly
pocket here and there, extends for some distance, immediately
beneath the soil. These accunudations occur in irregular
juxtaposition owing to the piped surface of the chalk, and in
places there is a kind of marl formed on the slopes by the
weathered rubbly chalk mixed with earth."

" Covering these subsoils there is a soil of grey Hinty or
pebbly loam, 10 inches or more in thickness, and varying in
character according to the number of stones in it ; in some
cases rough and unworn flints prevail, elsewhere there is an
admixture of pebbles ; and over some areas the soil consists of
loam with comparatively few stones. In all cases, excepting
on the chalk slopes and in the valley bottom, the soil is to be
regarded as a heavy mixed soil, for the subsoil is in the main
a hea^^ clay ; and were it not for the fact that the chalk here
and there approaches very near to the surface of the higher
grounds, the land would be much wetter after rain than is the
case. These underground pinnacles of chalk, and the pockets
of sand and gravel, act as dumbwells for the surface
drainage."

Notwithstanding the irregularity of the subsoil, the
agricultural character of the soil is fairly uniform all over the
estate ; some fields work rather more heavily than others, and
the proportion of stones lying on the surface varies somewhat,
but these differences are comparatively unimportant. The soil
passes into the subsoil without any sharp line of distinction,
and the distribution of flints in the subs(jil is very irregular,
while the solid chalk is reachod at depths varying between 8
and 12 feet.

The following Table (XI.) shows the mean results obtained
for the weight per cubic foot and the weight per acre of stones

26

COMPOSITION OF EOTHAMSTED SOIL

and fine earth for successive layers 9 inches thick, down to
depth of 3 feet, on each of the chief experimental fields :—

Table XI.

Broad balk
Field.

Hoos
Field.

Agdell
Field.

Barn

Field.

Average.

Average Weights of Fine Dry Soil per acre.

First 9 inches
Second 9 inches .
Third 9 inches .
Fourth 9 inches .

Lb.
2,559,000
2,592,000
2,815,000
2,886,000

Lb.
2,593,000
2,721,000
2,891,000
3,048,000

Lb.
2,348,000
2,448,000
2,533,000
2,442,000

Lb.
2,321,000
2,673,000
2,651,000

Lb.
2,455,000
2,609,000
2,722,000
2,792,000

Average Weights of Stones per acre. 1

First 9 inches
Second 9 inches .
Third 9 inches .
Fourth 9 inches .

498,000
443,000
213,000
164,000

481,000
346,000
238,000
170,000

837,000
480,000
363,000
477,000

769,000
530,000
415,000

646,000
450,000
307,000
270,000

Weight per cubic foot of Fine Dry Soil and Stones.

First 9 inches
Second 9 inches .
Third 9 inches .
Fourth 9 inches .

93-6
92-9
92-7
93-4

94-1
93-9

95-8
98-5

97-5
89-6
88-6
89-4

94-6
98-0
93-9

94-9
93-6
92-7
93-7

The mechanical analyses set out in Table XII. show that
the Eothamsted soil is fairly uniform in the diff'erent fields, and

Table XII. — Mechanical Analysis of Bothamsted Soils.

First 9 inches.

Second
9 inches.

Third
9 inches.

Broad-
balk.

Hoos
Field.

Barn
Field.

Broad-
balk.

Broad-
balk.

Fine Gravel, 3 to 1 ram.
Coarse Sand, 1 to 0-2 mm. ,
Fine Sand, 0-2 to 0-04 mm. .
Coarse Silt, 0-04 to O'Ol mm.
FineSilt, 0-01 to 0-002 mm. .
Clay, less than 0-002 mm.
Carbonate of Lime, Loss on Solu-
tion, etc

Hygroscopic INIoisture .

Per cent.

1-9

6-2
21-4
32-5
13-8
17-6

4-2
2-2

Per cent.
2-0
6-8
19-5
28-9
15-5
18-8

2-5

Per cent.

3-1

5-9
19-7
26-0
13-1
25-6

3-7

2-8

Per cent.

1-7

4-3
15-8
24-0
16-7
28-7

3-8

Per cent.

0-5

2-5
13-2
18-0
13-8
40-0

5-3

consists essentially of a heavy loam containing little coarse sand

CHEMICAL ANALYSES

27

or grit, but a consideraMe amount of fine sand and silt and a
large body of clay. In consequence, the soil has to be worked
with care, becoming very sticky and drvinL; to impracticable
clods if moved when w^et. It "runs together" if heavy i-ain
falls after a tilth has been established, and then dries with a
hard, unkindly surface, these difhculties being nuich exaggerated
on the plots which have been farmed for a long time without
any supply of organic matter in the manures.

The chemical analysis of the Rothamsted soils differs very
much from plot to plot according to the long-continued manu-
rial treatment which has been given to each plot. But every-
thing points to the fact that the soil was of an ordinary type
when the experiments began, certainly no richer in dormant
plant food than the majority of fairly heavy soils in this country.

The following table gives the results of analyses (made by
Dr B. Dyer as regards the mineral constituents) of samples
drawn from the Broadbalk wdieat soils in 1893 : —

Table XIII.

Soil dried at 100 C.

First 9 inches.

Second 0 inches.

Third 9 inches.

Plot 3.

Plot 2.

Plot 3.

Plot 2.

Plot 8.

Plot 2.

Un-

Farmyard

Un-

Farmyard

Un-

Farmyard

manured.

Manure.

manured.

Manure.

manured.

Manure.

Per cent.

Per cent.

Per cent.

Per cent.

Per cent.

Per cent.

Loss on Ignition .

4-20

6-76

4-61

5-11

Containing Carbon .

0-888

2-230

0-565

0-748

0-483

0-492

Containing Nitrogen .

0-099

0-221

0-073

0-077

0-065

0-066

Soda* . . . .

0-058

0-138

0-090

0-132

0-106

0-111

Potash*.

0-274

0-430

0-446

0-524

0-618

0-661

Potash, sohible in 1 per

cent. Citric Acid .

0-0032

0-0384

0-0060

0-0276

0-0072

0-0 1-28

Magnesia*

0-360

0-3-20

0-120

0-340

0-400

0-4-20

Lime * . . . .

2-486

2-665

0-460

0-616

0-538

0-504

Alumina*

4-486

4-805

7-107

6-829

11-623

10-477

Oxide of Iron *

3-400

3-600

5-200

4-800

7-200

6-400

Phosphoric Acid * .

0-114 -

0-215

0-113

0-111

0-097

0-083

Phosphoric Acid, soluble

in 1 per cent. Citric Acid
Sulphuric Acid t .
Carbonic Acid f .

0-0078

0-0560

0-0045

0-0094

0-0025

0-0034

0-048

0-055

0-011

0-041

0-038

0-031

1-300

1-400

0-050

0-JOO

0-100

0-050

Undissolved Matter* .

83-700

80 -800

81-480

82-520

73-220

76-120

• Determined in the solution obtained by treating the Ignited soil with strong Uyilrochlorlc Acid,
t Determined in the unignited soil.

The most notable feature in the Rothamsted soil is the
amount of calcium carbonate in the surface layer ; analyses of

28 COMPOSITION OF EOTHAMSTED SOIL

the earliest samples available (1856) show more than 5 per
cent, in the surface soil of Broadbalk field. This amount is
always being reduced by the action of the rain washing it away
as calcium bicarbonate ; it is still more rapidly reduced by the
action of many of the manures applied, particularly by the
ammonium salts, so that at the present time there is only about
3 per cent, present on any of the plots. In other fields less is
to be found, practically none at all in the soil of some parts of
Agdell and of the Park. The subsoil below the depth of 9
inches also contains little or no calcium carbonate, and this
fact together with the varying proportion in the surface soil
indicate that the original soil was almost devoid of calcium
carbonate, and that the quantity still found in the surface soil
has all been applied artificially. We read, indeed, that the
chief form of manuring known to Hertfordshire farmers in
the eighteenth century consisted in digging pits through the
clay soil until the chalk was reached, extracting chalk and
spreading it over the land, and all of the Rothamsted fields
show a depression or "dell" from which the chalk had thus
been formerly obtained. Arthur Young, the elder, in his
General View of the Agriculture of Herts, drawn up for the
consideration of the Board of Agriculture, and published in
1804, writes of "the prevailing practice of sinking pits for the
purpose of chalking the surrounding land," and mentions the
application of 60 loads of chalk every ten years as customary.
The chalk now present in the arable soil is visible in small
grains varying in size from that of a pea downwards, additional
evidence of its extraneous origin. But the amounts so added
to the soil are enormous : if we assume that the wastage in
the past had been at all comparable to that going on during
the last half-century on the unmanured plot, then Broadbaik
field must have begun the nineteenth century with something
like 100 tons of chalk per acre in its surface soil.

The proportion of organic matter, carbon and nitrogen,
present in the various soils is very variable and entirely
dependent on the character of the manuring and cultivation.

POTASH AND riTOSPlIOlMC ACID l>o

As "vvill be seen later, continuous cropping witliout manure
soon reduces such materials in the soil to a low ebb, below
which they do not fall ap[)rcciably in succeeding years ; the croi*
production becomes very nearly stationary and is accompanied
by a very small reduction in the ori<;inal stock of carbon and
nitrogen, even if there are not compensating,' iuHuenccs at
work maintaining the store at a constant low level. Similarly,
when very large amounts of organic matter are added every
year, as when plots are continuously dunged, after a time there
is buthttle increase in the proportions of carl)on and nitrogen
present in the soil, because the bacterial agencies which
generate carbon and nitrogen compounds of a gaseous nature
are so stimulated by the abundant food-supply as to keep
pace with the annual additions.

Of the other important constituents of ^^lant food the soil
carries an abundant stock of potash ; a complete mineral
analysis, in Avhich the Broadbalk soil was completely broken
up by hydrofluoric acid, yielded as much as 2 2(j per cent, of
potash, quite four times the amount that can l)e extracted by
long digestion with hydrochloric acid. Though this vast stock
of potash is in the main dormant, it slowly becomes availal)le
for crops through the weathering agencies which are Ijrought
into play by cultivation.

In phosphoric acid the soil is by no means so rich ; the
unmanured plots contain now rather less than 0"1 per cent.,
the highest limit reached on some of the very heavily manured
plots being about 0-25 per cent. ; under ordinary farming
conditions, however, the soil shows no particular need of
phosphoric acid, as do many clay soils.

Magnesia is fairly abundant in the Rothamsted soils ; in
the subsoil, indeed, it is present in almost the same proportion^
as the lime, it is only in the artificially chalked surface soil
that the ratio of lime to magnesia is a high one.

Soda is present in small quantities, partly combined with
chlorine as common salt derived from rain, and partly in the
double silicates of the clay.

30 COMPOSITION OF ROTHAMSTED SOIL

In general, it may be said that the Rothamsted soil
presents no striking peculiarities, either chemical or physical.

References

" Determinations of Nitrogen in the Soils of some of the Experimental
Fields at Rothamsted, and the bearing of the results on the question of
the sources of the Nitrogen of our Crops." American Association for
the Advancement of Science — Montreal, August, 1882. li. Mem.,
Vol. v., No. 19.

" On Some Points in the Composition of Soils ; with Results illustrating
the Sources of the Fertility of Manitoba Prairie Soils." Full Paper,
Trans. Chem. Soc, 47 (1885), 380. R. Mem., Vol. VI., No. 4.

" On the Present Position of the Question of the Sources of the Nitrogen of
Vegetation, etc., etc." Phil. Trans., 180, B (1889), 1. R. Mem.,
Vol. I. (4to), No. 2.

" On the Analytical Determination of Probably Available ' Mineral ' Plant
Food in Soils," by B. Dyer, D.Sc. Tra?is. Chem. Soc, 65 (1894), 115.

" Results of Investigations on the Rothamsted Soils, etc., etc.," by B.
Dyer, D.Sc. Bulletin No. 106, Office of Experiment Stations, U.S.
Department of Agriculture, 1902.

'•' A Chemical Study of the Phosphoric Acid and Potash Contents of the
Wheat Soils of Broadbalk Field, Rothamsted," by B. Dyer, D.Sc.
P/iil. Trans., 194, B (1901), 235.

"The Determinations of Available Plant Food in Soils by the use of weak
Acid Solvents," by A. D. Hall, and F. J. Plyraen. 'Trans. Chem. Soc.,
81 (1902), 117.

" The Geological Survey in Reference to Agriculture ; with Report on the
Soils and Subsoils of the Rothamsted Estate," by Horace Woodward,
F.R.S. Summary of Progress of the Geological Survey for 1903,
Appendix I. (1904), 143.

"The Mechanical Analysis of Soils and the Composition of the Fractions
resulting therefrom," by A. D. Hall. Trans. Chem. Soc., 85 (1904),
950.

"The Effect of the long-continued use of Sodium Nitrate on the Constitu-
tion of the Soil," by A. D. Hall. Trans. Chem. Soc, 85 (1904), 964.

CHAPTER IV

EXPERIMENTS UPON WHEAT

I. The Continuous Growth of Wheat, Bioadbalk Fit-Id :

A. Maintenance of the yield under Continuous Wlioat fri-owlnj^r ,,,, the

same land.

B. Effect of Nitrogenous Manures.

t'. Effect of the Mineral Constituents.
D. Retention of Manures by the Soil.

K. Character of the Crop as affected by Mainn-ing and Season.
II. Wheat after Fallow and in Rotation.
III. Trials of Varieties of Wheat.

Practical Conclusions and References.

I.— The Continuous Growth of Wheat, Broadbalk Field.
The experiments on the continuous growth of wheat were
begun in the Broadbalk field in 1843, but for tlie first eight
years the manuring was of a varied description, so that only
three of the plots have received the same treatment during the
whole period of sixty years. The plots as seen to-day began in
1852, since wliicli time the few changes in manuring have been
matters of detail and not of principle ; thus the results repre-
sent a continuous trial of wheat grown with the same manures
upon the same land year after year for more than half a
century.

The Broadbalk field has an area uf about 11 acres, and
slopes somewhat to the east ; the plots are each half an acre in
area, and consist of strips 351 yards long by about 7 yards
wide, running down the slojje for the whole lengtli of tlie field,
and separated by paths which are not cropped. Previous to
1843 the land had been cropped on a five-course system :
manure was last applied to the turnips in 1839, and two white

32 EXPERIMENTS UPON WHEAT

straw crops were taken immediately prior to the first experi-
mental crop of wheat sown in the autumn of 1843, so that the
land was in low condition from an agricultural point of view at
the beginning of the trials. This is also shown by the fact that
the first experimental crop in 1844 amounted to only 15 bushels
per acre on the unmanured plot, although the wheat crop was
generally much above the average in that year.

The soil of the Broadbalk field consists of a stiff greyish
loam containing an abundance of flints ; the subsoil is of a
similar character, rather stifi'er and redder in colour — "the clay-
with-flints " of the geologist. The chalk lies below at a variable
depth, rarely less than 8 or 10 feet, thus providing good
natural drainage. In addition, each plot has a tile drain
running down the centre of the plot at a depth of 2 to 2h feet,
the mouths of all the drains being led into a brick trench, where
the water draining from each plot can be separately collected
for analysis.

The field cannot be described as more than fair average
wheat land, nor do the analyses show any special reserve of
fertility beyond that natural to moderately strong land which
has been under arable cultivation for a very long time.

The usual practice is to scuffle the land immediately after
harvest and remove the weeds ; the land is then ploughed 5 or
6 inches deep ; the mineral and other autumn -sown manures
are sown and harrowed in, after which the seed is drilled. The
following varieties of seed have been used : Old Red Lammas,
five years, 1843-4 to 1847-8; Red Cluster, four years, 1848-9 to
1851-2; Red Rostock, twenty-nine years, 1852-3 to 1880-1;
Club or Square Head (Red), eighteen years, 1881-2 to 1898-9 ;
and Square Head's Master (Red), in 1899-1900 and since.

The chief difficulty experienced in growing wheat con-
tinuously is that of keeping the land clean ; not only does the
crop occupy the ground for the greater part of the year, and so
leave little opportunity for cleaning operations, but the weeds
whose habit of growth is favoured by the crop tend to
accumulate from year to year. Thus in spite of repeated hand-

GENERAL SCHEME :;:!

hoeings, some weeds, like the "Black Bent" grass, Alofu'cum.^
apresti^, are kept under with the greatest difiiculty.

The general scheme of the experiments in the l^roadhalk
field has been to test the manuiial re(iiiirements of wlicat Ity
growing it continuously with various combinations of manures
repeated year after year on the same plots. .Vt the outset
of the experiments it should be remembered that little was
then known as to the manurial requirements of any crop.
Liebig had just stirred the agricultural world by the general
statement that if a plant were supplied with the mineral
constituents left as ash when the plant is l)urnt, it will re(inire
no fm'ther assistance in the shape of manure, but will draw its
carbon and nitrogen from the atmosphere. The first experi-
ments were designed to verify the truth of this statement, and
were extended to test the effect of each of the constituents
found in the plant. The eff'ect of mineral manures alone is
compared with that of nitrogenous manure in various forms, or
of a combination of the two. The constituents of the mineral
manure — phosphoric acid, potash, soda, and magnesia — are
variously combined with nitrogenous manures, so as to ascertain
the part each of them plays in the nutrition of the crop. Thus
Plots 6, 7, 8, 9, 15, 16, 17, and 18 receive varying amounts and
combinations of nitrogen, together with the same mineral
manure containing all the elements present in the ash of the
wheat plant. Again, all the Plots 10, 11, 12, 13, and 14 receive
the same amount of nitrogen, but differ in the arrangement of
the accompanying mineral manure. Some of the plots also
test the question of the season at which the manures are
applied, and whether any of the residues are carried forward to
another year. The long duration of the experiment serves to
eliminate many of the sources of error in field experiments,
such as initial variations in the condition of the soil of various
plots due to previous manuring, irregular attacks of insect and
other pests, and variations due to seasons wliicli may fav(Mn-
some manures and not others. Also by gradually exhausting
the soil of particular constituents, tlie continuity brings to ligiit

34

EXPERIMENTS UPON WHEAT

the function of any element of manurial plant food in a way
that is not possible in the first few years of an experiment^
because of the large reserves of all plant foods contained in
ordinary soil.

Table XIV. shows the nature and quantities of the manures-
applied each year to the plots. The mineral manures (by
minerals is understood at Rothamsted the phosphoric acid^
potash, magnesia, soda, and other constituents left as ash when
the plant is burnt, but not any manure containing nitrogen)
are sovr^n before the seed in the autumn, the rape cake and the
farmyard manure, and a portion of the ammonium-salts are
also supplied in the autumn before seeding, but the nitrate of
soda and the greater part of the ammonium-salts are put on
as top-dressings in the spring.

Table XIV.' — Experiments on Wheat, Broadhalk Field. Manuring of
the Plots per acre per annum, 1852 and since.

Plot.

Abbreviated Description
of Manuring.

Nitrogenous Manures.

Mineral Manures.

s c

1

S
1

11

S

3 .

P-

S

<

o

11

!=«■

f"

2
3
5
6
7
8
9
10
11
12
13
14
15

16
17
18
19

Farmyard Manure ....

Unmanured

Minerals

Single Ammonium- salts and Minerals
Double do. do.
Treble do. do.
Single Nitrate and Minerals
Double Ammonium-salts alone .

Do. and Superphosphate .

Do. do. and Sulph. Soda .

Do. do. and Sulph. Potash

Do. do. and Sulph. Mag. .
Double Aram. -salts in autumn, and

Minerals

Double Nitrate and Minerals
\ Minerals alone, or Double Amm. -salts/
J alone, in alternate years . . \^
Rape Cake alone ....

Tons.
14

...

...

Lb.

1889

Lb.

275

550

Lb.

200
400
600

400
400
400
400
400

400
400

Cwt.

3-5
3-5
3-5
3-5
3-5

3-5
3-5
3-5
3-5

3-5

3-5
3-5

Lb.

200
200
200
200
200

200

200
200
200

Lb.

100
100
100
100
100

366-5

100
100
100

Lb.

100
100
100
100
100

...

280

100
100
100

Notes on the Manures.

The ammonium-salts consists of a mixture of equal parts of sulphate an(J
muriate of ammonia ; 200 lb. supply 43 lb. of nitrogen, equal to the amount
contained in 275 lb. nitrate of soda, or 1889 lb. of rape cake. The super-

AVEKAGE PKODrci-: or IM.OTS :'>:,

phosphate contains 37 per eeiit. pliospliatc luaiK- si.IuhU-. or Ci; Ih. ,,t soluhU-
phosphorie acid.

On Plots 9, 15, 16, and 19 certain ehanjres in the niaiuirinjr have been
made (hning the progress of tlie experiments, which are set out in detail in
the "Memoranda" for 1901.

Table XV. shows the average production of grain and
straw for the whole period of fifty-one ycar.s for thr la.st ten
years, and for the single year 1902.

Table XV. — Experiments on IVlicat, Broadhalk Field, rrodnce of Grain
and Straw per acre. Average over 51 years (1852-1902); and ovrr 10
years (1893-1902) ; aho Produce in 1902.

Plot.

Abbreviated Desoriiitiori
of Mamiriii^'.

Dressed Grain.

straw.

h

If

i

It

\i

1

St

5"

it
r

<

1

fee
<

11

•<

^

Bush.

Bush.

Bush.

Cwt.

Cwt.

Cwt.

2

Farmyard Manure

35-7

40-0

41-5

34-1

40-4

46-9

3

Unnianured

13-1

12-7

13-3

10-5

9-3

9-4

5

Minerals

14-!)

15-4

15-5

12-2

11-8

11-4

6

Single Ammonium-salts and Minerals .

24-0

23-5

26-2

21-5

20-2

20-8

7

Double do. do. ...

32-0

32-4

38-2

33-0

32-2

40-0

8

Treble do. do. ...

37-1

39-2

45-2

40-9

43-0

48-1

9

Single Nitrate and Minerals

27-3

33-1

25-5

28-6

10

Double Ammonium-salts alone ....

20-7

19-6

23-7

18 -7

16-7

16-9

11

Do. and Superphosphate .

24-0

20-2

23-0

22-7

19-2

19-8

12

Do. do. and Suiph. Soda

30-0

27-6

33-4

28-3

25-2

:{2-2

13

Do. do. and Suiph. Potash .

31 T)

30-6

39-3

31-3

29-8

37-6

14

Do. do. and Suiph. Mag.

30-1

25-9

32-4

28-8

24-0

27-3

15

Double Anun.-salts in autumn, and Minerals

30-6

28-2

39-6

29-8

27-5

37-2

16

Double Nitrate and Minerals ....

32-5

33-5

33-3

35-4

17

\Mineral.s alone, or Double Ammonium-salts/*

15-3

15-9

20-2

I'S'l

12-8

16-8

18

j alone, in alternate years . . . . \t

30-4

30-0

36-9

29-5

29-0

40-1

19

Rape Cake alone

28-0

34-1

26 -7

3 J -8

Produce by Minerals

Produce by Ammonium-salts

The grain is expressed in measured 1)iis1il'1.s per acri", tiie
weight of the bu.shel depending on the plot and season. The
.straw, which includes chaff, etc., is given in cwt. per acre.

Table XVI. shows the average production of certain of the
plots for the five successive ten-year periods from 1862 to IImh.
Although ten-year periods are not long enough to entirely
remove the effect of season, yet the table enables one to judge

36

EXPERIMENTS UPON WHEAT

whether the fertility of the plots has increased or diminished
under the treatment they receive.

Table XVI. — Experiments on Wheat, Broadhalk Field. Average Produce
of Grain and Straw per acre the first 8 years (1844-1851), anc? over the
successive 1() -year periods (1852-1901) inclusive.

Plot.

Averages over

Abbreviated Description
of Manures.

1

i!

II

22

i

ii

it

Dressed Grai

n.

Bush

Bush

Bush

Bush

Bush

Bush

Bush.

2

Farmyard Manure

28-0

34-2

37-5

28-7

38-2

39-2

35-6

3

Unmanured

17-2

15-9

14-5

10-4

12-6

12-3

13-1

5

Minerals

18-4

15 -.0

12-1

13-8

14-8

14-9

6

Single Ammoniinn-salts and Minerals

27-2

25-7

19-1

24-5

23-1

23-9

7

Double do. do.

34-7

35-9

26-9

35-0

31-8

32-9

8

Treble do. do.

36-1

40 -.0

31-2

38-4

38 -.T

36-9

10

Double Aranionium-salts alone .

25-1

23-2

25-1

17-3

19-4

18-4

20-7

11

Do. and Superphosphate

28-4

27-9

21-7

22-7

19-5

24-0

12

Do. do. and Sulph. Soda

33-4

34-3

25-1

30-1

26-7

29-9

13

Do. do. and Sulph. Potash .

32-9

34-8

26-8

32 -.0

29-6

31-3

14

Do. do. and Sulph. Mag. .

...

33-5

34 4

26-4

31-1

25-0

30-1

Straw.

Cwt.

Cwt.

Cwt.

Cwt.

Cwt.

Cwt.

Cwt.

2

Farmyard Manure

26-6

33-9

34-0

28-0

34-8

38-7

33-9

3

Unmanured ....

15-5

15-2

11 -.5

8-5

8-5

9-1

10-6

5

Minerals

17-1

12-8

9-7

9-9

11-5

12-2

6

Single Ammonium-salts and Minerals

26-3

22-8

17-7

20-5

20-0

21-5

7

Double do. do.

36-4

.34-3

28-7

34-1

31-1

32-9

8

Treble do. do.

40-5

43-2

36-6

42-5

41-7

40-9

10

Double Ammonium-salts alone .

23-7

24-5

21-9

l.T-2

1.5-8

lfi-2

18-7

11

Do. and Superphosphate

28-2

24-5

21-3

20-8

18-8

22-7

12

Do. do. and Sulph. Soda .

34-2

30-5

25-0

27-3

24-0

28-2

13

Do. do. and Sulph. Potash .

34-4

.33-4

27-6

31-9

28-6

31-2

14

Do. do. and Sulph. Mag. .

35-0

30-7

26-3

28-6

23-4

28-8

A. Maintenance of the yield under Continuous Wheat
growing on the same land.

The curves in Fig. 2 show the fluctuations in the yield of
total produce for the first eight-year and five ten-year periods
from the beginning of the experiment on certain of the plots
— Plot 3, which is unmanured ; Plot 2, which receives farm-
yard manure every year ; Plots 6 and 7, which receive a

FLUCTUATIONS OF VIKI.D :I7

complete artitici.'il maiuire containing varvini; i|iiaiititic.s of
nitrogen ; and Plot 10, which receives nitrogen only.

Considering the unmanured plot fh-st, it will l»e seen thai
while there is evidence of a small decline in pioduction t<>r the

ROOD lb.

Plot 2.

::;i.piot7.

- Plot 6

Plot 10.

"Plot 3.

1844-51. 1852-61. 1862-71. 1872-81. 1882-91. 18921901

Fk;. 2.-Broa(n)alk Wlu-.it. Total rr.Mln. . .

first eighteen years, yet the crop has been practically constant
(hiring the last forty years. The fluctuations during this period
are in the main due to season, and correspond very closely with
those of the completely manured Plots 0 and 7. For example,
there was a considerable drop during the decade 1872-sl, a
period of notoriously bad seasons ; then followed a consi(leral)le

38 EXPEllIMENTS UPON WHEAT

recovery in the next decade which has been maintained for
the last ten years. But all the evidence seems to point to
the fact that this plot, which has been without manure of
any description since 1839, has reached a stationary con-
dition, and that the average crop of twelve and a half bushels
for the last forty years will in future diminish very slowly, if at
all. It has been already pointed out that the Rothamsted soil
is by no means exceptionally rich, how then can this continued
production of crop without manure be accounted for ? It is
estimated that the average crop on this plot has removed about
17 lb. of nitrogen, 9 lb. of phosphoric acid, and 14 lb. of
potash per acre per annum. In the drainage water there is
also a further loss of nitrogen, which has been estimated at 10
lb. per acre per annum ; some nitrogen is also removed in
weeds. Per contra, the rain brings about 5 lb. of nitrogen each
year, and the seed supplies perhaps 2 lb., thus leaving a nett
annual loss of nitrogen of at least 20 lb. per acre. The
analyses of the soil taken in 1865, 1881, and 1893, show that
there is a steady diminution in the amount of combine<l
nitrogen present in the soil ; but since in 1893 the proportion
present was 0*099, or rather more than 2500 lb. per acre in the
top 9 inches of soil, there is still an enormous reserve un-
touched. There may also be hitherto unrecognised gains of
nitrogen from the atmosphere. For example, the Black
Medick is a common weed on this plot, and like other legu-
minous plants fixes some nitrogen from the atmosphere, part
of which will be left behind in the soil when the roots decay.
Soil bacteria are also known which are capable of fixing
nitrogen independently of the higher plants ; but until the
analyses of the soil have been repeated after another long
interval it is not possible to say whether such recuperative
agencies have any practical effect, or whether the crop is still
being grown out of the original resources of the soil. A s regards
potash and phosphoric acid there can be no external sources
of recovery, but the reserves are very great, amounting in 1893
to about 3000 lb. of phosphoric acid and as much as 50,000

TXCKEASKI) FKiniLrrV OF DT'Xr.F.r) IMOT :;•!

lb. of potash per acre in tlie top \) inches of soil, though of
course tlie greater part of the hitter would only ])econie avail-
able for the plant very slowly.

On Plot '2 there has been a yearly dressing of 14 tons of
farmyard manure, and though the composition of the duuL: is
so far variable that it is impossible to say exactly what
quantity of plant food has been supplied, the annual applica-
tion is estimated to contain al)out '200 lb. of nitrogen, 78 lb. of
phosphoric acid, and 235 lb. of potash ; whereas the average
crop has only removed al)out ^fo lb. of nitrogen, 27 lb. of
phosphoric acid, and 52 lb. of potash per acre. There should
be an accumulation of fertihty on this plot, and an examination
of the curve shows that after a rapid rise during the first eight
years of the experiments, when the land was recovering from
a state of comparative exhaustion, the yield of grain has been
slowly increasing, despite the depression during the decade
1872-81. The increase is particularly manifest during the last
ten years, on the whole a period of dry seasons, when the
moisture retained by the accumulation of hunuis from the dung
also had its effect. Tlie increased fertility of this plot would
doubtless have been more manifest were it not for the tendency
of the crop to be laid in the heavier yielding seasons. The
analyses show that enormous reserves of plant food have been
accumulated in the soil of this plot, the amount of nitrogen in
the surface soil l)eing more than double that of the unmanuretl
plot, the phosphoric acid being also almost doubled, and the
potash showing a very considerable increase. While some of
these reserves are in a readily available form, there is evidence
from the other experiments at Itothamsted that even in fifty
years it would ])e impossible to crop them entirely out, if ;i
course of iirowin^i; corn without further nianuiinu were now
entered on.

Regarding now Plots 6 and 7, receiving artilicial manures
which supply nitrogen, potash, and phosphoric acid, but no
organic matter to form humus, we see that Plot 7 has
throughout yielded a crop very little inferior to that lmowu

40 EXPERIMENTS UPON WHEAT

on the dunged plot, and shows no evidence of a decline in
fertility. The manure on this plot supplies 86 lb. of nitrogen
per acre, whereas the average crop has taken away not more
than 50 lb. The phosphoric acid and potash supplied are also
in excess of the requirements of the crop. On Plot 6 only
43 lb. of nitrogen per acre are supplied, little more than the
amount removed in the crop. If we consider the other sources
of loss of nitrogen to the soil, such as the removal of weeds,
drainage, etc., it becomes clear that the 43 lb. of nitrogen
in the manure are not sufficient to repair the annual with-
drawals of nitrogen. Consequently we should expect some
diminution of fertility on this plot, and analyses of the soil
seem to show that it is slowly losing nitrogen. The curve
expressing the crop on Plot 6 is very similar to that of the
unmanured plot, indicating a considerable fall in fertility
during the first ten years, and a comparatively constant
position for the last forty years. Thus this plot like the
unmanured plot seems to have reached a position of com-
parative stability, when the annual withdrawal of nitrogen
by crop and drainage, etc., is almost balanced by the
additions from all sources, so that the fertility of the land
is declining very slowly, if at all. Though no material to form
humus has been supplied to Plots 6 and 7, and analysis shows
that the soil is gradually being deprived of its original stock,
yet the wheat crop so far seems to be unaffected by the loss
of this important constituent of the soil.

Plot 10 has received an annual dressing of nitrogen only, in
the shape of 400 lb. of ammonium-salts since the earliest date
of the experiments. It will be evident from the curve showing
the crop production that, despite this long-continued use of a
manure supplying but one element of plant nutrition, the crop
has been wonderfully maintained. Whereas the average pro-
duction over the whole period is increased by the supply of
minerals to the extent of 1'8 bushels, the nitrogen alone has
produced an average increase of 7 '6 bushels, the unmanured
plot being taken as the standard in either case. The curve.

WHEAT (;i;()\VX CONI IMOrsiA If

however, shows that llie production on tliis IMot lo i>
(lecliniiiLT, notwithstanding the great reserves of niinerul plant
food with wliich the soil started. At tlie present time also
the crop on this plot presents a very unhealthy appearaiu-r.
is very slow to mature, and is extremely liahle to rust.

We thus see that it is possible to grow a cereal crop likr
wheat year after year on the same land for at least sixty years
without any decline in the productiveness of the soil, provided
an appropriate manure be supplied to replace the nitrogen,
l)hosphoric acid, and potash removed by the crops. There is
no evidence in fact that the wheat gives a smaller yield wIkmi
following a long succession of previous wheat crops than when
grown in rotation, although the vigour of the plant does not
appear to be so great. The real difficulty, however, in con-
tinuous corn -growing is to keep the land clean ; certain weeds
are favoured by the wheat and tend to accumulate, so that the
land can only be maintained clean by an excessive expenditure
in repeated hand-hoeing. Notwithstanding all the labour that
is put on the plots, the " Black Bent " grass, Alopecurus (((/rcafis,
has from time to time become so troublesome that special
measures have had to be taken to eradicate it and to restore
the plots to a reasonable degree of cleanliness.

How little the wheat plant is able to survive when in
competition with weeds, may be seen from a portion of the
Broadbalk field where the wheat crop in 1882 was allowed to
stand and shed its seed, the soil not being cultivated in any
way. In the following season a fair wheat plant came up and
gave about half a crop, but after it seeded the weeds increased
their hold upon the ground until in the fourth season only two
or three stunted wheat plants could be found, which have never
reappeared since. The fundamental importance of cultivation
and the suppression of weeds is further to be seen in the
returns from the continuously unmanured plot. This piece of
land at the beginning of the experiments was not only in poor
agricultural condition but had been under arable cultivation for
at least two or three centuries, and was therefore far removed

42 EXPERIMENTS UPON WHEAT

from the condition of virgin soil with its accumulation of
fertility, and yet by cultivation alone it has been able to grow
for sixty years a crop averaging 13 bushels to the acre. This
is almost the average crop produced in the United States, and
is very similar to the general average production of the great
wheat-growing areas of the world. Nor is there, as far as
can be judged from the records of the last forty years, any
reason to expect that this crop cannot be maintained in the
future, provided that the cultivation and cleaning of the land
be continued.

B. Effect of Nitrogenous Manures.

It will be remembered that one of the main objects in
starting the Pothamsted Experiments was to ascertain the
value of nitrogenous manures, and test the truth of Liebig's
opinions that the crop could obtain a sufficiency of nitrogen
from the atmosphere provided the ash constituents were
supplied. Plots 5, 6, 7, and 8 all receive the same dressings
of mineral manures, i.e., phosphoric acid, potash, magnesia,
and soda, in greater quantities than are removed in the crops.
Plot 5 receives no nitrogen, Plots 6, 7, and 8 receive increas-
ing quantities of ammonium-salts, supplying 43 lb. of nitrogen
per acre on Plot 6, double that quantity on Plot 7, and
treble the quantity on Plot 8. [An average crop of 30 bushels
of grain, and 28 cwt. of straw, will remove about 50 lb. of
nitrogen per acre.]

The diagram Fig. 3 shows the crops on these j^lots over
the whole period since 1852.

Plot 5, which receives the minerals but no nitrogen, grows
very little more than the continuously unmanured plot; its
average over the whole period is only 14*9 bushels, as against
13'1 without manure of any description. The other three plots
yield crops which increase with each addition of nitrogen ; the
grain increases from 24 bushels with 43 lb. of nitrogen, to 33
bushels with 86 lb. of nitrogen, and to 37 bushels with 129 lb.
of nitrogen ; the straw is even more affected by a free supply of

EFFECT OF MIKOCKNOrs MAMIMO

i:;

nitrogen, rising from '21. \ cwt. to 33 and 41 cut. as the nitrogen
is doubled and trebled. It is thus seen tliat thi* wlieat crop is
very specially dependent upon the supi)ly of nitrogen in the

Total Produce
per Acre

7000 lb

Plots 3i-4.

[S^ Grain per Acre, lb

Straw per Acre, lb

Fig. 3.-Broadbalk Wheat. Effect of inereasing amounts of Nitrogen on th.- |.r...I... l.on

of Wheat (Grain and Straw). AveniKc, .M years ( 1 s5-J-lW-')-

The figures in the labels indicate bushels of grain .md cwt. of straw .

44 EXPERIMENTS UPON WHEAT

manure. With nitrogen alone {e.g., ammonium-salts alone on
Plot 10, nitrate of soda alone on part of Plot 9, and rape cake-
alone on Plot 19), even over a long period of years, the crop
is considerable, and much superior to that grown by minerals,
without nitrogen. Being a deep-rooted plant and possessing a
comparatively long period of growth, wheat is well able to
search the soil for mineral plant food ; hence when grown
under ordinary farm conditions in rotation, it is rarely necessary
to supply it with any but nitrogenous manures. As it is ^Iso
grown during the cooler season of the year and with very little
cultivation of the ground, the natural nitrifying processes are
slow, hence the special need for an external supply of nitrogen
in the shape of manure.

Plots 9 and 16 receive nitrate of soda and mineral manures,
so that Plot 9 has the same manuring as Plot 6, and Plot 1^
as Plot 7, except that the ammonium-salts on Plots 6 and 7
are replaced by equivalent amounts of nitrate of soda. The
manuring of Plots 9 and 16 has however been changed
during the progress of the experiments, so that they are only
comparable with 6 and 7 since 1885. Taking the averages of
the last ten years, as set out in the diagram Fig. 4, it will be
seen that nitrate of soda is a more effective source of nitrogen
than the ammonium-salts ; the single application yields 16 per
cent, more grain and 26 per cent, more straw than the corre-
sponding amount of ammonium-salts : the double application,
however, yields practically the same amount of grain and only
about 1 cwt. more straw. This superiority of nitrate of soda
for wheat is no doubt partly due to the fact that it remains
soluble, thus diffusing deep into the soil and encouraging a
greater range of roots, whereas the ammonium-salts are
retained near the surface. The injurious effects of continuous
applications of ammonium-salts, which are due to the removal
of the carbonate of lime from the soil and its resultant acidity,
now so strikingly shown on the corresponding permanent
wheat and barley plots on the Royal Agricultural Society's
farm at Woburn, are not apparent at Rothamsted, where the

NITRATE VERSUS AM MOM l.M SA ITS i:,

soil started with a gootl sup})ly of chalk. Analyses iua<lr in
1904, show that the soil of Plot 7 si ill contains more than
*2\ per cent, of carbonate of lime.

Total fVoduce
per Acre

6000 lb —

Grain per Acre . lb

Fig. 4.— Comparison of Nitrate of Soda and Aninioniuni-salLs on \Mi. af.
10 years (1 893-1902). -Ml Plots receive Minerals alike.

It should be noticed that the increase <»f crop for cac-h
application of nitrogen is not proportional to the e.xiia nitrogen
.supplied, but that each successive addition gives a smaller
return in the crop. Thus l^ot G with 4:J lb. of nitrogen gives

46

EXPERIMENTS UPON WHEAT

91 bushels more than Plot 5 with no nitrogen, another 43 lb,
of nitrogen on Plot 7 produce a further increase of 8 "9 bushels^
whereas the next addition of 43 lb. of nitrogen only produces
an increase of 4*2 bushels.

During the first 13 years of the experiment one of the plots
received a still further addition of nitrogen, making 172 lb. in
all. The Table (XVII.) shows the yield of grain and straw of
the plots receiving successive increments of nitrogen during
this period. It will be seen that the last 43 lb. of nitrogen had
practically no effect upon the amount of grain produced and
but little upon the straw.

Table XVII. — Experiments on Wheat, Broadbalh Field.
Averages over lo years (1852-1864).

Plot.

Manures per acre.

Dressed Grain.

straw.

Pro-
duce
per
acre.

Increase
for each

additional
43 lb. N.

in Manure.

Pro-
duce
per
acre.

Increase
for each
additional
43 lb. X.

in Manure.

I

7
8
16

Minerals alone

Do. and 4-3 lb. N. a.s Ammonium-salts
Do. and 86 1b. do. do.
Do. and 129 lb. do. do.
Do. and 172 lb. do. do.

Bush.
18-3
28-6
37-1
39-0
39-5

Bush.

10-3
8-5
1-9
0-5

Cwt.
16-6
27-1
38-1
42-7
46-6

Cwt.

10 -5
11-0
4-6
3-9

These results illustrate very clearly what is known as the
" law of diminishing returns," i.e., that each increment in the
cost of production, whether labour or manure, gives rise to a
smaller proportionate return, until a point is reached when the
value of the increased yield is more than balanced by the outlay
required to bring it about. This point, when the extra croj)
ceases to pay for the manure or labour expended on it, is
sooner reached with low than with high prices for the crop.
Hence high farming (intensive cultivation and liberal expendi-
ture on manure) is only justified in times of high prices and
is no remedy for low ones.

LAW OF DIMIXISIIINC IMVmJNS \7

The (liagrani Fig. 5 shows a cH)ini)aris()n l)et\vi'('n iIk-
returns from these plots, (1) witli corn at 24s. a (luarlcr and
straw at *20s. a ton, and (2) when corn is :V2s. and straw
at 30s.

The straight line indicates the cost of production taking an
arbitrary base of 80s. per acre for the cultivation, and adding

Returns &. Cost
Shillintfs.

Mineral Manures +200 lb.

400 lb.

600 lb.

800 lb. Amm. Salts.

Fk;. 5. — Relation between Cost of rrodiietion anil Ilelurns with varying
quantities of Mainirc.

30s. for each 200 11). of ammonium-salts, ft will l.r s<'cn tliat
with the lower prices the crop ceases to be proiital>lc before the
third addition of manure is made; tiie second addition is the
most profitable, the extra 30s. for manine has produccMJ an
increased return of 30s. in the cro}). At the higiier .scale
of prices the crop remains profitable throughout, though the

48 EXPERIMENTS UPON WHEAT

third addition of manure only returns 14s. for an expenditure
of 30s., and the fourth application only produces an increase of
€rop worth 8s.

C. Effect of the Mineral Constituents.

The series of Plots 7, 10, 11, 12, 13, and 14 all receive
the same amount of nitrogen — 86 lb., in form of 400 lb.
of ammonium-salts per acre— but differ in regard to their
mineral manuring. Plot 10 receives nothing beyond the
nitrogen, Plot 11 has superphosphate also, while 12, 13,
und 14 receive a further addition of sulphate of soda,
sulphate of potash, or sulphate of magnesia respectively, all
three of which are combined to form a complete mineral
manure on Plot 7. It should be remembered that soda,
magnesia, and potash are always found in the ash of plants,
and at the time the experiments were started little was known
about the part they played in the nutrition of the plant. And
although we know to-day that for practical purposes potash
iilone of the three need be supplied in a manure, we are still
uncertain what is the function of the other two, which being
present in every plant can hardly be without some action.
Fig. 6 shows the crops upon these plots in successive ten-
yearly periods. It will be seen that Plot 11, receiving super-
phosphate, has always given a better crop than Plot 10, without
it. This superiority was more marked in the early years of
the experiment, when the reserves of potash, etc., were
abundant in the soil, and when in consequence the nitrogen
and phosphoric acid together had practically the effect of a
complete manure. Latterly, as the potash has become ex-
hausted by the continual cropping, the yield with nitrogen and
phosphoric acid has been but little superior to that produced
by nitrogen alone. Similarly, in the earlier years of the experi-
ment the crop on Plots 12 and 14, where soda and magnesia
.are added to the superphosphate and ammonium- salts, was
but Httle inferior to that of Plot 13, which receives

EXHAUSTION OF POTASH

lit

potash. The results in later years show, however, that neitlicr
magnesia nor soda can rephice potasli, tlieir good effect in tlic
first few years being due to the fact tliat tlie addition of aiiv

Bushels
per Acre.

30

10

n: qi ~" x:

_i

, ,. _i_

^ ^ - n:

rT'..'g'"^N*' ^^"^""^^^S 1 ?'~"~''*i

"'^ 'TCs ^^ ■"•- ~''''^«*^

\ \ '!? ^ w ?«''*.. r" '

sSi iz,z>:;^^^ ^-i^

^*5s ^^^:<ii=^^n^ T^'^

— k-^. . 3 "vi>^ >^'>^.■••' ^'v,..

.. \\S^ " Sn"-

^.- '•..^t''r.> ^'s,i'>2

^_-o 1 5^ !i-' !S ..

X-t-^^^-^ ^-<^ ii i - -

^<^' ^5it ^u it - -^

^ S ^^ ^^--' .- it

1 '-. V.-.i-f- '■s,,^ j

'S, "''^yji

5[5'5! ::

1 _r ■

1

~r

1852-61 1862-71 1872-81 1882-91 1892-1901

Fig. i3. — Production of Wheat with varyinijc MintTal Maiitiros. All Plots receive finally
86 lb. N. as Ammonium-salts. Averages over 10-year periods (18.52-1901).

soluble salts to the soil brings into action some of the dormant
potash. At first this is sufficient to grow as large a crop as
where a potash manure is directly supplied, Init in course of
time the available potash becomes exhausted, and tht'ie is a
manifest decline on the plots receiving magnesia or soda only.
Plot 7, which differs only from Plot 13 in receiving magnesia
and soda in addition to the potash, phosphoric acid, and nitro-
gen applied to 13, gives throughout a .somewliat higher (ro|>.
This is not due to any specific effect of magnesia and soda,
because Plot 13 does not show any progressive decline as com-

50 EXPERIMENTS UPON WHEAT

pared with Plot 7, although its soil must be becoming exhausted
of these constituents by their constant removal in the crops.
Doubtless the effect of the sulphates of magnesia and soda on
Plot 7 is due to their action as soluble salts, maintaining in
a more soluble condition the other manurial constituents
necessary to the crop.

D. Retention of Manures by the Soil

It has already been stated that, as a rule, 100 lb. of the
ammonium-salts are applied in the autumn when the seed is
sown, the rest being reserved for a top-dressing in the
spring. On one of the plots, however. Plot 15, the whole
400 lb. of ammonium-salts is applied in the autumn,
otherwise the manuring is identical with that of Plot 7.
The crop, however, on Plot 15 is on the average below that
of Plot 7, showing that some loss takes place when the
ammonium-salts are applied before the plant is able to utilise
them. Although the ammonium-salts are soluble in water
they are caught by the soil and held very near to the surface,
so that the loss does not arise by the washing out of the
ammonium-salts themselves. They are, however, rapidly con-
verted into nitrates when the land is warm and moist,
especially after it has been recently stirred by the autumn
cultivations. The nitrates thus produced are not retained by
the soil, and wash out very readily if heavy rain falls during
the early winter. This is seen in the analyses of the drainage
water collected beneath Plot 15. It is generally very rich in
nitrates in the autumn as compared with Plot 7 ; whereas in the
spring, when the ammonium- salts are aj^plied, a corresponding
loss does not happen with Plot 7, because the crop then
occupies the land and is able to take up the nitrates as fast as
they are formed.

The diagram Fig. 7 shows the estimated loss of nitrates in
lb. per acre on these two plots during the summer and winter
respectively, between the spring sowing of manures in 1879 and
the corresponding date in 1881.

XTTKATKS LOST T\ DIJAIXACK r,i

Plots 17 and 18 further illustrate the fate nf aimnouimii-
salts. These plots reecivc the dressiiiL,' of I'h.t 7 Km) II..
ammonium-salts and eomplete minerals hut the animoiiiuiii

N.aifl.trtu

SpnngSoKin^ to Harvest Harvest to Sprin|So»«ing Sprin^Sowin^ to Harvest Harvest to Sprin^Sowmg
1879. 187^80. 1880. I88O/8I.

I Drainage (in Inches) through 60 Soil.

Loss of N.aa Nitrales perAcr
Manure Spring Sown

E^'

Fig. 7. — Loss of Nitrogen as Nitrates in the Drainage WatiT, lb. pi-r atrc
Comparison of Plot 7 nvinured with Aminoniuin-salt.s in tiu- spring', ami
Plot 15 in the autumn.

salts and the minerals are applied in alternate years to the t\v»)
plots. Thus in 1903 Plot 17 received annnonium-salts hut nn
minerals, and IMot 18 the minerals without the ammonium-
salts, and the treatment was reversed in llM)ii and aj^ain in
1904. It will be seen from Table XV., or Irom the dia<,Mam
Fig. 8, that the plot which in any year is receiving minerals
without nitrogen derives little or no benefit from tiie anunoma

/<^Ar^

52 EXPERIMENTS UPON WHEAT

it had the year before. The crop shows every sign of nitrogen
starvation, and amounts on the average to only 15*8 bushels
of grain, as compared with 14*9 bushels on Plot 5 which has
received minerals without any nitrogen every year since 1852.
On the Rothamsted soil, then, we may conclude that the effect
of sulphate of ammonia applied to a cereal crop is confined to
the season of its application. In the seasons when the
ammonium-salts are applied the crop is but little short of that
on Plot 7, where minerals are used every year with the same
amount of ammonium-salts, thus showing that the previous
mineral manuring is carried forward and has an effect in
seasons beyond the year of its application.

Much of our knowledge of the process of nitrification, by
which not only ammonium-salts but other compounds of
nitrogen, such as are contained in dung, are converted into
nitrates, was worked out in the Rothamsted Laboratory by Mr
Warington. From the continued analyses that have been made
of the water flowing from the drains beneath the Broadbalk
wheat plots, we learn that not only may readily nitrifying
manures suffer great losses through nitrates forming and being
washed out when a crop does not occupy the ground, but that
the same causes lead to continuous loss of nitrogen from all
cultivated land. This loss is at its highest when heavy rain
falls after the land has been broken up after harvest ; then the
conditions occur which are most favourable to nitrification,
i.e., warmth, moisture, aeration, and stirring of the soil. Thus
analyses of the soil show that, despite the fact that much larger
amounts of nitrogen are applied to Plots 7 to 18 than are re-
moved in the crop, the soil is not getting any richer in nitrogen ;
and even on Plots 2 and 19, where organic compounds of
nitrogen are used, the accumulation of nitrogen is far less than
the difference between the nitrogen applied and that removed
Avould indicate.

Table XVIII. gives an estimate of the nitrogen per acre
supplied in the manure and recovered in the crop over a fifty-
year period, 1844-1893, together with the nitrogen contained

SPRING AXl^ AUTrMX SOWX MAMRKS :,:;

in the soil at the close of that period for the umnanun-d I'lot
3, and Plot 2 receiving farmyard manure. The toj) 1> inc-lics u[
soil only are considered, because the analyses do not indicate

Total Produl
per Acre

Plot

Minerals
only.

7 15 17 16

Minerals Minerals Minerals

+ 861b.N. +86lb.N. -►86lb.N. e6!b.N.

Sprinf Autumn. for Previous a^'ter Miner«!i only

Crop. • in Previous Year.

^^^Grain per Acre. lb.

l^^H Straw per Acre, lb.

Fui. 8.— Conipanitive KfTcL-ts on Wheat of .\im.ioniuin-saIt.s npi.lieil at (lifTtTctit times.
Averages for 51 years (1^52-1902). Plots 7 and 1'., 25 years (.nly (1>7S-19U2).

that any appreciable amoimt of ()r:janic matti-i- has t».und its
way into the subsoil.

It will l^e seen that of al)out 1(),(MM) lb. of nitrogen supplied

54

EXPERIMENTS UPON WHEAT

as dung during the whole period, only about 2600 lb. have
been recovered in the crop, or about 26 per cent., and that
although the nitrogen present in the soil at the end of the

Table XVI II.

Plot.

Manuring.

Nitrogen in Soil,

9 inches deep,

1893.

Approximate

of ^ itrogen

in

Manure

in 50 Years.

Approximate
Removal

of
Nitrogen
in Crops,
50 years

(1844-1893).

Surplus of

Nitrogen

over Plot 3,

unaccounted

for in
Crop or Soil.

Per cent.

Pounds
per acre.

3
2

Unmanured
Farmyard Manure .

0-0992
0-2207

2,570
5,150

Lb.

io',ooo

Lb.

850

2,600

Lb.
5,670

period has been doubled, the excess over the manured plot is
only 2580 lb. per acre ; so that there is still 5670 lb. which
has been supplied in the manure, but is unaccounted for either
in the crop removed or in the accumulation in the soil. Some
of this has no doubt been washed away as nitrate into the
drains and the subsoil water, some has been removed in the
weeds, but much must have been lost by the conversion,
through bacterial action, of nitrogenous compounds in the
manure into free nitrogen gas.

Phosphoric acid and potash, however, behave very differ-
ently from nitrogen ; but little of these substances are ever found
in the drainage waters, and Dr Dyer's analyses show that the
greater part of the excess of phosphoric acid supplied over that
removed in the crop is still to be found in the top 9 inches of
soil, where it remains in a condition readily available for the
plant. The potash is not quite so completely retained as the
phosphoric acid, and descends further below the surface. There
is still, however, no practical loss to be feared when potash is
applied to the land before there is any crop immediately able
to utilise it.

E. Character of the Crop as affected by Manuring and Season.

Table XIX. gives certain particulars regarding the quality of
crops grown during the last fourteen years, covering the years

QUALITY or WHEAT dJOPS

65

in which Mr E. Ilewlins of St Ives has iiuide vahiations of the
grain from each of the plots. These valuations and figures
respecting quality are to a certain extent disturbed by factors

Table XIX,

iriicat, Broadhalk Field. Averayr.t over 14 years
(1889-1902).

Plot.

Abbreviated Description
of Manures.

ll

i

k

Si

e i

■Hi

'I

a

°2

H

^8

1?

a
g
O

a 3

I-

1

§5

il

Lb.

Gms.i

2

Farmyard Manure

61-3

56-7

102-3

3-8

2536

3-94

4

Unmanured

60-7

77-2

100-3

4-3

2708

3-69

5

Minerals

60-8

74-4

100-5

4-7

2586

3-86

6

Minerals and Single Ammonium-salts .

61-1

66-3

101-4

4-0

2520

3-97 1

7

Do. and Double do.

61-1

57-2

101-1

3-7

2578

3-88

8

Do. and Treble do.

60-8

51-5

100-8

4-2

2636

3-79 !

9a*

Minerals and Single Nitrate ....

60-8

59-5

100-9

3-5

2612

3-83

16

Double Nitrate and Minerals ....

60-5

53-1

100-8

4-4

2772

3-61 1

10

Double Aiumonimn-salts only

59-6

66-6

98-7

6-1

2966

3-37

11

Do. and Superphos.

58-6

59-5

97-1

7-4

3238

3-09

12

Do. do. and Sulpli. Soda .

59-9 61-9

99-2

4-8

2926

3-42 1

13

Do. do. and Suljili. t'otash .

61-0 157-3

101-0

3-6

2592

3-86

14

Do. do. and Sulj^h. Mag. .

59-9. 60-2

100-1

4-6

2978

3.,e;

and h, 1894 and since.

Average for 7 years (1803, '94, '90, '97, '98, 1900,

arising only at secondTiand out of the manuring. For
example, Plots 8 and 2 are very liable to l)e lodged and
to show a much higher proportion of sprouted corn in
a wet harvest like that of 1902. These effects may easily
overpower the differences directly due to the manuring and
visible in normal seasons. The farmyard manure plot, No. 2,
has given on the average the best grain, .showing the highest
weight per Inishel and the highest price in the valuation,
but there are several years in which the corn from this
plot occupied a very low place in the series. IMot lo, a^ain,
receiving ammonium-salts only, shows ahnost the lowest
weight per bushel and the lowest price. In some years,
however, the highest valuation has been put on the corn from
this plot. It is important to notice that tlie continuously
unmanured plot, with its small yield, yet produces grains of
corn which are almost up to the average in size, weight per

56 EXPERIMENTS UPON WHEAT

bushel, and value from a commercial point of view. The plant,
when starved, diminishes the number but not the quality of the
seed; even the proportion of "tail" corn is not above the
average on this plot. The proportion of corn to straw is the
highest on this plot, as though starvation resulted in con-
centrating the highest possible proportion of material on the
reproductive parts of the plant.

The plot receiving minerals only differs very little from the
unmanured plot, but with each successive addition of nitrogen
on Plots 6, 7, and 8, the weight per bushel, the size of the
grain, and the value somewhat diminish ; at the same time the
proportion of straw to corn is much increased. The effect of a
given quantity of nitrogen in the directions thus indicated seems
to be intensified when it is applied as nitrate instead of
ammonia.

Turning to the Plots 7, 10, 11, 1*2, 13, and 14, which receive
the same amount of nitrogen but vary in their mineral manures,
we get the highest weight per bushel, the largest grains, and
the greatest value on Plots 7 and 13, where potash is supplied ;
on these plots also the proportion of straw is at a maximum,
facts which depend upon the function of potash in the formation
of carbohydrates — starch in the grain, and woody-fibre in the
straw. The soda and magnesia applied to Plots 12 and 14
have rendered some of the potash of the soil available, and the
quality of the grain is better than on Plots 10 and 11. Plot 11,
receiving nitrogen and phosphoric acid, produces distinctly
worse grain than Plot 10, showing by far the smallest grains,
the lowest weight per bushel and value, and the highest
proportion of " tail " corn ; again demonstrating how the
continued use of phosphoric acid and ammonia has depleted
the potash in the soil of this plot. The plot receiving farm-
yard manure gives corn of about the same size and weight
per bushel and also the same proportion of corn to straw, as
Plot 7, which receives a medium amount of ammonium-salts.

Turning now to the influence of season on the wheat crop,
Table XX. shows the yield of both grain and straw, the

COMPARISON

^ OF

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58

EXPERIMENTS UPON WHEAT

weight per bushel, and the proportion of grain to straw, in
1879, a typical wet year, and in 1893, an exceptionally dry one ;
the corresponding averages for the whole fifty-one years being
put alongside for comparison. Table XXI. shows the
monthly rainfall for the same periods, during the harvest-year
from 1st September to the following August 31st.

Table XXI. — Rainfall at Eothamsted {Large Gauge). Com-
parison of a wet and a dry harvest-year with the average
over 50 years (1852-3 to 1901-2).

isrs-o.

1S92-3.

Average, 50 years
(1852-3 to 1901-2).

Septembe

October

Novembei

December

January

February

March

April

May

June

July

August

•

Inches.
1-46
2-99
4-5fi
1-60
2-85
3-80
1-18
2-79
3-48
5-55
4-24
6-56

Inches.
2-46
3-99
2-06
1-63
2-05
3-62
0-42
0-25
1-22
1-00
3-00
2-38

Inches.
2-56
3-15
2-68
2-33
2-35
1-79
1-78
1-86
2-23
2-31
2-55
2-65

Tota

I

41-05

24-08

28-24

It will be seen that for the crop of 1879 there was a total
rainfall of 41 inches, of which 23*8 inches fell in the last six
months, as against 8-3 inches out of a total of 241 inches for
the corresponding periods of the harvest-year of 1892-3.
While the amount of grain produced is not so very different in
the two years, the wet year grew a far bigger crop of straw,
so that the grain weighed httle more than one-third of the
straw, whereas in the dry year grain and straw weighed about
the same. The weight per bushel of the grain is very much
higher in the dry than in the wet year, averaging 61*2 lb.
against 55*0 lb. In the dry years the manures have com-
paratively Httle effect, the crops on all the plots being brought
nearer to a uniform level ; in the wet year, on the contrary, the
difference due to manuring are very much accentuated. The

COMPAEIS(^\ OF WKT AND DIJV SKASONS ."O

plot receiving farmyard niaiuirc occupies about its usual position
in the wet year ; but whereas it usually gives about the same
proportion of grain to straw as the medium nitrogen plots, in
1S79 it was rather better than they were in tliis respect. In the
dry year this plot gives by far the heaviest yield of grain, almost
up to its usual average ; the straw also is nmch less reduced
than on the plots receiving artificial manures, due no doubt t(^
the water-retaining powers of the dung. It is interesting to find
that Plot 9, receiving nitrate and minerals, gave the best crop
both of grain and straw in the very wet year 1H79, whereas in
the dry year, 1893, the crop on this plot fell below the crop of
Plot 6, which received the same amount of nitrogen as
ammonium-salts, though on the average of years the nitrate
answers better. This is contrary to the generally received
opinion that nitrate of soda is the more effective in dry, and
ammonium-salts in wet seasons.

The very low crops on Plots 9b and 10, which receive
nitrogen only, show that in a wet season the plant has very
little power of obtaining minerals from the reserves in the soil :
and the great jump in crop produced l)y adding superphosphate
to the ammonia on Plot 11 shows that the phosphoric acid is
then more difficult to obtain. In a wet season when the
maturity of the plant is retarded, the ripening effect of
phosphoric acid will be exceptionally beneficial. In the dry
season the lowest returns come from Plots 10 and 11 (witli-
out potash), and the potash on Plots 7 and 13 has an
exceptionally marked effect, showing that under conditions
of drought the plant specially responds to an abundance of
potash in the manure. Probably the explanation is that a
free supply of potash prolongs the growth of the plant, and
tliat in the absence of jootash the ripening action of the
phosphoric acid comes into play prematurely and stops
development at a very early date, since it is acting in the
same direction as the heat and dryness of the season.

The indication of the 1879 and 1903 returns, that the
superiority of nitrate of soda over ammonium-.salts is more

60

EXPERIMENTS UPON WHEAT

marked in a wet than in a dry season, is confirmed by a
further examination of the records over a series of years.
Taking the last thirty years and dividing them into two groups
according as the rainfall is above or below the average, and
then comparing the yields of the two plots, which receive equal
amounts of nitrogen, but one as nitrate of soda and the other
as ammonium-salts, we find that in the dry seasons the yield
from ammonium-salts is 86 '6 per cent, of the yield from
nitrate of soda. In the group of wet seasons, however, the
yield from ammonium-salts is only 78 "8 per cent, of that given
by nitrate of soda, as shown in Table XXII. Thus the wet
seasons are on the whole more favourable to nitrate of soda
than to ammonium-salts. Presumably in the very wet and
cold seasons the conditions are unfavourable to the nitrifica-
tion of the ammonium-salts, and the immediately available
nitrate of soda is more effective.

Table XXI 1. — Broadhalk Wheat. Comparison of the yield of Dressed
Grain ivith Nitrogen as Ammonium-salts or Nitrate of Soda, in seasons
when the Rainfall was heloio or above the average, 30 yeai^s (1873-1902.)

Rainfall.

Dressed Grain
per acre.

Ratio
of yield

Am. -salts

to that

of

Nit. Soda
= 100.

Plot 9a.
Nitrate Soda.

Plots
6 and 7.
Ammonium-
salts.

14 Seasons heloio average Rainfall
16 Seasons alove average Plainfall

luclies.
24-23
33-13

Bushels.
30-6
32-1

Bushels.
26-5
25-3

S6-6

78-8

One of the most critical periods in determining the yield of
wheat appears to be the winter months ; if the wheat be sown
in October or early November it spends the next three or four
months almost wholly in developing its system of roots.
Should the weather be wet and the soil in a satui'ated condition
the root- system will be restricted, both because of the deficient
aeration and because the roots need not extend far in order to
obtain the water necessary for its growth. From the indifferent

EFFECT OF AVINTKIJ IJAIWAI.I

CI

development of roots which thus results, the plant scciii>
never able to recover, so that a wet winter is almost invaiiai)lv
followed by a poor wheat cro}) at harvest. This fact is illu>
trated by Table XXIIL, in which a comparison is made
l)etween the average wheat crop on three of the i)lots ((J, 7.
and 8) following the ten wettest and the ten driest winters
respectively during the period ls.")2-HH)*2, as measured by the
rainfall in the four months November to February inclusive.

Table XXIll.—BroadbalJc Wheat. Comimrison nf 10 Wet test and
10 Driest Winters (1852-1902).

10 U'eltesl
Winters.

10 Dritil
Winters.

Rainfall, November to February inclusive
Average Crop per acre, Plots 6, 7, and 8

. Inches
. Bushels

13-01
26-2

5-79
34-9

Comparison of Winters with more oi
(1S70-1 to

less than th
1903-4).

e average percolation

19 Seasons

above

average

Percolation.

15 Seasons

bflOW 1

average
rercolation. ;

5 02
31-5

Percolation (60-inch gauge), Nov. to Feb.
Average Crop per acre, Plots 2, 6, and 7 .

. Inches
. Bushels

9-43
26-8

The ten dry winters with an average rainfall of ")"70 incho
were follow^ed by an average wheat crop of 3-l"9 bushels per
acre on the plots selected for comparison. The ten wet winters
with a corresponding rainfall of 13 inches were followed by an
average wheat crop on the same plots of only !20-'2 bushels.

Making the comparison in another way and dividing the
thirty-four seasons 1870-1004 into two groups according to
whether the percolation during the winter months, November
to February, was above or ])elow the average, we obtain a
similar result. In fifteen seasons with a low winter pei-colation
averaging 5*02 inches, there was an average crop on tlie
selected plots of 31 5 Inishels per acre; in the other nineteen
seasons of high percolation, 043 inches, the avei-agf emp on

62

EXPEEIMENTS UPON WHEAT

the same plot was only 26 '8 bushels. Although of course the
weather later in the season has a great effect in determining
the wheat crop, it is yet evident that the most critical period of
its growth lies in the first four months, when the foundation of
roots is being laid.

On the whole, it will be seen that the great diff'erences of
manuring to which the Rothamsted plots have been subject
for so long a period have a much greater effect on the gross
amount of crojD than on the quality of the grain. Space does
not admit of a discussion of the detailed analyses of the crops,
but they show similar results in regard to the comparative
stability of the nature of the grain. Fluctuations in the amount
of the crop due to season or maniu*ing are reflected to a much
smaller degree in the composition of the grain ; the composition
of the straw, however, shows wider variations, induced by the
differences in the manure applied.

II. — Wheat after Fallow, and in Rotation.

Since the year 1856 two half-acre plots in the Hoos field
have been cropped in alternate years with wheat without
manure ; every year one of the plots is in wdieat while the other
is being fallowed, so that the wheat crop always succeeds a
year's bare fallow.

The accompanying Table (XXIY.) shows the average

Table XXIV. — Wheat ivithov.t Ilanurc. — Grown continuously {Broadbalk
Field), and in alternation ivith Falloio {Hoos Field). Average Proeluce
per acre, 47 years (1856-1902).

Wheat every Year.
(Broadbalk Field, Plot 3.)

Wheat after Fallow.
(Hoos Field, Plot 0.)

Dressed Grain.

straw.

Dressed Grain.

Straw.

Bushels.
12-7

Cwt.
10-0

Bushels.
17-1

Cwt.
14-2

produce, grain and straw, on the cropped plot following fallow,
compared with the crops on the plot in Broadbalk, which
is continuously cropped w^ithout manure. It will be seen that

EFFECT OF FAI.l.oWINd 63

the produce of wheat after fallow is consi(leral)ly hi^lKM* than
when it is grown continuously, 171 against 1*J7 l>iishols per
acre ; but if reckoned as produce over the whole area, lialfin ciMip
and half fallow, the whole acre grows nuich less huth of grain and
straw than where the crop is grown year after year on the same
land. A given area of land would therefore be more productive
when cropped every year than if the crop were alternated with
fallow. The superior yield t)f the portion in crop after a
ffiUowing may to some degree be attributed to the greater
freedom from weeds, but in the main it is due to the production
of nitrates from the humus of the soil during the sunnner when
it is fallow, a process which is much stimulated by the stirring
and aeration the soil receives. The success of a fallowing
depends upon these nitrates remaining for the succeeding croj),
since they are not retained by the soil they may be entirely
washed out by heavy autumnal rains.

That the autumnal rainfall is the great factor in determining
whether a bare fallow shall be profitable or not to the following
crop, may be well seen by comparing the crops yielded by
these plots with the rainfall and percolation which took jjlace
during the autumn previous to each crop.

The percolation through GO inches of bare soil for the four
months September to December inclusive, as measured by the
drain gauge, amounted on the average to 6 ■•45 inches for the
seasons 1870-1901. If, then, we divide the years into tw<.
groups according as the autunmal percolation is al)ove or l»el(»w
the average, and allot to each year the crops on the continut»us
wheat and wheat after fallow plots for the harvest following
the given percolation, we shall obtain the average results shown
in Taljle XXV. and illustrated in the diagram Fig. 1>.

Taking the seasons of small rainfall, averaging .s-88 inclies
f(jr the four months September to December inclusive, the
percolation was only 4 inclies, and the total {»n.diut' on the
wheat after fallow plot was -27 \V> U*. as against 1^10 11>. nn
the continuous wheat plot, or a gain of O:?:! 11«. dn-- to
fallowing.

64

EXPERIMENTS UPON WHEAT

Table XXV. — Effect of Wet or Dry Autumns on the increase of the
JVheat Croi) due to FallovAng (1870-1902).

16 Seasons

less

than average

Rainfall.

le Seasons

more

than average

Rainfall.

Rainfall (Sept. to Dec. inclusive) In.

Percolation through 60 in. of Soil (Sept. to Dec. inclusive) In.

Total Produce (Wheat after Wheat) . . . .Lb.
Total Produce (Wheat after Fallow) . . . .Lb.

Increase due to Fallowing Lb.

Percentage increase due to Fallowing .....

8-88

13-66

4-03

8-92

1810
2743
933
51-5

1627
1757
130
7-9

For the wet autumns, however, with an average rainfall of
13 -66 inches and a percolation of 8-92 inches, the wheat after

Small Rainfall and Percolation

Large Rainfall and Percolation.

CROP
-30001b,

RAiN
Inches

Rainfall -Inches] ^^ Wheat after Wheat - lb. per Acre

> Sept.toDec.
R??^ Percolation -inches I [JJ^ Wheat after Fallow - lb. perAcre ,

mB Increase due to Fallowing.

Fig. 9.— Effect of Wet or Dry Autumns on continuous Wheat, and Wheat
alternated with Fallow.

WHEAT GIJOWX IN IJOTATloN .;:,

fallow yielded 1757 11). against lOiT lit. on the coniiiuKuis
wheat plot, or a gain of 130 ll)s. only dne to t'allowinL;.

It will be seen that the bare ftillow increased the wheat crop
coming after it by nearly 52 per cent, when a comparatively di y
autumn succeeded the fallow, but the increase was less than s
per cent, when there was much rain and percolation after the
summer fallow.

It is interesting to compare these two plots, both without
manure, with the continuously unmanured plot in the Agdell
field, which comes into wheat once every fom* years in the
course of the rotation (see p. 100). The plot in question has
received no manure since 1852 ; it is cropped on a four-course
rotation, beginning with turnips which are completely removed

Table XXVI. — Wlienf gwicn vnthouf Manure al liofliiniistnf.
(1) Grown continuously ; (2) In alternation v:ifh Fa / loir ;
(3) In Four-course rotation. Average for the 12 yearn
(1855, '59, '63, '07, '71, '75, '79, '83, '87, '91, '95, and 1899).

Dressed Grain per acre.

Continuous Wheat.
(Broadbalk, Plot 3.)

Wheat after Fallow.
(Hoos Field, Plot 0.)

Itotetion Wheat.
(Agdell Field, Plots 21-22.)

Bushels.
12-4

Bushels.
18-1

Bushels.
23-6

from the land, after the turnips barley is taken, then comes a
season of bare fallow before the wheat. It will thu.s be seen
that three crops are removed in the course of the four year.'^,
but so very small is the turnip crop that practically the land i.s
cropped only every other year. For the twelve years during
which comparison is possible the average crop of wheat grown
thus in roUition on continuously unmanured land lia.s been 2s»;
bushels per acre, as against IS'l bushels for wheat afbr fallow
and 12"4 liushels for continuous wheat.

It is diilicult to explain this superiority of the wheat grown
in rotation over the wheat atler fallow. There are lui ihoil'
residues in the land in the one case than in the other, the land

66

EXPERIMENTS UPON WHEAT

is equally clean and has similarly received a summer fallowing
before the wheat crop. In the case of the rotation plot, however,
the particular stratum of soil usually occupied by the wheat
roots is only drawn upon once in four years, the intermediate
crop being the much shallower-rooted barley.

III. — Trials of Varieties of Wheat.
In the eleven years 1871-1881, trials were made of about
twenty varieties of wheat under the ordinary conditions of

Table XXVIIa.— Varieties of Wheat groion at Rothamsted. Produce of
Grain 'per acre ihiisheh). Results arranged in order of highest average
yield.

1871.

1S72.

1873.

1874.

1S75.

1876.

1877.

1878.

1879.

1880

1881.

Mean.

Rivet (Red)

48-1

67-0

48-4

42 -.5

49-6

66-1

16-0

22-4

52-2

45-8

White Chaff (Red) .

40-6

.5.5-1

40-2

49-5

48-4

59-0

22-8

28-1

,54-5

44-2

Club Wheat (Red) .

36-0

45-8

47-5

59-6

46-6

47-6

49-5

61-0

23-5

16-4

43-4

43-4

Golden Drop (Red),
Hallett's

39-5

49-8

44-2

.51-8

38-1

48-4

49-5

.52-8

21-0

18-9

50-8

42-3

Bole's Prolific (Red) .

33-6

42-8

45-2

48-1

43-8

41-4

44-8

52-8

31-0

24-5

46-5

41-3

Hardcastle (White) .

46-5

42-0

49-6

33-9

44-0

42-1

54-0

21-5

24-4

45-6

40-4

Red Rostock .

37-0

46-3

53-8

37-4

40-0

46-4

57-0

8-5

28-4

4.5-8

40-1

Red Lani^ham .

30 8

43-8

34-1

53-1

34-9

42-5

42-9

.50-8

25-8

28-6

48-5

39-6

Bristol Red

29-4

44-4

39-5

.53-4

31-6

42-4

44-1

.52-1

21-6

30-6

46-2

•39-6

Red Wonder .

31-2

43-8

37-1

55-1

33-2

44-2

41-6

52-1

22-0

28-2

45-9

39 %5

Red Chaff (White) .
Browick (Red) .

32-8
35-3

37-0
40-5

35-3

38-5

48-8
51-1

34-3

38-5

43-8
39-]

41-0
40-9

49-5

24 -0

19-6

47 -3

39-0
38-6

Casey's White .

29-9

42-1

.37-0

.52-1

39-0

45-5

43-0

47-8

L5-4

24-1

42-9

38-1

Red "Nursery .

34-1

4.5 -3

27-1

41-1

39-0

37-5

40-6

47-8

.30-9

27-5

46-0

37-9

Woollv Ear (White) .

31-2

42-8

37-0

51-3

36-1

46-6

37-5

48-3

20-0

21-0

44-1

.37-8

Burwell (Old Red

Lammas)

31-1

41-3

35-1

47-3

38-5

38-4

39-0

46-3

27-0

27-0

44-8

37-8

Golden Rough Chaff
(Red) .

33-0

39-3

38-5

.52-1

38-8

38-4

36-4

46-8

14-4

31-3

41-6

37-3

Chubb Wheat (Red).
Original Red (Hal-

28-4

40-0

35-8

50 5

38-3

40-3

41-0

55-1

20-8

14-9

36-6

lett's) .

30-0

35-3

36-4

43-6

26-0

40-1

44-4

36-0

Victoria White (Hal-
lett's) .

33-8

45-3

38-3

44-3

33-8

41-1

42-6

43-9

14-9

15-8

44-0

36-2

White Chiddam

26-9

38-8

31-8

42-0

32-4

37-0

37-6

49-8

1T9

27-4

47-1

34-8

Hunter's White (Hal-
lett's) .

Mean

26-9
32-2

39-8
42-3

38-6

38-8

45-4
50-7

26-4

43-0

42-5

40-0

42-3

17-4
20-5

22-8

46-5

.34-3
39-1

36-8

42-9

51-8

24-1

farming, the wheats being grown in a different field each year.
Table XXVIIa. shows the results obtained in bushels per
acre each year, and Table XXVIIb. the same results
reduced each year to the common ratio of the average

VARIETY riMAl.S

crop taken as 100. The final order represents tlie mean
of these last figures, and shows the average relative jjusition
occupied by each variety when seasonal tluet nations are
eliminated and each year is allowed the same weight in

Tablk XXVIIb. — Varieties of Wheat grinm at Eothaimted, 1871-lKSl.
Mean Froduce of all the vaneties each year taken cw 100.

Variety.

1871.

1872.

1873.

1874.

1875.
131

1870.
100

1877.
116

1878.
128

1879.

18S0.
93

1881.
112

Mean
118

Rivet (Red)

125

132

78

White Chaff (Red) .

105

109

109

117

113

114

111

117

117

112

Chib Wheat (Red) .

112

108

122

119

127

112

115

118

115

68

93

110

; Golden Drop (Red).

i

Halielt's

123

119

114

102 1 104

114

116

102

102

78

109

108

Bole's Prolific (Red) .

104

101

116

95

119

97

104

102

151

102

100

108

j Red Langham .

9.5

104

88

105

95

100

100

98

126

119

104

103

Red Wonder .

97

104

95

109

90

104

97

101

107

117

99

102

i Bristol Red

91

105

102

105

86

100

103

101

106

127

99

102

Hardcastle (White) .

110

108

98 i 92

104

98

104

105

101

98

102

Red Rostock .

115

119

106

102

94

108

110

41

118

98

101

Red Nurserv

106

107

70

81

106

88

95

92

151

114

99

101

1 Browick(Red) .

109 1 96

99

101

105

92

95

96

117

81

102

99

Burwell (Old Red

t

Lammas)

97 98

90

93

105

90

91

89

132

112

96

99

WooUv Ear (White) .

97 1 101

95

101

98

111

87

93

98

87

95

97

! Casey's Wiiite .

93 100

96

104

106

107

100

92

75

100

92

97

1 Red ChaflF (White) .

102

ss

91

96

93

103

96

...

96

i Golden Rough Chaff

(Red) .

102

93

99

100

106

90

85

90

70

130

90

96

1 Chubb Wheat (Red) .

88

95

92

100

104

95

97

107

101

62

94

Victoria White (Hal-

lett's) .

10.5

107

98

87

92

97

99

85

73

65

95

91

Hunter's White (Hal-

lett's) .

S3

94

99

89

72

103

93

82

85

95

90

. Original Red (Hal-

i letfs) .

93

83

94

86

71

94

104

...

89

i While Chiddam

83
100

92
100

82
100

83
100

88
100

88
100

88

100

58
100

114
100

I'oi

100

88
100

100

making up the average. It is evident from the tluetuating
position any wheat occupies from year to year that variety
tests require a good many repetitions before great trust can
be placed in their results. In the present case five wheats
stand out as considerably heavier croppers than the others on
the strong Ilothamsted land —Rivet, White Chaff (Ive<|), Club.
Golden Drop, and Bole's Prolific. ( )f the.se. liivet is perhaps the
oldest English wheat remaining in cult i\ at inn. known everywhere
for its heavy yields on strong land, its coarse straw, tlie inferior
quality of its grain, and its bearded character. White Chafl

68 EXPERIMENTS UPON WHEAT

(Red) appears to be the wheat now grown as Square Head's
Master, Teverson, etc., just as Club wheat is the original form
of the wheat now generally known as Square Head. These
two wheats are perhaps the most generally grown of any
at the present time. Golden Drop is an old wheat of fair
quality, still very generally grown. Bole's Prolific is no longer
grown as such, but may represent the wheat now known as-
Pilgrim's Prolific and Red Giant, not uncommon in the South
Midlands.

Practical Conclusions

1. The results obtained on the rotation field show that
wheat, with its deeply-rooting habit and its long period of
growth, is in less need of direct manm'ing than most crops of
the farm. If the land is in good heart it can usually be grown
with the residues in the soil, especially if it follows a clover
crop.

2. Whenever manure is needed it should be mainly nitro-
genous, and nitrate of soda generally answers better for wheat
than sulphate of ammonia. After a wet autumn and winter
a top-dressing of nitrate of soda, 1 to 1^ cwt. per acre, will be-
found particularly valuable.

3. When wheat is grown two or three times in succession,,
about 1 cwt. per acre of some slow-acting nitrogenous manure-
and 2 cwt. of superphosphate, should be ploughed before-
seeding, and a top-dressing of 1 to 2 cwt. per acre of nitrate
of soda should be applied in February. Only on the lightest
sandy and gravelly soils will any return be obtained for the-
use of kainit and other potash salts with wheat.

References

" Report of Experiments on the Growth of Wheat for Twenty Years in'
succession on the same Land." Join: Roy. Ag. Soc, 25 (1864), 93 and
449. Rothamsted Memoirs, Vol. III., No. 4.

"Our Climate and our Wheat Crops." Jour. Roy. Ag. Soc, 41 (1880), 173.
Eothmnsted Memoirs, Vol V., No. 11.

'^ On the Composition of the Ash of Wheat Grain and Wheat Straw, grown.

KEFKKKXCKS <;0

at Rothanistod, in dirtciTiit Seasons, juul by (liHcrt-iit Manurts. '" 'I'lau.y.
Chvm. Sor., 45 (1884), 30."). Untlunusti-d Memoirs, Vol. VI., No. 2.

Report of Experiments on the (irowth of Wluat for the Second Period
of Twenty Years in succession on the same Land." .Iimr. lunf. .tg. S(m:,
45 (1884), 391. Rothamsied Mnimirx, \'ol. VI., No. 3.

On Airrieultural Investigation; illustrated by Results of I'.xperinit iits at
Rothamsted, on the Growth of Wheat, for Forty ^ears in siucession on
the same Land." Being a Lecture delivered at the .Michigan State
Agricultural College, Lansing, Michigan, October 14, 1^84; and at
Rutgers' College, New Brunswick, N..I., October 27, 1884. Roihanistcd
Memoirs, \'ol. W., No. 5.

CHAPTER V

EXPERIMENTS UPON BARLEY

I. The Continuous Growth of Barley upon the same Land, Hoos Field :

A. Maintenance of Yield under the Continuous Growth of Barley on

the same Land.

B. Effect of Nitrogenous Manures.

C. Effect of Minei-al Manures.

D. Character of the Crop as affected by Manuring.
IL Barley grown in Rotation — Agdell Field.

Practical Conclusions and References.

I. — The Continuous Growth of Barley upon the same
Land, Hoos Field.
The experiments on the continuous growth of barley were
begun in the Hoos field in 1852. The arrangement of the
plots and the manures applied to each plot have practically
been unchanged since, so that the plots to-day show the
effects of more than fifty years' continuous growth of barley
under the same treatment year after year.

The Hoos field adjoins the Broadbalk wheat field and the
soil is very similar.

The following varieties of seed have been sown : — Chevalier,
twenty-nine years, 1852-1880 ; Archer's Stiff Straw, ten years,
1881-1890; Carter's Paris Prize, seven years, 1891-1897 ; and
Archer's Stiff Straw, 1898 and since.

The manures are sown in the spring, and ploughed in about
a week or a fortnight before seeding. The plots do not run the
whole length of this field, as in Broadbalk, Instead, there are
four longitudinal strips receiving different combinations of the
mineral manures; these are all crossed by four breadths

]\rANUHIX(; OF TLOTS

71

receiving different nitrogenous manures. The niinoral nianurin*^
on the strips is as follows :— (1) none ; ('2) phosplioric acid only,
no potash or alkali salts ; (:3) potash, magnesia, and soda, im
phosphoric acid ; and (4) complete nu'neral manure, supj)IviiiL:
both phosphoric acid and the alkaline salts. l\aeh of tlicse is
combined with the four different cross-dressin«:s of nitro<'enous
manures—Series O no nitrogen, Series A anunonium -.salts,
Series N nitrate of soda, and Series C rape cak(\ There
are other plots, one of which has received farmyard manurt'
each year, and a second which received farmyard manure for
the first twenty years but has since been unmanured.

Table XXVIII. shows the nature and (pianLity of thr

Table XXVI I L — Experiments on Barley, Hoos Field. Mnnurintj of
the Plots per acre per annum, 1852 and since.

Plot.

Abbreviated Description
of Manures.

Nitrogenou8 Manures.

Mineral Manures.

II

1

1

V

•<

Lb.

It
5|

Lb.

11

Lb.

Lb.

Tons.

Lb.

Lb.

C«t.

10
20
30
40

Xo Minerals, and no Nitrogen .
Superphosphate only, do.
Alkali Salts only, " do.
Complete Minerals, do.

3\.

200
200

fob

100

16b
100

lA
2 A
3A

4A

Ammonium-salts alone
Superphosphate and .\mmonium-salts
Alkali Salts and do.
Complete Minerals and do.

200
200
200
200

3-5

260
200

16b

100

ibb
100

IN
2N
3N
4N

Nitrate of Soda a'one ....
Superphosphate and Nitrate of Soda .
Alkali Salts and do.
Complete .Minerals and do.

...

275
27.'i
275
275

3-5

26b
21(0

100
100

10b
100

IC
2C
3C
4C

R.il)e Cake alone ....
Superphosphate and Kape Cake
Alkali Salts and do.
Complete Minerals .md do.

...

1000
1000
1000
1000

...

:::

:j-5
3-5

26b
200

ibb
100

fob
100

7-1

Unmanured (after dung 'JO yrs.,lSr.2-71)

...

7-2

Farmyard Manure ....

U

...

manures applied each year to the plots. Table \ X I X. sh()w>
the average production of ^n-ain and straw for ilie whole
period, for the last ten years. an<l toi- the single year I'.Hrj.

72

EXPERIMENTS UPON BARLEY

Table XXIX. — Experiments on Barley, Hoos Field. Produce of Grain
and Straio per acre. Averages over 51 years (1852-1902), find over
10 years (1893-1902). Also Produce in 1902.

Plot.

Abbreviated Description
of Manure:?.

Dressed Grain.

straw.

<

1

<

c

if

•<

of

i.i

<

i

a

Bush.

Bush.

Bush.

Cwt.

Cwt.

Cwt.

10
20
30
40

No Minerals, and no Nitrogen .
Superphosphate onlv. do.
AlkaH Salts only, * do. . .
Complete Minerals do.

15-3
20-1
16-1
20-4

10-1

13-6

8-9

12-4

14-3
21-7
13-3

18-2

8-8
10-2

8-9
10-8

6-4

7-8
f.-9
8-0

5-6

9-9

6-3

10-9

1 A
•2 A

3 A

4 A

Ammonium-salts alone
Superphosphate and Ammonium-salts .
Alkali Salts and do.
Complete Minerals and do.

26-5
39-9
29-4
42-1

16-2
26-8
20-8
35-1

21-7
39-8
20-0
40-3

14-9
22-5
17-0
24-9

10 -.T
16-5
12-9
20-5

9-7
20-8
10-4
23-1

IN
2N
3N

4N

Nitrate of Soda alone ....
Superphosphate and Nitrate of Soda .
Alkali Salts and do.
Complete Minerals and do.

30-4
44-0
31-5
43-5

20-5
35-9
23-4
34-9

25-1
45-9
22-0
36-5

18-1
26-2
19-7
27-4

14-4
23-0
15-3
22-6

14-1
26-1
10-0
23-4

IC
2C
3C
4C

Rape Cake alone .....
Superphosphate and Rape Cake .
Alkali Salts and do.
Complete Minerals and do.

39-2
41-0
37-7
41-0

31-0
33-2
29-6
32-5

38-7
41-4
39-7
40-7

22-4
23-9
22-4
24-5

18-4
19-6

18-1
20-1

20-5
24-2
22-7
25-4

7-1
7-2

Unmanured (after dung 20 yrs., 1852-71)
Farmyard Manure . . . j

27-0*
47-6

19-9
42-6

27-5
42-4

15-4*
29-1

12-8
28-8

14-3

- Average, 31 years (1S72-1902).

Table XXX. shows the average production during each of the
successive ten year periods from 1852.

A. Maintenance of Yield under the Continuous GrowtJi
of Barley on the same Land.

One of the plots, 1-0, has been without manure since the
beginning of the experiments. Under the continuous barley -
growing the decline in production has been much more marked
than on the wheat plot similarly treated, the average crop having
been only 10 bushels for the last ten years, against an average of
more than 15 bushels for the whole period. The continual fall of
crop from decade to decade would seem to show a progressive
exhaustion of the soil, without reaching the comparatively stable
condition of the continuously unmanured wheat plot. The more

YIELD IX SUCCKSSIVK DKCADKS

Table XXX. — U.q)crimcn/s mi Jiorlci/, JIaos Field. ^lrinii/,J'ii,ih('ij>ir
acre of D/rsscd Grain and Straw over siirrrssivr lO-i/ear jtrriods, /mm
1852-1901 inclusive.

Plot.

Abbreviatmi Description
of Maimros.

AvormKM over

1

i

If

2|

1

1

Dressed Grain.

Bu«h.

1

Uush.

Bll8h.

Uuah.

Buiili. 1

Bu«h.

lO
20
30
40

No Minerals, and no Nitrogen
Superphosphate only, do.
Alkah Salts only, " do.
Complete Minerals, do.

22-4
27-9
24-7
30 5

17-5
23-2
20-1
24-4

13-7
17-9
14-5
17-7

12-7 ,
17-7 1
12-4
16-9 1

100

13-r.

91

12-8

15-3
20-0
16-2

20-5 ;

lA
2A
3 A
4A

Ammonium-salts alone ....
Superphosphate, and Ammonium-salts
Alkali Salts, do.
Complete Minerals, do.

33-6
45-6
35-0
46-1

31-2
48-4
35-0
46-4

26-2
40-5
30-1
41-0

25-0
36-7
25 •.'i

40-7 ;

16-6
28-0
22-1
36-3

26-5
39-8
29-5
421

IN
2N
3N
4N

Nitrate of Soda alone ....
Superphosphate, and Nitrate of Soda .
Alkali Salts, do.
Complete Minerals, do.

39-7
48-9
38-6
49-9

34-2

49-6
36-1
49-5

28-2
42-0
29-9
42-2

28-5
42-7
29-1 ,
40-4

21-9
36-5
24-8
36 0

30 -.5
43-9
31-7
43-6

IC
2C
3C
4C

Rape Cake alone

Superphosphate, and Rape Cake .
Alkali Salts do.
Complete Minerals, do.

47-0
47-8
44-0
47-4

43-6
4.5-7
43-2
47-2

39-0
41-5
37-4
41-9

35-4
38-4
33-8
36-0

1

31-3
33-7
29-7
32-4

39-3
41-4
37-7
41-0

7-1
7-2

Unmanured (after dung 20 yrs. , 1 852-71 )
Farmyard Manure ....

|45-0

..{

34-2
50-2

26-4
47-6

20-3
41-3

3;V5
47-7

Cwt.

Strav

r.

Cwt.

Cwt.

Cwt.

Cwt.

Cwt.

10

2 0

3 0
40

No Minerals, and no Nitrogen
Superphosphate only, do.
AlkaU Salts only, do.
Complete Minerals, do.

' 13-4
14-9

, 13-9
16-1

10-2
11-8
10-7
12-6

6-9
8-4
7-1
8-5

6-8
8-1
6-8
8-4

6-6
7-8
6-3
8-0

8-8
10-2

9-0
10-7

lA
2 A
3A

i4A

Ammonium-salts alone ....
Superphosphate, and Ammonium-salts
Alkali Salts, do.
Complete Minerals, do.

19-8
27-9
21-9
28-9

17-4
27-5
19-7
28-0

13-6
20-5
15-6
23 -y

13-4

19-7
14-ti
23-4

11-0
17-0
13-9
21-1

l.'.-O
22-5

IN
2N
3N
4N

Nitrate of Soda alone . . . .
Superphosphate, and Nitrate of Soda .
Alkali Salts, do.
Complete Minerals, do.

24-0
31-9
25-8
34-6

20-1
29-2
22-1
30-1

15-4
22-8
17-5
24-4

16T.
23-9
l7-«
24-5

14-8
23-3
16-4
23-5

18-2
26-2
19-9
27-4

IC
2C
3C
4C

Rape Cake alone

Superphosphate, and Itape Cake .
Alkali Salts. do.
Complete Minerals, do.

29-4
30-8
28-9
31-3

24-3
26-0
2.'i-3
27-8

21-1
22-3
20-8
23-1

18-9
20-7
18-9
20-5

18-6
19-8
IS -4
19-9

22-5
23-9
22-5
21-5 ,

I7-I
7-2

Unmanured (after dung 20 yrs., 18r> 2-71)
Farmyard Manure ....

\26'6

29 -9 {

18-5
801

14-5
29-8

13-3
29-9

20-6
29-2

74

EXPERIMENTS UPON BAKLEY

limited root-range of the plant would luring about a complete-
exhaustion of the available soil much sooner with barley than
with wheat, but there is evidence that the decline in the yield
of these barley plots is to some extent due to a run of les&

GRAIN

Bushels
per Acre

bU

y

.y_.,

"■■••■•..

7-2

•

'■•••....

mean of
4A,N8tC.

•3 n

>

^^

— - — --_

-^^

1-0

10

562-187I

ieS2-l9C

Fig. 10.— Yield of Barley during successive 10-year periods (1852-1901).

Plot 7-J.— Farmyard Manure. Plots 4 A, N, and C— Each receive Complete Minerals,

+ X. as .\mm,-salts. Nitrate Soda, or Rape Cake. Plot 1-0.— Unmanured.

ftivourable seasons. Both the continuously dunged plot, which
must be gaining fertility, and the plots which receive heavy com-
plete dressings of artificial manures show a similar decline in the
average production for the last four decades, as may be seen

COMPAKMS(^\ WIIFA' GKOWN IN IJOTATION 7.".

from diagram Fii:. 10. wliicli sliow.s tlir avurage yield of grain on
the mimamired plot, on the dunged plot, and the mean ol" tlie
three plots completely manured with artitieial manures. 'I'hr
decline in the production of the dunged plot is the least markrd.
although consitlerable.

Again, the Agdell field, which conuvs into harley everv
four years, has shown a decline in its yield of harley during
the last fifty years, wdiich is very similar to tliat of tli<>
continuous l)arley plots when the yields of each lidd an-
compared for the same years. Table XX XL shows the total
produce from the uiimanured and two of the completely

Table XXXI. — Barlei/ r/nncu lontinuoiisJy, JFoos Fic'd, ami in fwr-roursr
rotation, Agdell Field. Convpari<ion of the Total Produce (Grain and
Straw) per acre in the years 1853, '57, '61, '65, '69, '73, '77, 'Hi, 'xr>.
'89, '93, '97, and 1901.

Continuous Barley,
U(xw Kield.

Kotation lUrlev.
Agdell Field.'

OompMe
,. , Farm- Minerals

— ''• .M^nl. 1 Nrt';i.e
1 Soda.

1 1

Complete

fn- Minerml

manurp<l. and Nit.

Manure.

Plot
1-0.

Plot
7-2.

Plot
4N.

1

PloU PloU

2l»nd22. 8 and 4.

Mean of :-

First r, vears (18.->.3. Y.7. '61, '6.', 't59)
Middle ■-, vcars (18(39. 73. 77, 'si, 'Sr,) .
Last :. years (ISSr.. '89. '9:3. '97. 1901) .

Mean of 13 years

Lb.
2.121
lt>2<)
1001

Lb.
5738
6028
5122

Lb.
6694

.5681

40<;»>

Lb. Lb.
3922 90.15
2730 5718
2100 4579

173.-) 5.'.I9 .M'l-'

2960 5394

manured plots in the Hoos field for the years when barley
was grown in the Agdell rotation Held, for which field the
crops on the unmanured and the mo.st highly iiiaiiuivd pl«»t
are also given. It will be seen that the barley crop grown
in rotation on the plot that is highly manured (a complete
manure is put on for tiie preceding Swede crop, which i.s
returned to the land) shows the same decline in yield as the
crop on completely manured plots growing barley continuously,
the average production ovei- the whole period and in succes.sive

76 EXPERIMENTS UPON BARLEY

twenty-year periods being very similar. This seems to show
that the decline in production on the manured plots in the
later periods in the Hoos field is due to season, and not
to the fact that barley has been grown continuously on
the same land. The unmanured plot, however, under con-
tinuous barley shows a much greater progressive decline
than the corresponding unmanured plot growing barley in
rotation, where the land is practically fallowed in alternate
seasons. On the whole, the results point to the probability
that unmanured land will become unable to grow barley con-
tinuously at a much earlier date than will be the case with
wheat, so comparatively restricted is the range of the barley
roots.

B. Effect of Nitrogenous Manures.

The effect of nitrogenous manures upon the barley crop is
best seen by comparing the yields of the various Plots 4, all of
which receive the same mineral manures ; the diagram Fig. 11
shows this comparison in a graphic form. Plot 4-0, receiving
no nitrogen, has only given an average crop of 20 4 bushels per
acre, and this has been more than doubled by the application
of 43 lb. of nitrogen per acre to the other three plots. But little
difference is seen in the return for this amount of nitrogen,
whether it be applied as ammonium- salts, nitrate of soda, or
rape cake. Over the whole period the nitrate of soda gives the
highest return by about 3 per cent., but during the last two
decades, the plot receiving ammonium- salts has been slightly
the best of the three. In the straw, again, the differences are
very small, though the superiority of nitrate of soda is rather
more pronounced with the straw than with the grain. The
fact that ammonium- salts answer better with barley than witli
wheat is due to their retention by the soil close to the surface ;
the comparatively shallow-rooted habit of Imrley and its growtli
during the warmer portion of tlie year when nitrification is
active, renders such a surface accumulation of nitrogen as
readily available to the plant as the nitrate of soda itself

On the completely manured plots the rape cake, 4 C, is

AVITII VAlMors XITIvMXJKNors MAM IM-

not (juile so effective as tlie more active tonus of niiro^'tMi.
giving over the whole period an average yield of 41 ai^'aiust
48'5 and 4*2"1 l)ushels of i;rain. Tliis small dericicncv has
not diminished in the later years, which seems tu indiciite

6000 lb.

Grain per Acre

lb.

Straw per Acre, lb

1 u;. 11.— Yield of Barley (Grain and Straw) with different sounes

of Nitrogen. Averages for .".1 years, 18:.-J-190'J.

The figures in the labels indicate bushels of grain and cwt. of straw

that the nitrogen compounds of rape cake are almost wholly
utihsable by the crop to which they are applied. At any ratr.
no large amount of residue slowly becoming availal)le is left
in the soil, as in the case of faiinyard manure.

The plot receiving farmyard manure, 7-'J, ^Mves a higher
crop than any other, but the amount of nitro.^en suppli.d in

78

EXPERIMENTS UPON BAELEY

this case is very high, being estimated at nearly five times as
much as on any of the other plots.

One of the permanent barley plots (Plot 7) received 14 tons
of farmyard manure per acre each year for tv^^enty years in
succession, viz., from 1852 to 1871. It was then divided into
two plots, one of which, 7-1, has received no manure of any
kind since ; the other, 7-2, continued to get its annual dressing
of 14 tons of dung. After the discontinuance of the dung, the
barley crop on that half of the plot naturally began to fall off",
but only slowly, and even now, after thirty years' cropping
without manure, the effect of the residues left by the previous
twenty years' application of dung is still to be seen in a
yield that is double the crop obtained from the continuously
unmanured plot. Table XXXII. shows the total produce

Table XXXII. — Total Produce per acre of Barley Plots, shovjin;/ Prsid/a'l
affects of Dung.

Dung for

Dung

20 years,

every year,

1852-71.

Unmanured

Kelation to Produce of Plot 7-l',

1852

continuously.

reckoned as 100.

and since.

Unmanured
since.

Plot 7--2.

Plot 7-1.

Plot 1-0.

Plot 7-2.

Plot 7-1.

Plot 1-0.

Mean, 1852-1871
1872

Lb.

Lb.

2454

Lb.

Lb.

Lb.
41

59

33

100

5202

4870

1282

100

94

25

1873

6561

5165

1570

100

79

24

1874

7943

5675

1922

100

71

24

1875

5825

3955

1448

100

68

25

1876

6166

4010

1561

100

65

25

Mean, 1877-1881

6167

3305

1528

100

i 54

25

„ 1882-1886

6546

3494

1529

100

i 53

23

„ 1887-1891

5334

2664

1379

100

50

26

„ 1892-1896

6477

3101

1508

100

i 48

23

„ 1897-1901

5349 '

2251

1141

100

! 42

21

obtained from the three plots in question for the thirty years
tvhich have elapsed since the dung on Plot 7-1 was discontinued,
the first five years are given singly, after that five years are
grouped into one period and the mean result given. In order

EESIDUAL EFFEC'T OK FAIJ.MVAIM) M WIIM; 7\\

to eliminate the ettect of seasons the crop nsiilt> li.ivc all
been reduced to the conmion standard of the ci-oit on the
continuously dungiMl plot, 7--J, which lias xaricl \,iv little
during the period.

eo —

10 —

'

1

1

■

•■!v

,.

.

i

-

1

1

':

IBS

3/Ti

h7i

(f

•■'

18

'«

.6

7!>

IB

7S

187

7/.,

/St

le

b; )i

ID*

;'■>*

,<.•.•

^*0l

I

Dun| to laTl.then Unmanured.

i

Unmanured the whole time

Fk.. IJ. — IJ.irlt'y TiiS'il PnKliicf. showinjf residual cfTe«-t of Dun;? ami t\,
Munuff in relation to tlu- Dunjf I'lol ]>>'<.

Diagram 12 expresses these resnh.s in a ^'raphic loiin, and
shows that, though the crop gi-own uith tie- lesidues of dnng is

80 EXPERIMENTS UPON BARLEY

continually falling, it will only reach the level of that on the
continuously unmanured plot after a long time.

C. Effect of Mineral Manures.

The Rothamsted barley field affords a more thorough series-
of comparisons of the effect of the various mineral manures than
does the wheat field, for in conjunction with each of the nitro-
genous manures we get plots receiving no minerals (1), phos-
phoric acid alone (2), potash and the other alkahne salts, but no
phosphoric acid (3) ; and the complete mineral manure, con-
taining both phosphoric acid and the alkaline salts (4). In the
absence of nitrogen tlie mineral manures have but little effect,
though they produce a much greater increase of crop over
that of the unmanured plot with barley than with wheat.
Ammonium-salts and nitrate of soda used alone are not so
effective as with wheat, but the rape cake used without
minerals gives almost as big a crop as when supplemented
with a complete mineral manure. Of course rape cake is not
a purely nitrogenous manure, but itself supplies about 24 lb. of
phosphoric acid and 17 lb. of potash per acre per annum.

The diagram Fig. 13 shows in a graphic form the effects of
the various mineral manures, the nitrogen supply being the
same in all cases.

The great importance of phosphoric acid to the barley crop
is seen on comparing Plots 3 and -1, which only differ from
one another in the omission of phosphoric acid on Plots 3.
It will be seen that Plots 3 give but little more crop than Plots
1, which receive nitrogen alone — only 32-9 bushels per acre
against 32, taking the average of the three series A, N, and C
— but that a very marked increase to 42*2 bushels per acre is
found on Plots 4 for' the addition of phosphoric acid. The
straw shows just as marked an increase of crop brought about
by phosphoric acid as does the grain, rising from 197 cwt. to
25"6 cwt. per acre. In the field the most striking effect is
seen in the hastened matm^ity brought about by the phosphoric
acid. Not only are Plots 2 and 4, which receive phosphoric

IMPORTANCE OF PIK )S1MI()1M( ' ACID m
acid, in tlie ear long before Plots :) and (to a less extent)

Nitrogen Nitrogen

only. and

Phosphoric

Acid.

^

Grain per Acre Jb.

Nitrogen Nitrogen,

and Phosphoric Acid

Potash. and

Potash.

Straw per Acre, lb.

Vh;. 1:3.— Effect of Mineral Manures on the yield of Barley (Grain and Straw).
Mean of Series A. N. and C. .M years (1^.V2-190'J).

Plots 1, but tliey will have l)egiin to yellow for harvesl when
Plots 3 still show only upright green ears.

82

EXPERIMENTS UPON BARLEY

Comparing Plots 2 and 4, we see that a manure supplying
phosphoric acid and nitrogen is almost as effective as a complete
manure containing also potash and the other alkaline salts.
There is a great increase of crop caused by the superphosphate
and nitrogen on Plots 2, over the nitrogen alone on Plots 1,
and very little further increase for the further addition of
potash and other alkaline salts on Plots 4. Where the nitro-
genous manure is nitrate of soda or rape cake, the omission of
the potash on Plots 2 compared with Plots 4, receiving a
complete manure, shows no effect, whether Ave make the
comparison over the whole period or for successive ten-year
periods. With ammonium-salts, however, as the source of
nitrogen the omission of potash does eventually diminish the
crop ; for the first thirty years the crops on Plots 4 A and 2 A,

Table XXXIII. — Batio of yield of Barley (Grain) loithout Botash to yield
with Botash, for successive 10-year periods, Ammonium-scdts and Nitrcde
of Soda being the respective sources of Nitrogen.

1852-61.

1862-71.

1872-81.

1882-91.

1892-1901.

Ratio of 2 A to 4 A, Ammonium-salts . 98-9
Ratio of 2 N to 4 N, Nitrate of Soda . 98-0

104-3
100-2

98-8
99-5

90-2
105-7

77-1
101-4

with and without potash, were equal, but in the fourth decade, as
the soil became depleted by the continual removal of potash,
the crop on Plot 2 began to fall off, and the diminution is much
increased in the next decade. That there is no similar falling-off
in the yield of the corresponding plot receiving nitrate of soda,
is partly due to the greater root-range induced by the soluble
nitrate, and partly to the effect of the soda base of this salt in
rendering available to the plant the potash reserves of the soil.
Table XXXIII. shows very clearly how the omission of
potash begins to tell upon Plot 2 A, manured with ammonium-
salts and superphosphate, after the first thirty years, whereas
on the corresponding Plot 4 A, receiving nitrate of soda and
superphosphate, the omission of potash has made no difference
to the yield up to the end of the fifty-year period. The figures

QUALITY OF CIJOP 83

show the ratio the yield of Plot 2 (without ])()t;isli) Ijoiv to iliat
of Plot 4 (with potash), during each decade.

Thus the yield on Plot 2 A (annnoniuni-salls and suimt-
phosphate), which for the first thirty years was practically ccjual
to that on Plot 4 A (ammonium-salts, superphosphate and
potash), fell off by 10 per cent, in the fourth decade and '2'.) per
cent, in the fifth ; whereas the corresponding yield on Plot 2 X
(nitrate of soda, and superphosphate), is as good as that of 4 N
(nitrate of soda, superphosphate and potash) up to the end.

Potash plays a less important part than phosphoric acid
in the manuring of barley. Very little increase of crop has
resulted from its use on the Rothamsted soil, and the oidy
indication of the supply in the soil giving out has been seen in
the last twenty years on the plot receiving superphosphate and
ammonium-salts. Of course the Rothamsted soil starts with
a very large original store of potash.

Speaking generally, we find that barley is nuich more
dependent on a supply of mineral manures than is wheat, a
free supply of phosphoric acid in particular beinu- essential to
its proper development.

D. Character of the Crop as affected Jnj M<nnn''ni(j.
Table XXXIV. shows some of the characteristics of the
barley crop during the last fourteen years compared with the
average market valuations put upon the sami)les by .Mr J-'ew,
of Cambridge, who has examined them from year to year.
The current market price prevailing at the time of the
valuation is taken as 100, and the value j)Ut on each saniph-
is calculated on that basis. The first thing that becomes
apparent on inspecting the table is that it is impossible to grow
high-class barley by simply starving the plant. In each of tlir
series it will be seen that the barley showing the higiiesi
average value, the best wei'jht per bushel, the largest grains.
and the smallest j)roportion of tail corn i> that gn.wn on IMots
4, where a complete manure containing both nitrogen and
minerals is supplied. It does not, however, follow that any

84

EXPERIMENTS UPON BARLEY

kind of manure will improve the quality of the barley. The
grain from the plot receiving farmyard manure every year,
despite the high weight per bushel, and the bold berry indicated

Table XXXIV. — Experiments on Barley, Hoos Field. PartieuJars of
Quality. Averages over 14 years (1889-1902).

S d

s

■ii

§

3

l.-^

2-5

is

^ >,

'l

0 gf:

Plot.

Abbreviated Description
of Manures.

3 t.

§

i

2-g —

£5

0

ill

t°

2

"3 o

.5P

§S,i

^°

o

3 *3

o

^

T'^

Lb.

Grams.

lO

No Minerals, and no Nitrogen

52-4

86-3

97-3

7-9

3-67

20

Superphosphate onlv ....

53-4

96-5

104-1

6-9

3-93

30

Alkali Salts only . ' .

53-0

79-2

96-6

7-8

3-91

40

Complete Minerals ....

53-5

86-8

99-4

5-9

3-91

1-45 ,

lA

Ammonium-salts alone

52-3

84 -.5

91-1

8-5

4-03

2A

Superphosphate, and Ammonium-salts
Alkali Salts, and do.

52-2

88-1

92 -G

8-1

3-86

3A

.53-3

81-2

93-8

5-5

4-14

4A

Complete Minerals, and do.

53-8

84-6

104-3

2-6

4-21

1-44

IN

Nitrate of Soda alone ....

52-6

82-2

91-3

8-9

4-05

2N

Superphosphate, and Nitrate of Soda .
Alkali Salts, and do.

53-6

84-6

100-0

7-5

4-04

3N

53-4

80-9

93-6

6-1

4-12

4N

Complete Minerals, and do.

53-9

79-1

100-3

4-6

4-10

1-53

IC

Rape Cake alone .....

.53 -7

89-4

102-0

4-9

2 C i Superphosphate, and Rape Cake .

54-1

87-1

103-2

3-3

3 C ' Alkali Salts, and do.

53-8

83-4

101-5

4-3

4 C Complete Minerals, and do.

54-2

83-2

103-2

4-0

1-52

7-1 Unmanured after Dung

54-2

84-0

100-5

5-9

7-2 Farmyard Manure ....

54-6

75-9

96-4

4-3

4-47

1-51

* Based on average samples of 24 years (1S72-1S95). See " Manurial Conditions afl'ectiug the Malting
Quality of English Barley," by Munro & Beaven, J. R. Ag. Soc, 1S97.

by the high weight of 100 grains, has yet a value considerably
below the average. Again, the use of nitrogen alone on Plot
1 A or 1 N gives the lowest weight per bushel and the lowest
valuation of the whole series. It has already been seen that
the yield of the barley crop is very dependent on the supply of
minerals, especially of phosphoric acid, and the table now
under consideration shows that the same effect extends to the
quality of the crop. The use of superphosphate on Plots 2 as
compared with Plots 1 gives a better proportion of grain to
straw, a higher weight per bushel, and a greatly increased
value ; similarly, the omission of superjjhosphate on Plots 3 as

EFFECT OF SEASON rroN (^)rAMTV 8:.

compared with Plots 4 results in a deterioration of all thr
(palities making for value in the barley. Comparing tin-
barley from riots 3 and Plots 1, in the absence of super-
phosphate the potash salts on Plots o do not effect much
improvement, though their presence on Plots 4 as compared
Avitli Plots 2 results in an improved quality. Tlie presence of
potash in the manure increases the straw more than the grain.
In all the series it will be seen that Plots o and 4, receiving
potash, give a lower proportion of grain to straw than do Plots
1 and '2, without potash.

If we compare the series together, the rape calie gives
better barleys than either ammonium-salts or nitrate of soda,
but the sample which on the average is the best is that grown
with the full minerals and ammonium-salts.

Table XXXV. gives a comparison of the crop of grain and
straw, the weight per bushel of the grain, and the proportion
of grain to straw, in 1893, a typically dry and hot year, and in
1891, a wet but free-growing year.

The amount of grain produced is not dissimilar in the two
years, but 1894 grew very much more straw, the average
proportion of grain to straw l)eing only about 7n as
against 90 in the dry season. The weight per bushel
of the grain is also higher, averaging 557 lb. in the dry
year 1893 as against 52-5 lb. in the wet year 1894. In the
dry year the plot receiving farmyard manure had a very great
advantage, and grew 25 percent, more than the other completely
manured plots ; whereas in the wet season when it gave about
its average crop, several others gave almost as nmch, and it was
actually excelled l)y the plot receiving nitrate of .-^-oda and
minerals. As was n(jticed in the case of the whrat erop.
nitrate of .soda an.swered better than ammonium-salt >^ in the
wet year, giving on Plot 4 N 45 bushels of grain and :):) \ cwi.
of straw against 41 -4 bu.shels of grain and 2«)s c-wt. of >tra\v on
Plot 4 A; whereas in the dry year the annnonium -sdts had a
slight advantage. Taking, however, averages over the whole
period, it is found that the seasons in which the ammonium-

86

EXPERIMENTS UPON BARLEY

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EFFECT OF SEASON VVi)^ OrAMTV s7

salts give a better crop than the nitrate u\' soda are wi'tter
througliout than those in which the nitrate of sixhi is tlie more
effective source of nitrogen. A wi't AFareli seems to he tlir
most liurtful to the nitrate of so(hi pU)t. Tlie comparative
effect of the mineral manures in a wet and (h*y season are also
similar to those noticed in tlie ease of tlie wheat. Inllicwct
season the crop is very dependent upon supplies of minerals in
the manure, and especially on an abundance of phosphoric
acid. In 1894 the addition of phosphoric acid raised the
yield from 10-4 bushels per acre on Plot 1 A to 134 '9 bushels
per acre on Plot 2 A, and from 17 "8 Inishels per acre on
Plot 3 A to 41-4 bushels per acre on Plot 4 A. In a dry
season it is potash that chiefly tells ; for example in 1S93 the
addition of potash on Plot 4 A to the superphosphate and
anunonium-salts on Plot 2 A, produced a specially marked
increase of crop, from 181 to 30"8 bushels per acre.

Doubtless in the wet season the ripening ef!ect of the
phosphoric acid is specially valual)le, while in a dry season tlie
potash, by inducing a longer period of growth, is more effective
in increasing the crop. The ripening action of the phosphoric
acid may also be seen in the way it increases the weight per
Inishel of the orain in a wet season, whereas in a drv season it
has little or no effect.

In the dry season the weight per bushel is much higher
than in the wet, and the grain is about e<[ual in weight to the
straw, whereas in the wet season the weight of grain only
amounts to about 70 per cent, of the straw.

Taking the results as a whole, it is seen that season has a
nuich greater effect in bringing about changes in the composi-
tion of the barley grain than have variations in the manuring,
but that the best barley will be grown with a fair but not large
amount of nitrogenous manure c()nd)ined with a free supply of
phosphoric acid in some way or other.

It does not appear possible to establish any such critical
periods for the rainfall in relation to the growth of barley as
could be done for wheat.

88

EXPERIMENTS UPON BARLEY

The Table (XXXVI.) shows the fifty-three barley crops
since 1852, taking the average of the completely manured
plots divided into five groups according to their yield of grain,

Table XXXVI.

Produce per Acre.

Average of Plots

7-2, 4A, 4AA, and 4 0.

Rainfall.

March.

April.

j

July.

Total.
March,
April,
May.

Total.
June,
July.

Grain.

straw.

Bushels.
50-2
43-4
38-6
34-8
27-7

Cwt.
29-2
25-5
21-6
22-5
18-1

Inches.
1-442
1-909
1-938
2-092
1-590

Inches.
1-649
1 -803
1-609
1-940
2-086

Inches.
1-919
2-122
1-996
2-048
2-807

Inches.
2-302
2-769
2 -.506
2-386
2-103

Inches.
2-967
2-801
3-074
2-666
1-840

Inches.
5-010
5-8.34
5-543
6-080
6-483

Inches.
5-269
5-570
5-580
5-052
3-943

together with the mean rainfall for each of the five months
during which growth is proceeding. No very definite relation-
ship is observable, though a general tendency will be seen
to get the heaviest average yield when the earlier months of
growth (March to May) are dry, also the lightest average yield
when the latter months of growth (June and July) are the
driest.

II. — Barley Grown in Rotation, Agdell Field.

It has already been stated that the production of barley in
the rotation field shows much the same decline on the manured
plots as it does on the completely manured plots in the Hoos
field, but that the decline must on the whole be set down to
unfavourable seasons.

For selected plots on the rotation field. Table XXXYII.
gives the production of grain and straw and certain particulars
as to quality, taking an average of the last five courses only.
The first plot has been wholly unmanured, and all the crops
in the rotation are removed from the land ; the average produc-
tion is, however, higher than on the unmanured plots growing
barley continuously, because of the fallowing the land receives.
When minerals only are applied to the root-crop on Plot 2
(roots are grown immediately before the barley), there results a

QUALITY OF ILVIILKV (IKOWX ]\ KoTA IK >\ -'.»

comparatively large i)i()(lucti()n of roots; sinee these are re-
moved and since no nitrogen has been supplied, they take away
a certain quantity of nitrogen, and theret'ori' exhaust the soil

Table XXXVI I. — AndrJl Iwtatiun Jiarlci/. Avcrtujc of 5 ycurs
(1885, '89, '93, '97, and i901).

Manuring

for Roots before

Barley.

Treat-
ment of
Roots.

Tliir.l
Course

in
Rotation.

Produce per
acre.

Weight

per
Bush.

Grain

to
100 of
Straw.

Weight
of 1000

Mtrog«n
iwr (»iit.
Ill Dry
Grain.

Kiillmat«d 1
Value |>rr 1

Grain.

Straw.

Grains.

(iuarV-r.

1. Unmanured

2. Minerals .

3. Do. . .

4. Do. . .

5. Complete .

Carted

Carted

Carted

Fed

Fed

Fallow
Fallow
Clover
Clover
Clover

Bush.

13-6
19-9
28-9
34-1

Cwt.
10-8
9-3
12-8
17-5
23-4

53-8
54-0
54-4

55-3

76-6
77-3
80-0
85-9
74-9

Grams.
42-4
39-7
43-0
44-3
46-2

Per cent.
1-562
1-484
1-5.19
1 -.'.76
1-693

H. I>.

27 10

28 7

29 0
•J9 11
29 «;

on this plot of its nitrogen to a much greater extent than on
Plot 1, which grows a very small root-crop; hence a smalltr
barley crop follows the roots on Plot '1. The minerals in
fiict do not increase the production of the liarley to an extent
which will compensate for the loss of nitrogen in the increase<l
root-crop previously brought aliout by the minerals.

On Plot 3, however, clover (or beans) is grown as the third
crop in the rotation, and by collecting nitrogen from the atmos-
phere leaves behind a residue in the soil which is still available
for the barley crop coming three years later. On IMot 4 there
is a still greater supply of nitrogen, for not only is a leguminous
crop grown, but also the root-crop preceding the clover is
returned to the land. On Plot 5 the barley timls the
maximum amount of nitrogen; here clover is grown, and the
root-crop receives a nitrogenous dressing of rape cake and
ammonium-salts; all this nitrogen is rcturiicd to the .-oil
in the root-crop which precedes the barley. It will be seen
that on the.se five plots the growth of barley is j.roporti(»nal
to the amount of nitrogen which may be supposed to be
available; all except IMot 1 receive heavy mineral dressings
containing both phosphoric acid and potash, yet in tlie
absence of nitrogen these minerals on I Mot '1 are not able

90 EXPERIMENTS UPON BARLEY

to raise the crop above, nor even up to the level of the wholly
unmanured Plot 1.

The weight per bushel increases with each addition of
nitrogen ; up to a certain point the proportion of grain to straw,
and the weight of 1000 grains also increases, but on Plot 5,
with the highest nitrogen, these characters begin to show a
decline. The percentage of nitrogen in the barleys increases
with the supply in the soil, but only becomes at all above the
average with the highest sample from Plot 5. The valuation
rises with the supply of nitrogen in the soil up to a certain
point, but shows a slight decline for the last sample from
Plot 5.

Summarising these results, we see that a good weight per
bushel and a large berry cannot be obtained without a
sufficient supply of nitrogen in the soil, but when a certain
point has been reached further excess of nitrogen in the soil
results in coarseness and an excessive proportion of nitrogen
in the grain, deteriorating the quality. A fair supply of
phosphates are also necessary to ensure early and complete
maturation. In the Agdell field, Plot 4 represents the best
soil conditions to obtain high quality in the barley ; on Plot 5
this optimum point has been passed, and the land has become
too rich in nitrogen compounds.

The barley grown in rotation is on the whole much superior
to that grown continuously, mainly because its supply of
nitrogen is derived from the nitrification of nitrogenous residues
in the soil, i.e., from what a farmer would call "condition," and
not from nitrogenous manure directly applied.

Practical Conclusions

1. The barley crop is far more dependent than wheat upon
a supply of manure, and will require manuring when it is
grown as a second white-straw crop, except on land in very
good condition. After roots which have been wholly or
partially fed on the land, or after a clover ley, there is already
sufficient, and often too much, nitrogenous matter in the land.

PRACTICAL COXCl.T'sroxS im

•2. The artificial manure used in tlie first ease slioiild contain
a fair amount of nitrogen, as witliout it ])otli tlie yii'M will l.r
low and the berrv small. Sulphate of ammonia is a Ix'ttcr
barley manure than nitrate of soda, giving erjual yield and
generally superior quality. The quantity used should not Iw
more than 1\ cwt. per acre. Rape cake up to .') cwt. per acre is
also a good source of nitrogen for the barley crop.

3. Barley is particularly dependent on a free supply of
phosphoric acid, 3 cwt. of superphosphate per acre may br
profitably used on most soils, especially where the climate is
wet. Even with, barley after roots superphosphate is valualde.
hastening the ripening and making the sample more uniform.

4. An artificial supply of potash is rarely likely to be
wanted, except on dry sands and gravels and in dry seasons.

Rf.kf.hkncfs

"On the Growth of Barley by different Manures continuously on th<- sanu-

Land; and on the position of the Crop in Rotation." Jtn/r. Rotf. Aii.

Soc, 18 (1857), 454. Uuthamsled Memoirs, Vol. I., No. 11.
" Report of Experiments on the Growth of Barley for Twenty Years in

succession on the same Land." Jour. Roi/. A<^. Soc., 34 (1873), 81» and

275. Rolhamsted Mevwirs, \'ol. HI., No. 13.
"On the more frequent Growth of Barley on Heavy Land" — Farnirrs'

Club, Feb. 1875. Rolhmnsled Memoirs, Vol. \ ., No. 1.
" Results of Experiments at Rothamsted on the Growth of Barley for ni..r«-

than Thirty Years in succession on the same Land." Aiiricultmal

Student' Gazelle, New Series, \'ol. III., Part 1, ISSH. Rnthamshd

Memoirs, Vol. VI., No. 8.
" Manurial Conditions affectin.ir the Maltinj; (^lality of Knglish B.irley.' by

J. M. H. Munro and E." S. Beaven. Jour. Ro,,. Ag. Sue., 58 (I8'.t7). <;:..
"Various Conditions affecting the Malting Quality of Barley," l)y J. M. H.

Munro and E. S. Beaven. Jo„r. Rn>/. Ag. So',:, 61 (1900), IS.',.

CHAPTER VI

EXPERIMENTS UPON OATS

Experiments upon Oats grown continuously upon the same Land,
Geescroft Field.

Experiments upon oats on very similar lines to the trials with
wheat and barley were begun in 1869 in the Geescroft field, but
on a smaller scale, as only six plots, each one-eighth acre, were
set out. These experiments were, however, abandoned after
ten years : the Geescroft field, although it shows on physical
analysis a lighter texture than either Broadbalk or Hoos
fields, yet always lies comjjaratively wet, and appears to
suffer more than any other field from the continued use of
nitrate of soda, probably because the chalking to which the
other fields have been subjected has not been carried out in this
field. As the experiments ran into the cycle of wet seasons
from 1873 onwards, it became almost impossible to work the
land, and the experiment was abandoned after 1878.

The average results set out in Table XXXVIII. are for the
first five years only of the experiment.

Putting aside the deterioration of the texture of the land,
which may be taken as an accident independent of the nature
of the crop, there is no evidence that oats cannot be grown
continuously on the same land — the tenth crop on the
unmanured plot, for example, was larger than any other since
the first. The manurial requirements of the oats are also very
similar to those of the other cereal crops, resembling barley
perhaps more than wheat. The crop shows some response to
minerals only, but the chief increase of crop comes with

OATS GKOAVX C'ONTl M'orsi.V «.::

applications of nitrogen. I'vrn alhnvini; i'or the (li'lerioration
of soil texture which so niuth affected the nitrate of soda
plots, ammonium-salts appea'- to he the hotter soiuvc of
nitrogen.

Table XXXVIIT. — Oats, Gcesvroft Field. Avcmiie rmhur per m ,r, 5 t/aiis
(1869-1873). Descriptum of Outa—Blark Tarlarinu.

Vlot.

Jlanures

per acre.

IVoduea per

ten. j

Mineral.

Nitrogenous.

Oraln.

'

i!

il

II

|1

fl

II

-1

e

7.

■^?

5 =

'•1

<

y-'z

O"

'**.

Lb.

Lb.

Lb.

Cwt.

Lb.

Lb.

Uusli.

Lb.

C»t.

1

19-9

33-8

10-4

2

200

100

100

3-r.

24 -5

35-0

131

3

400

47-0

35-9

2^L

4

200

100

100

3-5

400

59-0

37-0

41-1

5

550

47-1

35-5

27-.'.

6

200

100

100

3-r.

550

57-5

35-8

».. ^

* Equal parts of Sulpli.itf aii'l Muriate Ammonia of Comiiierco.

For the manm-ing of oats in practice the recommendation.^
set out for barley may l)e followed, except that tlie (luantitic-
there given may be somewhat increased for oats.

CHAPTEE VII

EXPERIMENTS UPON ROOT-CROPS GRO^YN CONTINUOUSLY ON THE
SAME LAND

I. Experiments upon Mangels, Barn Field, 1876-1904:

A. Effect of Nitrogenous Manures.

B. Effect of Mineral Manures.

C. Comparison of Nitrate of Soda and Ammonium-salts as sources of

Nitrogen.

D. Effect of Nitrogenous and Mineral Manures when used in Con-

junction with Dung.
IJ. Proportion of Root to Leaf.

F. Proportion of the Nitrogen recovered in Crop to that suppHed in

Manure.

G. The Composition of the Mangel Crop as affected by Manuring.
General Conclusions.

II. Experiments upon Turnips, Barn Field, 1847-70.
Practical Conclusions.

III. Experiments on the Continuous Growth of Potatoes on the same Land,

Hoos Field, 1876-1901.
Practical Conclusions.

IV. Experiments on the Growth of Sugar-Beet, Barn Field :

A. First Series, 1871-75.

B. Second Series, 1898-1901.
Practical Conclusions.
References.

As the original design of the Eothamsted Experiments
embraced all the crops of the farm, so essential a feature of
English farming as the root-crops naturally occupied a
prominent place ; indeed we find that the second paper of
experimental results issued from Eothamsted in 1847 dealt
with turnip culture. In 1843, accordingly, the Barn field was
set aside for experiments on turnips, the trials being on
Norfolk white turnips for six seasons, 1843-1848, followed by

GENERAL HISTORY OF FIELD (^.KMnVINC IJOOTs n:.

Swedes for four seasons, 1840-Ls:)l>. Larlcy was then ^towii
for three years to equalise the soil comlitions, and the pl.H^
were rearranged on substantially the plan they occupy to-day.
Swede turnips were grown for fifteen seasons, Ls.lO-iisro, hut
it was found impossible to continue the growth of Swedes
upon the same land year after year with any success. This
was mainly due to the incidental circumstance that on growing
the same description of crop, with the same comparatively
limited and superficial root-range, for so many years in
succession, the surface soil became less easily worked, and the
tilth, so important for turnips, was frequently unsatisfactory ;
whilst for want of variety and depth of root-range of the crop,
a somewhat impervious pan was formed below. After the
Swedes sugar-beet followed for five years with the same
manures, except that in the last two the nitrogenous manures
were omitted, and in 1876 mangels took the place of sugar-
beet and have continued ever since. No difHculty has been
experienced in growing mangels continuously on the siime
land, as may be seen from the fact that the twenty-fifth crop in
1900 was the largest of the series. This success nuist be
attributed partly to the extended root-range of the mangel,
partly also to its freedom from insect and fungoid attacks,
which tend to accumulate on land carrying one crop con-
tinuously. The only difficulty is experienced on the plots
receiving saline manures only, especially where large dressings
of nitrate of soda are repeated every year. Owing to the
constant removal of organic matter and the injurious action of
the saline manures upon the textm'e of the soil the land gets
into a bad mechanical condition, veiy sticky when wet, and
drying with a hard crust, so nuich so that there is occasionally
a complete loss of plant from this ciiuse alone.

In the Hoos field experiments upon potatoes were begun
in 1876, and continued for twenty-six years; they were then
discontinued, because the crop on the plots receiving no organic
manures had fallen to a very low ebb in consefpicnce of the
deterioration of the texture of the soil. But on the jilots

96 EXPERIMENTS UPON ROOT-CROPS

receiving farmyard manure, and even on those receiving only a
complete artificial manm-e, the crop was maintained in favom^-
able seasons. No falling- off was observed wdiich could be
attributed to the land having become "sick" through the
continuous growth of the same crop, or through the accumula-
tion of disease in the soil.

The essential feature of the root-crops is the large amount
of digestible carbohydrate they contain ; in the case of Swedes
this consists of glucose, which forms 6 to 7 per cent, of the
whole weight of the Swedes, the total dry matter being about
11 percent, of the whole. In the mangel there is about 8*5
23er cent, of cane sugar, the total dry matter being about 12-5
per cent. In potatoes the carbohydrate is starch, of which
the tubers contain about 20 per cent., out of a total dry matter
content of 25 per cent.

I. — Experiments upon Mangels, Barn Field,
1876-1904.

The area under experiment amounts to about 8 acres, most
of the plots being about one- seventh acre in extent ; the whole
produce from each plot is weighed, but the roots only are
carted away, the leaves after weighing being spread and
ploughed in.

The field is divided longitudinally into seven strips running
the whole length of the field ; each of these strips receives
one manure throughout its length ; farmyard manure alone on
Stri^D 1, and in combination with superphosj^hate and sulphate
of potash on Strip 2, nothing on Strip 8, superphosphate
alone on Strip 5, superphosphate and sulphate of potash on
Strip 6 ; and complete minerals, including fmther sulphate of
magnesia and common salt, on Strip 4. The strips are then
subdivided into plots by cross - dressings of nitrogenous
manures ; nothing on the O Series, nitrate of soda on
Series N, ammonium-salts on Series A, rape cake on
Series C, and a combination of ammonium-salts and rape
cake on Series AC. Thus, as shown in Table XXXIX.,

VALUE OF FAIJMVAIM) MANTIM': <»7

there are plots showing every coinbiiiiition Ijt'twccii the vaiidiis
mineral and nitrogenous dressings eniploycfl.

The mineral manm-es, the dun^' and tlic lapc cal^c, are

Table XXXIX. — Experiments on Mmij/cl Win-zel, Jinni Field, U;/innini/
1876. Quantifies of Manures per acre per annum.

Stiip Maiiuros

NitrogenoUH Hanurm running acroM
all the StrliM..

4

.

SeuesO.

N.

A.

AC.

0.

strip.

!i

^

^1

-5

«■!

«> .

t
1*

ti

ill

-I

II

i ■
e

11

1.

1^

li

Tons

Cwt.

Lb.

Lb.

Lb.

Lb.

Lb.

Lb.

Lb.

Lb.

Lb.

Lb.

1

14

550

400

2000

400

2000

2

14

3-5

soot

550

400

2000

400

2000

4

3-5

500

200

260

550

400

2000

400

2000

^

3-5

550

400

2000

400

2000

6

3 -a

.^00

550

400

2000

400

2000

3-5

500

36-5

550

400

2000

400

2000

8

...

550

400

2000

400

2000

Equal parts Sulphate and Muriate Ammonia of Comnipfce.
The addition of Potash to Plot 2 began in 1895.

Its and

ploughed in just before seeding, the annnonuiin-saits
nitrate of soda are sown as top dressings.

The seed was dibbled in the earher years of the expcrinu'nt ;
it is now drilled, 26 inches between the rows, and the ])lants
are singled out to 10 inches apart.

The following tables give, (XL.) the average weight of roots
grown on each plot during the twenty-seven year.s 1H70-11MH> ;
(XLI.) the weight of roots and leaves grown in the best season,
1900.

A first inspection of the results shows the enormous value
of farmyard manure in growing mangels, especially when tliey
are grown continuously on the same land. In tavouiabh'
seasons it is possible to obtain good crops by ilie aid of
manures containing no organic matter, as seen in I'.MJU; l)ut
in ordinary years the bad texture of the soil and its tendency
to lose water on account of the lack of lniiiius atVcet both tlie
germination of the seed and the growtli of tiie plant in it.s early
fita^'es. It will be convenient, therefore, to e(.n>id(i- separately

98

EXPERIMENTS UPON ROOT-CROPS

the plots receiving dung and those which are manured exchi-
sively with "artificials."

Table XL. — Barn Field Mangel Wurzel. Average Produce of Boots
per acre over 27 years (1876 to 1902).

strip.

strip Manures.

Cross-Dressings.

O.

N.

A.

AC.

C.

None.

Nitrate
of Soda.

Ammonium-
salts.

Rape Cake

and
Ammonium-
salts.

SS.

1
2
4
5
6
7

8

Dung only

Dung, Super., Potash* .
Complete Minerals
Superphosphate only
Super, and Potash
Super. , Potash , and 7 -8 lb.

N. as Amm. -salts
None ....

Tons.
17-44
17-95
5-36
5-21
4-55

5-93
3-91

Tons.
24-74
25-19
18-01
15-40
15-38

15-63
10-24

Tons.
21-73
22-35
14-86
7-66
14-03

14-60

5-89

Tons.
24-05
24-91
25-49
10-38
22-48

22-30

9-84

Tons.
23-96
24-43
21-33
11-13
18-63

19-19
10-00

The addition of Potash to Plot 2 only began in ;

Table XLI. — Baom Field Mangel Wurzel. Produce of Boots and Leaves
per acre. Season 1900. {Good season.)

strip Manures.

Cross-Dressings.

O.

N.

A.

AC.

C.

None.

Nitrate
of Soda.

Ammonium-
salts.

Rape Cake

and
Ammonium-
salts.

s.

Tons.

Tons.

Tons.

Tons.

Tons.

1

Dung only .

{

R. 25-25
L. 2-15

41-30

4-35

26-10

3-65

27-65

3-55

30-35

3-10

2

Dung, Super. , Potash '

{

R. 28-05
L. 2-60

41-85

5-00

35-70

5-60

38-40

6-00

35-55

3-55

4

Complete Minerals

R. 8-75
L. 1-10

33-10

4-95

28-95

3-25

43-20

6-30

34-55

3-80

^

Superphosphate only

R. 9-15
L. 1-30

28-35

3-85

12-00

2-95

14-95

2-15

14-90

2-60

6

Super, and Potash

r

R. 7-05
L. 0-95

29-65

3-60

28-20

3-60

37-55

5-65

29-40

2-95

7

Super., Potash, and 7*8 f
lb. N. as Amm. -salts \

R, 10-80
L. 1-35

28-70

4-85

28-70

5-10

36-95

7-20

29-20

4-20

8

None .

•{

R. 7-75
L. 1-15

22-55

4-85

12-85

3-65

15-65

3-35

15-40

3-40

The addition of Potash to Plot 2 only be-an in 1S95.

DEPENDENT UPON NlTKOdFAOlS MAMIM'.s <.'.»

A. Ejfect of Nitro(h'n()ii.< Munun.^. Tlic nianu'fl wm/fl,
being a plant with a large leaf development, was at one time
to a certain extent regarded as one of the restorative crops,
capable, with its large area of leaf, of drawing npon the
atmospheric nitrogen and thus rendering itself independent of
nitrogenous manures. Though it was obvious that nitrogenous
manm-es had a powerful effect even upon leafy crops, it was
urged that the benefit consisted in starting the crops, which,
as soon as they had attained their proper development of leaf,
would continue to feed themselves by drawing upon the
nitrogen of the atmosphere. It was with the view of testing
the truth of this opinion that the manuring on Plots 7 was
arranged. They receive superphosphate and sulphate of
potash as mineral manures, together with a small quantity of
nitrogen, 36! lb. per acre of ammonium-salts conUiining 7'8 lb.
of nitrogen per acre, i.e., about one-eleventh of the amount
applied to the plots in Series A.

On the hypothesis indicated above, the small quantity of
nitrogen would act as a starter, and establish the plant, which
should then be able to maintain itself upon atmospheric
nitrogen.

The results, however, yielded by Plots 7 as compared with
Plot 6 show this opinion to be mistaken, the small addition of
7'8 lb. of nitrogen per acre produces an increase of crop of 1'4
ton per acre only, whereas a further 86 lb. of nitrogen raises
the crop by 87 tons per acre.

Thus the opinion may be dismissed that the mangel plant
when once started can become independent of the nitrogen in
the soil and manure.

AVe may next pass on to a consideration of the effects of
the varying forms and amcjunts of nitrogen when use<l with-
out any mineral manuring, l.r., on Plots 8, where no standard
manures are applied. The entirely unmaiunvd plot (8 ())
has produced an average crop of :) !) tons of roots only,
which is increased by the application of 86 H). nitrogen in th.-
ammonium-salts to T)!* tons, and l)y 08 lb. of nitrogen in tlie

100 EXPERIMENTS UPON ROOT-CROPS

form of rape cake to lO'O tons. A further addition of 86 lb.
of nitrogen (as ammonium- salts) to the 98 lb. of nitrogen in
rape cake (Plot 8 AC) produces no more increase of crop,
which remains practically stationary at 9 '8 tons. However,
with 86 lb. of nitrogen in the shape of nitrate of soda the result
is somewhat higher than in any other case, for the crop
amounts to 10"2 tons, a result which will be more intelligible
later. In all these cases, however, the crop is a very indiffer-
ent one for the large amounts of nitrogen employed, and the
aspect of the plots clearly show that the plant has received
far more nitrogen than it can effectively utilise in the absence
of the other mineral constituents which go to make up a
complete plant food.

We may now turn to Plots 4, where superphosphate,
sulphates of potash and magnesia, and common salt are used
in conjunction with nitrogenous manures, thus constituting a
complete manure which supplies all the elements of plant
nutrition.

The diagram Fig. 14 shows on the left hand the average
results obtained with the varying amounts and compounds of
nitrogen on the Plots 4 in question, where there is an abundant
supply of mineral manure. The right-hand half of the diagram
shows the effect of the same nitrogenous manures when used
in conjunction with dung instead of complete minerals, for
an account of which, see page 108.

Without nitrogen (Plot 4 O) a very small crop is grown,
5 "4 tons per acre, which is increased to 14 '9 tons per acre
by the addition of 86 lb. nitrogen in ammonium-salts, or to
18*0 tons per acre by the same amount of nitrogen applied in
the shape of nitrate of soda. The application of 98 lb. of
nitrogen per acre in rape cake increases the crop to 21 "3 tons
per acre, and when both rape cake and ammonium-salts
are used together, making an application of 184 lb. of
nitrogen per acre, the crop is raised to 25 "5 tons per acre.
Thus when all the other elements of a plant food are present,
the crop increases with each addition of nitrogen. The increase

RELATION OF YIKLD TO X1T1;()( IFA SI riM \ KM

of crop is somewhat (lepeii<k>iit on tlie source of nitrogen
employed: thus I Ih. of nitrogen as animonium-sahs gives un
increase of 01 10 ton, as nitrate of soila the increase is 0147

ton fov each lb. of nitroi^'en, while with rape cake the increase

WITH COMPLETE MlNEKAl.s.
(Plots 4.)

WITH l)LX(i.
(P1.0TH 1.)

Fill. 14. — Maiifrtl Wur/.el. KfTict of iiureasiiif; ainoimts of Nitrop n. Avini;.'c
Produce of Roots per acre. 1 876-1 W2.

O = No Nitrogenous Manure. I N = S(5 II). Nitrogen as Nitrate of Stnlii.

A = 86 lb. Nitrogen as Ainmoniuin-salts. I C = 9S lb. Nitrogen as Ha|>o Cake
AC - P-^ lb. Nitrogen as Rape Cake, and *"') Ih. Nitn>;,'<'n as ,\mnioniiiin-salts.

is 0T03 ton for each II). of nitrogen api)lic(l. IJape cake, in fact,
is not strictly comparable with the other two sources of
nitrogen, for not only does it contribute a consideiable aniouni
of organic matter to t):e soil, thus improving its texttuc arnl
water-retaining power, l»ut it is also a more .sl.)wly-aeting
manure. Some of its residues accumulate from .sea.son to
sea.son, and little by little become available for ihe later crops,
while we have plenty of evidence that, on the liothamsted soil.

102 EXPERIMENTS UPON ROOT-CROPS

neither nitrate of soda nor ammonium-salts leave any effective
residue.

In seasons of exceptional growth, with a big crop Hke that
of 1900, it might be expected that as the plant was utilising
much more thoroughly the supply of nitrogen, then the smaller
amounts on some of the plots, plentiful enough for an ordinary
year, might prove to be insufficient. There is no indication, how-
ever, of this being the case, as may be seen by a consideration of
Table XLT. ; the increase of crop on Plots 4, receiving no dung
but a complete mineral manure, continues with each application
of nitrogen, but not more so than in normal seasons. On the
dunged plots, indeed, it is not those receiving most nitrogen
(Plots 1 and 2 AC), which give the highest crop, but those
cross-dressed with nitrate of soda, as though the availability of
the nitrogen and the presence of a large supply of alkaline salts
had been the determining factors in producing the maximum
crop. The whole results go to show that, dependent on
nitrogen as the mangel crop is, the first application is the
most effective, each succeeding addition of nitrogen producing
a smaller return in the shape of an increase of crop.

The injurious effects of the very large amounts of nitrogen
added to some of the plots is very manifest wherever there is
more nitrogen than the plant can properly deal with. The
leaves have a dark green appearance, are much curled and
crinkled, and show an increased tendency to variegation, the
chlorophyll collecting into dark green or almost black blotches
on the lighter background of the leaf. The leaf-stalks are
often much more coloured, and become a bright orange
yellow.

On these plots the leaves do not ripen off and obtain the
general yellow flaccid appearance presented on the more
healthy plots when the crop is ready to lift ; instead, the outer
leaves begin to die and shrivel up quite early in October ;
in some places they show numbers of dead spots and burnt -
looking patches round the edges of the leaf.

The destruction appears to be due to a leaf- spot fungus,

EFFECT OF EXCESS OF MTL'OCKX lo:}

Uromi/ces heta>, and to a Tonila, wliicli is abundantly developed
on tlie mangels on the plots receiving an excess of nitrogen
but is not present elsewhere in the field.

Thus, towards the end of October the plots receiving the
excess of nitrogen present a very unhealthy appearance ; a
large proportion of the plants seem scorched and withered as
regards the outer leaves, and only show a cluster of small dark
green active leaves at the heart.

The above appearances are not confined to the phjts
receiving very large amounts of nitrogen ; it is rather a
question of the relative excess of nitrogen as compared with
the quantity of available alkalies, especially of potash. Thus
the plants on Plot 1 AC are particularly bad, as they receive
the maximum amount of active nitrogen in addition to the
dung, whereas the plants on Plot 2 AC, which receive the
same nitrogen but also sulphate of potash, arc comparatively
healthy. The plants receiving nitrate of soda as a source of
nitrogen show less damage than those receiving an equivalent
amount of nitrogen in the shape of ammonium-salts. Super-
phosphate, in the absence of alkaline salts, seems to increase
rather than diminish the injurious effects.

B. Effect of Mineral Manures. The effect of the difierent
mineral constituents of a manure upon the mangel crop can be
seen by an examination of the results yielded by Plots 4, 5,
and 6. Plots 5 receive superphosphate only at the rate of
392 lb. per acre. Plots 6 receive 500 lb. per acre of sulphate
of potash in addition to the superphosphate, while on IMots 4
the other alkalies which are taken up by the plant are added
in the shape of 200 lb. of sulphate of magnesia and 200 lb. of
common salt per acre. In the cross-dressings of nitrogenous
manures it should be noticed tliat all the plots in Series N
receive soda through the use of nitrate of soda, whereas the
other nitrogenous dressings, being either ammonium-salts or
rape cake, provide no appreciable amount of alkaline sidts.

The following diagram (15) shows the results given in
Table XL., but set out in a graphic form, for Plots 8, 5, 6, and

104

EXPERIMENTS UPON ROOT-CROPS

4 ; the first column in each group represents the mean crop for
twenty-seven years on Plot 8, receiving no mineral manures ; the
second column represents the crop of Plot 5, receiving super-
phosphate only ; the third, that of Plot 6, with potash in

Ammonium Salts.

□ NoMinerals. p^Superphosphate. IpSuperphosphate ■ Superphosph

y^yj [^\2j and Potash. H Magnesia s

ate. Potash,
and Soda.

Fig. 15. — Mangel Wurzel. EiFect of variou.s Mineral Manures.
Produce of Roots per acre, 1876-1902.

Average

addition to the superphosphate ; and the last column represents
the crop of Plot 4, which receives superphosphate and all the
alkalies — potash, magnesia, and soda. The four plots in each
series are grouped together. To the first group (O) no
nitrogenous manure is applied ; in the second (N), nitrate of
soda ; in the third (A), ammonium-salts ; in the fourth (C), rape
cake ; and in the fifth (AC), rape cake and ammonium-salts^
are respectively the sources of nitrogen.

A first inspection of the diagram shows that superphosphate

VALT'K ()|- POTASH 10.%

produces but little increase of crop cxccjit when uxd wiili
nitrate of soda ; the average increase of cro}) due to sujx'rjdios
pliate on Series A, AC-, and (', where ammonia or rape cake is
the source of nitrogen, is only 1 l' loiis per acre, whereas tlie
average increase it causes where nitrate of soda is used
amounts to d"2 tons per acre. This latter result demonstrates
that phosphoric acid is necessary for the proper (h'velopment
of the mangel plant, but that in the absence of alkaline salts
on the ammonia and rape cake plots it cannot exercise any
sensible influence.

The great increase of crop comes as a rule when potash is
added to the superphosphate : the crop on the plots receiving
ammonium-salts rises from 77 to 14"0 tons per acre; with
rape cake the rise is from 11 T to 18"6 tons per acre; with
rape cake and ammonium- salts the increase is from 104 to
22 5 tons per acre. Only with nitrate of soda as the source of
nitrogen is there no increase for the addition of potash, the
crop being practically equal on the two plots 0 and ;'>, with and
without potash. The necessity of potash for the mangel crop
is still more strikingly seen in the seasons of large crop : where
no potash is supplied in the manure the plant has to get as
nuich as it can from the reserves of potash contained in the
soil, and, as it is difficult to accelerate this process, the crop on
these plots cannot make nearly such good use of favourable
conditions for growth as the crops which have a large amount
of potash at command. For example, in 1000 the addition of
potash to superphosphate and ammonium-salts raised the crop
from 120 to 282 tons per acre, and on the plots receiving rape
cake and ammonium-salts the rise was from 14i> to !57"» tons
per acre.

A further inspection of the diagram shows thai the ailditioti
of magnesium sulphate and salt to the plots receiving potash
and superphosphate, as represented by the last columns in the
figure, brings about a further small but perceptible incicase of
crop, and the increase is proportionately more for the larger
crops. The most probable cause is that the 400 lb. of soluble

106 EXPERIMENTS UPON ROOT-CROPS

salts, the magnesium sulphate and sodium chloride added to
Plots 4 but not to Plots 6, though providing no direct plant
food, yet so assist to render soluble the reserves in the soil and
to economise the supply of potash, that the crop receives an
indirect benefit equivalent to an addition of the more indispen-
sable elements of nutrition.

The great effect of potash, and to a less degree of the other
alkaline salts, upon the mangel crop is very striking, and is to
be correlated with the fact that the mangel is essentially a
sugar-producing plant, and that large supplies of potash seem
to be essential to the processes in the plant which result in the
formation of sugar and similar carbohydrates.

Doubtless the long period over which the experiments have
been continued has intensified the effect, because the soil of
Plot 5, which has received no potash for at least forty- seven
years, must by this time have been very thoroughly exhausted
of available potash. The poor returns of Plots 5, receiving no
potash, have been progressive, getting worse each year as the
initial stock of potash in the soil has become more and more
exhausted. For this reason, the farmer taking his mangel
crop in rotation need not expect to find an addition of potash
produce such a very large proportionate increase as is here
manifest.

The effect of potash and of the other saline manures is
plainly visible in the appearance of the plants themselves.
On the plots receiving potash the plant begins to ripen early,
the leaves turn yellow and become flaccid, so that in October
these plots may be seen outlined from the rest by their lighter
tint at any distance from which the field can be viewed. The
ripening effect and the lighter colour are even more apparent
where the complete mineral manure, containing also magnesium
sulphate and salt, has been applied, than where potash has
been used alone. On the contrary, the plots receiving no
potash show all the signs previously described as indicating an
excess of nitrogen — the premature death of the outer leaves,
and the dark green, curled, and unhealthy appearance of the

NITRATE OF SODA AND AMMOM r M S A ITS i(»7

remaining tufts of small loaves, which show no >iLMi> of
completing their growth however prolonged the si'ason may he.

C. Comparison of Nitrate of Soda and Amman} nw-.oilt.-' as
sources of Nitrogen. It has already been pointed out that the
plots of Series N cross-dressed with nitrate of soda, give
better crops than the corresponding plots of Series A. whicli
receive the same amount of nitrogen in the form of ammonium
sulphate and chloride. This is particularly the case on Plots
5 and 8, w^here no potash is added, for the soda of the nitrate
of soda seems to supply the alkali needed by the plant, or at
any rate enables it to utilise the reserves contained in the
soil. The superiority of nitrate of soda is, however, also Ncry
evident on the other plots receiving potash or the comijlete
alkaline salts. Taking the mean of Plots 1, 2, 4, 6, and 7. and
comparing Series N and A, the crop obtained with 80 11 >. of
nitrogen in the form of nitrate of soda exceeds the crop of the
corresponding plots in the ratio of 100 to 89. On the
Rothamsted soil nitrate of soda always gives rather a higher
return than ammonium-salts, but not quite to the same extent
with other crops as with mangels ; the superiority of nitrate
of soda is, however, not so marked as to suggest any specific
affinity of mangels for nitrate of soda, lovers of saline matter
and of nitrates though they are.

The cause of the superiority of the nitrate of s(j(la is
probably to be found in the different character of the growth it
induces ; being freely soluble in water and not retained in any
way by the soil, it sinks more readily, with the result that the
plant develops a longer and deeper root-system to follow the
nutriment. Ammonium-salts, on the contrary, are immediately
absorbed by soil of the Kothamsted type, and are retained
very close to the smface ; the plant in consequence deveIoj)s a
root-system correspondingly near the surface, and does not
search the subsoil so thoroughly for either food or water.

The appearance of the mangel cnjp when it is ready to lift
also confirms the opinion expressed al)ove, that the superiority
of the nitrate of soda is partly due to the increased I'oot -range

108 EXPERIMENTS UPON ROOT-CROPS

it induces. If we compare the plots receiving potash, viz., 4,
6, and 7, those which are cross-dressed with ammonium-salts
are dead ripe and the leaves all yellowing off, when the corre-
sponding nitrate of soda plots are still green and growing
vigorously. The droughts and heat of the summer and the
autumnal fall of temperature all have a greater effect on the
more shallow -rooted mangels grown with ammonium -salts,
and bring their growth to an earlier conclusion ; the pro-
longed growth with the nitrate of soda helps also to explain
the greater weight of produce on these plots. If, however,
we compare the appearances presented by the mangels grown
with nitrate of soda and with ammonium-salts on Plots 5 and
8, where the manure contains no potash, the nitrate of soda
plants are far healthier and more mature. In this case the
nitrate of soda seems to be also able to do some of the work of
the potash, both by enabhng the plant with its extended root-
range to draw more freely upon reserves of potash in the soil
and subsoil, and also by the soda acting itself as a potash
substitute, or perhaps more correctly, as a potash economiser.
Here, with no potash supplied, the superiority of the plots
receiving nitrate of soda over the corresponding plots with
ammonium-salts has been a progressive one, increasing from
year to year ; while the relative effect of nitrate of soda and
ammonium-salts when potash is also supplied in the manure
is constant, or only varies with the character of the seasons,

D. Efect of Nitrogenous and Mineral Manures when used in
Conjunction with Dung. It has already been indicated that the
crops on plots receiving dung are on the average much better
than those grown with artificial manures only. To a large
extent this is due to the imjDrovement in the texture and water-
retaining capacity of the soil which has been effected by the
repeated application of farmyard manure. The seed always
germinates better on these jDlots and grows away at an earher
date, so that in some years of great heat and drought, like
1895 and 1901, a crop is obtained on the dunged plots when
the plant fails almost entirely on the plots receiving no organic

VALrK OF FAI.'M\AIM) \l WIIM Km

maiuire. Even wlion \hv plant docs not cntiiclx fail it lias
been often nt)tieeil that, if a spoil uf liot weather comes in the
early part of the season, the plant on the dnn^ed plots will lie
growing vigorously when that on the othei- plots is still
struggling for exislenee. Later on, when all ihe jilani i^
•established, the ditierences are not so marked, an<l in la\onial)|r
seasons the crop on the plots manured with artilieials ri\al>
the crop grown with dung, if due allowance be made for the
larger amount of nitrogen actually supplied to tlie dunged plots.

The right-hand portion of the diagram Fig. 14, page KM.
shows the effect of the successive additions of other niti-ogeiions
manm'es to dung.

Considering first the crops on Plot 1, in each series (see
Table XL., page 98), we find that notwithstanding the large
amount of nitrogen which the dung supphes, and its accunuila-
tion in the soil, yet dressings of quickly-acting nitrogenous
manures will still bring about an increase of crop, 'i'he
amount of nitrogen annually supplied to Plot 1-0 is mnch
greater than is removed by the crop, hence there nuist be a
considerable accumulation of nitrogen from year to ycai- in the
soil of this plot. Nevertheless, these reserves cannot become
active quickly enough for the needs of so rapidly growing a
plant as the mangel, hence the increase which is seen when a
further addition of active nitrogen in the shape of ammoninm-
^alts or of nitrate of soda is made.

When more than 86 lb. per acre of nitrogen is adde<l, as on
Plot 1 C, which receives 98 lb. of nitrogen as rape cake, or
as on Plot 1 AC, which receives 184 lb. of nitrogen as rape
■cake and ammonium- salts, no further increase of crop is >. i n,
the average remains stationary at 24 tons per acic The (r(»p
has, in fact, attained its maximum, and is limited, noi b\ the
amount of nitrogen and other plant food available, bm l.\ its
restricted period of growth, or l)y a scarcity of water, sindiiiht,
and other factors of development.

Turning to a comparison of Plots 1 and 2, some interesting
results are to be seen ; both receive a sinnlar dressing of

no

EXPERIMENTS UPON ROOT-CROPS

14 tons per acre of farmyard manure every year, but for the
first nineteen years of the experiment, from 1876 to 1894,
Plot 2 received in addition 3J cwt. per acre of superphosphate.

Tons
perAcre.

1876-94

1895- 1902.

Series 0

AC

25

^ % ^

-I n

o // //

m m m

:■:■ '// ' /■/; ■.■■■■/

. ii % %

1 i

liili

III 1
1 1

AC

P^Dung ^ Dung and Super- [^^Dun| H Dun|,Superphosph,

•.vj°"'y- "■ ^ phosphate(l9years) -V-^ only. ■ and Potash (/years

ate
ears)

Fig. 16. — Mangel Wurzel. EiFect of addition of Mineral Manure to Dung, with
various Nitrogenous Cross-dressings. Average Produce of Roots per acre.

From this first period we can ascertain the effect of super-
phosphate as a supplement to dung. In the second period,
which begins in 1895, sulphate of potash has been added to
the superphosphate on Plots 2, so as to institute a com-
parison between the effect of dung alone and of dung in
conjunction with potash and phosphates. The results are
set out graphically in the accompanying diagram Fig. 16.
The left-hand half of this diagram shows the first period, when
dung is compared with dung and phosphates. The right-hand

VALUE OF I'OI'ASIl I II

half of the diagram ivfrrs to {\w second [x'riod, ls<i;, 1 <)():.'.
when potash was being used on Plot '2.

The dotted cohimns in the diagram rei)reHent tlie crops on
Plots 1, where no mineral manm-es are used witli the (hing ; the
cross hatched columns represent Plots 2, to wliicli in the first
period superphosphate was added ; the black columns the
same Plots 2 in the second period, wdien potash was also being
employed. Each of the pairs of columns represents a dilfcrent
nitrogenous cross-dressing.

From the left-hand half it is evident that superpliosphate
when used with dung has produced no effect upon the crop
during the nineteen years of the first period. With no other
nitrogenous manures, or when nitrate of soda is used as a
cross-dressing, there is a small increase from the use of super-
phosphate, but it seems to cause even a faUing-off wlien added
to ammonium-salts or rape cake and dung.

Turning now to the effect of sulphate of potash when added
to dung, as represented by the right-hand diagram in Fig. IG,
we find that the potash produces a very marked effect. During
this last period the crops on Plots 2, receiving potasli and
phosphates, have been much superior to those on IMots 1,
receiving dung alone ; although in the earlier period, when
phosphates but no potash were used on 2, the two series of
plots were practically equal. The increase caused by potasli is
naturally most seen in Series O, A, C, and AC ; in Scries N,
which is cross-dressed with nitrate of soda, nuich less benefit
is seen for the addition of potash.

Considering the large amount of potash contained in <hmg,
and the enormous residue which must have accumuhited by
the yearly application of 14 tons per acre for the last forty-seven
years, the result is very striking, as showing the dependence of
the mangel crop on an abundant supply of potash. The a|t|)Ii<a-
tion of farmyard manure is generally considered to supply
sufficient potash to remove the need for any further spccitic
manuring with potash salts even to so potash-loving a crop as
mangels, but these experiments show that even when (hmg has

112 EXPERIMENTS UPON ROOT-CROPS

been applied continuously for a long time, the application of
potash will still result in an increase of crop. The appearance
of the crop is even more indicative of the value of the potash
dressing ; where it has been applied the crop is altogether
healthier and rijjer, especially where the excessive dressings of
nitrogen have been used.

E. Proportion of Root to Leaf. At the time the crop is
lifted the leaves are weighed, then they are spread upon the
land to be ploughed in again.

The amount of leaf grown is almost wholly dependent upon
the supply of nitrogen, and variations in the mineral manures
have but little effect. When the growth is normal, the weight
of leaf is about 20 per cent, of that of the root, and the more
the alkaline salts, potash, soda, and magnesia, are added in the
manure, the more thorough is the maturation of the crop and
the lower does the proportion of leaf become. The highest
proportion of leaf to root is shown on those plots which receive
.a comparative over-supply of nitrogen, but no alkaline salts,
potash, soda, or magnesia, to restore the balance of the
constituents of the manure.

In good seasons when the crop of roots is large, the amount
of leaf shows little corresponding increase, hardly more than
would be accounted for by the comparative absence of blanks
<ind missed plant which characterises a good season.

It is evident that when once the plant has developed a
.sufficiency of leaf, the difference between a good and a bad
season depends upon the rapidity with which the leaves can do
their work of carbon assimilation from the atmosphere, for all
the products of that action are at once passed on to the root
^nd stored there, in the case of the mangel chiefly in the form
of sugar. A good season with a heavy yield of roots does not
involve any greater luxuriance of leaf than usual, just as, in a
similar manner, plots which grow a small crop of roots because
of the absence of alkaline salts may yet possess a normal
•development of leaf

F. Proportion of the Nitrogen recovered in Crop to that

RECOVl'i:\' oi" MTi:()(ii;\ I\ CL'ol

1 i::

supplied i It Mdiiurc. In view ot tlic l.ir^.' aiiKuiiits <.t nitrogen
applied in the nianurt's, ii is important to consider what
proportion of I'arh of tlie dilVcrent nitrogenous conijxiund.N
is recovered in the crop.

If the soil has sutfered no loss of nitrogen, then the whoir
of the nitrogen removed in the crop must have heen di-rived

T.vr.LE XLII. — Man(/el Wurzel. Rrlation hdvccn the yitroi/en roovcral
ill Crop and that supplied in Manure.

Series.

Cross-Dressings.

1 =

11

Ii

Nitrogen.

5i

5

1

Plots 4.— Superphosphate, Sulphates of Potash and Mtignesia, and Common

Salt.

N

A
AC

C

Nitrate of Soda, 550 lb. = 36 lb. N.
Animonhim-salts, 400 lb. =86 lb. N. .
Rape Cake, 2000 lb. =98 lb. N. and Am-
monium-salts, 400 lb. =86 lb. N.
Rape Cake, 2000 lb. =98 lb. N. .

Tons.
17-95*
15-12*

24 -git

20 -951

Per cent.
0-164*
0-1 45*

0-184+
0-148+

Lb.
67-2
49-3

103-0
69-4

Lb.
86
86

184

n

Per cent.
78-1
57-3

56-0
70-9

Plots 1.— Farmyard Dung, 1 1 tons.

0

N
A
AC

C

None

Nitrate of Soda, 550 lb. = 86 lb. N.
Ammonium-salts, 400 lb. =86 lb. N.
Rape Cake, 2000 lb. =98 lb. N. and Am-
monium-salts, 400 lb. =86 lb. N.
Rape Cake, 2000 lb. = 98 lb. N. .

17-44
24-74
21-73

24-O.T
23-96

0-162:
0-209:
0-217:

0-241:
0-207:

63-3
115-8
105-6

129-8
111-1

200
286
236

384
298

81-6
40-5
36-9

83-8
37-3

» Average for 21 years, omitting 187i)-7, 1885, 1895, 11*01-2.
\ Average for 22 years, omitting 187(3-7, 1885, lttOl-2.
X Percentage calculated from 9 years, 1878-82, 18!>7-1900.

from the manure, and on that assumption the percentages given
in the following table are calculated. In calculating the
amount of nitrogen recovered each year no acctnint has ]>een
taken of the leaves, because they are returned to the soil and
their nitrogen i.s not removed from the land ; if both leaf and
root were taken into account the recovery of iiiticLit'n tor any
single year would be very much greater; indeed in some
seasons when a big crop is grown more nitrogen is removeil in

114 EXPERIMENTS UPON ROOT-CROPS

the roots alone than was supplied in the form of manure.
Table XLII. shows the nitrogen supplied and removed from
Plots 4, where there was a full supply of mineral manures, and
from Plots 1, where dung was used with nitrogenous manures.

The results show that both the nitrate of soda and the rape
cake are very effective manures, about three-quarters of the
nitrogen they supply each year being recovered in the roots
removed from the land ; the ammonium-salts, and ammonium-
salts mixed with rape cake are less effective, the recovery being
between 50 and 60 per cent, of that applied. On the plots
receiving dung, the proportion of nitrogen recovered at once
becomes very much less, sinking to about one-third of that
supplied in the manure. It is known that there is a very large
accumulation of nitrogen in the soil of these continuously
dunged plots, though not sufficient to make up all the difference
between the nitrogen supplied and that removed in the crop.
Of the nitrogen unaccounted for, some has been washed as
nitrate into the subsoil, and some liberated as nitrogen gas by
the agency of bacterial changes.

Thus, when dung and nitrate are used, 115*8 lb. of nitrogen
is recovered in the crop as compared with 63*3 lb. recovered
from the dung when used alone ; if we deduct the 63*3 lb., as
due to the dung, from the 115"8 lb. we obtain 52 '5 lb., which
may be taken as the return from the nitrogen of the nitrate of
soda when it is used in conjunction with dung. This amounts
to 61 per cent, of the 86 lb. of nitrogen supplied, a proportion
which compares favourably with the proportion recovered from
nitrate of soda when used with a mineral manure only, if we
take into consideration the fact that a much bigger crop is being
grown with the two manures in conjunction than with either
singly ; and, as we have seen before, it is the smaller applications
of manure which give the best proportionate returns.

These results, showing the large proportion of the nitrogen
of nitrate of soda and other nitrogenous manures that is
recovered, even when they are used in large amounts with
dung year after year on the same land, lend no colour to the

CoMrosri'ioN oi' M \N(;i:i.s iis

opinion that in oniinary tarniing there is likoly to be serit)U.s
loss ofnitrogen by " denitrihcation " ^ whtMi iiit ro^onous manures
and dung are used together. Tiie soil is undoubtedly alwuys
suffering losses of nitrogen in the gaseous state through various
bacterial changes which can be roughly grouped togetlier
under the term "denitritication," and these losses will increase
the higher the condition of the land becomes and the more
nitrogenous bodies of an easily decomposable naturi' are
present. But there is no evidence in the Kothamsted mangel
experiments to support the view that specific and excessive
loss will set in when dung and nitrate of soda, or other
active nitrogenous manure, are used together.

G. T/te Composition of the Mangel Crop as ajcrtrti hi;
Manuring. In many of the years during which the mangels
have been grown, determinations have been made of the
amount of sugar contained in the roots from tlie ditterent
plots, sugar being the chief constituent of the dry matter of
the mangel and the main element in its value as food. Tal)le
XLIII. gives a summary of the results obtained in 1000 and
1902, years when crops were obtained above the average both
in regularity and magnitude. In the various ct)lunms are set
out the average weight of the roots, the prt)portions of dry
matter and of sugar, both the glucose or reducing sugai- and
the more important cane sugar, also the dry matter and sugar
in pounds per acre on each plot. Other columns give tiir
<luotient of purity, by which is meant the percentage of lanc
sugar in the dry matter, and the glucose coeflicient or the
relation per cent, of the glucose to tlie cane sugar.

It will be at once seen that the variations in the eompo>i-
tion of the roots are small compared with the variations in liu-
yiehl i'vom plot to ph^t ; the average weight of root varir>
from 071 to 305 lb., but the pr()])ortion of dry malt.r ohIn
fluctuates between 153 per cent, and lol> per (rnt. In ilif
main the root grows as a whole tioni a very early stage,
increasing in size but maintaining a fairly uniform coniposition.

♦ Seep. 219.

116

EXPERIMENTS UPON EOOT-CROPS

If one or other element necessary to the nutrition of the plant
be lacking, the root ceases to swell instead of altering its
composition to meet the deficiency.

Table XLIIl. — Composition of MaiKjd Roots. Mean of two Seasons
(1900 and 1902).

Sugar.

Per acre.

Nitrogen

per acre

in

Average

Series
and

Weight

Matter.

Quotient

Glucose

Dry

Matter.

Total

Plot.

Manure.

Roots.

Reducing.

Cane.

of
Purity.

Co-

efficient.

Sugar.

Lb.

Lb.

Per cent.

Per cent.

Per cent.

Lb.

Lb.

(1

200

2-44

13-37

0-34

8-64

64-6

3-9

6644

4292

2

200

2-81

13-03

0-29

8-32

63-9

3-5

7247

4620

0^4

0-74

14-89

0-23

9-78

65-7

2-4

2433

1579

5

0-76

1.5-25

0-21

10-85

71-1

1-9

2801

1996

u

0-71

15 -30

0-23

11-02

72-0

2-1

2074

1505

(1

286

3 -65

11-87

0-38

7-42

62-5

5-1

9833

6099

2

286

3-95

11-65

0-42

6-47

55-5

6-5

9684

5370

N\i

86

3-16

11-77

0-23

7-64

64-9

3-0

7699

4972

5

86

2-47

11-87

0-42

7-10

59-8

5-9

6629

3973

u

86

2-69

12-47

0-26

7-76

62-2

3-4

7305

4519

[1

286

2-89

11-40

0-25

6-87

60-3

3-6

6368

3828

2

286

3-22

11-90

0-25

7-09

59-6

3-5

8622

5112

Aj4

86

2-29

12-75

0-27

8-10

63-5

3-3

6487

4088

86

1-10

12-69

0-17

7-79

61-4

2-2

2950

1791

V6

86

2-41

13-43

0-25

8-81

65-6

2-8

6877

4488

[1

384

2-74

10-94

0-23

5-70

52-1

4-0

6294

3268

u

.384

3 -.59

11-83

0-24

6-30

53-3

3-8

9619

5101

Ad 4

184

3-72

11-60

0-25

6-74

f.8-1

3-7

9542

5449

1-5

184

1-.30

11-86

0-lS

6-85

57-8

2-6

3218

1835

u

184

3-07

11-70

0-26

7-OS

60-5

3-7

8739

5257

[1

298

2-86

11-87

0-33

7-29

61-4

4-5

7382

4522 {

2

298

3-29

13-04

0-28

7-92

60-7

3-5

9579

5801 1

CJ4

98

3-25

12-05

0-32

7-76

64-4

4-1

7997

5127 1

98

1-25

12-84

0-25

7-95

61-9

3-1

3561

2193 1

16

98

2-69

12-94

0-44

8-28

63-8

5-3

7700

4904

There are, however, certain differences in composition which,
if not large, are regular, and brought about l^y the differences
in manuring. Dealing with a series of roots which receive an
ample supply of mineral constituents, as on Plots 2, 4, or 6, the
size of the root and the proportion of water rise with each
addition of available nitrogen. The smallest and richest roots
are those grown without nitrogenous manure, the largest and
most watery are those wdiere nitrate of soda is used in con-
junction with dung. The roots grown with ammonium-sahs

srCAK 1\ .MAMii:i.S 117

or willi Vi\\)c viikc as llic sourci' of nitmi^M-n arc less watfiv
tlian tliDse ^^"()\^•n witli iiiti'alr of soda, rapi' cake |»ro(lu('iii;:
the richest roots for tlirir size. As reirai'ds its {'\]\'{\ lioth on
the ina<j;iiitiiile and (.-oinpoNition of tlic crop. I'do 11». of iiiiid;,'(Mi
in (lung are less effective than 80 11). in nitrate of soda or O.s jh.
in rape cake, and have about the same value as SO 11). of nitro^'en
in annnoniuni-salts.

It has already been noticed that the use of anniioniuni
salts promotes an earlier maturity than does nitrate of soda :
this is seen in the generally higher "quotient «>f purity " of the
"A" as compared with the "N" series. The glucose co-
efficient is correspondingly lower in the *'A" scries. Excess
of nitrogen has the same effect as the sul)stitution of nitrate of
soda in lowering the quotient of purity and raising the glucose
coetticient. For instance, Plot 2 N gives a (|uoticnt of pni-ity
of 55'5 as compared with 64'9 and 62*2 on IMot^ 4 N and «) N.
which receive the same mineral manures but not the extr.i
nitrogen of the dung on Plot 2 X; .similarly, ilie glucose co-
efficient is 6 5 on Plot 2 X and only ;3 0 and oA on 4 N and
6 X"". Again, all the plots on the AC series, receiving both
rape cake and ammonium-salts, show worse results as regards
purity than the corresponding plots on either the A or the C
series, which receive only one portion of the nitrogenous
manure on series AC.

The dependence of sugar-formation upon potasli is well
seen by comparing the weights of sugar per acre produced on
Plots 4 or 0, receiving potash, with the corresponding weights
from Plot 5, without potash ; or by comparing Plots 2. where
dung, nitrogenous manures, phosphates, and potash arc applied,
with Plots 1, which receive dung and nitrogenons mainn*cs only.
To this latter statement the nitrate Plots 1 and 2 affbrd an
exception. As a rnle, however, the percentage tif sugar in tin-
root is little if at all increased by the u.se of jMitash ; the effVct
comes from the increased crop, and is aj)parent in tli*- amount
of sugar grown per acre. The ([uotient of purity is. however,
better on IMots 4 and <3, with potash, than on Plots ."i, witiioul

118 EXPERIMENTS UPON ROOT-CROPS

potash ; but this effect of potash in inducing the ripening of
the mangel is not visible in the dunged plots.

Although the analyses which have been made of the nitro-
genous constituents of mangels are not yet wholly satisfactory,
certain results are apparent.

As regards the total nitrogen, the proportion present in
the root reflects the supply of nitrogen in the manure, and
as the roots get larger and more watery with the use of
nitrate of soda or any excess of nitrogenous manure, so
also does the proportion of nitrogen rise in the substance of
the root. As to the forms in which the nitrogen is combined :
the proportion of nitrogen in the proteid condition, whether
soluble or insoluble, is at its highest in the plants which
are nitrogen starved, and falls to its lowest point where
nitrate of soda or any excess of other nitrogenous manures
are used.

The amides are also at their highest on the plots which
show immaturity because of the use of large quantities of
nitrogen, and especially of nitrate of soda ; on the contrary,
the use of potash at once diminishes the proportion of
amides. The proportion of nitrates present is less affected
by the manuring, but it is highest when an excessive amount
of nitrogenous manure is used, or when nitrate of soda supplies
the nitrogen in the manure, and is usually diminished by the
use of a free supply of potash.

Speaking generally, then, it will be seen that though the
composition of mangels is not greatly influenced by manuring,
yet certain factors go together. Highly nitrogenous manure,
especially when the nitrogen is in the form of nitrate of soda,
produce large and watery roots, whose immaturity is reflected
in the low quotient of purity, the high glucose coefficient, the
high content of nitrogenous matters, of Avhich again a large
proportion is in the form of amides and nitrates. If the
nitrogen is in excess and the mineral manures are deficient
these differences are intensified, whereas an abundant supply
of potash tends to produce a more normal root.

PRACTK'AI. CONCUSIONS 119

Pk ACTUAL ('(»N(l,rsi(tNS

Looking at the ivsults of ilic cxjttM-imciits at IJotliaiiistciI
on tlie continuous growth of niani^cls with \aiious manures
for twenty-seven years, from tlie point of view of the practical
farmer the following general (■onclu>ions can he drawn :

1. Mangels can be grown continuously on the same land
without injuring the tilth of the land or the health of tlu^ crop.

2. A liberal dressing of farmyanl manure forms tin- br>t
basis of the manure for mangels.

3. The crop will further respond to considerable addition.^
of active nitrogenous majiures to the dung, particularly of
nitrate of soda.

4. A free supply of potash salts is essential to the pi-oper
development of the mangel, hence a specific potash mamn-ing
is desirable even when dung is used in large ([uantitie.s, and
on a strong soil initially rich in potash. When nitrogenous
manures are used in addition to <lung, the potash salts should
be increased pro rata, in order to maintain the health and
feeding value of the crop and to bring it to maturity.

5. Superphosphate or other phosphatic manure is hardly
necessary with dung, and will give little appreciable return.
especially when the crop is grown in rotation.

6. Since soluble alkaline salts are l)eneficial to the mangel
crop, either as direct foods or as economisers of potash, a
<lressing of salt should always be included among the manures
for the mangel crop.

II. — Experiments upon Tium rs. IJaiin Fii.i.o. ls4:;-70.
The experiments u{)on tiu'uips may be dividi'd into fom-
series, the two earlier dealing with Norfolk white turnips, the
two later with vSwede.s. The chief difference between these
two crops lies in the gi-eater proportion of leaf and the more
watery nature of the white turm*i>.

It will not be necessary to give th«' results obtained in the
first trial 1843-5, but the three later experiments were set out

120 EXPERIMENTS UPON ROOT-CROPS

on practically the same lines as have been maintained for the
mangel crop to-day, and are summarised in Table XLIV.

These results show the great dependence of the turnip crop
upon the supply of a phosphatic manure like superphosphate,
whereas there seems but little need of any external supply of
alkaline salts when turnips are growing on a soil like that of
Rothamsted. The crop was increased by each addition of
nitrogen, but the increase was not large, and affected the leaf
more than the root. Until the soil had become depleted of its
available nitrogenous compounds by repeatedly growing the
crop without any aj^plication of nitrogen, superphosphate alone
without any nitrogenous manure gaA^e rise to a comparatively
good crop. The value of superjDhosphate as a manure for
Swedes and turnips of all kinds was found to lie in the
extended root-development it induced, especially when the
plant was young. It was from these early experiments that
agriculturists first learnt how essential were phosphatic
manures to the growth of turnips, and the fact that the
manure for turnips should consist of superphosphate in the
main with but little nitrogenous manure, soon passed into
the common stock of farming knowledge and is universally
acted upon to-day. At the same time the success of super-
phosphate manuring for Swede and turnip crops led to an
enormous development of the manufacture of superphosphate
from mineral phosphates, which was then beginning under the
patents taken out by Lawes.

In the earlier years l3ut little return was obtained for potash
manures, but as the plots continued to be cropped with nitrogen
and phosphoric acid but without jDotash, the soil became
gradually depleted of available potash and the potash manures
began to show large eff'ects.

As has already been mentioned, it was soon found necessary
to discontinue the attempt to grow Swedes year after year on
the same land. The soil at Rothamsted is not very well
suited to the crop, being heavy and awkward to work, and in
consequence of the use of saline manures and the restricted

/

AWUAT. PKODUCE OF KOOTS I'KK' ACIM; li'l

Table XLiy.— 7"iiniips grown in Bam Field, Jiothiniistrd. J'rodnrc
of Eoots per acre per annum.

strip.

Strip Manures.

CroH-DTMaIng*.

0.

N.

li

A.

B

H

E 3

AC.

y

n

c. 1

1

Norfolk White Turnips, 4 seasons (1845-48).

3

4
5

Nitrogen per acre in Cross-Dressings

Lb.

Lb.

Lb.
45

Lb. 1 Lb. 1
135 1 90

Gypsum. 1845 ; afterwards Unmanured(av. IS 16-47-48)
Superphos. each year; Pot., Sod., and Mag., 1847-48
Superphosphate

Superphos. each year; and Potash in 1847-48 .

Cwt.

24

161

176

160

Cwt.

Cwt.
27
195
198

196

Cwt. Cwt.
110 131
205 ' 222
201 ' 218

207 [217

1 !

Swedes, 4 seasons (1849-52).t

3
4

0

^ J

Nitrogen per acre in Cross-Dressings

Lb.

Lb.

Lb.
43

Lb. 1 Lb. 1
141 1 98 1

No Standard Manure, 1846 and since

Superphos., Sulphates Pot. and Mag., and Soda-ash

Superphosphate ........

Superphosphate and Sulphate Potjish

Cwt.

46

157

149

136

Cwt.

Cwt.

77

189

174

174

Cwt. 1 Cwt.
140 i 154
261 247 '
224 210

24S ' 234 1

1 1

Swedes, 5 years (1856-60).:

1
2
3
4

6

7
8

Nitrogen per acre in Cross-Dressings

Lb.

Lb.
43

Lb.
43

Lb.
51

Lb.

98 1

14 tons Farmyard Dung

Do. and Superphosphate .
No Standard Manure, 1S4I) and since
Complete Mineral Manure . .....

Superjjhosphate ........

Superphosjjhate and Sulphate Potash
Superphos., Sulph. Pot., and 36i lb. Amm. -salts
No Standard Manure, 1853 and since

Cwt.
145
155

17
106

96

82
100

39

Cwt.
156
152

24
124
123
103
116

48

Cwt
190
191

21
130
108
129
143

34

Cwt.

181
171

30
134
119
128
152

46

Cwt.

127

119
24
95
86
91

111
59

Swedes, 10 years (1861-70).

1
2
3
4

6

8

Nitrogen per acre in Cross-Dressings

Lb.

Cwt.
143
143
11
52
49
45
49
22

Lb.

86

Cwt.
177
183

21
115
103
105
104

35

Lb.
86

Cwt.

194

190
13

100
81
88
95
23

Lb.

184

Lb.

98

Cwt.
202
198

95
131
124
126
1.30

93

14 tons Farmyard Dung

Do. and Superphospiiate .
No Standard Manure, 1S4G and since
Superphos. only ; previously Complete Minerals
Superphosphate . . . .

Do. ; previously Sulph. Potasii also
Do.; previouslySulph. Pot.,and:!tlUb. Amm.-saltsalso
No Sbindard Manure, 1S53 and since

Cwt.
210
210

89
158
138

ir.o

156
104

^<1 an Nitric Acki nilxwl witb uwdiut.

• In the 0 yi-ars ( Is.'-O-eO) the .Vitroneii wm apiil

t No Cross-Dri-ssiiiKH applicl in 1851 or 18.'>2.

t Average produce of 3 years only (180<J-.')8), an the crops of 1861t aii<l 1800 r«llW.

122 EXPERIMENTS UPON ROOT-CROPS

root-range of the plant, a satisfactory tilth on some of the
plots became so difficult to establish that a good plant rarely
resulted.

Practical Conclusions

1. The experiments show that Swedes and white turnips
cannot be grown repeatedly on the same land, or even at short
intervals.

2. The manuring for Swedes must be liberal, as the yield
is much more quickly affected by poverty or exhaustion in
the soil than is the case with the other crof)s of the farm.

3. Although under favourable conditions Swedes can be
grown with artificial manures only, yet they are so dependent
on a good tilth and on the retention of moisture in the surface
soil that the manuring should begin with an application of
farmyard manure, unless the land is already in high condition.

4. Since Swedes grow at a warm time of the year and
receive much cultivation of the soil, nitrification is active and
the crop does not require a large amount of nitrogenous
manure. In the absence of dung, about 2 cwt. per acre of
some nitrogenous manure like fish guano or rape dust, together
with 1 cwt. per acre of sulphate of ammonia, will be sufficient.
When dung is used, the latter only is necessary. For the
shallow-rooting Swede crop sulphate of ammonia appears to
be a better manure than nitrate of soda.

5. The phosphatic manuring is most important, and should
consist of 3 to 5 cwt. of superphosphate or an equivalent of
basic slag in the case of strong soils. Only on the lighter
soils will potash be required ; about 3 cwt. of kainit per acre
in the winter may then be used.

III. — Experiments on the Continuous Growth of Potatoes

ON THE SAME LAND, HOOS FlELD, 1876-1901.

These experiments were commenced in 1876, and went on
for twenty-six seasons until 1901. The varieties grown were
— " Rock," four years ; " Champion," eleven years ; " Sutton's

AVERAGE YIELD ()!• I'OTATols ij:;

Abundance," five years; "Bruce," one yaw; and "Wliii.-
Beauty of Hebron," 1807-1001. Tlie question was not as to
the comparative merits of different varieties, l)ut different
sorts were selected on the supposition tliat in irrowiii^ tlir crop
year after year, a change was desiral)le, especially witli a view-
to the avoidance or lessening of disease. The special object
was to ascertain the manurial re(]uireinents of the cro[) and
the comparative character and composition of the produce.
Table XLY. gives the details of the manuring and the
average produce for the whole period of twenty-six years.

Table XLV. — Potatoes, overage yield ^Kr acre over 26 yenrs
(1876-1901).

Plot.

Manures per acre per aununi.

Average Produce per acre.

1

1

1^

E

a

1-2

<

if

5o

■S'i

■3.1

i

3.

1
0

1

1

I

1

3
4
5
6
7
8
9
10

Tons.

(14)*
14

14

Lb.

400
400

Lb.

550
550.

Lb.

300
300 •

300

Lb.

100
100

100

Lb.

160
100

16b

Cwt.

't
t

.3-5
3-5
3-5
3-5

Cwt.
22-7
47-5
82-6
87-4
27-9
36-2
93-5
96-4
48-3
52-3

Cwt.
3-8
4-7
4-7
4-6
4-7
4-3
5-1
4-8
4-2
3-9

Cwt.
0-9
2-6

7-8

10-2

1-4

?:;

7-5
1-9
2-0

Cwt.
27-4

54-8
95-1
102-2
34-0
42-.^.
105-7
108-7
54-4
58-2

Per

cent.

3-3

4-7

8-2 1
10-0 1

4-1 !

4-7

6-7

6-9

3-5 1

3-4

* Applied in the first 6 years only (1870-81).

t 3-5 cwt. Superphosphate also in the first 7 years (1876-82]

t 550 lb. Nitrate of Soda also in the first 0 years (1876-81).

The crop was grown continuously without manure, with
various artificial manures, and also with farmyard manure, both
alone and with some artificial manures. There were ten
differently manured plots, and under each of the ten conditions
the crop more or less declined over the later compared with the
earher years. The average produce per acre of total tubers
over the twenty-six years w\a.s — without manure, only l'7 4
cwt; with ammonium-salts alone, 34-0 cwt.; with nitrate of
soda alone, 42-5 cwt. ; with superphosphate alone, r)4-4 cwt. ;

124 EXPERIMENTS UPON ROOT-CROPS

with mixed mineral manm'e, including potash, 58 '2 cwt. Thus,
purely nitrogenous manures yielded less than purely mineral
manures, indicating that the potato finds a difficulty in
obtaining ash constituents rather than nitrogen from an
impoverished soil.

By superphosphate of lime alone the produce was raised
from an average of 27 '4 to 54'4 cwt. ; and by a mixed mineral
manure containing besides superphosphate of lime, salts of
potash, soda, and magnesia, to 58*2 cwt. ; that is to very little
more than by the superphosphate alone. It is clear that as
regards the small crops in question the land is still able to
supply sufficient available potash when it has become
comparatively exhausted of the phosphoric acid which can
reach the crop.

In reference to this increase of produce of potatoes by
mineral manures alone, it may be observed that the result is
quite consistent with that obtained with other root-crops
having comparatively shallow root-development ; and in such
cases the source of the nitrogen is chiefly the store of it in the
surface soil. The beneficial effects of mineral manures, and
especially of phosphates, are indeed ol^served generally with
all crops which are spring sown and have but a short period
of growth, so that they possess a comparatively superficial
root system, and are therefore forced to rely much on the
stores of food in the surface soil only.

It is remarkable that there is much less increase of produce
of potatoes by nitrogenous manures alone than by mineral
manures alone. Thus by ammonium-salts alone there is an
average j)roduce of 34 cwt., or only between 6 and 7 cwt. more
than Avithout manure ; and with nitrate of soda alone there is
an average of only 42 'S cwt. per acre.

With the mixed mineral manure and ammonium-salts
together, the average produce of total tubers was 1057 cw^t.,
and with the mixed mineral manure and nitrate of soda, 1087
cwt. per acre. The better result from the nitrate of soda is
doubtless due to its nitrogen being more immediately available

POTATOKS liT,

and more rapidly distributi'd within tlic soil, tliu> inducinL' a
more extended development of feeding umi. 'YUr n\vi'ivj.i'
produce by the mineral and nitrogenous manures together, over
twenty-six years of continuous growth, was very nearly that ot
the estimated average produce of Great Britain under ()r(hnary
cultivation, and much more than that of Ireland.

The plots receiving farmyard manure, containing al)()iit lMmi
Ih. of nitrogen, gave less produce than the mixture of mineral
manure and ammonium-salts or nitrate of soda, supplying only
86 lb. of nitrogen. In fact, only a small proportion of tin-
nitrogen of farmyard manure is rapidly available, that (hie t<»
undigested matter being more slowly available, and tliat in the
litter remaining for a long time inactive. Farmyard nianuri"
is, however, often applied in very large quantities for potatoes,
the process being to a great extent one of forcing, after which
remains a great amount of unexhausted manure-residue within
the soil.

The characteristic effect of nitrogenous manures, provided
there be a sufficient availal)le supply of ash-constituents, and
especially of potash, is to increase the amount of tlie non
nitrogenous substance — starch, in the tubers. Thii>. the
produce of starch per acre was about 650 lb. without manure,
about 1350 lb. with purely mineral manure, and with nitro-
genous and mineral manures together al)out '2~A)0 lb., or rather
more than 1 ton. In other words, the increased produce of
starch by the use of mineral and nitrogenous manures together
was more than J ton per acre.

Since we know that a free supply of potash is essential t<»
the j^roduction of any carl>oliydrate like starch, it might have
been expected that a bigger crcjp an<l an increased ])roduetion
of starch would be obtained from Plot 10, receiving a eninplete
mineral manure containing potash, than from l*lot 1> which
receives superphosphate only. There is, however, j)ractieally no
difference in the yield from the two plots; in the absence of
nitrogen and the exhaustion of the soil of its available supplies
(jf this constituent, the small crojis grown could always obtain

126 EXPERIMENTS UPON ROOT-CROPS

a sufficient quantity of potash from the soil, as may be seen
from the fact that while the unmanm-ed crop withdrew about
21 lb. of potash per acre per annum from the soil, the addition
of superphosphate on Plot 9 raised this to 51 lb., and the
further addition of potash salts and other alkaline salts to Plot
10 only increased the amount annually withdrawn to 54 lb.
Clearly the soil, which is known to have been originally well
stocked with potash and also to contain considerable residues
from potash manurings previous to this experiment, could
from its own resources supply ample potash for the require-
ments of a crop averaging no more than 2 to 3 tons per acre.
Where, however, big crops of potatoes are grown with the
aid of dung and artificial manures, it is well known that an
abundant supply of potash salts is essential both to the yield
and the quality of the potatoes.

It is well known that season has much to do with the
development of potato disease ; and there was on the average
much more disease in the w^etter seasons. As regards the
influence of manure, the proportion of diseased tubers was
the least where there was no supply of nitrogen ; that is, where
there was the least luxuriance, the most restricted growth, and
where the ripening was early developed. On the other hand,
with liberal supply of nitrogen and luxuriant growth there
was the greatest proportion of diseased tubers ; these being
the conditions resulting in a juice relatively rich in nitro-
genous and mineral matters.

Practical Conclusions

1. The best basis for the growth of potatoes is a supply of
well-rotted farmyard jmanure, 12 to 15 tons per acre. In the
absence of farmyard manure it should be replaced by some
manure containing organic nitrogen, e.g., by 5 cwt. per acre of
a good Peruvian guano, or by a meat or fish manure, or hy
10 cwt. per acre of shoddy.

2. A free supply of ash-constituents is essential to the
successful growth of the potato ; 3 cwt. of superphosphate

SUGAK BEET 1_'7

and 1 to 1^ cwt. of sulphate of potash per acre should ])e sown
in the drills before the seed is planted. If kainit is used as a
source of potash, it should be sown broadcast some time ])ef<>r('
the land is got ready for jDlanting.

3. A little active nitrogen is generally also needed, 1 cwt.
of nitrate of soda as a top-dressing when the haulm is growing
or 1 cwt. sulphate of ammonia with the other manures at
planting time will be sufficient.

IV. — Experiments on the growth of Sugar-Bekt.

A. First Series, 1871-1875.

The experiments made at Rothamsted with sugar-beet were
commenced in 1871 and continued for five years in succession
to 1875 inclusive. They were conducted on the land which
had been devoted to the continuous growth of root-crops
(Norfolk Whites and Swedes) from 1843 to 1870; excepting
that in the three years 1853-55 barley had been grown without
manure to equalise the condition of the plots as far as possible
before re-arranging them and the manuring.

During the first three of the five years of sugar-beet the
arrangement of the plots and of the manures was substantially
the same as during the preceding ten years with Swedish
turnips and the subsequent years with mangel wurzel. But
during the last two years of the five, neither farmyard nor any
other nitrogenous manm^e was applied ; the object being to
determine the eff'ects of the unexhausted residue of the nitio-
genous application during the preceding three years. The
description of sugar-beet groAvn was Vilmorin's '* Green-top
White Silesian." In 1871 the seed was dibbled on ridges in
rows 26 inches apart, and 10 inches from plant to plant in \\\r
rows; in 1872 and subsequently it was dibbled on the flat, in
rows 22 inches apart, and 11 inches apart in the rows; tht>
plants being moulded up afterwards. The roots were all carted
off and weighed; the leaves were weighed, spread on the
respective plots, and ploughed in.

128

EXPERIMENTS UPON ROOT-CHOPS

Table XLVI. shows, for selected plots, the manuring, the
average produce of root and of leaf, the average percentages
of nitrogen and of mineral matter in the dry matter of the
roots, and the average percentages and amounts per acre of
sugar in the roots, over the three years 1871-73 during
which the farmyard manure and the nitrogenous cross -
dressings were annually applied.

Table XLVI. — Sugar-Beet, Averacje inodihce of Roots, and Sugar
per cent, and per acre in the Roots, 3 years (1871-73).

standard Manures.

Standard Manures and Cross-Dressings
each year as under.

9.^
If

3W a,,

issg

Produce of Roots per acre.

4&6

Farmyard Manure (14 tons)

Superphosphate alone

Superphos. and Sulphate of Potash

Tons.

Tons.

Tons.

Tons.

Tons.

16-3

23-8

22-3

25-1

24-9

5-9

19-5

13-4

17-7

16-2

0-9

18-8

14-9

22-1

17-8

Sugar per cent, in the Roots.

4&

Farmyard Manure (14 tons)

Superphosphate alone

Superphos. and Sulphate of Potash

Per cent.
11-84
13-08
12-97

Per cent.
10-42
10-66
11-04

Per cent.
10-84
11-88
12-16

Per cent.

9-99

9-89

10-66

Per cent.
10-81
12-17
12-07

in the Roots.

Lb.

Lb.

Lb.

Lb.

Lb.

4309

5508

5413

5630

5976

1731

4661

3563

3886

4407

1704

4635

4063

5279

4788

Farmyard Manure (14 tons)

Superphosphate alone

Superphos. and Sulphate of Potash

It will be seen that the nitrogenous cross-dressings, which
were the same as those before and subsequently adopted for
feeding roots, were very heavy ; indeed, much heavier than is
recognised as suitable in the case of beet grown for the pro-
duction of sugar. The result was that when these were used

MANUKINC AM) SI CAi: (ONTI-.N'r 1-J!^

in aclditiun to lannyaid inamirr, tlu> produce of roots jin- -.n-vr
was large, in some eases al)out twice .is nuicli as tli.il oliiaincd
in the growtli of sugar-beet for tlio nianufaeture of sngai- in
Germany or France at tlie })resent time.

The figures in the table for Plot 1 show, liowevcr, that
when farmyard manure was used the amount of sngai- in the
roots never reached 12 per cent. ; but it was the highest,
11-8-4 per cent, on Plot 1-0, with the farmyard manure alone,
and the smallest crop; it was lowest, 9-1)1) per cent, on IMot 1
AC, with the farmyard manure and the heaviest nitrogenous
cross-dressing, and the heaviest crop. The roots of the other
series, with intermediate amounts of crop, had also inter-
mediate percentages of sugar — namely, 10-42, 10-84, and
10-81; Further, the crop grown with the farmyard manure
alone, which had the highest percentage of sugar in the roots,
had the smallest amount and proportion of leaf, and the
smallest percentages of both nitrogen and mineral matter in
the dry matter of the roots ; whilst the crop yielding the
highest produce, but the lowest percentage of sugar in the
roots, had the highest proportion and amount of leaf (y tons
12 cwt. per acre), and the highest percentages of nitrogen
and of mineral matter in the roots, conditions indicating
immaturity.

The results next recorded in the table (l*lots 4, f), and (3)
show the amounts of roots and of sugar obtained with
artificial mineral manures, both when used alone and with
the nitrogenous cross-dressings.

The figures further show that there was a greater pi-oducc
in the case of three out of the four cross-dressings where
potash was used as well as superphosphate ; but that the omis-
sion of p(jtash was with(jut ettect where nitrate was used as the
soui'ce of nitrogen.

The result with potash is fully established in other experi-
ments; namely, that a liberal supply of it tends to matuiation,
a condition favoui'able for the production of sugar.

The percentage of sugar in the roots is, with one exception,

130 EXPERIMENTS UPON ROOT-CKOPS

considerably higher where the mineral manures were used than
where farmyard manure was employed, whether alone or with
the cross-dressings. With the mineral manures used alone,
and less than 6 tons of roots produced, there was in one case
rather over, and in the other very nearly, 13 per cent, of sugar
in the roots ; and in several other cases there was nearly, or
over, 12 per cent.

The lowest percentage of sugar comes where the very
excessive cross-dressing of 184 lb. of nitrogen was employed ;
the nitrate of soda produces almost as bad a result, and in both
cases the sugar is lowest where potash is omitted and only
superphosphate is supplied with the nitrogenous manure. The
l)est results, as to proportion of sugar, come where rape cake
or ammonium -salts are used as sources of nitrogen and where
potash is also supplied. The amount of nitrogen and of
mineral matter in the roots was found to vary in the opposite
sense, being at the highest where the sugar was lowest, and
vice versa.

It is quite evident from these results, that the amount of
crop grown depends very largely upon the amount of nitrogen
available within the soil ; but that with crops forced beyond a
certain moderate limit of produce, the proportion of leaf is
unduly large, the percentages of nitrogen and of mineral
matter in the root are relatively high, and the percentage of
sugar is objectionably low ; all these conditions indicating
too much luxuriance and defective maturity at the time of
taking up the crop.

B. Second Series, 1898-1901.

The conditions under which the sugar-beet was grown in
the first series were so different from those which prevail when
the crop is grown for sugar-making that a second series was
begun in 1898, when much smaller amounts of nitrogen were
employed and the plants were grown more closely together.

The land was a portion of the mangel field which had
previously been receiving dung. It was subsoiled and well

SUGAR BKEr

i::i

workinl l)ctbro thi' trials began, so that it was in L^otxl tanniipj
C'Oiulitiun. Tlio seed {Vilinorin's Wliite (Jrccn-top lirahaiit)
was sown in rows 17 inches apart, with 8 inches apart in the
rows.

The following Table (XLVII.) shows the averaire ivsuhs
for the four years 1898-1901.

Table XLVII. — Sugar-Bcct, Second Scries. Avcratjc i>i'^»liirc. per arre,
Siufar per cent, and per cure in the Roots, 4 years (1898-1901).

Roots per acre (as carted) Tons

Leaf do. Tons

" Cleaned and Trimmed " Roots per acre . . Tons
Sugar per cent, in "Cleaned andTrinimcd" Roots per cent.
Sugar per acre Lb.

Plot 9-1.

Basic 8lag,

400 lb.,

and
Sulphate
Potash,
5001b.

12-8
4-5
11-7
14-11
3693

Plot 9.2.

Plot 9-8. 1

As 9-1,
and

2cwt.
Sulphate
Ammonia.

A»9.1.

ami
•.'72 lb.
.Mtratfl
.So<la.

—

14-6 14-0
5-9 6-5

13-3 12-7

13-.')3 13-63

4099 :!938

Tlic results go to show that the land was initially in very
good condition, for very little increase of root is produced by
the use of the nitrogenous manures. Even in the fourth year
of the experiment the plot receiving no nitrogen still grew
nearly 13 tons of roots; the nitrate produced no increase, and
the sulphate of ammonia an increase of 1 ton only. As a
nitrogenous manure sulphate of ammonia was more effective
than nitrate of soda; this is never the case with mangels, but
the sugar-beet, growing smaller and more closely planted roots
than the mangels, does not search the ground so deeply, and
derives more benefit from a manure like sulphate of aninmnia,
which is held up near the surface. The proportions of su<,'ar
obtained were not in any case high, and considering that no
very large crops were grown the amount of su^Mr produced
and the low quotient of i)urity were (lisa[)pointin,<:. i'lohal.lN
the land is too heavy and its situation too hi^h and rxjid.-cd
for a good result to ))e expected, save in rather exceptional
seasons.

132 EXPERIMENTS UPON ROOT-CROPS

Practical Conclusions

1. As the value of sugar-beet depends so much on its
purity, it should be grown rather on land in high condition from
previous manming than enriched by the direct application of
manures. If farmyard manure has not been used for the
previous crop a fair dressing should be given for sugar-beet,
but it should be ploughed in during the autumn before sowing.

'2. Just before sowing the seed, 3 cwt. of superphosphate,,
1 cwt. sulphate of potash, and 1 cwt. of sulphate of ammonia
per acre, should be appHed and harrowed in. Nitrate of soda
is not so desirable a manure for sugar-beet as it is for
mangels.

3. The high quality of the crop will much depend on the
thorough and deep cultivation of the soil before sowing, and on
planting very closely as compared with mangels.

References

"Agricultural Chemistry, Turnip Culture." Jour. lioj/. Ag. Sac, 8 (1847),

494. Roihamslcd Memoirs, Vol. I., No. 2.
" Results of Experiments at Rothamsted on the Growth of Root-crop,s for
many years in succession on the same land." AgriciiHiiral Sludents"
Gazette, New Series, Vol. III., Part V., 1887. Rothamsted Memoirs, VoL
VI., No. 12.
" Results of Experiments at Rothamsted on the Growth of Potatoes for
twelve years in succession on the same land." Agricultural Students'
Gazette, New Series, Vol. IV., Part II., 1888. Rothamsted Memoirs, VoL
VI., No. 13.
" The Rothamsted Experiments : being an account of some of the Results
of the Agricultural Investigations conducted at Rothamsted, Trans.
Highland and Agricultural Society of Scotland, Fifth Series, 7 (1895),
19-67.
" The Growth of Sugar-Beet, and the Manufacture of Sugar in the United
Kingdom." Jour. Roy. Ag. Soc, 59 (1898), 344-370. Rothamsted
Memoirs, Yo\. VII., No.' 11.
" Experiments at Rothamsted on the Changes in the Composition of Mangels
during Storage," by N. H. J. Miller. Jour. Roy. Ag. Soc, 61 (1900),
57; and 63 (1902), 135.
"The Continuous Growth of Mangels for twenty-seven, years on the .same
land. Barn Field, Rothamsted," by A. D. Hall. Jour. Roy. Ag. Soc, 63
(1902), 27-59.

CHArTER VI 11

KXPERI.MENTS IPdN THE CoNTINroiS crvOWlll (>l MCI MINOrS

cr.ops

I. The Continuous Growtli of Beans on tlie same land, Geeseroft I'icld.
II. The Continuous (irowtli of Red Ch)ver on ordinary Arahic Land. I loos
Field,
ill. The Continuous Growth of Clover on Rich (Jarden Soil.
Referenees.

I. — The Continuous Growth of Beans on the same land,
Geescroft Field.

From the outset of the Rothamsted Experiments repeated
attempts have been made to grow leguminous crops year after
year on the same land. The particular importance of these
attempts comes from the special po.sition occupied hy the
leguminous plants. It is well known that ordinary farming
^'xperience considers that the land requires a "rest" before the
growtli of any of these crops is repeated. Satisfactory crops
of clover are rarely obtained except at intervals of four year.s,
and on many soils even six or seven years nnist elapse before
the gi'owth of clover can l)e renewed with any prospect of
success. Not only does land l)ecome "clover sick." but the
farmer considers it will equally become b(>an oi- ])ea "sick";
even lucerne, though it stands without failure foi- five or six
years or more, rarely succeeds when re-sown innncMJiately after
the removal of a previous crop of the same kind. The
leguminous crops of course ccmtain far greater auiounts of
nitrogen than any others, but it is now known that the greater
part of this is obtained from the atmosphere, so that the

134 EXPERIMENTS UPON LEGUMINOUS CROPS

ground, instead of being impoverished, is actually enriched by
the residues left behind after the growth of some of these
crops.

In the Geescroft field, which is no longer under experiment,
and where the land lies wetter than in any of the other
Rothamsted fields, trials with beans began in 1847 and were
continued with several years of failure until 1878, when they
were finally abandoned. Table XL VIII. shows a summary
of the crops obtained under the three conditions of no manure,
mineral manures only, and a complete manure containing
minerals and nitrogen ; the nitrogen was applied at first as
ammonium-salts, which, because of their ineffectiveness, were
afterwards replaced by nitrate of soda.

It will be apparent from the table that the mineral
manures containing potash were the most effective factor in
promoting the growth of the beans, the addition of nitrogenous
manure producing little or no increase in the crop. The crop
shows a continual deterioration, but this is more apparent in
the failures of the plant than in the diminution of the crop
whenever a plant could be obtained ; the crops of 1874 and
1875, for example, being only exceeded a few times during
the whole course of the experiments, though it should be
observed that these crops followed three years during which
the land lay completely fallow.

The difficulty of obtaining a plant which characterised the
later years of the experiment cannot, however, be wholly attri-
buted to what might be termed bean "sickness," for the tilth
of the land had deteriorated considerably through the repeated
growth of a shallow-rooted crop. The use of nitrate of soda
and other saHne manm-es had also a bad effect on the texture
of this soil, and from the combination of these causes it
acquired a close and unfavourable condition, with a compara-
tively impervious pan in the subsoil below.

The whole evidence points, however, to the land becoming
gradually unsuited to the growth of beans, independently of
the deterioration of the tilth of the soil.

BEANS GROWN CONTINUorsiV

i:;.')

After the exporinients witli beans ceased in l«7s ili<- lan.l
was left fallow until 1883, when barley was grown and eh.vtr

Table XLVlll. — Beans </ro7vii year after year on the same land, Gcesrrofl
Field, Bothamsted. Hesulfs, tvithout Manure, with Mineral Maniur,
and icith Mineral and Nitrogenous Manure. Produrr per mrc, eii,h
year, in lbs.

* 5 years (1847-1851), 46 lb. Nitrogen as Ammonium-salts; 11 ye»r«(18«2, 1804-1870, 1875, 1870, »nd

1878), 86 lb. Nitrogen as Sodium Nitrate.
f Accidentally not weit'hed. J Wheat.

136 EXPERIMENTS UPON LEGUMINOUS CROPS

Table XLVIIL- — Continued.

Years.

Tota] Corn.

Total Straw.

Total Produce
(Corn and Straw).

1
S
5

c -g

a -a

1
g

5

^1

t

2*

HI

Average per acre per annum, over each period of 8 years, and the total period
of 32 years.

8 years (1817-1854) .
8 years (1855-1862) .
8 years (18r.3-1870) .
8 years (1871-1878) .

?.2 years (1847-1878) .

Lb.
1205
676
150
409

Lb.

1573t
960
580
713

Lb.

1763

1013

881

749

Lb
1216
988
456
455

Lb.

1635t

1506

1042

793

Lb.
1792
1616
1317

897

Lb.

2421

1664

606

864

Lb.
32081
2466
1622
1506

3555
2629
2198
1646

610

937+

1102

779

1231t

1405

1389

2168+

2507

Average per acre per annum, over the years of crop only, each period.

1st 8 years, 8 crops
2nd 8 years, 7 crops
3rd 8 years, 7 crops
4th 8 years, 4 crops

32 years, 26 crops

1205
773
171
819

1573§

1097

663

1426

1763
1158
1007
1499

1216

1129

521

910

1635§
1721
1191
1585

1792
1847
1506
1793

2421

1902

692

1729

3208§
2818
1854
3011

3555
3005
2513
3292

751

116211

1356

958 ! 152611

1

1730

1709

2688 !!

3086

* 5 years (1847-1851), 40 lb. Nitrogen as Ammonium-salts ; 11 years (1802, 1804-1870, 1875, 1870, and

1878) 80 lb. Nitrogen as Sodium Nitrate.
+ 7 years, excluding 1840. J 31 years, excluding 1849.

g 7 crops, excluding 1849. || 25 crops, excluding 1849.

sown in the barley. From the first the clover grew luxuriantly,
and in 1884 and again in 1885 a large crop was obtained.

The following Table (XLIX.) shows the yield of dry matter
and the quantity of nitrogen it contained, taking an average of
the three plots which had been differently manured during the
times the beans occupied the ground. Analyses of the soil
had also been made before and after the clover was sown, and
from these it is seen that the soil, which was somewhat
impoverished in nitrogen after the continuous growth of beans,
gained a considerable amount of nitrogen during the years of
clover, notwithstanding the large quantities removed in the
clover.

In this case the land showed no reluctance to grow clover,

WILD VEGETATION AlTKi: Will; AT, IK '. i::7

another leguininous crop, atU'r it li.ul hcctniic '-sick' tliit>iii:li
the long-continued growtli of beans; thei-e is oilirr cn idrncc.
liowever, that the growtli of one leguminous cioi) rtii(lti> ilir
aoW less fitted to carry another, even of a diiVrrcnt spceics.

Tahlk XI ax.

18S3.»

1884. j iss:..

Crop per acre (Dry Matter) . . Lb.
Nitrogen in Crop per acre . . Lb.

Nitrogen per cent, in Surface Soil .
Nitrogen per acre in Surface Soil . Lb.

3457
53-8

0-1081
2657

7649
194-2

3:V2.-.
71-4

0-11. -.-J

* Barley and Clover together.

After the removal of the clover crops in 1SS5 this portion
of the field was fenced off to exclude cattle, and has been left
uncultivated ever since. A luxuriant growth of gra»("> and
other vegetation soon established itself, which may be profit-
ably compared with the similar natiu-al vegetation tliat has
established itself after the wheat at the top of Broadbalk tidd
(see p. 41). In the summer of 1903 a ])()rtion of the herbage
was cut on both these portions of land which had been allowed
to run wild after wheat and leguminous plants respectively :
these were sampled as usual and a full l)otanieal analysis made,
the results of which are set out in Table L. Karly in 11M)4
soil samples were also obtained from three places in each
field, and determinations of carbon and nitrogen have been
made to compare with those made at the beginning of the
experiments, so as to ascertain the accumulation of fertility by
the land left under "prairie" conditions for twenty years.

It will be observed that the leguminous plants have never
been able to obtain a footing in the Geescroft field afiri' elowr
and bean.s, although in the similar wilderness following wheat
in the Broadbalk field, Lat/f//r/(s con.stitutes a considerable
proportion of the herbage. The conclusion seems inrvitablr
that the prehminary long-continued growtli of leguminous
plants (beans and clover) has in .some way unfitted the soil for

138 EXPERIMENTS UPON LEGUMINOUS CROPS

Table L. — Botanical Composition of Self-sown Herbage from an uncultivated
portion of land in Broadbalk and Geescroft Fields. Season 1903. Numler
of Species and Percentage hy weight of each Species in the Herha/je.

Broadbalk.

Geescroft.

Gramineous Herbage.

Number of Species.

11

10

Botanical Names:—

1. Phleum pratense .

2. Agrostis alba .

3. Aira ccespitosa

4. Avena elatior

5. Dactylis glomerata .

6. Lolimn perenne

Other Species amounting to

Total .

Per cent.

4-89
11-02

3-50

35-12

3-22

1-89

Per cent.
0-08
0-20
86-19
2-34
4-53
0-05
1-87

Ordinary English Names ;—

1. Meadow Cat's Tail.

2. Marsh Bent Grass.

3. Tufted Hair-grass.

4. False Oat.

5. Cock's Foot.

6. Perennial Rye.

59-64

95-26

Leguminous Herbage.

Number of Species.

, , .

1. TrifoUum repens .
•1. Trifolium pratense- .
:'. Lathyrus pratensls .

4. Vicia sepium .

5. Medkago lupulina .

3-08 0-05
0-55
18-36
0-40 0-38
2-92

1. White or Dutch Clover.

2. Common Red Clover.

3. Meadow Vetchling.

4. Bush Vetch.

5. Black Medick or Nonsuch.

Total .

25-31 0-43

Miscellaneous Herbage.

Number of Species.

24

14

1. Heracleum sphonch/lium .

2. Scahiosa arvensis * .

3. Centaurea nigra

4. Carduus arvensis .

5. Plantago lanceolata

6. Rumex obiusifolius .
Other Species amounting to

Total

4-28
2-87
1-05
0-81
2-46

3-58

1-71

0-30
0-26
0-94
1-10

1. Cow Parsnip or Hogweed.

2. Field Scabious.

3. Black Knapweed.

4. Creeping Plume Thistle.

5. Ribwort Plantain.

6. Broad-leaved Sorrel Dock.

15-05

4-31

St'mmary.

Total Number of Species.

40

26

Total Gramineae
Leguminosae
Miscellaneae

59-64
25-31
15-05

95-26
0-43
4-31

Total .

100-00

100-00

ACCUMUJ.ATION Ol' FKiMII,ir\

i:;i^

carrying other Icgimiiaou.s plants, ur at least has so reduce. 1
ley are unable to resist the coiniKiition

their vigour that tl

of the grasses in a natural herbage.

Table LI. — Accumulation of Carbon and NUroncn in >>t)i/ of .\r„},l,
Land allowed to run wild for over 20 years.

IVr (-out. ill Fine Dry Soil.

Carbon. 1 Nitrogen. 1

aS81-83.*

1904.

1881-88. 1004.

Broadbalk, 1st 9 inches .
Do. 2nd do.
Do. 3rd do.

Geescroft, 1st 9 inthes .
Do. 2nd do.
Do. 3rd do.

1 1
1-143 ! 1-233 0-1082
0-624 0-703 0-0701
0-461 0-551 0-0581

1-111 1-494 0-1081
0-600 0-627 0-0739
0-447 i 0-435 1 0-0597

! 1

0-14iiO
0-0955
0-0839

0-1310
0-08*29
0-0652

* IJroadbalk, 1881 ; Geescroft, 1SS3.

Note. — In November 1885 (that is, after the land had grown Barley and Clover in 1883,
and Clover in 1884 and 1885), samples were taken of the first 9 inches of soil from the
same portion of the field as in 1883 (Plots 1-10), and gave a mean of -ll')2 percent, of
Nitrogen.

The most noteworthy fact is the enormous accumulation of
nitrogen : during the twenty-year period the Broadbalk wilder-
ness would appear to have gained nearly 98 lb., and Geescroft
a little more than 44 lb. of nitrogen per acre per annum. The
gain in carbon is less pronounced, although the amount accumu-
lated is greater than that of nitrogen, yet the ratio of carbon
to nitrogen in the increase is very much lower than the ratio
in ordinary vegetable matter or in the original organic matter
of the soil.

Owing, however, to changes in the consolidation of the
ground it is difficult to secure an exact comparison of the
same layer of soil at the two periods, i.e., the surface nine
inches after the land has been in grass for some time will contain
a certain amount of recent turf, and less of the poor subsoil than
the original sample from arable land. For these reasons it is
necessary to reduce the estimate made of the annual gain of
nitrogen, but however large an allowance be made on this

140 EXPERIMENTS UPON LEGUMINOUS CROPS

score, it is still difficult to account for the magnitude of the
accumulation, especially for Geescroft, where, as the botanical
analysis shows, there are no leguminous plants.

The other sources of nitrogen which may be invoked, such
as the rain, dust, and absorption from the atmosphere, would
equally affect the arable land, yet, as the various unmanured
plots on the wheat, barley, and rotation fields show, there is
no evidence of a corresponding gain of nitrogen on the arable
land.

The only explanation that seems at all probable depends
on the intervention of the bacterium Azotohacter chroococcum
(Beyerinck), which possesses the power of fixing atmospheric
nitrogen without any host plant, and which has been found in
all the Rothamsted soils. On the arable soils this bacterium
would not be able to effect much fixation because of the lack
of recent organic matter, by the combustion of which the
necessary energy for Ijringing the nitrogen into combination
could be obtained. On the wild grass-land, however, there is
every year an accumulation of vegetable matter which would
supply the bacterium with its needed carbohydrate, and in
consequence considerable fixation is possible. The greater
gain on the Broadbalk land may be due to the presence of
leguminous plants in the herbage, or to the comparative rich-
ness of the soil in calcium carbonate, since the Azotohacter
has been found to be active only in soils containing calcium
carbonate.

It would appear from the chemical analyses that the Gees-
croft field has never been subjected to the chalking operations
previously described (p. 28), since the surface soil in 190-1:
contained only 016 per cent, of calcium carbonate, about the
same quantity as was found in the soil of the adjoining un-
cultivated common land, whereas the soil of Broadbalk wilder-
ness contained as much as 3*3 per cent.

Mechanical analysis shows the two soils are practically
identical, the subsoil of Geescroft being somewhat the lighter
of the two, and the situation of the two fields is equally good

KED CLOVKi; 141

as regards surface drainage. The eoiistant \\(iiic» and im
workal^ility of Geescroft appears to Ite entirely due to the
unfloeculated character of the clay (hie to tlie ahsenee of elialk.
in other words, the cultivation of the other Kot hamstcd ridd-.
has been rendered possible by the iin[)roveni(Mit in the texture
of the soil effected l)y the large quantities of ehalk put on.
probably in the eighteenth century. Even at the present time
water will often stand on the surface of the Geescroft land,
and the predominant growth of Aif<f nrs/fitostf is additional
evidence of the persistent wetness of the soil, a wetness which
cannot be accounted for by the situation, the nature of the
sul)soil. nor the constitution of the surface soil, but only b\ its
bad condition incUiced by the absence of lime or chalk.

II. — The Continuous Guowth of Red Clovek on oim)1nai;n
Arable Land, Hogs Field.

In the Hoos field, experiments upon the growth of legunii
nous crops began in 1849 with red clover. The following table
shows the results for a period of twenty-nine years, dminu
which clover was sown fifteen times but only produced a ero]>
in seven of the years. Even with the many interniission>.
when the land grew wheat or barley or was left fallo\N,
oidy the first crop of all was a satisfactory one ; nor, as will
be seen., had either mineral or nitrogenous manures any effect
in keeping the land in a condition to grow clover success-
fully.

In 1878, the land on which these attempts to grow re(l
clover had been continued since 1849 was divided into a
number of small plots, and sown with various leguminous
plants. Various systems of nianui'ing were tiie<l on each
series of plots, which carried the following leguminous
plants — lucerne, peas or beans alternately, IJokhara clover,
sainfoin, white chjver, red clover, and vetches; the same j»lot
being always re-seeded when necessary with the same legumi-
nous plant. The results are described in detail in the

142 EXPERIMENTS UPON LEGUMINOUS CROPS

'Table LII. — Bed Glover sown frequently on the same land, in Hoos Field,
Bothamsted. Total produce per acre per annum ; Clover as Hay, other
Crops Corn and Straw together.

Year.

1.

2.

Description of Crop.

Mineral Manure

Mineral
and Nitrogenous

1

Manures.

Lb.

Lb.

1849

Clover ....

10,214

10,326

1850

Wheat

(6,261)

(6,345)

1851

Clover

2,309

2,368

1852

Clover

5,895

4,914

1853

Clover

No crop

No crop

1854

Fallow

1855

Clover

1,281

2;606

1856

Fallow

...

1857

Fallow

1858

Barley

! (6,5'?8)

(7^578)

1859

Clover

2,752

3,087 1

1860

Clover

No crop

No crop '

1861

Fallow

1862

Barley

(5'745)

(6^30)

1863

FaUow

1

1

1864

Clover

No crop

No crop

1865

Clover

2,467

4,500

1866

S. 1 Clove

r, S.

2 Barley '.

No crop

(2,974)

1867

Fallow

1868

Clover

No crop

No crop

1869

Clover

No crop

No crop

1870

Barley

(3,328)

(3,312)

1871

Clover

No crop

4,085

1872

Fallow

1873

FaUow

1874

Clover

1 No crop

Fallow

1875

Clover

4,277

Fallow

1876

Fallow

1877

Barley

(i:864)

(U864)

SiiM.MARY. Produce.

29 years (1849-1877) •{ J^^^V \ \

52,991
1,827

60,689
2,093

Years of Crop only . Average

4,416

4,668

Years of Clover only (7) { '^S^Lge '. '.

29,195
4,171

31,886
4,555

StTMMAuv. Nitrogen (Estimated).

29 years (1849-1877) • {it-lge' '. \

929-4
32-0

1043-1
36-0

Years of Crop only . Average

77-5

80-2

Years of Clover only (7) {Total^g^- ; ;

700-7
100-1

765 -3
109-3

RESIDUES LEFT BY l.EGl .M 1 Nol s Cljol

I l:

"Memoranda," and Table LI 1 1, sliows typical iv>iilis in the
earlier and later years of the experiment.

At first a fair growth of some of tlie i)lants was ohtaiiicd
on the land which had ceased to carry red clover, Iml in later
years the growth of any but the powerfully-rooting' lueerne and
Bokhara clover became very poor, and repeated failures to

Table LIII. — Hoos Field, Leguminous ExperimcnU. Dry Matlrr m
produce per acre per annum. Mean of Plots 4, 5, and 6.

Lucerne.

Peas

or

IJeans.

Bokhara
Clover.

Sainfoin.

White
Clover.

Red
Clover.

Tarr*.
Lb.

Lb.

Lb.

Lb.

Lb.

Lb.

Lb.

1878

Not sown

Neither

1,854

No cutting

No cutting

1,100

1879

No crop

Peas nor

4,498

\o crop

2,275

1,722

1,742

1880

843

Beans

1,240

No crop

5

270

1,666

1881

809

grown

2,085

780

215

716

2.501

1882

4,458

till 1SS4.

10,804

5,450

2,087

615

4.401
j. 2.416-

2,343 -

Not

Not

Not

Not

1898

626

sufficient

sufficient

sufficient

sufficient

crop to cut

crop to cut

crop to cut

crop to cut

1899

4,799

2,940

7,143

2,090

No crop

No crop

681

1900

4,014

3,302

FaUow

1,611

313

705

697

1901

4,010

957

963

758

No crop

No crop

382

1902

1,890

729

7,431

No crop

No crop

No crop

SIO

1903

No crop

Plot 4 only.

obtain a plant occmTcd on re-seeding. The land itself got
very foul and in a poor mechanical condition ; so that in 1898
the greater part of the land under experiment was sown with
wheat without manm'e, only a portion of each })lot Ix'ing
retained for continuous experiment.

Five successive crops of wheat were taken and liarve.sted
separately from each of the old plots, the combined result
from the various plots which had previously carried the same
leguminous plant being put together in the Table 1.1 \'. it
will be seen that all the leguminous crops left a lai'ge residue
containing nitrogen in the soil, so that the cro|) of wlieat
which followed was generally more than 40 bushels j»ei- acre
with 2h tons of straw. But this residue was rapidly exhausted ;
the succeeding crop was very poor, and fell to a jjoint from

144 EXPERIMENTS UPON LEGUMINOUS CROPS

which it has deteriorated but Httle since. The hicerne, how-
ever, left behind a much larger and more enduring residue ; and
thouu'h the crop on the plots following lucerne has been falling

Table \A\.— Wheat following Leguminous Croi^s, Hoos Field. Produce
and Nitrogen per acre per annum, 1899-1903.

Harvest.

Leguminous Plants prev

ously grown.

Lucerne.

Peas

(or

Beans).

Bokhara
Clover.

Sainfoin.

White
Clover.

Red
Clover.

Vetches.

1899

39-3

42-6

43-7

45-2

43-5

43-0

39-9

Dressed Grain

1900

28-9

14-3

16-4

19-1

19-3

19-1

14-2

per acre.

1901

27-0

16-8

20-1

20-9

21-4

21-4

17-7

bushels.

1902

20-1

14-0

15-6

15-8

17-9

17-7

13-9

1903

19-9

13-0

14-8

14-7

17-2

16-7

14-0

{

1899

5499

5622

5592

5611

5404

5580

5051

Total Straw

1900

2722

1312

1549

1788

1707

1787

1360

per acre.

1901

2312

1484

1748

1796

1822

1824

1591

lb.

1902

2327

1495

1688

1627

2011

1934

1390

1903

1837

1156

1317

1380

1602

1526

1261

Total Produce |
(Grainand Straw).!

1899

8108

8430

8508

8639

8308

8505

7766

1900

4.^54

2202

2582

2986

2927

2992

2262

1901

4054

2571

3038

3137

3201

3185

27-i9

per acre,
lb.

1902

3553

2379

2542

2600

3086

3023

2257

1903

3035

1926

2205

2256

2635

2528

2102

1

Nitrogen
in Total Produce.

i 1899

88-9

61-9

72-1

75-0

70-9

74-5

1 63-6

1 1900

42-3

17-7

21-2

24-6

25-7

25-3

\ 19-3

1901

38-2

22-0

25-8

27-8

29-1

28-8

24-0

per acre, 1
lb. 1

1902

27-0

17-9

18-2

18-9

22-3

22-1

! 16-7

j 1903

24-7

15-3

16-9

17-3

20-7

: 19-5

i

16-3

year by year, in 1903 it ^vas still much greater than on the
other plots. Per contra, after the first year, the crop on the
plots following peas or beans has always been a little below
that of the other plots. Of the other plots, the crops on those
following white and red clover have been a little better than
those following sainfoin, Bokhara clover, or vetches.

In 1904 the land was sown with oats and seeded afresh
with leguminous plants in plots which run at right angles to
the old plots.

III. — The Continuous Growth of Clover on rich

Garden Soil.
In 1854, after it seemed clear that clover would not continue
to grow on the arable land, it was sown in a garden only a few

CLOVER (ilJOWN IN (;A1M)I:N sou, 11.-,

huiulred yards distant from the ('\[)('rimrii!al fuld, on soil
which had been under ordinary kitelicn-^ardcn cultivation lor
probably two or three centuries. In view of the failuiv> in
the attempt to grow clover continuously on ordinary arabli
land, it is remarkable that, under these conditions, the crop
has gi'own luxuriantly almost every year since — 100:3 bein«^' the
fiftieth season of the continuous growtli. At the comnu nee
nient the percentage of nitrogen in the surface-soil of the
garden w^as four or five times as high as in that of the arable
soil of the field; and it would doul)tless be richer in all other
manurial constituents also. Indeed, after the growth of clover
for twenty-five years in succession, even the second 9 inches of
the garden clover soil was found to l)e still very nuich rieher
in nitrogen than the first 9 inches in the Hoos field. Table
LV. gives the results for each of the fifty years of experiment
with clover on the rich garden soil. The second cohunn
shows the number of cuttings each year, the third the
amounts of produce per acre reckoned in the condition oi
dryness as hay, the fourth the amount of dry substance, and the
last the estimated amounts of nitrogen per acre in the crops.
At the bottom of the table are given the average annual result.^
over the two periods of twenty-five years each, and over the
total period of fifty years, 1854-1903. It should be stated that
as the garden clover plot is only a few yards square,
calculations of produce per acre can only give approximation^
to the truth; but it is believed that they can be thoroughly
relied upon so far as their general indications are concerned.

Confining our attention to the amounts of produce reckoned
as hay, and to the estimated amounts of nitrogi'U in the product,-,
it is seen at a glance that, excepting a few occasional years of
very high produce during the later periods, the amount of crop
is very much greater in the first twenty-five years than in the
second twenty-five year.s. In fact, as is seen at the foot of thr
table, there was an average annual jnoduec (Mpial to 7»;<)1 n>. ot
liay over the first half, but of only :)'.tL!4 lb. ovef the latter iiall
of the period of fifty years.

146 EXPERIMENTS UPON LEGUMINOUS CROPS

Table LV. — Bed Clover grotvn year after year on rich Garden Soil,
Ilothamsted. Hay, Dry Matter, and Nitrogen per acre, 1854-1903.

Year.

Number of

As

Dry

Nitro-

Seed Sown.

Cuttings.

Hay.

Matter.

gen.*

Lb.

Lb.

Lb.

1854

2

5,191

4,326

(125)

1854, March.

1855

3

18,113

15,094

(435)

1856

2

11,027

9,190

265

1857

3

14,855

12,379

357

1858

2

7,608

6,340

183

1859

2

6,227

5,189

149

1860

1

8,679

7,233

208

1860," May.

1861

2

13,353

11,128

'

1862

2

10,042

8,368

1863

2

11,798

9,832

1 1,123

1864

2

5,500

4,583

1865

1

2,044

1,704

1865," AprU.

1866

2

10,456

8,713

1867

2

6,748

5,624

1868

1

991

826

1868," April.

1869

2

4,183

3,486

679

1870

1

1,741

1,451

1871

1

4,513

3,761

1871, April.

1872

2

10,142

8,452

J

1873

2

9,287

7,740

1

1874

3

5,899

4,916

1874, May and July.

1875

1

2,731

2,276

\ 607

1875, July and September.

1876

2

3,517

2,931

1876, September.

1877

1

3,533

2,944

J

1877, May.

1878

3

13,416

11,180

...

1879

1

2,738

2,282

1879, May.

1880

2

5,742

4,785

- 856

1880, April.

1881

2

4,262

3,552

1881, April (mended).

1882

3

6,433

5,361

1882, April (mended).

1883

1

2,716

2,264

1883, May.

1884

3

9,990

8,325

1885

3

6,511

5,426

- 680

1886

1

2,702

2,252

1886, April.

1887

2

3,287

2,739

1887, April (mended).

1888

1

1,841

1,535

56

1888, April (mended, June).

1889

2

8,664

7,221

203

1889, April (mended).

1890

1

2,817

2,348

73

1890, April.

1891

2

6,696

5,580

163

1891, May (mended).

1892

1

3,568

2,973

100

1892, May 7 (May 27, mended).

1893

2

5,941

4,951

135

1893, April (mended).

1894

2

5,347

4,456

127

1894, April (mended).

1895

No crop

1895, AprU, May, and July.

1896

1

'412

'344

'■(10)

1896, July.

1897

2

6,381

5,318

169

1897, April.

1898

2

2,188

1,823

56

1899

2

3,095

2,579

74

1900

No crop

1900, August.

1901

2

3,464

2^887

"84

1902

2

1,403

1,169

39

1902," April (mended).

1903

1

1,907

1,589

64

1903, May.

SuMMi^

RY. Av

erages.

25 years i

1854-1878)5

7,664

6,387

179

25 years i

1879-1903)

3,924

3,270

101

50 years

1854-1903)"

5,794

4,829

140

* For the years 1854-1860, and also for 1896, the Nitrogen is estimated, but for all other years it is
according to direct determinations either in mixed or individual year samples.

NITROGEN ACCUMULATED IN CLoVKi: CI.'OPS 117

Now even this latter amount eorrcspon*!.-- lo what wdiiM I'r
considered a fair, though not a large erop, when elovrr is grown
in rotation once only in four or eight years or more ; so tliat tin*
produce in the earlier years on this rich garden soil was very
unusually heavy. Indeed the average annual produce over tlie
whole period of fifty years — namely, 5794 lit., or more than 2\
tons of hay — would be a good yield for the eroj) grown only
occasionally in the ordinary course of agriculture.

But it is when we look at the figures in the last eohunn of
the table, which show the estimated amounts of nitrogen in the
crops, that the importance and significance of these results
obtained on rich garden soil are fully recognised ; and this is
especially the case wdien they are compared with those
obtained on ordinary arable land.

Thus the amount of nitrogen in fair crops of wheat, barley,
or oats, would be 40-50 lb. j^er acre, of beans about 100 lb., of
meadow hay about 50 11)., and of clover grown in rotation, from
100 to 150 lb. ; but on this rich garden soil the produce of
clover has in one year contained more than 400 lb. of niti-ogen,
and the average over the first ten years was 247 il>. The
average over the whole period of fifty years is 140 lb., or about
as much as a fair but not large crop gi'own occasionally under
the ordinary conditions of agriculture.

Analysis of the soil taken at intervals would seem to show
a considerable falling-off in the amount of nitrogen and carbon
contained in the surface soil, not sufiicient however to account
for all the nitrogen removed by the clover crop.

It will be apparent from a consideration of the eiops
reported for the later years of the experiment that great dilli
culty is beginning to be experienced in maintaining a plant
of clover ; re-seeding, which was only necessary live times in t In-
first twenty years, had to be carried out nine times in the last
ten years, during which time also the crop has wholly failed for
two years, and almo.st wholly for a third.

Dm-ing January 1897 the plots were inoculated with the
watery extract of the rich kitchen-garden soil at Kothamsted.

148 EXPERIMENTS UPON LEGUMINOUS CROPS

This did not however arrest the faihire which was in progress
at that time. Again, in March 1897 and in July 1899, all the
plants were removed by hand, burnt, and their ashes returned,
and the surface soil was carefully picked over by hand, to
remove the Sclerotia of the fungus Sderotinia trifolioriim, many
of which were found. The soil was also dressed with carbon
bisulphide as a fungicide, before fresh seed was sown. In 1903,
which was a favom*al:)le year for the growth of clover, a fair
plant was obtained by re-seeding, and in the spring of 1904 the
best crop for many years was cut from this plot. Notwith-
standing the repeated failures to grow clover continuously on
ordinary arable soil and the increasing- difficulty of maintaining
a plant on the rich garden soil, which is the one place where any
growth has been continuous, it is noteworthy that when clover
grows in a mixed herbage on grass-land it increases in amount
from year to year under suitable conditions of manm-ing. It has
already been pointed out that on the grass plots in the park,
where mineral manures including potash are applied every year,
as on Plots 15, 6 and 7, the proportion of leguminous plants,
including red clover, increases fi'om year to year, without there
being any sign of " clover sickness " setting in. Nor can this
result be due to manuring only, for on the small plots in the
Hoos field all sorts of variations in the manuring were tried,
without enabling the clover to stand. On the grass paths,
however, separating these "clover sick" plots on Hoos field,
paths which are not more than a yard broad, both red and
white clover grow abundantly. Were "clover sickness" due
merely to the infection of the plant by Sclerotiula trifolioriim,
it is difficult to see how these plants could escape infection
when the neighbouring clover plants in the arable land
succumb. These and other facts would seem to show that
the presence of the fungus Sderotinia trifoUorum is not the
determining cause of " clover sickness " ; in many cases it is
the direct cause of the death of the clover plants, luit what
is not yet understood is why plants on " clover sick " land
alon(i succumb to the infection.

REFERENCES 149

Rkkkuencks

" Report of Experiments on the (Irowtli of Red Clover by different Manures."

Jour. lioi/. Ag. Soc, 21 (1860), 178. linllmmslcd Memoirs, Vol. I.,

No. 13.
"Notes on Clover Sickness." Jour. Roif. Ilort. Soc, 3 (1^71), SC). Hol/Kiwslnl

Memoirs; Vol. III.. No 1l».
"Results of Experiments at Rotliamsted on the (In.wth of l.t-^rumiiioiis

Crops for many years in succession on the .same hind." Agricullural

SliiJeiiLi' Cnicelle, New Series, 4 (18S9), l;37, and 4 (1890), 179.

Hot fi (misled Memoirs, \'ol. VI., No 15
"The Rothamsted Experiments: bein<^ an account of some of the Results

of tlie Agricultural Investigations conducted at Rotii.imsted." Triin.t.

Highland and Agrieii/liiral Soeieli/ of Scot I mid, Fifth Series, 7 (189:')),

100-136.
"The Accumulation of Fertility by Land allowed to Run Wild." A. 1). Halh

Jour. Agrir. Science, I. (IQOo), 241.

CHAPTER IX

EXPERIMENTS UPON GRASS LAND MOWN FOR HAY EVERY YEAR

I. The Unmanured Plots.

II. Use of Nitrogenous Manures alone.

III. Mineral Manures used alone.

IV. Complete Manures — Nitrogen and Minerals.
V. The Action of Organic Matter.

VI. Effects of Lime.
VII. Changes in Herbage following Changes in Manuring.
VIII. The Effect of Season.

Practical Conclusions and References.

The experiments upon grass at Rothamsted ]:)egan in 1856,
about 7 acres of the park close to the house being set aside for
the purpose. The land has been in grass as long as any
recorded history of it exists, for some centuries at least. It is
not known that seed has ever been sown, and at the beginning
of the experiments the herbage on all the plots was apparently
uniform. The soil is the same stiff reddish loam as is found in
the other fields, though owing to the length of time the land
has been in grass stones are not abundant near the surface.

The plots, of which there are twenty in all, vary somewhat
in size between one-half and one- eighth of an acre. Up to
1874 inclusive the grass was only cut once, the aftermath
being fed off by sheep. Since that time there has lieen no
grazing, and the plots are generally cut twice in the year. The
grass is made into hay in the usual way and the whole produce
of each plot is then weighed. On some occasions, however,
with the second crop, continuous wet weather has rendered
it necessary to weigh the jDroduce in a wet condition and

YIELD OF II A V

151

calculate its equivalent in hay from the amount of di-y matter
in the material as weighed. On most of the plots the
manuring has been continued without ehange from tin-
beginning of the experiments ; the cases in wliieh a ehaiiLre
has lieen made serve to show how rapidly the character of
the herbage will respond to alterations in the manure.

Table LVI. shows the amount and nature of the manm-es

Table LVI. — Manuring of the Permanent Grass Plots i^'^r arre per annum,
1856 and since.

Xitrogenous

Mineral Manures.

mot.

Abbreviated Description
of Manures.

Man

ires.

3 .
1-

II

i- 2

S -

Ij

11

li

^1

E S
<

Z-i

H

Lb.

Lb.

•1

Lb.

Lb.

Lb.

Lb.

Cwt.

3
12

\ Uninanured every year ....

...

2

Unmanured ; following Dung first S years . ...

...

■ 1

Ammonium-salts alone; with Dung also
first 8 years 200

...

4-1

Superphosphate of Lime . . . ....

3-5

...

8

Mineral Manure without Potash . . ....

3-5

250

ioo

7

Complete Mineral Manure . • ■■•

3-5

500

100

100

6

As Plot 7; Ammonium-.salts alone first 13

15

years

As Plot 7 ; Nitrate Soda alone first IS years ...

:5-5
3-5

500
500

100
100

100
100

5

Ammonium-salts alone (to 1897) . . .400

17

Nitrate of Soda alone

27r.

...

4-2

Superphosphate and Ammonium-salts . 100
Mineral Manure (without Potash) and . Am-

3-5

...

10

monium-.salts 400

...

3-5

250

100

9

Complete Mineral Manure and Ammonium-

salts 400

3-5

500

100

100

13

As Plot 9, and Chaffi-d Wheat Straw also

to 1897 400

3-5

500

100

100

11-1

Complete Mineral Manure and .Kininoniuiii-

salts tiOO

3-5

500

100

100

11-2

As Plot 11-1, and Silicate of Soda . .600

3-5

500

100

100

400

16

Complete Mineral Manure and Nitrate Soda ...
Complete Mineral Manure and Nitrate Soda ...

275

3-5

500

100

100

14

5r.o

3-5

500

100

100

appUed each year to the plots, and Table L\'1I. the average
produce over the whole period, over the last ten years, and
for the sinde vear 1002.

152

EXPERIMENTS UPON GRASS LAND

Table LVII. — Produce of Hay per acre. Average over the period of 4:1 years
(1856-1902), the 10 years (1893-1902), and the individual year 1902.
Rothamstcd. Total of first, and second crops {if any).

Averages over

Season

Plot.

Abbreviated Description

of Manures.

47 years

10 years

1902.

(1856-1902).

(1893-1902).

Cwt.

Cwt.

Cwt.

3
12

Unmanured every year I

21-9
24-5

15-9

18-5

11-4

13-8

2

Unmanured; following Farmyard Dung for first

8 years

27-9*

17-4

12-4

1

Ammonium-salts alone ( = 43 lb. N.); with Farm-

yard Dung for first 8 years ....

35 -41

24-9

21-8

4-1 ; Superphosphate of Lime

23 -Sg

17-8

19-0

8 Mineral Manure without Potash ....

28-1

21-6

25-8

7 Complete Mineral Manure

38-8

36-5

53-6

6

Complete Mineral Manure as Plot 7 ; following

Ammonium-salts alone first 13 years

37-4+

36-0

52-5

15

Complete Mineral Manure as Plot 7 ; following

Nitrate of Soda alone first 18 years .

37-011

40-8

54-0

5

Ammonium-salts alone = 86 lb. Nitrogen

(26-1)**
35-311

17

Nitrate of Soda alone = 43 lb. Nitrogen .

30-6

26-4

4-2

Superphosphate and Ammonium-salts = 86 lb. N. .
Mineral Manure (without Potash), and Ammo-

35-5§

28-3

27-1

10

nium-salts = 86 lb. N

49-3

38-1

40-4

9

Complete Mineral Manure and Ammonium-salts

= 86lb. N

54-1

46-8

55-5

13

As Plot 9, and Chaffed Wheat Straw also to 1897

inclusive ........

61-3

50-8

54-3

11-1

Complete Mineral Manure, and Ammonium-salts

= 129 lb. N

65-5

64-6

86-3

11-2

As Plot 11-1, and Silicate of Soda .

72-0

68-0

84-8

16

Complete Mineral Manure and Nitrate Soda

= 43 1b. N

48-oir

42-4

46-8

14

Complete Mineral Manure and Nitrate Soda

= 86 1b. N

59-311

53-4

60-8

After the change. Before the change 42-9 cwt.

,, ,, 49-5 cwt.

,, „ 30-6 cwt.

,, 3o-4cwt.

§ 44 years only (1859-1902).
1 45 years only (1858-1902).
** 42 years (1866-1897).

Table LVII I. shows the first crops only for four successive
ten-year periods, and one eight-year period, 1856-1903.

In dealing, how^ever, with the produce of grass land, which is
a mixed herbage consisting of many different species of grasses,
leguminous plants, and other orders, it is not sufficient to
consider only the gross weight of produce. The various
species are differently stimulated by particular manures ; even
among the grasses themselves, such a difference of habit as a

COMPETITION OF PLANIS IN CI.'ASS LAND i:,:{

deep 1)1' shalK)W root system will (U'ti'iiiiiiic lo wliicii iii.niiirt'
tlie grass will respond. The aspect of any meadow represents
the results of severe competition among the various sprciis

Table LVIII. — Avcnufc prodiu-e of Hay per ncrc over (he four sii>,,s.-.tri-
lO-i/('(ir jxriods, and the suhscqticyif 8 years, from 1856 - 1003.
Rothamsted. First crops only.

Abbreviated Description
of Manuring.

4-1

V Unraanured every year

Ammonium-salts alone ; with Dung also first
8 years

Superphosphate of Lime alone
Mineral Manure without Potash * .
Complete Mineral Manure . . . .

17 I Nitrate of Soda alone = 43 lb. N. .

4-2 SuperphosphateandAmmonium-salts^So Ib.N
10 Mineral Manure (without Potash),* and Am-
monium-salts =^o lb. N. .
9 Complete Mineral Manure and Araraoniura-

salts = S6 lb. N

11-1 Complete Mineral Manure and Ammonium-
I salts = 129 lb. N

16 . Complete Mineral Manure and Nitrate Soda

I =43 lb. N

14 Complete Mineral Manure and Nitrate Soda

I =86 lb. N

Averages over

Cwt.
22-6
2.T-1

24-4+

33-6

33-9

34-3:

39 -61

52-8

53-6

61-7

48-i;

53-i:

Cwt.
20-0
22-9

21-3
26-6
36-8

33-5

30-5

39-6

48-4

53-6

47-6
60-5

Si

Cwt.
17-5
18-0

19-1
21-8
32-3

30-1

30-4

38-6

50-5

48-5

41-0
53-8

ver

i

i

Cwt.

Cwt. '

16-8

11-7

17-1

14-2

23-8

19-2

16-5

15-2

16-5

18-6

27-1

31-9

27-0

26-8

29-0

25-0 ,

35-5

34-0

39-3

42-6

47-6

58-6

37-4

38-6

45-6

48-5

Including Potash, lirst 6 years.

Seven years only (1859-65).

J Eight years only (lSi8-65).

represented; the dominant species are tho.sc most suited to
their environment, l.<\, to the amount and nature of the ])lant
food in the soil, the water supply, the texture of the soil,
and other factors. If any of these factors lie altered, as
is done in the case of the Rotham.sted i)lots l>y iiiaiiuriii;^ i"
dififerent fashions, the original equilibrium hetwccn I In- eon-
tending species is disturbed; some species are liivomcd, and
increase at the expense of the others until a new eciuilibrium
is attained, and the general character nf th.' herbage from
the botanical point (jf view is completely altered. Tt tlius

154 EXPERIMENTS UPON GRASS LAND

becomes important to ascertain the natm-e of the plants
comprising the herbage produced by a given manm^e, as well
as to determine its amount ; from time to time therefore at
Rothamsted a carefully selected fraction of the herbage from
each plot has been separated into its constituent species, the
relative proportions of which are determined by weighing. As
this complete separation involves a great amount of work, a
partial separation only is made every year, in which case the
herbage is separated into three groups — the grasses, the
leguminous plants, and the miscellaneous species respectively.
Table LIX. shows the results of these partial separations
as averages for the whole period of forty-seven years, and
for the single year 1902. Summaries of the five comjDlete
separations made in 1862, 1867, 1872, 1877, and 1903 are
given in Table LXII. (see p. 173).

I. The Unmanured Plots.

Two of the plots have remained without manm'e during
the whole of the experiment. They are situated near the
extremities of the field, and show a slight but constant
difference in crop. Taking the average of the whole period,
these unmanm-ed plots have produced rather more than a ton
of hay per acre per annum. If we compare the successive
ten-year returns, there is no sign of approaching exhaustion or
great falling-off" in crop from year to year. The impoverishment
of these unmanured plots is more to be seen in the character
of the herbage than in the gross weight of produce. Weeds of
all descriptions occupy the land, and the relative proportion
they bear to the grasses and clovers has increased from year to
year. A fair proportion of clovers, both red and white, is
found on these plots, l:)ut the weeds, which amount to 26 per
cent, taking the average over the whole period, have of late
years constituted nearly one-half of the herbage. Tlie most
prominent species among the grasses are the Quaking Grass, so
generally taken as a sign of poor land, which constituted 20
percent, of the whole herbage in 1903, and Sheej^'s Fescue;

THE rXMAMlM:i) IM.oTS i:.:.

hints till' liii'd's Foot 'rrrfnil ; and liui-nrt.
Hawkbit, and Black KnapwoiMl aiiionu' tlic weeds.

Table LIX. — Percentages of Gmmincous, LegHviinovs, autl Misrrlhtucoiin
Herhujc. Aucraffc of 47 yrnrs (1856-1902. >n„I 1902 sejun-'ffeh/).
Bofhnmsfcd. First crojts.

Mamirt's.

Averages over 47
(1S56-1902).

years

SeMon 1002

1

i'lot.

Grani-

Legu-

Miscel-

Oram- 1

Legu-

MUcel.

inea-.

miuosiv.

laiieiF.

,„«,.. ,

mliiosii-.

lanev.

Per cent.

Per cent.

Per cent.

Per cent.

Per cent.

Per cent.

3

Unmanured every year . -!

64-8

8 -9

26-3

34-3

7T.

58-2 I

12

64-9

9-0

26-1

38-1

16-1

4.V8

2

Unmanured; following Farm-

yard Dung for first S years .

7D*f>

4-3

20-2

24-4

5-7

69-9

1

Ammonium-salts alone( - 43lb.
N.); with Farmyard Dung

for first 8 years !

87-8

0-7

11-5

77-6

1-4

21-0

1-1

Superphosphate of Lime

68-0

:rS

26-2

54-4

15-4

30-2

s

Mineral Manure without Pot-

ash *

70-6

6-8

22-6

28-8

22-1

49-1

7

Complete Mineral Manure

62-0

23-8

14-2

20-3

r..V3

24-4

6

Complete Mineral ^lanure as
Plot 7 ; following Ammo-

nium-salts alone first 13 yrs.

18-4

61-0

20-6

i ^''

Complete ^Mineral Manure as
Plot 7 ; following Nitrate of

Soda alone first IS years

...

26-2

63-1

10-7

5

Ammonium-salts alone = 86 lb.

N

80-5

0-4

19-1

17

Nitrateof Sodaalone = 43 Ib.N.

71-0

1-3

27-7

13-=^

S-4

SSl'-Q

4-2

Superphosphate and Ammo-

nium-salts =S6 lb. N. .

88-2

0-1

11-7

91-:.

(0-01)

8*5

10

Mineral Manure (without Pot-
ash).* and Ammonium-salts
= 86 lb. N

90-7

0-1

9 '2

97-6

(0-01)

2'i

9

Complete Mineral Manureand
Ammonium-salts = S6 lb. N.

_

88-7

0-4

10-9

91-2

1-3

7*5

13

As Plot 9, and Chaffed Wheat

1

Straw also to 1897 inclusive

92-3

0-3

1 7-4

98 1

0-6

1 ■■>

11-1

Complete Mineral Manureand
Ammonium-salts = 129 lb. N.

95-8

0-1

4-1

99-2

s

0-8
0-5

11-2

As 11-1, and Silicate of Soda.

97-5

0

2-5

99-5

0

16

Complete Mineral Manure and

Nitrate Soda = 43 lb. N.

82-9

r>-4

11-7

()1 "7

].j-s

-■' •'

14

Complete Mineral Manureand

88-8

o.-

T-'". '

Nitrate Soda = sr. lb. N. .

90-6

1-3

8-1

"'

" 1

liii-liiiliiig Potash tlrst t> .ve

Speaking generally, these plots now present tin- .ipi.caranc.-.
perhaps in a rather exaggerated degree, of nmcli <.f tlir poor

156

EXPERIMENTS UPON GRASS LAND

pasture and meadow land in this country, wherever milch cows
and wet flocks are habitually grazed and the land occasionally
hayed, without anything being restored in the shape of artificial
food or manure. Fig. 17 shows a photograph of a piece of turf
taken from this plot at the end of June 1903.

The great value of occasional dressings of farmyard manure
to grass land may be seen in the returns from Plot 2, which
for the first eight years of the experiment received farmyard
manure at the rate of 14 tons per acre. The application was
then discontinued, but the effect has persisted to the present
day, i.e., for forty years.

Table LX. shows the produce on this as compared with

Table LX. — Produce of Ray per acre, first and second crops, shoiving
residual effect of Dniuj. Bothamsted.

1

Average of

Plot.

Manures.

If

i

i

i

If

ll

°2

1!

it

Lb.

Lb.

Lb.

Lb.

Lb.

Lb.

Lb.

Lb

2

Farmyard Manure, 8 yrs.
(1856-63) ; Unmanured
since ....

4804

5392

2848

3726

3748

2791

1747

581

3

Unmanured continuously

2665

2688

1296

2374

3025

2621

1568

516

Relation to

Produ

?e of PI

ot 3 rec

koned

as 100.

-

Farmyard Manure, 8 yrs.
(1856-63); Unmanured
since ....

180

201

220

157

124

106

111

113

3

Unmanured continuously

100

100

100

100

100

100

100

100

the unmanm^ed plot for the preliminary period for which the
dung was used, for the two years following its discontinuance,
for three ten-year and one five-year periods afterwards, and for
the season 1901. Although the yield on this plot remains at a
higher level than where the land has been continuously un-
manured, yet the plot now shows great impoverishment in the
character of its herbage, having about the same proportion of

If'Kcr pagf ISA.

^^ Of THE ^ .>

EFFECT OF MTKMXiKN Al.ONK i:,;

weeds and the same general aspct-t as tlic (•<»iitiminii>l\
iinnianured plot.

II. Use of Nitrogenous Mdmnrs ah^nr.

Three of the plots — 17, 5, and 1— show the efVcct of tlic
long-continued use of nitrogenous without any mineral iiianun >.
Plot 5 has been receiving 86 lbs. of nitrogen as .iimiK.niiiin
salts, Plot 17 half the quantity of nitrogen in the sha^x' nt
nitrate of soda, and Plot 1 the same half quantity of nitii)L:(n
as ammonium-salts, though on this plot dung was ai)pli((l in
each of the first eight years of the experiment. It is ww
evident when a nitrogenous manure is used alone for uras>,
nitrate of soda is far more effective than the ammonium-salts;
('.a., on Plot 17 it has given an average crop of :]."> ewt.
against 26 cwt. produced by double the quantity of nitni;_;en
in ammonium-salts on Plot 5.

For this superiority of the nitrate of soda twcj reasons may
be traced ; being completely soluble it sinks deeply into the
soil, and encourages grasses of a deeply-rooting habit, \\lii(li
not only obtain more food from the soil, but also are better
al)le to withstand the droughts of spring and early summer.
On Plot 17 (nitrate) deep-rooting grasses like Mmdow
Foxtail and Downy Oat Grass are prominent, whereas the
plots receiving only ammonium-salts are almost wholly occupied
l)y Sheep's Fescue and Connnon Bent, whose feeding- roots are
close to the surface, where the ammonium-salts are cauulit and
retained by the humus in the soil.

The continued use of large applications of amiiionimii->alt-
has also had an injurious effect upon the reaction of the soil,
since it behaves as an acid, and C(jntinually remov(\s carlKHiatc
of lime. The creeping surface vegetation tends to aceiiniiilatc
and decays into a substance resembling peat ; at the same tiim-
the vegetation shrinks into tufts, between which ai-e bare
patches of l)lack soil, showing- an aeid reaction to liinni-
paper. So pronounced had this effect become on Plot .">.
which received the larger amount of anunonium-s^ilts, that the

158 EXPERIMENTS UPON GRASS LAND

application has been discontinued since 1897, lest the turf
should be entirely killed. Another sign of the sourness
caused by the use of ammonium- salts without minerals is
seen in the prevalence of Sorrel on this plot ; it forms nearly
15 per cent, of the whole herbage, and it is interesting to
note that the only portion of the plot from which the Sorrel
is absent is a strip that was dressed with chalk in 1883 and
1887.

The aspect of the plots receiving only nitrogenous manure
shows very characteristic differences ; both possess a very dark
green unhealthy colour, but, while the ammonium plot seems
in the main to be clothed with Sheep's Fescue and other
grasses, amounting to 83 per cent, of the whole, the nitrate of
soda plot possesses a much more varied herbage, of which
weeds form 40 per cent. Leguminous plants are practically
absent from both plots, though a small proportion may be
found where the nitrate of soda is used. The impoverish-
ment due to the continual use of a manm^e like nitrate of
soda supplying one element only of plant food is to be seen
in the gradual decline of production on Plot 17, and in the
present predominance of weeds there. Considering, however,
the length of time that nitrate has been used on this plot,
the crop has been wonderfully maintained ; the deep root-
range induced by the solubility of the nitrate enables the plant
to feed widely in the soil, and the soda base assists in bringing
the dormant potash into a form available for the plant. The
photographs. Figs. 18 and 19, show the characteristic appear-
ance of the tm-f from Plot 5, with ammonium-salts alone, and
Plot 17, with nitrate of soda alone.

III. Mineral Manures used alone.
On three of the plots no nitrogenous manm-es have been
applied since the beginning of the experiments. On Plot 7
a complete mineral manm-e, supplying phosphoric acid, potash,
magnesia, and soda, is used ; Plot 8 has received the same
application, but without potash, since 1861, while Plot 4-1

\ f

\ /

\fae* fxii/r l.'>

EFFECT 0¥ MIXKKAL MANTKES i:.'.»

receives superphosphate only. Willi the coiuplcte minerals
a fair crop is grown, averaging over U ton of hav lor the
first cut alone, and when the successive ten - vear averages
are considered tliere are no signs that the fertility of
this plot is decHning, since the production only shows Mieh
fluctuations as may be put down to seasons. The reason that
the crop on this plot is maintained, although no nitrogen is
supplied in the manm-e, lies in the free growth of leguminous
plants. It will be seen that, taking the average over the wliole
period, the leguminous plants form 24 per cent, of the herbage,
and the proportion has increased from year to year. These
leguminous plants are not only themselves independent of
nitrogen in soil or manure, but by fixing the atmospheric
nitrogen and leaving it jjehind in the residues of their dead
roots, they provide a supply for the grasses and other plants
which cannot of themselves feed on the nitrogen of the air.
The predominant leguminous plant is Latf/j/rus j/j-dtc/isi.t, but
Red and White Clover are also abundant. A large number
of species of grasses are represented on the plot, none of which
are specially prominent. Amongst the weeds, Yarrow is
very abundant, and there is also a rather large projjortion of
Sorrel. The general aspect of the vegetation is shown by the
photograph of tm'f, Fig. 20.

The omission of potash on Plot 8 has caused a very
striking difference both in the crop and in the character of the
herbage. Tlu average crop has been about one-quarter less
over the whole period, and shows a progressive decline in
fertility, until at the present time it is little more than half
that of Plot 7. The poor results on this plot, as compared
with Plot 7, must be put down to its poverty in Iegunn"nous
herbage, the development of which seems to depend on a free
supply of potash. Of late years the proportion of legiimiiioiis
plants on this plot has amounted to al)out one-half of that
found on Plot 7, the grasses are about the same, the (lillerciice
being made up by an increased amount of weed. The
characteristic leguminous j^lant is the Bird's Foot Trefoil,

160 EXPERIMENTS UPON GRASS LAND

which has an opportunity to develop because it is not crushed
out by the competition of taller-growing herbage, such as is
found with the bigger crop on Plot 7. The characteristic
weeds of this plot are the Buttercup, the Black Knapweed,
Plantain, and Yarrow ; see photograph, Fig. 22.

Plot 4-1, which each year has received superphosphate only,
now presents a very impoverished appearance, and is giving very
little more crop than the unmanured plots. Indeed, the aspect
of this plot, where the most abundant grass is Quaking Grass,
and where weeds, chiefly Hawkbit, Burnet, and Plantain, are
unusually prominent, would seem to indicate that the land is
more exhausted here than on the unmanured plot. It is not
uncommon to find cases where the appHcation to grass land of
a purely phosphatic manure, like superphosphate or basic slag,
is followed by a great increase of crop, the addition of the
phosphoric acid to the dormant nitrogen and potash in the
soil having supplied the missing element in a complete plant
food. The result, however, of this plot shows how disastrous
a continuation of such one-sided manuring may l;)ecome ; a
nitrogenous manure alone is often thought exhausting, but
probably a phosphatic manure used singly will even more
quickly impoverish the soil. The photograph. Fig. 23, shows
the impoverished and weedy aspect of this plot in 1903. The
diagram, Fis;. 21, shows the effect of the mineral manm-es, and
particularly of potash, both with and without nitrogen, on the
yield of grass.

IV. Complete Manures — Nitrogen and Minerals.
Four of the plots receive a complete artificial manure. On
all of them the mineral manuring is the same, and supplies
both phosphoric acid and potash ; on Plot 9, ammonium -salts
containing 86 lb. of nitrogen are added ; and on Plot 11-1
the amount of ammonium- salts is increased by one -half,
to 129 lb. of nitrogen. Plot 14 receives 86 lb. of nitrogen
as nitrate of soda, and therefore compares with Plot 9.
Plot 16 also receives nitrate of soda, but only half the

\fMt ;xi|/* 100.

EFFECT OF NITKOCtEXOUS MAM IMS

h;i

amount on Plot 14. Considering Plots \) and 11-1 lirsr, it
will be seen that, large as is the amount of nitrogen ap})li('d
to Plot 9, the increased quantity on Plot 11- 1 has its

Without Nitrogen
.A.

With Nitrogen

Fig. 21.— Effect of the various Ash constituents with and without Nitrogen on the
produc-e of Hay per acre. Average over 47 years (1 S.'iG-l 902).
Plots 3 and 12. Unmanured. Plot 4-2. Super, and Amm.-salLs ^ >t; lb. N.

Plot 4-1. Superphosphate. Plot 10. Minerals (without Potash) and

Plot 8. Minerals with Potash. Amm.-salLs - S»i lb. N.

Plot 7. Complete Mineral Manur.'. Plot 9. Complete Mineral >I:inun- and

' Amm. -salts ^') lb. N.

effect in an increased crop. On Plot 0 the liay has averaged
54 cwt. over the whole period, on Plot ll-l the crop is
increased to more than 65 cwt. Comparing these results with
the 39 cwt. obtained from IMot 7 (minerals without nitrogen),
it will be seen how gi-eat is the effect of nitrogen in the produc-
tion of hay. The hay, however, is by no means so good in

162 EXPERIMENTS UPON GRASS LAND

quality as that grown with mineral manures alone, because the
large amounts of nitrogen have so stimulated the development
of the grasses that leguminous plants have disappeared entirely,
and even the weeds are crowded out. In 1903 the latter formed
only a trifle more than 4 per cent, of the herbage on Plot 9,
and were barely perceptible on Plot 11-1, as may be seen in the
photographs, Figs. 24 and 25, representing turf from these plots.
The dominant grasses on Plot 9 consist of False Oat Grass,
Smooth-stalked Meadow Grass, Sweet Vernal, and Sheep's
Fescue ; Meadow Foxtail, Cocksfoot, Yorkshire Fog, and
Bent Grass constituting practically the rest of the herbage.
On Plot 11-1 there is every sign that an excess of nitrogen has
been employed ; the vegetation is very rank and soft, and tends
to grow in tufts with bare patches between ; the smaller grasses
are almost wholly crowded out, and the coarse vegetation is
generally laid and begins to rot at the bottom before the grass
is ready to cut. Owing to the great competition of the strong-
growing grasses the numl:)er of species on this plot has been
reduced to a minimum ; 97 per cent, of the herbage is made
up of three species alone — False Oat Grass, Meadow Foxtail,
and Yorkshire Fog, the latter repTesenting 45 per cent, of the
whole herbage. In the earher years of the experiment this
latter grass was by no means so prominent. As late as 1872
it only formed 10 per cent, of the herbage, while more than
39 per cent, was composed of Cocksfoot, which has now
practically disappeared. The replacement of Cocksfoot by
Yorkshire Fog seems to have been coincident with the abandon-
ment of the practice of grazing the aftermath ; the custom of
late years has been to cut it.

On Plot 11-2 the same manure is employed as on Plot 11-1,
with the addition of 400 lb. of silicate of soda. The silicate of
soda has resulted in a considerable increase of crop, which has
averaged as much as 72 cwt. for the whole period ; the grass
on this part of the plot is also more healthy and uniform, and
ripens earlier. The effect of the silicate of soda must probably
be attributed to the soda base rather than to the silica : for with

•_.«:-

i^c

NITRATE OF SODA T. AM MOM T M SA l.TS h;:;

the great excess of iiitrogm applied to tliis jtli.t any >iilistaiR'«'
like soda, which supplements and economises the potash avail
able, will be of service to the plant.

Turning now to Plot 14, which receives the same manure
as Plot 9, ])ut with its nitrogen in the form of nitrate (tf soda,
we notice first that the nitrate of soda has been the more
effective soiu'ce of nitrogen, giving an average crop of .")!> cwt.
against 54 cwt. with ammonium-salts. The superiority tA' iUv.
nitrate of soda has been most pronounced in dry seasons,
owing to the generally deeper-rooted habit of the grasses found
on this plot.

Daring the great drought of 1870, holes were dug for the
examination of the subsoil on this plot and on Plot 0. On the
latter, where ammonium-salts formed the source of nitrogen,
very few roots could be distinguished below 36 inches, and the
ijubsoil below 27 inches seemed to have been but little changed
by the development of roots and their decay. On Plot 14.
Avith the nitrate of soda, wiry roots extended nearly to 4 feet,
and the subsoil down to 4 feet 6 inches had suffered a marked
change.

The vegetation on plots grown with nitrate of soda is more
varied, nor are the leguminous plants so completely .suppresse<l
by the large amount of nitrogen. This j^lot, for I'xampU'.
showed in 1903 more than 8 per cent, of ]\read"\v ^'('t(•llli^g
and a trace of White Clover. The aspect of the nitrate and
ammonia plots is strikingly different, as may be seen by com-
paring the tAvo photographs taken in 1903, Figs. 26 and 24.
With the nitrate of soda a great part of the herbage, 23 \)vv
cent., is composed of Soft Brome, a grass hardly to be found
on any of the other plots. Again, Beaked I'arsh'v is very
prominent, though it is hardly to l^e found on any of the otlicr
plots; it constituted 10 per cent, of the herbage in 19(13. so
that just ])efore hay time the whole plot .shows white with its
flowers. In addition to the Soft Brome, the gra.sses whu-li
predominate are Meadow F'oxtail, l^ilsc Oat. and Smooth-
.stalked Meadow^ Grass.

164 EXPEEIMENTS UPON GRASS LAND

Plot 16, which receives the smaller quantity of nitrate of
soda, still grows a very large crop, averaging 48 cwt. over the
whole period. The vegetation resembles that of Plot 14, but is
even more varied, there being about four times as much
leguminous herbage, among which the Meadow Yetchling
predominates. This plot probably marks the limit of the
amount of nitrate of soda which it would be profitable to apply
in ordinary farming, since the second 275 lb. per acre of nitrate
of soda on Plot 14 has only produced an average increase of 11
cwt. of liaj^

Reviewing the whole of the evidence, nitrate of soda is
distinctly a better manure for hay on the Rothamsted soil
than are ammonium-salts, producing more grass and that of
a better quality.

On Plot 10 the potash is omitted from the mineral manm'e,
though the other minerals and the nitrogen are the same as on
Plot 9. The result of the omission of the potash is a consider-
able decline in yield, which has become more accentuated as
the experiments have progressed and the original stock of
potash in the soil has been reduced. The herbage consists
even more wholly of grass than does that of Plot 9, and the
development of flower and seed is distinctly later.

Plot 4-2 receives the same ammonium-salts, supplying 86
lb. of nitrogen, and superphosphate only, so that it compares
with Plot 9, except for the entire absence of alkaline salts.
The lack of potash shows itself in a great reduction of crop, the
average over the whole period having been only 35 cwt. against
54 cwt. on Plot 9. It is thus much below Plot 10, also with-
out potash, but which receives magnesia and soda. The herbage
on this plot again consists almost wholly of grasses, which have
a very dark green colour and are late to mature. The dwarf-
growing and shallow-rooted grasses predominate ; Sheep's
Fescue constitutes more than one-half, and Avith Sweet Vernal
and Smooth-stalked Meadow Grass, as much as 85 j^er cent, of
the whole herbage.

The characteristic appearance of the herbage is well seen in

/

■y.,rf pogf

VALUE OF FAKMYAHJ^ .MANUIIK Toi: (;1:AS> k;:,

the pliotograpli, Fig. '27, of turf taken {'nnw this phM in \\h)V,.
Anotlier feature in these two IMots, 10 and 4--J, wliieh i-i-eeive
nitrogen but no potasli, is the weakness of tlie stems; sln.rt as
the grass is, it is often laid l)efore it is ready to cut. The grass
is also found to l)e more susceptil)U' to fungoid attacks on tlies(^
plots than elsewhere.

The diagram Fig. 28 shows a comparison of the yields of
the unmanured plot, the plot receiving mineral mamu'es only,
and the plots receiving mineral manures and varying amounts of
nitrogen as nitrate of soda or annnonium-salts.

V. T//e Artio)t of Organic Matter.
In the early years of the experiments farmyard manure
was applied every year to two of the plots, but owing to
the accumulation of unrotted material on the surface it was
found necessary to discontinue the experiment in this form.
On another of the plots, however, an attempt was made to
ascertain the effect of the organic matter present in dung
by adding to a complete artificial manure, such as is sup-
plied to Plot 9, 2000 lb. of chaffed wheat straw every year.
The wheat straAv will contain so little manm^ial matter, compared
with the quantities artificially supplied, that it may be neglected ;
thus the straw should ])e regarded as simply providing organic
matter. If we com23are the crop on this Plot i:3 with that of
Plot 9, we see that the straw has had its effect, and that on the
average a larger crop l)y about 7 cwt. per acre per annum has
been produced. The effect of the wheat straw has been due
partly to the shelter it provides in tlie early spring (for it is
noticed that the gi-ass starts more quickly on this plot than on
the others), and partly also to the water-retaining power of the
hunuis produced by its decay. Of late years the organic
matter added accumulated to such an extent as to form ;i
peaty layer that was beginning to injure the growth ol the
plant; in consequence the application of straw has been
discontinued. The value of occasional applications of farmyard
manure to trrass land is thus seen to be a mechanical factor

166 EXPERIMENTS UPON GRASS LAND

Cwt.perAc
60

Plots 3&I2

Fig. 28.— Effect of Nitrogenous Manures on the produce of Hay per acre. Average
over 47 years (1856-1902).

Plots 3 and 12. Unmanured.

Plot 7. Complete Mineral Manure, no Nitrogen.
Plot 9. Do. and Amm.-salts = 86 1b. N.

Plot 11. Do. do. =129 lb. N.

Plot 16. Do. and Nitrate of Soda = 43 lb. N.

Plot 14. Do. do. =86 lb. N.

EFFECT OF LIMl

167

depending very much upon tlie shelter wliicli the Inuic iiiaiiiuv
affords to tlie young grass in the early spring, and to its water-
retaining power when it has rotted down to hunuis in the soil.

VI. Elf\'('t,< of J/nii<\
In Xovember 1883, lime at the rate of 'lOOi) 11). per aere
was applied to one-half of each of the plots, and in isRf),
1886, and 1887 the limed and unlimed portions of ecrtain
of the plots, where the lime had obviously produced an etti'Ct,
were weighed separately and subjected to partial botanical
separation. The results of the liming may be seen in Table
LXL, wliich gives the averages of the three seasons, both as
regards crop and its botanical composition. It will be seen
that on three of the plots— 6, 7, and 15 — the liming has had ;i

Table LXI. — Effects of Lime on Grass Land. Mean of 3 years (1885-87),
first crops. Produce and Botanical Composition of the Ilcrbfii/i ,
Rothamsted.

Botanical Composition per cent.

Hay

Plot.

Mamiriiig.

cwt.

Graminese.

Legu-
mliiostt'.

Other
Orders.

4

1

^1

1

i1

1

'•^B

1

2

3-

Unraanured

18-6 18-9

76-0 1 69-0

7-1

16-0

16-9

15-0

6

Complete Minerals ; following Ammo-

nium-salts .....

23-8

28-7

72-8 67-7

11-7 20-1

IST) 12-2

7

Complete Mineral Manure .

26-1

33-1

64-3, 18-4

22-0 41-8

13-7 9-8

8

Mineral Manure without Potash .

17-0

16-7

60-6 71-8

7-5, 8-1

31-9 20-1

15

Complete Minerals ; following Nitrate

1

of Soda

12-4

25-6

67-4

53-8

3-2 35-3

29-4 10-9

Results for one year only (1885).

considerable effect in increasing the crop. On the unmaniuvd
plot and on Plot 8 the effect has been nil. Again, on examin-
ing the composition of the herbage it will be seen that on the
same three plots which gave an increase of crop the limr has
brought about a great increase in the proi)orti()n of leguminous
plants. On Plot 6 it has ri.sen from 11 to -JO per cent., on Plot
7 from 22 to 42 per cent., and on Plot 15 from :5 to :{5 per c<'nt.

168 EXPERIMENTS UPON GRASS LAND

The reason for these differences in the action of lime is
to be found in tlie previous manuring of the plots. On Plots
6, 7, and 15, potash has been applied every year, so that there
was a large accumulation of potash residues in the soil. On
Plots 3 and 8, on the contrary, no potash had been used ;
and as Plot 8 had been receiving phosphoric acid, the store
of available potash originally in the soil must have become
considerably exhausted. As we have also seen from the
effect of mineral manures with and without potash on the
other plots, that the development of leguminous plants is largely
dependent on the supply of potash, it is obvious that the effect
of lime had been mainly due to bringing into action the
residues of potash accumulated from the previous manuring ;
the lime only acts where there is such a residue of potash,
and has chiefly stimulated the growth of leguminous plants, just
as a direct application of potash would do.

The long-continued use of manures like ammonium-salts,
which are in effect acids, has altered the reaction of the soil
and made it som' on some of the plots. This is very palpable
on Plot 5, which has received a very heavy dressing of
ammonium-salts alone, and on which, as has before been
mentioned, there is now a large amount of Sorrel, except on
a small portion where chalk had been applied. A dressing
of lime is, without doubt, necessary for grass land on most
soils, in order to neutralise the acidity produced by decaying
vegetation, and to enable the manures to exert their full effect.
Thus although the liming at the rate of 2000 lb. per acre above
mentioned was extended in 1887 to cover the whole of the
experimental field, yet a fmther dressing of lime in January
1903 to the halves of the plots had an immediate effect upon
the following crop. As the results of only one or two years
are available as yet, they need not here be considered.

VII. Changes in Herbage following Changes in Manuring.
On two of the plots, which had received ammonium-salts and
nitrate of soda respectively until the herbage consisted entirely

I

EFFECT OF CHANGINCI 11 1 1: MANURES UJO

of grasses, tlie nitrogenous iiianuiH's were (liscontiiiucd, and ii.
their place a complete mineral manure containing potash was
applied. The diagram Fig. 29 shows the elleet of this change
of treatment on the composition of the heritage; the columns
.show the average proportion of gi-asses, leguminous plants, and

nefor.>. Aft.>r.

U.-fore. Aflor. Hefor-. AOor.

Plot 6.

Change to Minerals

from
Ammonium-salts.

I

Plot 15.

Change to Minerals

from

Nitrate of Soda.

Le|umInosa

per cent

i

Plot 8.
Omission of Potash.

Weeds, per cem

Fig. 29.— Progressive effect of Changes in the Manuring on the Composition of the
Hay Crop. Five-year periods.

weeds before the change, and for succe.s.sive five-year periods
afterwards.

On Plot f3 annnonium-salts alone was applied up to 1868,
at which time the grasses constituted 03 per cent, of the
herbage, and the weeds 37 per cent.— tlie leguminous jjlanis

170 EXPERIMENTS UPON GRASS LAND

being barely perceptible. In 1903 the leguminous plants had
risen to over 40 per cent, of the herbage, but the weeds had
not altered much. The change, as is seen in the diagram, did
not take place at once, the leguminous plants requiring nearly
twenty years to spread and establish themselves ; after five
years, for example, they constituted less than 5 per cent, of the
herbage. The photograph, Fig. 30, shows how closely the
herbage on this plot now resembles that on Plot 7, which has
never had anything but minerals.

On Plot 15 nitrate of soda Avas used up to 1875, when the
nitrate was dropped and a change was made to the same
complete mineral manure as is used on Plots 6 and 7. At the
time of the change the grasses constituted 80 per cent, of the
herbage and the rest was weeds, the leguminous plants being
again almost imperceptible. At the present time this plot is
almost identical in aspect with the one previously described
and with Plot 7 Avliich has received only mineral manures
from the beginning ; it contained in 1903 about 50 per cent, of
grass and 30 per cent, of leguminous plants. The photograph.
Fig. 31, shows that Lathy r us is more prominent than the
clovers. The change in the herbage on this plot took ^^lace
rather more rapidly than on the plot which had received
ammonium-salts beforehand, being practically complete in ten
years.

Plot 8 had received mixed mineral manm-e containing potash
up to 1861, by which time the herbage had become largely
leguminous, as on the adjoining Plot 7. The potash was
dropped in 1862, though the superj^hosphate, magnesia, and
soda have been continued. The effect of the absence of
potash was seen very quickly, the proportion of leguminous
plants dropping from 20 to about 9 per cent, in the first
five years. Owing to the continued manuring with phosphoric
acid and the lack of potash, this plot has become seriously
impoverished, and is now very little better than Plot 4-1 which
has received superphosphate only since the beginning of the
experiments, the weeds constituting about one-third of the

firtf^u^iJCJr

(flit* i<<t0t ITO.

CHANGES IN TRKATMEXT UXDKSI i: Al'.IK I7i

}ierl)age. The pliotograj)li, V'vji. '22, shows the present state i.f
the tiirf.

It should l)e reniemhered that no new seed of anv IJnd lias
been sown on the plots; the increase in the amount of clovei-
and other leguminous plants is therefore due either to spi-eadini;
from occasional stunted plants which were hardly percept 11 >le
in the herbage before, or to the blowing on of seeds which
find after the change a congenial soil for their development.
Immediately after the change the crop falls off, and only
reaches a new constant level when the redistribution of the
species occupying the ground has taken full effect. After
the change in the manuring the herbage is not suited to
the new conditions; at first the particular species favoured
l)y the manure are not prominent, and it is only when they
l)ulk largely in the herbage that the new manure can sho^\• its
full effect. Hence it would seem desirable in manuring grass
land to keep to the same kind of manure year after year,
so as to produce herbage which will get the maxinuun effect
out of the particular manure that is used. Again, if land
is grazed one year and laid up for hay the next, the grasses
which were at first fiivoured by the grazing will l)e dis-
com-aged during the growth of the hay crop : a better result
will probably be attained by always grazing or always haying
the same piece of land, so that there is present at the beginning
of any season the special class of herbage which has been
stimulated by the same conditions previously, and is tlierefoi-e
likely to give the best return.

The changes which manuring can produce in the composi-
tion of the herbage is perhaps best seen in Table LXII., where
the complete separations of the herbage in the years ls()i>,
1867, 1872, 1877, and 1903 are summarised for the more
abundant species. Figs. 32-40, again, show in a graphic
form the distribution on certain selected plots of these more
important species.

172 EXPERIMENTS UPON GRASS LAND

26/-

Fig. 32.— Percentage of Anthoxaiithum odoratiim in the Herbage of the Grass
Plots. First Crop, Season 1903.

Unmanured.

Minerals only.
4-1. Superphosphate.
8. No Nitrate.
7. Complete.

Nitrogen only.
5. Amm. -salts.
17. Nitrate Soda.

Nitrogen and Minerals.
Amm.-

4-2. No Potash \

9. Complete \ ,.
11. Excess N. J ^*'^'
14. Complete; Nit. Soda

ROTHAMSTKl) VWIK IIAV

17:;

Table LXII. — Rothamstcd Park Hay. rcrvciitaijc of carh Spoicji by wciyht

ill the Mixed Hcrhdiic from Twelve aelectnl plitt< (f!,-./ ,,-,,,. o F"--
separations, 1862, '07, '72, '77, cud 1903.

(The maxinuim attained by each species in tlie partiiuliir \ car
heavier type.)

priiiti-il

1

Years

GRAMIXEJS.

Plot

S

4rl

8

7

6

15

5

17

4-2

9

11-1

14

Anlhoxanthum odoralutn (Sweet-scented Vernal Grass).

1362

4-28

3-66

3-72

3-06

3-92

1-82

6-77

2-06

2-24

1-24

0-09

0-35

1867

8-66

7-16

6-98

3-93

4-31

1-83

5-51

2-31

5-52

3-59

0-06

0-13

1872

5-20

4-74

7-94

2-72

6-22

4-49

3-04

4-50

1-47

2-25

0-78

0-02

1877

5-12

5-11

7-55

3-lS

4-89

4-16

4-09

5-32

2-36

2-94

0-19

0-06

1903

1-34

2-40

1-50

1 -30

1-90

1-67

12-29

11-06

28-44

16-19

0-98

0-13

Alopecurus pratensis (Meadow Foxtail). |

1862

4-49

1-32

0-39

0-34

1-70

6-90

0-65

28-94

0-66

0-27

2-80

0-22

1S67

5-82

1-84

0-88

0-88

0-02

5-95

0-47

21-71

14-75

0-07

13-11

3-54

1872

0-52

0-86

0-52

1-17

0-03

2-46

0-83

16-25

3-94

2-76

12-35

.•!-7l'

1877

0-30

1-40

0-87

0-48

0-09

7-17

0-23

12-72

1-58

0-96

9-91

2018

1903

0-59

0-31

0-55

4-51

0-59

10-21

0-27

9-74

4-56

4 -OS

28-51

28-72
1

Agrostis vulgaris (Common Bent).

' 1862

11-36

7-21

10-01

7-14 21-43

7-65

24-30

11-01

19-38

12-81

13-17

0-42

1 1867

8-63

6-08

4-32

5-69 1 14-41

6-86

20-97

7-05

14-00

13-43

19-27

0-61

, 1872

16-14

13-88

9-32

11-72 123-37

7-66

26-62

10-60

20-59

15-46

13-56

0-24

! 1877

13-28

9-87

12-40

12-02 1 8-58

12-90

29-46

17-92

24-39

12-23

29-20

l-r)5

; 1903

0-19

0-03

0-72 3-34 2-51

1

2-99

11-65

1-76

2-04

3-81

1-12

0-14

Hole

us lanalus (Woolly Soft Grass, or Yorkshire Fog).

1862

5 -01

11-82

4-51

5-06 8-17 7-61

10-08

8-23

16-21

12-14

9-92

6-60

1867

7-97

9-16

10-25

11-81 1 307 11-81

5-15

8-13

10-53

9-84

2-SH

6-63

1872

■■i -GO

4-71

4-61

3-16 : 5-31 5-32 1-90

5-87

2-03

7-61

10-88

3-67

1877

12-55

19-35

18-22

13-16 14-89 14-95 3-01

10-91

6-03

10-37

20-29

12-75

1903

5-07

4-74

6-31

3-07 2-87 2-35 0-03

4-84

1-05

3-94

46-67

0-02

Arrhenatherum arevaceum (False Oat Grass).

1862

0-07

0-13

4-62

2-41 ' 3-44 ' 0-04 3-93

0-68 2-46

0-77

,u

1867

0-21

0-18

3-16

0-06 ' 6-50 ...

2-78

0-23

0-41

2-50

4 -55

1872

0-13

0-15

4-40

0-46 3-60 ...

1-49

0-48

2-48

11-40

10--11

1877

0-05

0-05

3-17

1-29, 2-77 ...

0-23

0-01

1-02

13-23

14 86

6-32

1903

0-10

0-03

4-20

1-16 1 1-94 0-16

1

0-19

...

0-95

48-80

23-00

17-28

Avena pubescena (Downy Oat Grass).

1862

9-65

9-42

12-68

13-81

14-64

3-53

7-31

4-24

7-38

10-22

1-88

0-90

1867

3-07

4-97

3-44

3-90

0-90

0-70

0-63

1-15

3-94

1-41

001

0-92

1872

3-55

i 4-09

3-66

2-36

1-83

1-56

0-24

4-09

0-28

0-49

o-i»

1877

2-69

4-02

1-67

2-25

1-67

3-13

0-12

4-27

0-03

0-07

0-47

1903

4-76

9-n

8-04

4-28

7-50

4-18

0-01

8-69

0-06

2-82

174 EXPERIMENTS UPON GRASS LAND

3 4-18 7 S 17 4-2 9 II 14

Fig. 33. — Percentage of Festuca oi'ina in the Herbage of the Grass Plots.
First Crop, Season 1903.

Unmanured.

Minerals only.
4-1. Superphosphate.
8. No Potash.
7. Complete.

yUroffen only.
5. Amm. -salts.
17. Nitrate Soda.

Nitrogen and Minerals.
4-2. No Potash ^ .

9. Complete r ,
11. Excess N. J '^^^'•
14. Complete; NIL Soda.

ROTHAMSTEl) PAKK HAY
Table LXII. — Continued.

i:.-)

Years.

GUAMINE.*: Vontinutd.

Plot
3

4-1

8

7

"

16 6

1

17

4-2

8

11-1

14

4-88
712

.i-e? 1

2-93
0-31

Avena flavescens (Yellow Oat Grass).

1862
1867
1872
1877
1903

2-37
1-86
3-49
1-08
0-92

4-12

4-28
6-09
2-47
2-83

5-42
3-52
6-94

2-45
3-94

4-02
4-84
3-72
3 -65
6-64

1-18 0-86 0-65
0-24 1 4-26 0-46
1-49 3-83 0-16
0-48 ; 2-98 i Q-Ol
1-47 5T.3 0-01

1-45
3-18
4-96
1-98

1-78

2-09
0-41
0-09
0-03

008

3-78
5-30
0-67
0-16

5-28
0-46
0-09
0-01

Poa p)

atensis

(Smooth-stalked Meadow Grass).

I 1862

; 1867

I 1872

i 1877

; 1903

0-29

0-56

1-72

1-13

2-28

0-14

1-07

0-02

0-67

10-68

0-17

0-26

1-50

1-05

1-65

0-13

0-65

0-21

3-87

13 02

0-09

0-45

2-11

2-27

2-42

0-37

0-61

0-09

r)-ii

22-67

0-07

0-02

1-03

1-75

1-73

0-11

0-23

0-09

1-56

18-08

0-33

0-83

0-98

2-34

3-74

2-52

0-90

0-20

7-67

11-68

9-43

12-86

10-40

1-47

0-17

l-4j
1-05 j
2-57 1
4-01
9 -JO

Poa trh'ialis (Rough-stalked Meadow Grass).

1862
1867
1872
1877
1903

1-54

5-16

5-48

3-81

1-17

5-65

3-48

4-38

0-50

3-79

1-62

2-30

0-56

4-72

3-20

2-11

0-01

0-64

0-10

1-00

1-53
0-40
0-98

6-53

23-67

7-95

0-19 1-20

0-89
0-30
0-59

5-21
12-08
2-74

8-14
2-15
2-10

8-72 13-25 22-48
2-14 0-14 32-98
0-64 0-09 24-76

Briza media (Quaking Grass).

1862

1-89

0-58

0-07

0-03

0-05

0-06

0-01

1867

0-68

0-32

0-08

0-06

0-02

0-07

1872

6-40

ii-12

1-16

0-10

0-01

0-20

0-01

0-31

6-bi

6-bi

1877

7-25

2-16

0-57

0-14

0-30

0-02

0-72

1903

20-15

1 1 •2'.

5-87

0-13

0-18

0-22

2-20

Dactylis glomerata (Cocksfoot).

1862

1-76

2-25

3-50

2-57 1

1867

1-74

0-99

1-48

4-67'

1872

0-90

0-57

0-66

1-68 '

1877

0-70

1-41

0-98

3-67 .

1903

1-05

1-30

1-12

4-97,

!

2-05
1-71
1-28
4-09

2-09
0-21
0-11
0-36

2-39 I
1-39
0-70
3-25 I

1-80
0-57
0-64
0-58

2-28
0-38
0-16
1 -83

5-58 24-16 10-00

4-64 I 89-81 7-28

11-88 89-28 3-33

14 07 1711 12-48

97, 3-511 0-48 1-32 1 0-92 l 0-14 1 5-14 1 0-15 O'"!

Festuca ovina (Sheep's Fescue).

1862
1867
1872
1877
1903

13-30
15-20
21 -67
21-89
17-45

10-20
16-75
20-44
16-02
8-81

7-51

13-73

13-33

13-69

17-74

11-38

25-93

12-08

23-95

14-86

31-15

34-71

19-76

26-59

38-02

'20-77

9-48

7-67

8-80

15-03

21-99* 9-43
80-57 11-18
46-56 18-05
53-31 12-04
66-66; 12-84

6-80

5-21

1-48

26-09

IS -42

0-50

49-29

8-68

0-38

55-20

21-80

4-1.'.

53-56

7-52

0-02

0-88
1 -58
0-l»i
0-4S

2-7:.

176 EXPERIMENTS UPON GRASS LAND

^o%-

Fig. 34.— Percentage of ^llopecurus pratensh in the Herbage of the Grass Plots.
First Crop, Season 1903.

Unmanured. Minerals onhj. Nitrogen only. Nitrogen and Minerals.

4-1. Superphosphate. 5. Amm.-salts. 4-2. No Potash \ a m^
8. No Potash. 17. Nitrate Soda. ' 9. Complete - ^^^^^'

7. Complete. 11. Excess N. /

I 14. Complete ; Nit. Soda.

KOTHAMSTED PATMC TT AY

T A BLE LX 11. — Con I i n acd.

177

6U AM 1 NE Ji-ContinHMl.

Years.

riot

S

4-1

8

7

6

15

6

17

4^

e

11>1

14

Bromus mollis (Soft Brome Grass).

1862
1S67
1872
1877
1903

0-13

0-52

1-38

1-26

0-15

2-12

0-08

0-18

0-33

4-46

1-39

0-05

0-43

0-43

0-98

6-27

2-26

0-20

0-11

0-04

0-01

0-09
0-01

0-09
0-01

0-04
0-01

0-01

...

4-00
1-65

0-81
0-15

0-02

0-10

0-01

...

0-59

0-21

3-42

0-01

0-20

0-01

...

18 04
17 88
4210
8-02
22-97

Lolium perenne

(Perennial Rye-grass).

1862

G-37

9-28

5-92

3-12

4-58

7-49

3-33

5-09

6-47

4-20

1-37

1867

4-03

5-24

2-61

2-40

1-39

3-24

1-21

3-23

1-36

1-01

0-08

1872

2-37

3-12

1-92

0-59

0-69

4-42

0-97

2-94

0-70

1-11

1S77

4-55

4-35

7-63

3-02

1-97

7-32

0-09

6-68

0-21

0-16

0-01

1903

0-02

0-12

0-11

0-12

0-02

0-54

5-66

2-63

Total of other Species under 5 per cent. {Phleum pratense. Air a caspitoaa,
Cynosurus cristatus, Festuca pratensis, elatioi; and loliacece).

1862

0-23

0-47

1867

0-13

0-84

1S72

1-13

1-11

1877

1-06

0-82

1903

0-27

0-06

2-47

0-67
1-36
1-68

0-57

0-27
0-86
0-21
1-06
0-58

0-45

0-17

0-37

0-61

0-46

1-42

1-91

0-04

0-48

0-15

0-50

0-01

0-07

0-03

0-72

0-03

0-36

0-04

0-04

0-15

1-60

0-89

0-08

0-01

0-08

0-04

0-04

0-28

...

0-88
0-20
0-10
0-34

LEGUMINOS^.

1862
1867
1872
1877
1903

1862
1867
1872
1877
1903

1862
1867
1872
1877
1903

Tri/olium repens (White or Dutch Clover).

0-53
0-21
0-38
0-13
0-14

0-61
0-09
0-48 I
0-85

2-70 j 3-08

0-10 I 0-47

0-25 1-77

0-10 0-01

1-25 4-27

0-01

0-04

0-01

0-05

0-01

0-01

0-01

0-08

0-01

0-32

0-01

0-01

...

0-01

0-06

0-01

0-09

...

0-01

0-01

0-01

0-01

6 -01

...

1-68

6-74

0-13

0-01

...

0-01
0-01

0-01

Tri/olium prateme (Common Red Clover),

4-48
2-11
1-68
2 09
1-44 i
I

1-45
0-17
0-11
0-30
2-71

7-71

1-13
0-27
0-36
1-.38

6-84
4-75
1-13
1-55
6-41

0-03

0-20

0-04

0-01

0-04

0-01 1

0-04

0-03

... ■ 1

0-08

0-31

1

5-91

5-76

... 1

0-31
0-26
0-12
0-11
0-01

0-01

6-bi

0 01
0-01
0-01

0-01

Lotus corniculalus (Bird's Foot Trefoil).

1-88
2-36
6-94
3-96

3-64

0-41

0-15

1-27

0-01

0-02 1

1 -23

0-83

0-69

0-08

0-35

3-71

3-51

0-19

0-06

0-03;

0-86

1-18

0-04

0-03

0-01 1

7-28

12-24

0-43

2-30

0-01

0-05
0-31
0-41
0-14

0-05
0-12
1-10
0-78
2-28

178

EXPERIMENTS UPON GRASS LAND

nil

Plot

Fig. 35. — Percentage oi Arrhenatherum avenaceum in the Herbage of the Grass Plots.
First Crop, Season 1903.

Unmanured.

M'merah only.
4-1. Superphosphate.
I 8. No Potash.
I 7. Complete.

Nitrogen only.
5. Amm.-salts.
17. Nitrate Soda.

Nitrogen and M'merah,
4-2. No Potash ^A^,^.
9. Complete r ^^,,3
11. Excess N. }
14. Complete ; Nit. Soda.

KOTHAMSTED PA1M< MAY
Table LXlL—ContinueU.

I7'.»

LEGUMIN08.E-Con/{nii*rf.

Years.

Plot
8

4.1

8

7

6

16

5

17

4-2

e

11-1

14

Lathyrus pratensis (Meadow Vctihhng).

1862

1-26

0-32

S-76

13-51

0-23

0-02

0-01 007

0-12

0-01 0-11

1867

0-68

1-34

6-82

6-78

...

0-04

0-01

... 1 003

0-15

0-37

1872

0-98

4-19

3-94

86-68

1-47

0-04

0-01 0 02

0-02

1-35

1877

2-37

3-38

2-37

12-11

0-56

1-47

0-05

0-01 1 0-03

0-06

0-76 \

1903

2-55

4-77

3-70

22-01

30-94

16-29

...

0-12

0-01

3-34

Total of all other Leguminous Spt-cics.

1862

0-01

1
...

1867

... 1 ...

1872

0-12

1

...

1 ...

1877

0-64

0-34

1903

017

MISCELLANEOUS SPECIES.

E<i

nnnculi

46- acris

, repeiis ei Imlbosiis (Upright, Creeping and liulbous Crowfoot). .

1862

4-89

5-90

.-,6

1-39

0-77

2-26

0-33

2-09 2-15

0-14

0-03

1-28

1867

2 02

1-39

1-21

0-50

0-16

0-64

0-10

1-33 0-05

0-05

...

0-40

1872

3-01

4-28

1-47

0-40

0-47

1-63

0-11

2-48 0-01

0-28

1877

3-45

610

1-74

0-69

0-57

4-23

0-16

4-91 , ...

6-04

0-71

1903

1-89

1-53

10-90

2-86

3-72

6-20

...

3-92 ...

0-19

Poterium sanguisorba (Common Burnet).

1862

0-01

■

1

1867

0-21

0-75

...

1872

0-49

0-09

1877

0-88

0-21

...

190.3

13-81

8-48

6-03 1 ...

...

... 1 ...

Conopodium denudatum (Earth or Pi}? Nut).

!l862

0-97

0-97

T59

2-03

0-55

0-.58

1-15

1-48 1-29

2-92

1
1-79! 1-55

1867

2-9.^

2-32

6-84

9-22

7-87

0-20

5-74

2-44 2-65

9-86

1-81 1-57

1872

2-85

1-17

1-73

1-31

2-47

0-43

1-02

1-51 0-39

1-51

0-04 0-61

1877

1-90

0-64

1-07

1-58

0-88

0-77

0-65

0-72 0-11

0-75

0-01 0-18

; 1903

0-92

0-23

0-79

1-69

1-28

1-07

0-07

0-61 ...

0-26

... j 0-02

1

Anthriscus sylvestris (Beaked Parsley).

-

1862

...

1867

...

...

152

1872

...

...

8-86

1877

...

4-64

1903

...

6-63

... 1

... 1 .«

180

EXPERIMENTS UPON GRASS LAND

50^-

Plot 3 4-18 7

S 17 4-2 9 II 14-

Fig. oi3.— Percentage of IIulcus lanatus in the Herbage of the Grass Plots.
First Crop, Season 1903.

Unmamired.

Minerals only.
-1. Superphosphate.
8. No Potash,
7. Complete.

Nitrogen only Nitrogen and Minerals.

5. Amra. -salts. 4-2. No Potash \ /.
17. Nitrate Soda. 9. Complete

j salts.

14. Complete ; Nit. Soda.

11. Excess N.

ROTHAMSTED V.WIK II AN
Table LX II.— Con/ in lud.

isl

MISCELLANEOUS 8PBCIK8 Con«<»..«/.

Plot

1

Years.

3

4-1

8

7

6

16

6

17 42

9

11-1

14

Cmtaurea nigra (Black Kiiapw.-.d).

1862

0-31

0-43

0-22

0-03

...

0-01

4-41 0-01

0-04

0-07

1867

0-59

0-36

0-45

0-79

1-40

0-17

2-43

4-10 0-21

0-01

1872

2-11

1-01

0-24

0-27

1-41

2-58

2-18

10-28 1 -25

0-02

1877

1-06

0-66

0-76

0-10

0-44

0-90

0-53

2-82 0-85

...

1903

4-05

4-77

7-21

1-03

1-35

0-81

0-71

11-20 1-^3

0-03

Achillea millefolium (Yarrow or Milfoil).

1862

1-53

1-42

0-93

1-69

8-34

2-53

1-33

2-14 i 1-77

1-95

1-45

0-24

1867

1-16

1-88

4-89

3-10

1-08

1-13

1-09

1-39 1-49

2-03

0-06

0-47

1872

1-78

5-38

9-75

5-23

4-09

2-60

1-05

2-91

1-75

1-50

0-21

1877

1-99

3 19

2-76

0-64

1-72

0-58

0-16

1-39

0-27

0-04

0-01

0-65

1903

2-67

1-80

3-50

8-95

7-62

9-95

0-04

2-82

0-01

0-37

...

0-12

Leontodon hispidus (Rough Hawkbit).

1862

0-06

0-59

0-01

0-02 ...

1367

0-64

0-62

0-01

0-01

0-05

...

...

1872

1-27

0-11

0-07 ...

...

6'bi

1877

1-32

0-92

6 -01

0-25 ...

1903

o'98

14-66

6-85

3-68 ...

...

Plantago lanceolata (Ribwort Plantain).

1862

7-34

5-63

0-71 ' 0-23 0-06 6-92 O'lO

1
3-85 ! 0-04

0-01

0-18

1867

10-73

9-66

1-53 1-10 ... 4-67 0-02

4-83 ...

0-01

0-01

1872

2-66

3-13

0-34 0-07 ... 0-28

2-41 ...

0-01

1877

3-16

8-78

0-26

0-09 0-01 0-56

7-99 0-01

1903

1-98

2-49

5-85

0-05 i 0-09 1 0-20

\ 1

"

10-70 ...

...

Rumex acetosa (Sorrel).

6-88

1862

1-40

3-94

1-93 2-10 12-11 6-64 9-15

3-57 13-39

'.-10

7-02

1867

1-76

0-47

7-86 1 8-88 24-27 ' 7-34 15-94

7-53 8-12

10 -89

;{-'.».i

1-11

1872

1-77

2-81

1-96 1-16 ' 7-51 2-06 7-13

1-58 6-S.">

4-60

1-09

0-61

1877

1-87

3-37

5-84 1 6-67 1 7-66 5-79 2-13

2-56 3-09

3-60

2-25

4-40

1903

2-21

1-51

1-91 1 3-71 5-24 , 1-56,14-84

1 1 i 1

1-80 0-54

2-79

0-13

0-57

Total of ail other Miscellaneous Species.

1862

4-79

3-35

2-45 3-18

2-37 2-53

1-49

0-66 0-95 1

0-82

0-2.'i

0-27

1867

9 06

7-84

5-31 1 4-42

2-46 5-31

2-49

1-91 1-01

0-45

0-01

0-27

187:^

6-42

6-38

4-98 I 2-97

3-24

11-54

3-35

4-11 1-07

0-ltf

0-02

0-23

1877

4-68

3-82

2-37 2-14

2-08

1-91

2-12

2-58! 1-00

0-.'.l

0-20

0-85

1903

6-49

3-95

6-92 6-83

4-25 ri3

1-99

6-67 1 4-38

0-69

0-02

0-69

182

EXPERIMENTS UPON GRASS LAND

Fig. 37. — Percentage of Tri/olmm repens, Trifolium pratense, and Lotus corniculatus
(together) in the Herbage of the Grass Plots. First Crop, Season 1903.

Unmanured. \ Minerals only.

4-1. Superphosphate.
I 8. No Potash.
7. Complete.

Nitrogen only. Nitrogen and Minerals.

5. Amm.-salts. 4-2. No Potash \ a „„ _
17. Nitrate Soda. 9. Complete \ ^ ,'~
11. Excess N. J '^'*'-
14. Complete; Nit. Soda.

EOTHAMSTED T'AKK H AV

Table LXll.— Confix lod.

SUMMART.

^:]

TOTAL PER CEiNT. OF GUAMINEOUS, LKGUMINOUH, AND OK OTIIEU OIlDEItM.

Plot

Years.

8

4.1

8

7 6

16

6

17

4-2

9

11-1

14

Total of Gramineous Species.

1862

t 1 i -
70-61 74-96 71-69 64-65 80-52 78-26 86-32

81-36

1
80-31 1 88-59

1
89-38 89-62

1867

65-53 66-88 63-03 59-29 62-66 80-02 71-85

75-72

86-13 : 77-06

9 J -12 94-26

1872

68-66 67-03 71-56 48-82 79-23 78-76 84-70

73-27

88-65 1 92-19

98-84 92-87

1977

71-15 71-78 , 81-19 74-38 79-96 83-45 94-06

75-87

94-63

94-65

97-53 87-81

1903

1

52-23 43-00 43-50 41-75 ! 35-61 50-05 82-37

56-01

93-65

95-90

99-82 S5-54

Total of Leguminous Species.

1862

8-10

2-79

19-32

24-70

0-28

0-27

0-12

0-42

0-09

0-13

0-01

0-18

1867

5-35

2-83

8-88

12-69

0-10

0-51

0-34

0-70

0-04

0-16

0-01

0-39

1872

8-98

8-61

7-97

39-77

1-58

0-12

0-46

1-38

0-03

0-02

0-01

1-36

1877

8-54

5-53

4-01

13-71

6-68

1-80

0-19

0-91

0-04

0-41

0-76

1903

7-77

17-58

18-57

33-15

40-83

28-97

2-59

0-01

0-01

3 -35

Total of other Orders.

1862

21-29

22-25

8-99

10-65

19-20

21-47

13-56

18-22

19-60

11-28

10-61

10-35

1867

29-12

30-29

28-09

28-02

37-24

19-47

27-81

23-58

13-83

22-78

5-87

5-86

1872

22-36

24-36

20-47

11-41

19-19

21-12

14-84

25-35

11-32

7-79

1-15

5-77

1877

20-31

22-69

14-80

11-91

13-36

14-75

5-75

23-22

5-33

4-94

2-47

11-43

1903

40-00

39-42

37-93

25-12

23-55

20-95

17-65 41-43

6-36

4-11

0-15 11-12

Number of Species.

1862

50

46

38

44

34

39

38

33

35

28

28

28

1867

43

46

42

42

32

39

36

47

30

29

18

30

1872

49

49

42

41

39

39

31

43

28

30

16

30

1877

62

45

48

44

38

43

29

49

26

27

15

27

1903

47

44

45

36

39

35

22

41

15

20

10

24

VIII. The Effect of Season.
The hay crop probably fluctuates with the seasons iiioic
than any of the crops on arable land, because the land does
not receive cultivation, which tends to regulate the supply
of water to the plant, and especially to preserve it fi'oni
wasteful evaporation during dry seasons. Not only does the
gross weight of crop vary very nuich, but the character of
the herbage alters considerably with the distribution of

184

EXPERIMENTS UPON GRASS LAND

25^

nil

nil nil

l_

Plot 3 4-18 7 5 J7 4-2 9 M 14

Fig. 38.— Percentage of Lathyrus pratensis in the Herbage of the Grass Plots.
First Crop, Season 1903.

Unmanured. Minerals only.

4-1. Superphosphate.
8. No Potash.
7. Complete.

Nitrogen 07ily. I Nitrogen and Minerals.
5. Aram. -salts. 4-2. No Potash ^ .
'" ^^^-^-^-" ' 9. Complete K"]J°'
11. Excess N. J '*'^-
14. Complete; Nit. Soda.

17. Nitrate Soda. 1

SEASON AND PIIK HAY ClJOl

1 ^r>

the rainfoll and temperature. Tlm.s the year MIO-J witli fre-
quent Hght rains was especially favoura])le to the ^Towth of
the shallow-rooted Lathyrus, and other leguminous plants, ilit«
proportion of which was doubled or more on some of the plots.
The Table LXIIT. shows the monthly rainfalls for the seasons

Table LXIII. — Rothamsted Park Hay. Seasons of hifihrsf tmd /oin-.tl
Yields compared with Monthly Raivfall.

Plot 9.

Plot 14.

Rainhll.

Years.

Minerals,
and

Minerals,
and

' '

"

400 lb.

r.50 lb.

ToUl.

Ainnionium-

Nitrate

March.

April.

May.

,I..n.-.

March to

salts.

of Soda.

June.

lOHij

jhest Yield

Is on Plot 9.

Lb.

Lb.

Inches.

Inches.

Inches.

Inches.

InchM.

1860

7700

8526

1-422

•2-129

3-231

1-061

7-843

1879

7668

5964

1-183

2-790

3-481

5-551

13-005

1904

7473

7340

1-578

1-252

2-152

0-813

5-795

1882

7266

7158

1-566

3-925

2-068

3-9-26

11-485

1858

7172

5646

0-967

2-439

2-531

0-958

6-895

1868

6622

7728

1-922

2-187

0-732

0-369

5-210

1871

6576

6930

1-503

2-890

0-955

3-866

9-214

1857

6422

1-495

2-171

1-088

2-227

6-981

1862

6402

5718

3-061

2-843

2-909

3-407

12-220

1856
Mean .

6363

0-994

2-615

4-872

1-742

10-223

6956

6876

1-569

2-524

2-402

2-392

8-887

lOLo^

Brest Yield

J on Plot 9

1893

1108

2592

0-424

0-249

1-221

0-999

2-893

1896

2267

4437

3-754

0-952

0-476

2-250

7-432

1901

2960

5061

2-565

2-511

1-806

0-841

7-723

1874

3290

5484

0-652

2-141

1-187

1-593

5-573

1870

3306

6300

1-789

0-488

1-324

0-979

4-580

1881

3307

4248

2-152

0-997

1-376

1 -633

0-158

1887

3608

6324

1-755

1-194

2-354

0-709

6-012

1865

3866

5292

1-435

0-426

3-048

0-914

5-8-23

1888

3958

5070

3-125

2-143

1-276

4-867

11-411

1900
Mean .

4246

5.^56

0-962

l-33>

1-080

2-634

6-008
6-361

3192

5027

1-861

1-243

1-515

1-742

giving the highest and the lowest yields on the completely
manured Plot 9, also the corresponding yields on Plot 14,
which receives an equivakmt amount of nitrate of soda
instead of the ammonium-salts on Plot 1». Although in a
general way it can be seen that a wet late .spring is on tin-

186

EXPERIMENTS UPON GEASS LAND

2-51-

Plot 3 4.-1

Fig. 39.— Percentage of Oentaurea nigra in the Herbage of the Grass Plots.
First Crop, Season 1903.

Unmanured. Minerals only.

4-1. Superphosphate.
I 8. No Potash.
7. Complete.

Nitrogen only. Nitrogen and Minerals.

5. Amm.-saits. 4-2. No Potash ^ .
17. Nitrate Soda. 9. Complete p™™""
11. Excess N. J '^"'•
14. Complete ; Nit. Soda.

CONCLUSIONS ls7

whole more favourable to the lo«;iiniiiu)iis plants, it is not easy
to trace any connection between the weather, as jiid^'cd Ironi
the meteorological records, and the character of the crop, since
so much depends upon the frequency of the rainfalls and tlir
relative predominance of particular species when the nio-t
favom-able period for growth sets in. In a dry >itrini: tin-
plots receiving nitrate have a great advantage over those
receiving ammonium-salts, but this is due to the deep-rooted
herbage they carry, rather than to any direct effect of the
mamu-e used. As regards rainfall, the critical months are
April and May : the rainfall of March appears to affect the
crop but little.

Practical Conclusions

1. It is better to lay up the same land for hay cacli year,
grazing the aftermath only, and, in the same way, always to
graze other land, rather than graze and hay in alternate years.
In this way we obtain the fullest development of those grasses
and clovers which are suited to haying and <:razinu'
respectively.

2. For the same reason the system of mamuiiiu once
adopted should be varied as little as possible, for even manures
as similar as nitrate of soda and sulphate of ammonia encourage
different kinds of grass.

3. On poor land any large expenditm-e on manures will lie
wasted ; the character of the herbage must be slowly reformed ;
a full manuring is only utilised when there are plenty of strong
and vigorous grasses or clovers among the vegetation.

4. Land which is growing hay requires a manure wliieli is
mainly nitrogenous, whilst pasture i-equires a mineral
manuring.

5. On strong loams, with a good mixed herbage, a dressing
of 10 to 15 tons of farmyard manure should be given eveiT
fifth year. In the other years a winter manm-ing (Jaiuiai y
or February) of 2 cwt. per acre of superphosphate (basic sla<;
on strong clay soils), and :3 cwt. of kainit, with lA cwt.

188

EXPERIMENTS UPON GRASS LAND

Fig. 40. — Percentage of Rumex acetosa in the Herbage of the Grass Plots.
First Crop, Season 1903.

Unmanured. Minerals only. Nitrogen only.

4-1. Superphosphate. 5. Amm. -salts.

i 8. No Potash. I 17. Nitrate Soda,
I 7. Complete.

Nitrogen and Minerals.
4-2. No Potash ^^^^.
9. Complete ,- ..
11. Excess N. J '*"'•
14. Complete ; Nit. Soda.

CONCLrsiONS ls.|

of nitrate of soda wIumi \\\v urass lic^iiis to ^i-ow. will !..•
remunerative.

6. On light dry soils, eitluT sandy <»r chalky, ihc niimuriioiiN
manures are the most important: (hiiiu, and cal^c-lrcdin- the
^iftermath, will best build up a vigorous heritage, and nntil tlii>
is done it will not be wise to spend nmch money on ariilieial
manures: 1 cwt. of nitrate of soda, 1 cwt. of siiperi»lio>|iliate.
and 3 cwt. of kainit, being about the l)est ])roportion in wliieli
to employ them.

7. On all old grass land an occasional dressing ot ground
lime, at the rate of half a ton per acre, applied in the early
winter (best in the year following the dunging), will sweeten
the herbage and utilise the reserves of past manuring.

Uekkuences
■'' lie port of Experiments with Difi'ereiit Manures on Pcrniiuunl Mt.ii(iii\v

Land, with Tabular Appendix." Jour. Rot/. Ag. Soc, 19 (18").*^), ").')2,

and 20 (1859), 228 and 398. Rothamsled Meinoirx, Vol. I., No. 12.
■"The Effects of Different Manures on the Mixed Herbanje of Grass Land."

Jour. Roy. Ag. Soc, 24 (1863), 131. RoUiamsted Memoirs, \'ol. I., No. 18.
■" Further Report of Experiments with Different Manures on IVrmunent

Meadow Land." Jour. Roy. Ag. Soc, 24 (1863), 504. Rnlhmnstcd

Memoirs, Vol. III., No. 3.
■"Effects of the Drought of 1870 on some of the Expcrinuntal Crops at

Rothamsted." Jour. Roy. Ag. Soc, 32 (1871), 91. Rol/iamslrd Memoirs,

Vol. III., No. 11.
•'' Agricultural, Botanical, and Chemical Results of Experiments on tht-

Mixed Herbage of Permanent Meadow, conducted for more than

twenty years in succession on the same land." Part L, 1 he

Agricultural Results. Full Paper. Phil. Trans., 171 (ISSO), 2S9.

Rothamsted Memoirs, Vol. II., 4to, No. 1.
■"Agricultural, Botanical, and Chemical Results of Experiiuenls on the

Mixed Herbage of Permanent Meadow, conducted for more tiian

twenty years in succession on the same land." Part II., The Botanical

Results. Full Paper. Phil. Trans., 173 (1SS2), llSl. Rothamsted

Memoirs, Vol. II., 4to, No. 2.
■^'The Hi.story of a Field newly laid down to Permanent (ira-^s." J«ur.

Roy. Ag. Soc, 50 (1889), 1. Rothamsted Memoirs, \'ol. \'l., .NO. II.
■".Agricultural, Botanical, and Chemical Results of llxperiments on the

Mixed Herbage of Permanent Grass Land, conducted for many years

in succession on the same land." Part III., The Chemical Results.

Section L, Full Paper. Phil. Tran.s., Series B., 192 (1900). 139.

Rothamsted Memoirs, Vol. II., 4 to, No. 3.
■"The Manuring of Grass Lands," by A. D. Hall. Jour. Roy. Ag. Soc, 64

(1903), 76.

CHAPTER X

EXPERIMENTS UPON CROPS GROWN IN ROTATION, AGDELL

FIELD
I. The Unmanured Plots.
II. Effect of the Manures.

III. The Effect of the Growth of Clover or Beans on the succeeding Crops.

IV. Effect of Manorial Residues on subsequent Crops.
V. Gain or loss of Manurial Constituents to the Land.

Practical Conclusions.
References.

The Agdell field, which was put under experiment in the year
1848, differs from the other Rothamsted fields in that it is
farmed on a four-course rotation of Swedes, barley, clover (or
beans) or fallow, and wheat, instead of growing one crop con-
tinuously. It is divided into three main plots, one of which (O)
has received no manm^e, the second (M) mineral manures only
(superphosphate alone in the first nine courses), and the third
(C) a complete manure, containing the same minerals, but also
nitrogen in the form of rape cake and ammonium-salts. The
manures are applied to the Swedes only, the other three crops
of each course being grown without manure. Each of the
three plots is further subdivided into four, so as to obtain the
following comparisons : — (1) Half the plots carry clover or
beans as the third crop of the course, and half the plots are
bare fallow. This shows the effect of introducing the legu-
minous crop into the rotation, as compared with the bare
fallow. (2) From half the plots the root crops grown in the
first course are carted ; on the other half the roots are eaten on
the land by sheep ; or rather, since the land is unsuited to winter
folding, the roots are chopped up and ploughed in. This shows
the effect on the succeeding crops of barley, etc., of the return
of a root crop to the land by folding.

The Table LXIV. shows the mean results for the last five
courses, 1884-1903.

CROPS IN ROTATION, AGDELL FIELD 1

r-l C.

CC 00 •^

^5

i g

U C5

c

1 1

I I

192

CROPS GROWN IN ROTATION

J. — The Unmanured Plots.

The various crops as grown in rotation are affected very
differently by the absence of manure than the same crops are
when grown continuously. In the case of the cereals, the
•crop is maintained far better on the rotation plots that are
unmanured than on the similar plots in Broadbalk and Hoos
field, where wheat and barley are grown continuously. The
root crop, however, falls to a minimum in the absence of
manure, and the mere act of growing in rotation is quite
unable to provide sufficient nutriment for the needs of even a
small crop. The clover and bean crops also grow very
indifferently on the unmanured plots notwithstanding the
rotation, though the falling-off" is not so marked as in the case
of the Swedes.

Although a rotation of crops, by alternating plants of
different requirements and different habits (some deep and

'Table LX V. — Crops grown in rotation, Agdell Field. Comparison of yield
at the beginning of the Experiment, and in later years (1852-1867 and
1884-1903). Average Total Produce per acre of four Unmanured and
four Mamired Plots.

Courses.

Swedes.

Barley.

Beans
(or Clover).

Wlieat.

Unmanured Produce

compared with that

by

Complete Manure

= 100.

J

1

Is

5s

(§1

ii

^1

E

Ii

6^

t5 1

Is

6s

1

>>

1

2nd to 5th
10th to 14th

Cwt.
19-3
19-7

Cwt.
263-7
435-4

Lb.
4190
2163

Lb.
5972
3662

Lb.
2002
1450

Lb.
3545
3592

Lb.

5526
3979

Lb.

6756
6033

7-3
4-5

70-2
59-1

56-5
40-4

81-8
66-0

some shallow-rooting), is able to utilise more thoroughly the
nutriment supplied as manure and the initial resources of the
soil, it is evident that it cannot enable the crops to dispense
with supplies of manure, but that its value largely depends
upon the opportunities it affords for cleaning the land and
maintaining a proper system of tillage. Table LXV. shows

MAINTENANCE OF YIEIJ) WITIIOIT MAM1:K 1<..:;

a comparison between the crops on tlii> uimianurnl aiid the
completely manm'ed plot for the iirst four (or i-athn- tin-
second to the fifth) and the last live courses of the n.iatinn.
from which an idea can he obtained of how far cadi cmj)

Manured Plots

■

1 l»> Four

= 100.

1

1 Courses.

Unmanured Plots.
Fig. 41.— Crops Grown in Rotation. Rehitive Yield on Manured and Urunanurcd Plots
in the earlier and later years of the Kxpcrinient.

has been affected during the fifty-six years of tli.' cxp.'iini.'ut
by the continued absence of niainu-c. Tlif sanu; resuhs are
shown graphically in Fig. 41.

Dm-ing the last five courses llie crop of Swedes on tli.'
unmanured plots has averaged only 16 cwt. per acre, and tli.-
roots have lost the appearance of Swedes, becoming taproots

194 CROPS GROWN IN ROTATION

with hardly any development of bulb. The crop, indeed, fell
away to nothing as soon as the manure was discontinued ; it
was less than 8 per cent, of the crop on the manm-ed plots
dm^ing the first foiu' com'ses, and it has fallen to about half
that quantity dm-ing the last five courses. Swedes have thus
very little power of growing upon the reserves of nutriment
in the soil, and they are almost wholly dependent upon an
immediate supply of manure.

The barley has yielded on the unmanm^ed plots 16 bushels
of grain and 11 cwt. of straw per acre dm^ng the last five
courses. This amounts to about 59 per cent, of the yield
on the manured plots in the same years, whereas for the first
four courses the yield on the unman ured plots was about
70 per cent, of that of the manured plots. As compared
with the corresponding plots in the same years in Hoos
field, where barley is grown continuously, the yield of barley
has been much better maintained when grown in rotation.
On the Hoos field in the later years the production of the
unmanured plots has fallen to 27 per cent, of that of the
manured plots, while the rotation barley on the unmanm'ed
had only fallen to 59 per cent, of that on the maniued plots, the
same years being compared in each case.

On the Rothamsted land it is not found desirable to grow
clover every four years, so only six clover crops have been
taken during the course of the experiment, beans having been
substituted in the other cases. On these leguminous crops the
absence of manure has had a very marked effect ; the produc-
tion, which was nearly 60 per cent, of the manured plots in the
earlier courses, has fallen to less than 41 per cent, in the later
ones. Thus the leguminous crops are much more affected by
the cropping out of the land than is the barley.

The wheat is better able to resist the deterioration of the
fertility of the soil than any of the other crops are. The
average production dm-ing the later courses has been 26 '2
bushels per acre on the unmanm'ed plots, as compared with
11*6 bushels per acre on the unmanured plot in Broadbalk

WHEAT BEST STANDS ABSENCE OF MAM IM

growing wheat continuously, and witli 17;") l.uslicls on ihf
similarly unnianured plot where wheat is grown after a hare
fallow. In the carhcr period on the rotation field the
uiimanm*ed plots yielded 82 per cent, of the wlieat on tJii-
manured plots, but in the later period tlie produelion without
niamu-e had fallen to 66 per cent, of that on the niaiuired
plots, whereas in the corresponding later years of tlic con-
tinuous wheat-field the production on the uninaiuired plot
lias fallen to 29 per cent, of that on tlie maiuirecl j)|(.t.
It is clear that the progressive cropping out of the soil is
telling upon the wheat, though it will take a very long time
before the crop grown in rotation is reduced to the level of
the nninanured land that is continuously cropped with wlieat.

II. — Effect of the Manlkes.
The three main plots into which the experimental field is
divided receive the following manurial treatment per acre : —
O. Unmanured continuously.

M. 3^ cwt. superphosphate, 500 lb. sulphate of potash,
100 lb. sulphate of soda, and 200 lb. sulphate of
magnesia for the Swedes.
C. Minerals as on Plot M., together with 200 lb. ammo-
nium-salts and 2000 lb. rape cake for the Swedes.

Table LXVI. — Effect of Manures on Crops grown in rofafiim, A'/dr// Fiehi.
Avcnific jproduce per acre over the jive last Courses^ 1884-1903.

O. 1 M.

('.

Unmanured. ,M.ue«.

Manun..

Roots (Swedes) .... Cwt.

Barley Grain .... Bush.
Barley Straw .... Lb.

Clover Hay * . . . . Cwt.

Bean Corn"+ Bush.

Bean Straw t . . . . Lb.

Wheat Grain .... Bush.
Wheat Straw . . .Lb.

1
l.-,-9 20S-2

l.-)-8 20-0
12(51 112 J

0-1 ■■\:>-',

1.V9 28-3
'Jir, 1>91

"2(J-2 ' 36-1
2328 3482

399-9

27-7
2068

37-8
190

1289

37 1
3698

Average of 3 courxes.

t Average of 2 coaw«.

196 CKOPS GEOWN IN ROTATION

It should be remembered that each of these three plots is
fm'ther subdivided into four quarter plots, in the first place the
third crop may be clover or a bare fallow, and again the
roots are carted off or fed on the land.

The effect of the mineral manures without nitrogen is very
marked on the roots; during the last five com-ses the crop
averaged 208 cwt. per acre, as against 16 cwt. per acre only
on the unmanured plot. Even on the most impoverished of
the quarter plots, that from which the roots are always carted
and where a bare fallow is taken after the barley, the produc-
tion amounted to 178 cwt. (see Table LXIV.), although the
plot had been receiving no nitrogen for thirty-six years
previously, nor had any residues of the previous crops, which
would contain nitrogen, been returned to the ground. Where
the roots had been put back and where also a leguminous
crop was taken in the rotation, the crop amounted to 245 cwt.,
the increase being due to the extra nitrogen thus returned
to the soil. These results illustrate the great dependence
of the Swede crop upon a plentiful supply of mineral, and
especially of phosphatic, manures ; the latter in particular
seem to stimulate the development of ii1:>rous roots, thus
enabling the plant to utiHse the resources of the soil. Again,
the cultivation to which the land is subjected for the Swede
crop is calculated to nitrify reserves of nitrogenous material in
the soil and render the plant more or less independent of a
direct supj^ly of nitrogen. Thus, in ordinary farming practice
with the land in good condition the Swede crop only requires
a small nitrogenous dressing, but should always have a
comparatively large amount of phosphoric acid, in order to
enable it to make the most of the reserves in the soil and of
the dung which is generally used with this crop.

The effect of the mineral dressing is much less marked on
the barley than on the roots, it only increases the average
crop from 15-8 to 20 bushels per acre. This increase again
is wholly found on the plots growing clover and beans
and so receiving nitrogen collected from the air; the two

EFFECT OF MINKKAT> M \Nn:r.S i!.7

quarter plots wliieli are tallowed after the Itarlcy aetually grow
less than the correspoiuliiijj; uniiianiired plots. On these lattrr
plots the preceding growth of a comparatively large crop nf
roots has removed so nnich nitrogen that the s(.il is left jioorcr
than on the wdiolly unmanured plot, whicli lias Ikmmi laxr.l
less severely, though both are alike in receiving no supplv of
nitrogen during the whole com'se of the rotation. i^M.ni this
we may conclude that, in the absence of nitrogen, mineral
manm-es are of no use to the l)arley crop, the magnitude of
Avhich will depend on the amount of nitrogen available, even
when the mineral resom'ces of the soil have been considerably
drawn upon. In other words, with barley on unmanured land
nitrogen starvation sets in long before the deficit in minei-als
is felt, the reverse being the case with Sw^edes.

Coming to the leguminous crop, the mineral maiuncs have
a very powerful effect, although they are applied a yeai- before
the clover is sown and two years before the crop is grown.
The increase brought about is from 9 to 33 cwt. of clo^ er
ha}^ and in the case of beans, from 157 bushels of corn and
87 cwl. of straw to 28*0 bushels of corn and 17 cwt. of
straws This illustrates well the generally accepted fact that
the leguminous plants are in the main independent of manurial
sources of nitrogen, which element they are able to draw fnjm
the atmosphere, especially when they are provided with ]»lenty
of mineral plant-food.

In considering the wheat crop, it is necessary to distinguish
between the plots which have previously grown clover (.r beans
and those which have been fallowed, because in the foniHi-
case there has been such an accumulation of nitrogen in the
soil that the succeeding wheat crop is very much stimulated.
It will be seen that the crops on the fallowed portions
averaged about 32-4 bushels per acre, as against 271 bushels
per acre on the corresponding unmanured plots, an iiiei-ease
Avhich nuist in the main be set down to the niin.Tjj dressings
received three years earlier in the rotation. ^VIll'I•e clover or
beans are grown the crop mounts up to nearly H) bushels p<r

198 CEOPS GEOWN IN EOTATION

acre, or to the maximum grown even on the plots receiving
nitrogen as well as minerals, so thoroughly have the leguminous
plants done their work of accumulating nitrogen for the
succeeding crop of wheat.

The application of the nitrogen (141 lb. in the shape of
rape cake and ammonium -salts) to the Swedes has nearly
doubled the crop, the average dm-ing the last five courses
having been 20 tons, as against less than 10*5 tons with the
minerals only. Dependent as the Swede crop has been shown
to be upon the minerals, the soil of the plots receiving no
nitrogenous manure has been so far depleted that nitrification
of the reserves of humus still remaining in the soil is not able
alone to supply enough available nitrogen for the needs of the
crop, as is shown by the increased yield produced by a direct
application of nitrogenous manure.

The effect of the nitrogen applied to the Swedes is still very
palpable in the barley crop, the yield of which is about 40 per
cent, larger on the completely manured plots than on the plots
receiving no nitrogen. Coming to the leguminous crop, the
nitrogen has no effect; the clover is slightly better, but the
beans are very distinctly worse where it has been applied.
This affords very strong evidence of the extent to which
leguminous plants are able to feed themselves Avitli nitrogen
from the atmosphere and become independent of nitrogen in the
soil, an excess of which may even be injm-ious to their growth.

The manner in which accumulations of nitrogen in the soil
interfere with the growth of leguminous plants is curiously
seen in another way on this field : one of the connnonest
^A^eeds among both the barley and the wheat on the unmanured
plots and on those receiving only minerals is the little legumi-
nous Black Medick [Medkago hipidina), which often almost
entirely covers the surface of the ground towards harvest time.
This plant, however, is much less abundant, and indeed is
hardly to be seen, on the other plots which receive nitrogen
for the Swedes, although no nitrogen has ])een applied dm-ing
the years in which the plant in question is growing.

EFFECT OF MAXU1M< UKSIDTES ON WIIIAT ]W

The wheat, wliifli comes last in the rotation, still >ho\\s
some effect for tlie nitroucii applied three years jM-cvioiisIy. If
we consider the fallow portions only, there aiv nearly :) hnsh.-U
more i^rain pro(hiced by the residue of the niti-ou'cnoiis
mamiring, so dependent is the wheat crop upon a sujiplv of
nitrogen. On the portions which ui'ow heans oi- clover tli.-
wheat crop gains so much from the nitrogenous material
left by the stubble of these leguminous crops that the effect
of the previous nitrogenous manuring is no longer apparent,
the average crop being actually highest on the portions
receiving only minerals, thus corresponding with the varying
yields of the previous leguminous crops rather than with the
direct nitrogenous manuring.

U nman u red

Minerals only,
no Nitrogen

Connplete Manure

Fin. 42.— Effect of Manure upon Crops thrown in Rotition. Totii! I'roducc. Averajjes
of Five Courses (1884-1903). Swedes in 100 cwt. ; Barlt-y find Wtu-at in luOO lb. ;
and Clover in 10 cwt.

Fig. 42 shows in a gTaphic form the effect of the.se three
systems — no manm-e, minerals without nitrogen, and a complete
manure — on the successive crops in the rotation.

200

CROPS GROWN IN ROTATION

III. — The Effect of the Growth of Clover or Beans on
THE Succeeding Crops.

It has already been stated that one of the main objects of the
experimental field is to compare the results of growing a crop
like beans or clover as the third item in the rotation instead of
taking a bare fallow. Of com^se, historically, this change from
bare fallow to clover marks one of the great advances in
agricultural practice, but its complete justification has only
been possible in the last few years, since the power of the
leguminous plants to fix atmospheric nitrogen has been known.
In the Agdell field clover has been grown six times and beans
eight times during the period under experiment. Table
LXVII. shows the average crops of each separately, together
with the total produce of the succeeding wheat crop on the
fallowed and cropped portions respectively.

'J' ABLE LXVII. — Cro^s grown in rotation, Agdell Field. Effect of Clover
or Beans on the following Wheat Crops. Total produce per acre —
Mean of "Fed" and "Carted" 2Jortions.

Clover
Crops.*

Wheat, t

Bean

Crops.:!:

-Wheat.§

After
Fallow.

After
Clover.

Tncrease
due to
Clover.

After
Fallow.

After
Beans.

Increase
due to
Beans.

0. Unmanured
M. Mineral Manure .
C. Complete Manure

Cwt.
44-4

r.2-9

Lb.
4173

5245
5479

Lb.
3475
5613
6130

Per cent.
-16-7
+ 7-0
+ 11-9

Lb.
1888
2615
3177

Lb.

4907
5528
6092

Lb.
4373
5447
5929

Per cent.
-10-9

- 1-5

- 2-7

'■ 5 years (1S74, 1882, 1886, 1894, and 1902).
t 5 years (1875, 1883, 1887, 1895, and 1903).

+ 8 years (1S54, 1858, 1862, 1866, 1870, 1878, 1890, and 1898).
§ 8 years (1855, 1859, 1863, 1867, 1871, 1879, 1891, and 1899).

The beneficial effect of the clover crop is at once apparent
from the table. On the unmanured plot the clover crop is a
small one, and apparently the nitrogen it has collected from the
atmosphere is not sufficient to compensate for the better tilth
and nitrification which are induced by a bare fallow. On the
plot receiving mineral manm^es a large bulk of clover is grown,
averaging 44*4 cwt. of clover hay, and notwithstanding that all
this is removed from the land the nitrogen accumulated in the
roots and stubble is sufficient to raise the total produce of the

BENEFICIAL EFFECT OF CLOVFIJ

.Ml I

wheat from .5240 lb. to .">(3i:} lb., or by 7 per (ciii. On ihr
completely mamired plot a still greater erop u[' clover is
obtained, averaging r>3 cwt., and this still further iiicrea.ses the
wheat crop from 'A79 lb. to OIHO lb., or by \'2 per cent.

With the beans an entirely different result appears; on
each of the three plots the bare fallow pi-oves a better prepira-
tion for wheat than does the bean croj), after which in all cases
the wheat crop is scmiewhat dinn'nished. On the nnniaiune.l
plot the average diminnticm is 11 i)er cent., on the mineral
manm-edj^lot it is I'o per cent., and on the completely manured
plot it is 27 per cent. In other words, the bean crop, which is
pulled, not cut, does not leave behind any great amount ol'
nitrogen gathered from the atmosphere — not sufficient to
compensate for the absence of the summer tillage that the
bare fallow receives. These results are even more clearly seen
Avhen the crops following the largest clover and bean crops
are considered, the results of which are set out in Table
LXVIII.

Table LXVIII. — Crops (jroion in rotation, Agdell Field. Effect of fh>-
largest Clover or Bean Crop on the following Wheat Crop. Total prod wr
per arre — Mean of " Fed" and "Carted" portions.

Clover,
1894.

Wheat, 1S95.

Beans,

1862.

Wheat, 1 80S. '

After
Fallows.

After
Ctover.

Increase
due to
Clover.

After After '2^^ !
Fallow. Beam. ^~ i

1 1 * 1

O. Unmanured

M. Mineral Manure .

C. Complete Manure

c...

16-5
.59-7
76-7

Lb.

:un

4220
4547

Lb. Per cent.
3193 4 2-0
5180 +22-7
5209 +14-6

1

Lb.
3603
4033
5755

Lb.
7222
7910
8792

Lb. Per c«nt.
5281 ' -26-9
6090 -23-0
7674 , -12-7 ,

1 1

In 1894 the clover on the unmanured jilot produce<l only
16-5 cwt. of hay and caused a barely perceptible increase in the
total produce of the wheat, amounting to only 2 per cent. On
the plot receiving a complete mineral manure, however, a very
large crop of clover was obtained, r)97 cwt. per acre, and this
increased the total produce of the wheat crop from 4220 lb. to
5180 lb., or by 227 per cent., the extra grain anmunting to

202

CROPS GROWN IX ROTATION

8 bushels per acre. On the completely manm-ed plot a still
greater clover crop was obtained, 76*7 cwt. of hay; this in its
tui'n increased the total produce of the wheat crop from 4547 11 >.
to 5209 lb., or by 14 '6 per cent. The increase of gi-ain in this
case was 7 bushels per acre.

Tm-ning now to the bean crojD of 1862, the largest of the
series, we find that it was also followed by a specially good
wheat crop in 1863, but that in each case the wheat was less
after the beans than after the bare fallow, the diminution
amomiting to 26 '9 per cent, on the unmanm-ed plot, 23 per
cent, on the plot receiving superphosphate only, and 127 per
cent, on the completely manured plot. These results can only

Table LXIX. — Croijs f/'rown in rotation, Agclell Field. Effect of Clover {or
Beans) on the succeeding Surde and Barley CrojJS. Mean of four
Courses — Produce iKr acre.

10th-l3th
Courses
(1SS4-99).

Clover
(or Beans).

llth to Uth Courses (1S88-1903).

Root Crops.

Barley.

After
FaUow.

After
Clover

or
Beans.

Increase
due to
Clo\er

or Beans.

After
Fallow.

After 1 Increase
Clover due to
or ' Clover
Beans. | or Beans.

0. Unmanured .

M. Mineral Manure
C. Complete Manure .

Lb.
1809

4777
4320

Cwt.

28-1

201-4

465-5

Cwt.

11-5

251-9

446-5

Per cent.
-59-1
+ 25-1
- 4-1

Lb.
2086
2037
3170

Lb. ! Per cent.
2115 +1-4
3007 I +47-6
3780 i +19-2

be interpreted by supposing that the large bean crop, so far
from obtaining all the nitrogen it required from the atmosphere,
drew extensively upon the resom^ces in the soil, consequently,
instead of enriching the land like the clover crop it actually left
it poorer than it was before.

Since the growth of clover has such a marked effect on
the subsequent crop of wheat, the question of the duration of
the benefit caused by the clover naturally arises. Table LXIX.
gives a summary of the results during the last fom* courses
which have been completed, showing a comparison of the roots
and the barley after fallow and after clover (or beans) re-

RESIDUES LEFT 1^' LECTM I NOIS CIJops -jo:;

spectively— /.e?., of the crops c-oiniiiL; in the srcmul aii.l thin I
yccirs after the growtli of the h\miininoiis crop.

The results show lliat wlicrc the inamirin^ i-, wiili miiicials
only the effect of tlie leguminous crop is very marked hoth in
the roots and in the barley, /.<'., that the nitrogen introdnc.-.l ])y
the growth of clover is operative, not only in the wiii-ai whicli
follows it, but also in the roots and the barley which follow tli.-
wheat; in fact, in all the crops of the rotation until the ch.v.r
comes round again. The root crop is increased by -J.") per cent.,
and the barley crop by' nearly .")() per cent., the magnitude (.f
the increase being due to the fact that the leguminous crop
represents the only source of nitrogen on this plot. AVhen,
however, the manure put on to the Swedes contains nitrogen, the
effect of the nitrogen stored up in the soil by the clover cro})
two seasons before is masked by the fresh nitrogen introduced,
and produces no increase of crop. It, however, becomes
manifest in the succeeding barley crop, which is 19 per cent,
greater on the portion cropped with leguminous plants than on
the fallowed portion, so that we can say the value of a c-Iovcr
crojD is felt for three years after its growth in all the crops of
the rotation, even under the ordinary conditions of fanning when
a manure introducing large quantities of nitrogen is use<l once
dm-ing the rotation. Of course it must be remembered that thr
above mean results are for the four last courses after ten
rotations had been completed, and that as the l)enetit is
doubtless somewhat cumulative from one rotation to the
next, the results represent not so nmch the value of a single
clover crop as of its constant introduction into the rtdation
in.stead of taking a bare fallow. On the otluM- hand, if wc
compare the effects of the single crops, we find that tin- (r«)p.>,
of beans, just as they show little effect in the succeeding wlirat
crops, so also they cause but a small benefit to the roots and
barley coming later still. The continuous enrichnimt ot" thr
land shown in the above table has therefc^re been duf in the
main to the five occasions on which clover has been taken during
the thirteen complete courses covere<l by the table.

204

CROPS GROWN IN ROTATION

The diagram, Fig. 43, shows in a graphic form the benefit
to the whole rotation of the growth of clover, even when the
root crop receives nitrogenous manures,

After Clover.

Wheat

Fallc

After Fallow.

Fig. 4.3.— Comparative Effect of Clover or Bare Fallow on the succeeding Crops in
the Rotation. Total Produce— In 1000 lb. for Clover, Wheat, and Barley,
and in 100 cwt. for Roots.

IV. — Effect of Manurial Residues on Subsequent
Crops.

It has already been stated that the manures on this experi-
mental field are applied only to the root crop, the three
subsequent crops in each course being grown without fmther

RESIDUES LEFT BY MANri;i>

•J(i.>

luanure. We thus obtain a iiR'ans of asccrtainiiii: uliat loidue
is left in the land after the removal of the crop to wliicli the
manure lias been applied. If, for example, we compair tin*
plots receiving minerals only with those receivinu^ nniH'i-;iI> and
nitrogen, on the fallow portion the additicm of nitmgcn [(nMhucs
an increase of crop from 188 to 44^^ cwt. jxm- acrr, nr of i:js
per cent. This crop of roots is entirely removiMl. but tlic suc-
ceeding barley crop shows a total produce of 'J.')?.') 11 >. on thr
plot where nitrogen was apphed to the roots, against Is-J.') II,.
on the plot without nitrogen ; thus the residue of the nitrogen
in the gromid after one crop had been grown and nMuovcfj was
still able to increase the next crop l)y 41 per cent.

The following Table (LXX.) shows the sununariscd icsuhs

Taule LXX. — Crops groioi in rotdJion, AgdcU Field. Ti>l(tl prodmr jicr
acre. Mean of five Courses, 1884-1903. Increase due to Nit roijcnovs
Manures applied to the Swede Crop only, and their Residues.

Manures.

Swedes.

Barley.

Fallow

(or Beaus or

Clover).

Wheal.

Roots carted. Fallow.

Minerals only

Minerals + Nitrogen ....

— ^{^:r"it'„t : : :

Cwt.
188-1
448

I.b.
182.^
2575

l.b.
1 Fallow {

Lb.

5180
5521

259-9
1.33-1

750
41-1

341
6-6

Roots carted. Beans or Clover.

Minerals onlj

Minerals + Nitrogen ....

1— ase{Actua.__.. ; ; ;

Til
44;-. -4

2548
354:3

.57.'. 1
:!:n7

5995
6140

21S-4
9*J-2

99-.
39-1

- 11-G

145
2-4

for the last five courses on both the fallow and tli.- clovi'i-
portions.

It will be seen that a nitrogenous dressing consisting of
rape cake and aminonium-.salts leaves in the groumi. after

206

CROPS GROWN IN ROTATION

growing a crop of roots, a residue which increases the barley
crop by 41 per cent. ; even two years later, after an intervening
bare fallow, sufficient still remains to increase the Avheat crop
by nearly 7 per cent. A very similar increase in the barley
crop, of 39 per cent, instead of 41 per cent., is brought about by
the residues of the nitrogenous manuring applied to the Swede
crop on the plots which, instead of being fallowed, carry clover
or beans as the third crojo in the rotation. On the leguminous
crop itself, however, the residues of nitrogen still in the soil have
a depressing effect, the average production of l^eans or clover
being 11 '6 per cent, less on the plots which receive nitrogen
for the SAvede crop than on the corresponding plots getting
no nitrogen, a result of nitrogenous manuring which has been
noted before.

Fmther evidence of the duration of manurial residues is to
be obtained by comparing the plots from which the roots are
removed with those to which the roots are returned, and noting
the effects on the succeeding crops of the rotation. For this
pmpose it will be wise to consider only the plots on which the
Swedes receive nitrogen as well as the minerals, for on them
only is there a crop of Swedes l^ig enough to leave any per-
ceptible residue. Table LXXI. shows tlie average results

Table l.XXr.

Average Produce per acre.

Relative Yield.

Roots Removed.

Roots Fed.

Roots Removed.

Roots Fed.

Swedes .

448 cwt.

440-1 cwt.

100

99

Barley .
FaUow .
Wheat .

2575 lb.
5521 ib.

3951 lb.
6224'lb.

100

100

153

113

(grain and straw) for tlie last five courses on the fed and carted
portions, where a bare fallow is taken in each course.

Taking the figures in the last column, we see that the effect
of the root crop on the succeeding barley is considerable, for

EFFECT OF FEEDING KOOTS OX TIIK LAM) jo;

the yield of l)arley is increased l)y as imic-li as ."):} per fciii.
through tlie return of the root crop to tlie land. The residues
have, however, but a small effect two years later on the wheat
crop which follows the bare fallow, for where the roots were
fed the wheat crop is only 1:3 per cent, larger than where
the roots were carted off. The residual effect has practieallv
<lisappeared by the fourth year, and when the roots (to w hieli
a fresh application of manure is applied) come round again
they are httle the better for any accumulated residues in the
soil, even though the treatment of returning or removing tlie
roots is repeated through thirteen rotations, or a period of
tifty-two years.

The next Table (LXXII.) shows the parallel experiment,
in which clover or beans are grown in the third year of the
course instead of taking a bare fallow.

Table LXXII.

Average Produce per acre.

Relative Yield.

Roots Removed.

Roots Fed.

Roots Removed.

Roots Fe<l.

Swedes .

Barley .

Clover or Beans .

Wheat .

445-4 cwt.

408-1 cwt.

100

92

3543 lb.
4066 lb.
6140 lb.

4579 lb.
4572 lb.
6246 lb.

100
100
100

128
109
102

1

In this case the effect of feeding the roots on the land is
plainly visible in the following crop, though the increase is not
so gi'eat (being 28 per cent, instead of 53 per cent.) as when the
rotation includes a bare fallow.

The second crop, clover or beans, is also benefited to some
extent, for the residue of the roots produces a mean increase of
9 per cent. Now, however, the new .stores of nitrogen intro-
duced by the clover crop practically obliterate all further eflect
of the residues, and the wheat crop is to only a trifling extent
the better for the return of the Swetles to the land three years
previously.

208

CROPS GROWN IN ROTATION

The diagram, Fig. 44, shows graphically the effect that
feeding off the root crop on the land has on the succeeding

6000 lb.

5000

4000

3000

Wheat

Roots Crops Carted off
the Land.

Wheat

Roots Crops Fed on
the Land.

Fig. 44.— Effect of Feeding or Carting the Root Crop on the succeeding Crops in
the Rotation. Total Produce— Averages over five courses (1884-1903). Roots
completely Manured.

crops under the ordinary conditions of farming when clover
forms parts of the rotation.

NITROGEN GAINKT) OIJ LOST

*J()9

V. Gain or Loss ok Manuhial Constitiknts to rm I, am..

From the analyses wliich have been uuulc from time to
time of the crops on A^dell Held it is ])ossil)l(' to estimate tlic
quantities of the chief manurial ingredients m'trogcn, jdios-
plioric acid, and potash \vhich arc removed from llic snil
(hn'ini;' a typical rotation. Thus we can form some iiliM (.f
what will be necessary to maintain tlie fertiHty of land midn-
ordinary crop, and whether there are any natural n-ciipcialivc
agencies which restore plant food to the soil.

Table LXXIII. shows the amount of nirro,i;en removed per
acre per annum on the three plots whieli are fallowed and
where also the roots are carted off where every thinu is, in
fact, removed, and no nitrogen is added except in the one case
on Plot C where the Swedes are manured.

Table LXXIII. — Nitroycn removed hy CroiJS r/roivn in rotation, Aiidill Fir/d.
Average of eight Courses, 1852-1883 Boots carted.

O.
Unmanured.

M.

Minerals oi)ly.

0.
Complete Msnnn.

Supplied in Manure

Removed in Crops :—

Swedes

Barley

Fallow

Wheat

Total in rotation
Per acre per annum .

Lb.
0

I.b.
0

1 10

11-;")
28-1

36 "-6

34-8

23-;]

39'-0

7.S •.'.
:!9-J

42-1

76-2
19-1

97-1
24-3

ir.fl-8

40-0 1

It will be seen that on the unmanured [)lol> llie reiii(»\al (»f
nitrogen is chiefly effected l)y the two cereal eroi)s, so small
has the crop of roots become. The average !'>>> iA' nitrogen
over the whole four years of the rotation amounts to just
over 19 11). per acre per annum, wliich agrees very closely
with the average annual ivnioNal of niti-ogeii from the
unmanm-ed plot in Broadbalk where wheal is giown yeai-
after year. When mineral manures ai'e used for the Swedes

210 CROPS GROWN IN ROTATION

the loss of nitrogen to the soil during the rotation is greater,
amounting to over 24 lb. per acre per annum, the increase
being almost wholly due to the much larger Swede crop
which is obtained by the help of the mineral manures.
Coming to the plot which receives a nitrogenous manure for
the Swede crop, we find the average removal of nitrogen
becomes 40 lb. per acre per annum, a slightly greater quan-
tity than is supplied by the manure, so that the net loss
is about 5 lb. of nitrogen per acre per annum, approximately
the amount annually restored by the rain. Thus, if we con-
sider this plot alone, an almost exact balance is obtained
l)etween the nitrogen supjDlied and the nitrogen removed, so
that the fertility of the land should be closely maintained.
There are, hoAvever, other sources of loss which the above
figures do not take into account — losses by the removal of
weeds, losses by the washing away of nitrates, especially
during the bare fallow, and losses due to the decomposition
of nitrogenous materials in the soil with the evolution of their
nitrogen as gas, " denitrification " so called. Possible sources
of gain are the absorption from the atmosphere of ammonia
otlier than the ammonia washed doAvn in the rain, and the
fixation of atmospheric nitrogen by soil bacteria which do not
require the co-operation of a leguminous plant. It is difiicult
to decide whether the fertility of this plot is i-eally falling off
or not, so great is the effect of seasons in causing fluctuations
in yield which cannot be gauged ; the last four root crops
have actually been greater than the first four, the wheat has
been somewhat less, Avhile the barley has given in the latter
years less than half the crop of the earlier ones. The seasons
in the latter years were, however, against the l^arley crop, so
that one can come to no very definite conclusion as to whether
the recuperative agencies indicated above are sufficient to com
pen sate for the unestimated but inevital^le losses.

Turning now to the plots on which clover or beans are
grown, it becomes still more difficult to estimate the gain or
loss of nitrogen to the land, since the leguminous crop gains an

NITROGEN GATNKI) oi: I.osT I'li

amount of nitrogen for the l.ind wliidi wf havr im humus
of calculating, but which we know is sulHciciit to lH>ii.'fii ilu-
succeeding crops for at least three years. r.il.lc l,XXI\'.
shows the removal of nitrogen per acre pci- .iiiiiiiiii mi the
plots growing beans and (^lover wlicre tlic root croii i-^ com-
pletely carted away.

Table LXXIV. — Nitrogen removed hi/ Crops (iruwn in rotation, A;fd>ll
Field. Avercuje of eight Cowr.sfs, 1852-1883 RooU varfal.

o.

Uiimanured.

M.

Minerals only.

Complete Manur*". |

Lb.

l.b.

I,\..

Supplied in INIanure

0

0

M"i

Removed in Crops :—

Swedes

Barley

Beans or Clover ....
Wheat

7-6
30-4
41-4
32-8

33-3
23-5
61-5
3.V9

10-7
l.J-7

Total in rotation
Per acre per annum .

112-2
28-1

1j4-2
38 -G

254-5
63-6

On the plot receiving mineral but no nitrogenous manure
the removal of nitrogen is now nearly 40 lb. per acre i»er
annum ; but if we exclude the clover or l)ean crop as proM'ding
its own nitrogen, the loss is only a little over '1'.) II ». pci- aci<'
per annum, some of which is undoul)tedly replaceil by iIh*
nitrogen drawn from the atmosphere and left in the roots and
stubble of the clover. With the nitrogenous manuring for tlie
Swedes the annual removal of nitrogen amounts to nearly «)4 lb.
per acre per annum, or again excluding the amount contaiinMl
in the clover or beans, to about 41 lb., of which the nitroumous
manm'c used for the Swedes provides IJo lb., reducing the net
loss to the soil to about G lb. of nitrogen per acre jx-r .•innuni.
This is easily compensated for by the amount of nitrogrn intm-
<luced by the clover crop, and there is every indication that the

fertility of this plot, so far from fallin-- oil', has I n increased

somewhaD by each completed rotation. Ilciicc wc can con-
clude that fairly strong land, such as wc arc dcalim: with,

212 CROPS GKOWN IN EOTATION

when farmed on the four-course system will rise rather than
fall in fertility if during the rotation it receives manure supplying
150 II3. of nitrogen j^er acre, even though the roots are wholly
removed from the land. Such a quantity of nitrogen would be
supphed by 15 tons of fair ordinary dung. It should be, how-
ever, remembered that the state of equilibrium thus attained is.
not a very high one, and that if the land is to ])e kept in higher
"condition," with a generally larger production throughout^
then the losses of nitrogen by drainage and denitrification will
also be greatly increased. Hence if the higher level of produc-
tion is to be maintained it will require an additional expendi-
ture of nitrogen as manure, not merely enough to make up for
the larger amount removed in the greater crops, but a consider-
able surplus in order to compensate for the increased wastage.

When the mineral constituents of plant food are considered
— the phosphoric acid and potash — there is no difficulty in
estimating the annual loss or gain to the soil, because we know
that there are no recuperative agencies at work to increase the
original stock of such mineral substances in the soil, nor, on
the other hand, are the only possible losses, those by drainage,,
of any moment. The annual draft on the soil can then be
estimated with accuracy if we know the amounts of the con-
stituents in question which are contained in the manure supplied
and in the crops removed.

On the unman m^ed plot, from which everything is removed,
the loss of phosphoric acid is about 7*5 lb. per acre per annum
under the rotation, a figure Avhich is very close to the annual
withdrawal of phosphoric acid from the unmanured plots
where wheat and barley are respectively grown year after year.
On the continuous wheat plot the amount removed in the crop
is 8 "9 lb. per acre per annum, on the barley it becomes 7 '8 lb.
per acre joer annum. Again, as regards the potash, the average
removal from the unmanured plot under rotation is 13 '2 lb.,,
whereas the continuous wheat plot similarly unmanured loses
14*3 lb., and the continuous barley plot 11 '6 lb. per acre per
annum.

REMOVAI, ()!• MIXKKAI. ( '( )\SI ITI•I•:\T

•_'l:;

It tliiis appears that wlicn laml is (•(.ntiiiiK.iisly cn.jtprd
-without manure and witliout tlir restctralioii ol" any parts of
the crops grown to tlie soil, tlie animal witlidrawal of the chicl

Table LXXV — Phosplwric Arid and J'utdsh rcmovrd hi/ f',i,j,
(jroion in Rotation. Agdell Field.

Phosphoric Acid.

i'..tft.iii.

Completely

l'onipl«-t»'ly

Unmauurod.

Maiuirni.

L'limanurod.

Matmrtyl.

FaUow.

Clover or

Fallow.

Clover or

Hoaim.

ItoaiK.

Roots

Itoots

Carte.l.

Hoots
Carteil.

I'artccl.

H«t«
CartwI.

Removed in: —

\.h.

Lb.

Lb.

Lb.

Swedes ....

1-5.1

20-19

6-07

78-31

Barley

l:Ml

21-59

18-96

31-49

Fallow, or Beans or Clover .

18-03

17-40

Wheat

Total ....

li.'-'-io

21-96

27*77

3S-29

30-06

81-77

r.2-80

195 49

Supplied in Manure .

Net Loss to Soil

64

150

30-06

17-77

.V2-80

i
45-49

Average Loss to Soil per acre

per annum ....

...

4-11

13-20

11 ■37

manurial constituents will be about the same wlictlici- the land
is put under a rotation or grows a cereal crop CNcry year. (Jf
course the rotation plot in this case is practically growing two
cereal crops only in the four years, with a fallow lietween each,
so small is the production of roots in the first year of the
com*se.

Table LXXVI. (p. 214) brings together for coini.arison
the annual losses on the three unmanm-ed plots in (piestion.

As regards the manured plots growing clover or bean.s. we
fin<l that a little more than so lb. of pliosj.lmiic acid i>
removed during the four years of the rotation and nm>t br
replaced by manure if the fertility of the land i> in br main-
tained. If 15 tons per acre of <lung be given during the
rotation, more phosphoric acid will be returned than is
withdrawn liy the crop; but, as tin; phosphoric aei<l in <lung is

214 CROPS GROWN IN ROTATION

not in a very active form and as the growth of Swedes is very
specially dependent on an abundant and active supply of
phosphoric acid, it would probably be necessary to use 4 cwt.

Table LXXVl

Removed in Crops per acre
per annum.

Nitrogen.

^^Zr^ Potasb.

Agdell— Rotation (Swedes, Barley, Fallow, Wheat)
Broadbalk— Continuous Wheat ....
Hoos— Continuous Barley

Lb.
19-1
17-0
17-7

Lb. Lb.
7-52 ' 13-20
8-93 14-29
7-80 11-64

or so of superphosphate per acre if a good average crop of
roots is to be obtained. The withdrawals of potash from the
soil during the rotation are more considerable, amounting to
nearly 200 lb. per acre, which in this experiment are only
partially replaced by the 150 lb. given in the manure for the
Swedes. We can assume, however, that even if this is not
supplied by the 15 tons of farmyard manure, which we have
l)een assuming as necessary to maintain both an average yield
and the fertility of the land, yet it will not be necessary to
afford any artificial supply of potash on a soil like that of
Rothamsted. The reserves of potash in such a strong soil are
enormous — at least 50,000 lb. per acre in the top 9 inches of
soil, of which 12,000 lb. is soluble in hydrochloric acid — and
a little of it becomes available every year under the action of the
weathering induced by cultivation.

Practical Conclusions

The following conclusions may be drawn from an examina-
tion of the results yielded by the Agdell Rotation Field :■ —

1. On land continuously cropped without manure the Swede
crop is the first to feel the Avant of manure, the yield being
reduced to a minimum almost immediately. The leguminous

CONCLrsiONS -ji:.

crops foil off more slowly, and tin* cereals. csiiccialK I In- wheal,
maintain a fair production for a lon^ period.

*2. The unmanurtMl wlu\ii and harlrv ^rown in i-otaiion
continue to .uive nuich .ureater produee than thev do on land
similarly unmanured but urowini: the same ci'ops vcar after
year. This is, however, chiefly in virlue of the two tallow in^^s
the laud receives duriuo- the four-years' couise. the umnannrcd
land losing about the same amount of plant food in the om-
case as in the other.

3. On the manured plots the yield of Swedes is determined
by ])oth phosphatic and nitrogenous mainuv, chiefly by the
former: the yield of cereals is determined by the available
nitrogen in the soil.

Leguminous crops like clover and beans are dependent on
the supply of minerals, particularly of potash, and are even
somewdiat decreased by the presence of nuich nitrogen in the
soil.

4. The inclusion of a clover crop in the rotation, besides
providing a crop of hay, leaves the land so nuich richer in
nitrogen that the succeeding wheat crop is greatly increased.
The good effect of the clover persists and may be traced through
all the crops of the rotation. With beans in place of the
clover, no beneficial effect is produced on the succeeding
crops.

o. The effect of such residues as are left by an organic
manure like rape cake applied to the Swedes, or those left on
restoring the Swedes to tlie land, or the residues left by a
clover crop, is to be traced in the three following crops at
least. In the third crop they are, however, becoming small,
and even in the second year after the apj)lieation of the
manure the effect of the residues becomes masked by any
new^ addition of nitrogenous manure, although they may still
remain and go to build up the "condition of the soil.

6. The losses of nitrogen to strong land farmed on the four
com-se system are almost made up by the growth of a crop of
clover, and w^ill be more than repaired by a dressing of 1.') tons

216 CROPS GROWN IN ROTATION

of farmyard manure or its equivalent dmnng the rotation. The
losses of phosphoric acid and potash would be similarly made
up, though it is well also to use about 50 lb. of phosphoric
acid per acre for the Swede crop, which is specially dependent
on a large quantity of available phosphoric acid.

References

" Rotation of Crops." Jour. Ttoy. Ag. Soc, 55 (1894), 5S5. Rothamsted Memoirs,
Vol. VII., No. 7.

CKAPTEK XI

MTlllFICATION AM) TIIK ('( »M !'( »SI TloN ol- 1H;A1N .\(.i; W \l M;s

I. The Process of Nitrificalion.

II. Dcnitrification.

III. Nitrates in Cultivated Soils.

lY. Nitrates in Manured and Cropped Soils.

V. The Nitrates in Draina<re Waters.

VI. Other Constituents of Drainaj^e Waters.
Referenees.

I.- The Procs:ss of Nitrification.
The fact that cultivated soils conkl induce tlic coiivcrsinii
of organic matter containing nitrogen into nitrates li;i> Imch
known for a long time, indeed it was fur many years utilised on
a commercial scale for the production of nitre. Many of the
conditions under which nitrification takes place liad heeii
worked out by the men in charge of the old .salt pet i-e lieds
before Boussingault and other investigators consideretl ihem
afresh from the point of view of agriculture. Tlie pi'esence
of calcium carl)onate or some other base, tlie aeration nf tlie
soil, warmth, and a certain pi-oportion of watei- had l»eeii
shown to be necessary, while it was known tliai iinieli i»rM.inie
matter was injurious. Tli.it tlie action is brought about by a
living organism, was first established by the experiment- ..f
Schloesing and Miintz in 1877: and on the ajipraiMner «.f
their paper, Mr Warington, who was ili.n working in tlie
Rothamsted laboratory on the subject (.!' nitrates in llie soil,
proceeded to a further investigation of tlii> iiii|)<.iiant -nbjcct.
His first experiments eonfii-med the eonelusinns reached by
Schloesincr and Mimtz, and .showed that the amount of nitrates

218 NITRIFICATION

in a soil increased when pure air was led through it, but that
no increase was observable when the air contained a trace
of an antiseptic like chloroform or carbon bisulphide. Further
ex23erinients cast Hght on the conditions under which the
nitrogen in ammonium - salts would thus pass over into
nitrates — a preliminary seeding from a previously nitrifying
solution or from soil or natural waters is necessary — bright
hght inhibits the process, and the drying up of a soil, even
at the ordinary temperature of a room, is sufficient to destroy
the agent of the change. All these facts showed that the
change to nitrate was effected by living organisms present in
the soil and in natural waters. It was also shown that certain
food substances, particularly phosphoric acid, are required in
the nitrifying solution. About the same time also, Munro
sho\ve(l that the organism can obtain its carbon from purely
inorganic sources like the carbonates of ammonia or calcium,
acquiring the necessary energy for splitting up the carbon
dioxide from the combustion of the ammonia to nitrous and
nitric acid. This remarkable fact was afterwards more
rigorously demonstrated by Winogradsky, who established a
relation of about thirty-five to one l)etween the nitrogen oxidised
and the carbon assimilated.

In the course of Warington's experiments he observed that
when a comparatively strong ammoniacal solution (containing
also phosphates, etc.) was seeded from a soil, the first product
of the oxidation was largel}', if not wholly, nitrites, and that
these nitrites were converted into nitrates at a later stage
when most of the original ammonia had been oxidised. This
seemed to indicate that the reaction takes place in two stages,
a preliminary oxidation to nitrite being followed by a second
independent change of the nitrite into nitrate. Warington
succeeded in separating by relocated cultivations one agent that
>^ould only carry on the first oxidation from ammonia to nitrite,
and a second that would oxidise nitrite into nitrate but would
not attack the original ammoniacal solution. Although
Warington was not able at that time to demonstrate in a pure

DFAlTIJIl'iCA'noN L'l!^

state the ()r<j;anisiiis res{)eetively eanvinu mi tliese rcNictioio. I.iii
liis experiments proved tliat tlie onlinarv procivss of nitrilK aiiMn
in soil etc., nnist l)e dne to two disiinci (.i'<:;iiiisnis, the iiiirmis
and nitric, eacli incapal)l(> of doinu the wm-k (.t llir (.tli.r.
Soon afterwards Warington's conclusions wciv coiiliniircl l.y
Winogradskv, who succeeded l)y a new nicthcMl in |uvparing
pure cuhures of the two organisms.

The position in which Warington's investigation.^ K'fi the
question of nitrification has not been materially advanced since ;
the process is carried out by two distinct organisms present iit
enormous numbers in all cultivated soils, l)eingonly absent from
soils possessing an acid reaction like peat. The action of these
organisms is dependent on certain conditions of temperature
and aeration, on a supply of inorganic food like phosphates,
on the presence of a l)ase and on the absence of any excess of
soluble organic matter.

II. — Dkmtiuficatklx.

During the progress of the investigations on nitrification
Warington found that under certain conditions soils possessed
the power of destroying any nitrates which had been formed
previously. This had been observed before, and shown to be
due to the action of sundry living organisms which arc univer-
sally distributed in natm-al waters, sew^age, and soil. The main
conditions necessary for the development of this reducing action
are the ab.sence of oxygen and the presence of a suflicicncy of
readily oxidisable organic matter; it will then depend on the
conditions to which the soil is subjected whether the nitrate-
making or the nitrate-destroying organisms l)ecomc active.
AVarington, for example, showed that if an ordinary soil wci-c
deprived of air by keeping it in a waterdogged condiiii.n.
any nitrates added to it would be rapidly desti-oycd with the
evolution of nitrogen gas.

The action of a number of organisms was sludir.l l.y intro-
ducing them into beef broth containing sonic nil rah- and
protected from the access of oxygen by a layer of pai-allin oil.

220 NITRIFICATION

Under these conditions, of thirty-seven distinct organisms
tested, nineteen rednced the nitrate to nitrite, one of them
producing nitrogen gas also, three brought about some sKght
reduction, and fifteen were without action on the nitrate.
Eeduction to a nitrite was the most general reaction, but
other organisms have been found capable of carrying the
reduction further to nitric or nitrous oxide, or even to nitrogen
gas.

It has been supposed that considerable losses of nitrogen
are likely to accrue from this cause Avhenever nitrate of soda is
used as a manure in conjunction with organic materials like
dung. But, notwithstanding the presence of denitrifying
bacteria in the soil, the conditions under which they become
active— absence of air, a high temperature and the presence
of large quantities of soluble organic matter — are so rarely
realised that denitrification probably plays no large part
in practice. For example, on the Rothamsted mangel plots,
where large quantities of nitrate of soda are used in conjunction
with dung applied every year, the recovery in the crop of the
nitrogen supplied in the nitrate compares favoural^ly with the
proportion recovered when nitrate of soda alone is used (see
pp. 113-4). In other words, the nitrate of soda produces
almost as large an increase when added to a dunged as to an
unmanured plot, hence very little of its nitrogen can have
been wastefully liberated as gas.

Latterly the term denitrification has been used in a Avider
sense for all bacterial decomposition of organic bodies containing
nitrogen, which result in the loss of nitrogen as free gas. Such
actions must be always going on in soil, and serve to account
for the fact that there seems to be a limit to the accumula-
tion of nitrogen in soils, because the destructive changes
proceed with greater rapidity as the amount of organic
matter in the soil increases and provides a richer medium for
the development of these bacteria. For example, it is found
that the amount of nitrogen accumulated in the soil of the Park,
which has been in grass from time immemorial, shows no

DISTRIBUTION OF MTK'IFVINC OIMIAMSMS -Jl

tendency to increase and isl)ut litilr liiuhcr tliaii the jJiojMii-iinu
in the soil of other adjoinini]: meadows wliicli have oiiK lu-i-n
kid down to grass for tliirty years or so. Again, in tin- I'.id.td
balk wheat tield, tlie j)lot wliieli receives farniy.ird manure is
snppHed annnally with far more nitrogen than is renioNcd in
the crop. Dnring the earher years of the e\|)ciimcni> tlniv
was in consequence a rapid rise in the jiro|iortion ot niirogrn
in the soil, but this rise has diminished, and lias liecn latterly
by no means equal to the annual increment of nitrogen. A
state of equilibrium is eyentually attained, when the destructive
agencies find the conditions so fayourable for their develop-
ment that the quantity of nitrogen compounds broken down
to the state of gas becomes equal to the surplus of eonibine(l
nitrogen that is added year by year.

III. — Nitrates in Cultivated Soils.

The nitrifying organisms are in the main present only in the
surface soil which is subject to cultiyation ; at depths greater
than 9 inches from the smface the organisms become more
scanty and less effectiye in inducing nitrification in a suitable
medium. Dming the sampling of several of the Kothamsted
soils Warington took advantage of the pits dng into tiie
subsoil to obtain small samples of the undisturbed snbsoil.
portions of which were then introduced into solutions capable
of undergoing nitrification. It was found that the nitri
fying organisms were present in all the samples down to
o feet from the surface ; at 6 feet, where the snbsoil was clay,
half the samples failed to induce nitrification, at 8 feet the clay
subsoil showed no evidence of the presence of nitritying
organisms. Whenever the subsoil passe<l into the clialk loek.
which in one case extended to A\ithin .') leet of the sinlaci', nn
nitrifying organisms were found. Fractieally the whole of the
nitrification going on in a com})aratively close soil like that ol
Rothamsted takes place in the lirst U inches which gets
stirred about and ai^-rated by the action of the j)longh.

It will now Ije reahsed that the most favomable condition.-

222

NITRIFICATION

for nitritication occur when the land is subjected to a bare
summer's fallow ; the land is being thoroughly worked, the
temperature is high through the complete exposure to the sun's
rays, and the soil also retains sufficient moisture for nitrification
because it is not being dried by the growth of a crop. The
favom^able results accruing from a l)are falloAv on strong land
have already been discussed, and though they are in part due
to the freedom from weeds and the improved tilth of the soil,
the main effect must l)e attributed to the accunuilation of
nitrates during the summer.

The following table shoAvs the amount of nitrogen as
nitrate found in various Rothamsted soils after fallowing : —

Table LXXVLI. — Effect of Fallowing — Nitrogen as Nitrates, lli. 2)or acir.

I

Alt

Rotation Field.

mate Wheat and Fallow.

Wheat.

Super,
only.

Complete
Manure.

Fallow Portion.

After Crop.

Fallow Portion.

Oct.

1S78.

March
1S81.

July
1883.

July
1884.

Oct.
1881.

Oct.
18S3.

Oct.
1878.

Oct.

1878.

First 9 inches .
Second „
Third „

28 -.5
5-2

7-05
3-35
3-13

19-48

8 -or.

2-47

17-12
3-67
2-76

9-9
.5-2
2-8

9-64
9-22
2-74

22-3
14-0

30-0 '

18-8

1

The accumulation of nitrates in the surface soil of the
uncropped land as the summer advances is to be seen very
plainly from the figures : the lowest amount of nitrate was in the
March sample, and both the July samples were poorer than that
drawn in October. In October also the continuous wheat land
had been broken up, and nitrification thus started afresh. It is
also plain that the fallow land was much richer in nitrates than
the plot which had been under continuous crop, although the
accumulation of nitrates was greater on the last plot where the
land had been manm^ed and was in good condition than on the
other plots, all of which had long been unmanured.

It has already been pointed out in dealing with the wheat

LOSS OF XITKATKS IN WKT \( TIMX- -':;

crop (p. 63) that \]\v incTeascd crop alter fallow i> .ilmost
wholly dependent oil t lie retention in llic soil of tlir nitrates
thus formed in the sunnner. Should a ucl autimm ;nid eariv
winter succeed, the nitrates ar(> \\aslied so tar dnwn in ih,.
subsoil as to be out of reach of the ei-o|), which tlnn -Imw- a
very small return for the previous sunniiei- fallow inu.

The rapidity with which nitritieation may take place after
harvest is also noticeable in the table. There is plentx of
evidence that for three months or so before the reinoxal of the
wheat crop the soil in which it is growinjj; is [tiactieallv fr-r
from nitrates, but if rain falls when the «j;r()imd has l)eeii
broken up after harvest the conditions l)ecome extremely
favom-able to nitrification, because the soil is warm and wdl
aerated by stirring, and possesses a suitable degree of moisture.
Hence heavy autumnal rains, before the land is again occui)ied
by a crop to take up the nitrates, may easily result in serious
loss to the land, and some quick-growing covering ci-op like
mustard is valuable, because it seizes upon the ready formed
nitrates. At a later date the nitrogenous compounds the
mustard has formed from the nitrates, which would otiierwise
have been washed away, are returned to the land, either by
being ploughed in or fed off, and become available on their
decay for the nutrition of the succeeding crop. Imcu a free
growth of weeds on the stubl)le will diminisli the los> of
nitrates to the land.

IV. — Nitrates in Manured and Cian'i'ii) Soils.

In several instances, as, for example, in the Broa«lltalk field
in 1893, soil samples have been drawn to depths of 1» feet,
and the distribution of the nitrates in the successive 1» inches
determined. Table LXXVIIT. shows the results for certain
of the plots sampled in Octolier of that year, after a very dry
summer yielding a crop mucli Ix'low the average, and als.» alter
a fall of about 4! Indies of rain between harvest and thr time
of sampling.

224

NITRIFICATION

Table LXXVIII. — Nitrogen as Nitrates in BroadbalJc Wheat Soils,
October 1893. Lb. per acre.

Plot

B.

2b.

19.

5.

li.

7.*

8.

16.

Minerals

Minerals

Minerals

Minerals

Un-
manured.

Dunged.

Rape
Cake.

Minerals
only.

+43 lb.

N.

as Amm.-

salts.

+ 86 lb.

asAmm.-
salts.

+ 129 lb.

N.

as Amm.-

salts.

+ 86 lb.

N.
as Sod.

Nit.

i 1st 9 inches .

9-64

10-53

22-06

10-53

14-13

14-96

17-40

13-59

' 2nd „

9-22

45-36

24-36

6-36

12-74

19-21

29-17

42-58

3rd

2-74

12-25

14-18

2-23

5-81

8-54

8-71

20-77

4th

0-95

2-98

5-32

8-71

13-03

5th

1-00

3-47

4-64

8-51

7-82

6th

0-71

3-72

4-40

7-46

5-96

7th ..

1-03

3-25

4-51

7-99

5-45

Sth .,

0-92

1-89

4-02

7-60

6-28

9th .,

0-87

2-46

4-29

6-13

...

10th
Total 1 to 90 .

0-57

2-16

4-38

5-64

25-17

52-61

74-27

107-32

115-48*

To 72 inches only.

It has already l)een pointed out that nitrification is practi-
cally confined to the siirfixce soil, where only do the desirable
conditions prevail of numerous organisms, free aeration and
stirring of the soil, and nitrogenous matter easily attackable by
bacteria. This opinion is also borne out by the fact that the
drain-gauge with soil 60 inches deep yields practically the
same amount of nitrate as the shallower gauge where the soil
is only 20 inches deep. From this it follows that the nitrates
to be found in the lower depths of the subsoil are all derived
from the sm*face, and have been washed down with the rain.

It will be noticed that in most cases shown in the tal)le the
second 9 inches contains a larger amount of nitrates than the
smface soil, in some instances even the third 9 inches are richer
than the surface. This is merely due to the downward dis-
placement of the nitrates produced after the harvest l^y the
heavy rain A\hicli had fallen immediately before sampling. It
will also be noticed that in several cases there is a break in
continuity in the amount of nitrates l^etween the third and fourth
depths. This is probably due to the tile drains, which lie at
about this depth and remove the drainage water charged with

N[TKATKS IN ■mi., soil

nitrates. Sucli a break in c'()m[)()siti(.ii is ii,,t s.-.-n in the
samples drawn from other fields wliidi aiv imi t ilc-draiiu-d.

The eharacter of the maiun-iii- n|)]>h('il to ihr sinfacc soil i>
well seen in the amount of nitrates in the sulisoil : i'nv cxamiile.
Plots ;\ (), 7, 8 form a series, all ucttiii.Lr tlic same niinn-al
manure, but Plot 5 has no niti-o^en, while Plots (;. 7. and s
receive successive increments of anunonium-salts. Down tn
the depth of 9 feet the samples contain nitrogen as nitrate in
approximately the same proportions as it is applied t.. tin-
surface in the form of anunonium-salts. Again, the total
amount of nitrogen as nitrate contained in the wln>le de[»th
below Plots 6, 7, and 8, as compared with that present below
Plot 5 receiving no nitrogen, is nuieh the same as the (piantity
of nitrogen applied as manure less the amount renioxed in
the crop of 1893.

Table LXX\X.—Xitro[in), Ik j)er acre, 1893.

Plot.

5.

G.

7.

8.

16.

As Nitrate in Soil to depth of 90 inches

Excess of Nitrate over Plot .")...
Nitrogen in Crop, excess over Plot o .

Nitrogen accounted for in Soil and Crop,

excess over Plot o

Nitrogen supplied in Manure

25-2

.52-6

74-3

107-3

82-1
14-8

96-9
129

115 -S*

...

27-4
8-7

49-1
12-9

90-3
11-7

36-1
43

62-0
86

102-0
86

Thus we have evidence that practically the whole of
nitrogen supplied as ammonium-salts is nitrified during
season of growth of the wheat, and whatever is not iciik
by the plant gets w^ashed down as nitrate into the snbsoil,
may be either intercepted by the tile drainage, if any. nr
its way into the general stock of undei-ground water. Jn>
the same w\ay the nitrate supplieil to Plot HI in excess of
requirements of the plant gets also \\a>lif(| (l(.\\n lo a e(»n>i(
able depth in the subsoil.

The large quantity of deep-seated nitrate >lio\\ii in
analyses is no longer available for crops on the Kothain.

the

th.>

.ve.l
and
lin.l
t in

thr

the
^ted

226 NITRIFICATION

soil, probably because the closeness of textm^e permits but
little capillary movement of water to take place. This we
learn from the comparison of the yields on Plot 5, receiving
minerals but no nitrogen every year, and on Plot 17 or 18,
which receives alternately minerals and ammonium-salts. As
has already been pointed out (p. 51), in the years this plot
17 or 18 receives minerals but no nitrogen, its crop sinks
almost exactly to the level of the crop on Plot 5, although it
had received 86 lb. of nitrogen as ammonium- salts the year
l^efore. Clearly, then, on the Rothamsted soil ammonium- salts
are not retained as such for more than the season of applica-
tion, nor are the nitrates resulting from them able to return to
the surface to feed the succeeding crop. On other soils of
better textm'e for allowing the movements of water by capil-
larity there can be no doubt that the nitrates in the subsoil
water will retmni to the suiface and be of service to the crop.

It must not be supposed, however, that dressings of
manures like nitrate of soda and sulphate of ammonia, which so
readily wash away as nitrates, are entirely without action on
the succeeding crops. Because of the very fact that they cause
a large growth, there is left behind in the soil a corre-
spondingly large development of root and stubble, which will
decay for the benefit of succeeding crops. Especially is this
the case where some considerable proportion of the crop grown
is not harvested, but is returned at once to the land, as is done,
for example, with the leaves of mangels or the haulm of
potatoes. A striking example is seen at Rothamsted, on the
plots which grew potatoes for twenty-six years, from 1876 to
1901, and were then sown with barley without fuither manuring.

Table LXXX. shows the total produce (grain and straw)
of the first and second crops (barley) and the third crop (oats),
after the manuring had been discontinued.

It will be seen that the change from potatoes to barley was
followed by enormous crops of grain wherever nitrogenous
manure has been used for the potatoes ; the two plots which
had previously been dunged gave over 70 bushels of grain per

RESIDUES OF NITKOGENOUS MAM IM.S I'-r

acre; the four ])lot.s wliicli liad nM-civcl niii-om'u as riilici
nitrate of soda or aininoiiiiiiH-salts pi\(> soiin-wliat less. Imi
still over 60 bushels ; wliilo tlie tnui" plots witliont niii()u'<'ii in

Table LXXX. — Total proiucd witliout Mnnnrc, folloxpiiuj l'otitto>s
mamLred for 26 years.

Lb. per acn».

Manure applieil to the Potatoes, ijTu-ljnl.

1902.

Unmanured | 3602

Unmanured, 1882 and since, pre\nously Dung . i 3804

Dung alone, 188.". and since 9024

Dung alone, 1883 and since I 9072

S<o lb. N. as Ammonium-salts . . . . i 6981

86 lb. N. as .Sodium Nitrate j 7692

86 lb. N. as Ammonium-salts -Minerals . . ' 7792

86 lb. N. as Sodium Nitrate -r Minerals . . .1 82.->3

Superphosphate only 3720

Complete Minerals 2953

lUrky.

1063

2331

1836

2129

6030

5492

5937

5974

2066

2211

1934

2236

3207

3024

3187

3045

1617

2089

15S6

2056

previous years gave between 25 and 35 Itiisliels. In thi-
following season these differences were still to be seen, and the
leading position of the previously dunged plots was naturally
more manifest than ever; while in the third season (oats) aftci-
the manuring had been discontinued, the order of the plots
remained the same, although only the dunged plots now grew
a large crop.

That the increase on the plots which had previously
received nitrate of soda or ammonium-salts was due to
crop residues rather than to the return of nitr.ites diri\<'d
from the manure and stored in the .subsoil, is probable from
the superiority of the crops on Plots 7 and 8, wliere iniiici-als
liad accompanied the nitrogenous manure-s over Plots 5 aii«l
6, where the same nitrogenous manures had been used alone.
When residues are being cropped out, the size of the cereal
crop grown is almost wholly determine<l l»y thr availablr
nitrogenous supply, and Plots 7 and 8, which foiinerly grew the
larger crops of potatoes, give better yieMs than Plots 5 and «).
<ilthough they had initially the same .supjily nf niticjcn

On

228

NITRIFICATIOX

the other hand, the rapid decHne in the production of Plots
5, 6, 7, and 8, following the discontinuance of the manure, is
more consistent with the existence of a residue of nitrate
rather than of slowly-decaying organic material derived from
the haulm of the potatoes.

Soil samples down to a dej^th of six times 9 inches were
taken from some of these plots in February 1903, after the first
barley crop had been removed. The following table shows the
average figures olitained.

Table LXXXI. — Nitrogen as Nitrates per million in dry Soil of former
Potato Plots.

Depth of Soil.

Unmaimred.

Dunged.

Ammonium-salts
only.

Xitrate of Soda
only.

Plot 1.

Plot 3.

Plot 5.

Plot 6.

1 1st 9 inches .
2nd „
3rd „
4th „
5th „
6th „

Means

1-92
1-68
0-7S
0-76
0-67
0-56

8-75
5-13
2-97
2-23
1-47
3-24

1-63
1-94
1-lS
3-18
2-14

5-7:.

1-68
2-03
1-21
0-S6
1-67
3-67

1-06

3-97

2-64

1-85

In this case the samples were taken in the early spring after
a winter of fair rainfall, which had distriljuted the nitrates
throughout the soil ; the total, however, present in the first six
depths roughly corresponds to the variations in the Ijarley crop
of 1903 which followed.

One striking fact in connection with these and similar
determinations, is the absence of any lateral diftusion of the
nitrates in the subsoil water beneath the plots. The Broadbalk
wheat plots, for example, are comjDaratively narrow, l.)eing about
7 yards in breadth, separated by paths of 4 feet in width. Yet,
as is seen in Table LXXVIIL, Plot 5, which receives no
nitrogen, shows no trace of the influx of nitrates by diffusion
froju the much richer subsoil water IdcIow the immediately
contiguous Plot 6, even down to the depth of 9 feet. Just

NOX-DIFFUSION OK MTU A IKS I\ >()||. •-,

in the sanu' way the aniomit of iiitrairs jn-.'sciit at racli .|r|,ili
in the subsoil water l)el()W Pints (>. 7. an<l ^, is pcrfeetlv
ilistinct and eliaracteristic of the mannrinu^ applied to tlir
ijiuface.

Additional evidence of the laek of lateral <litfnsion of tlie
nitrates in the soil water is to be seen in the permanent ^M-ass
plots; although no path separates the plots rec(ivin<: nitrate of
soda from the neighbom'ing plots, the eharactei-istic ve;^'ctatioii
induced by the nitrate of soda manuring shows no tendenev i«»
stray across the division line. For example, Plot 11. rcccivin;^'
a complete manure containing 550 lb. per acre of nitrate of
soda, is innnediately contiguous to Plot 1, receiving nitrogen
only as ammonium-salts; the vegetation on the two plots is in
marked contrast, yet the dividing line is singularly sharp, and.
<lespite the many years Plot 14 has received this large dressing
of nitrate of soda, there is not the least sign of its ditiusion into
the subsoil below the adjoining plot.

V. — The Nitratks in DKAfN,\(;K Watkrs.

The processes of nitrification in soils can also be studied by
the examination of the drainage water beneath cultivate(l lan<l.
It has long l)een known that all the soluble compounds of
nitrogen are retained by the soil with the exception of the
nitrates, hence an examination of the amoimt of nitrates
present in the water reaching the drains will tliiow liuht on tin-
rate at which nitrates are produced in the soil, and on ilieir
ultimate fate.

At Rothamsted the water which })ercolates thiongli tin-
drain-gauges is stored, and the nitrates are regularly determineil
in proportionate samples representing the percolation for the
month. These results have been combined for twenty-six years.
1878-1903, and the averages are set out in the accompanying
curves (Fig. 45), which show the rainfall, the percolation in
inches through '20 inches of bare soil, the c..iic.iiiiati(.n of the
percolating water in parts of nitric nitrogen per million, and the
total amount of nitric nitrogen reduced to lb. per acre.

230

NITEIFICATION

Neither the percolation nor the total quantity of nitrogen
removed differ much for the 40-inch and the 60-inch gauges ; but
owing to the greater amount of water retained l)y the deeper

1 1 i 1 i r T" - - -

T X -

- - Ti A

\ 1 \\\\\ \\\

1 1 " 1 1 ' II

/ \'

/ i \'

1 1 1 1 I 111

/M i \

1 1 li 1 i i ' 1 i 1

'•\ 1 l> i 1 1 ! ^ ' i '\. i 'i ' '^

1 1 Mi 1 1 i 1

1 i /I II!' ' 4 ' ' 1 \ ' 1

1 / I I 1 III' I I M I I L4' W

6 '

! /I I ' I ' ' ■• M A 1 ->

1/ 1 f •■ I

/ i 1 1 • ' M-^ X M-i .

- - -j: t

1

1 .' ' Nitrogen as Nitrate

^ '-AL '."."a'. "I

1 ; 1 " ' ^

s^ -<-___

-^x- XX---

■^ . _:":"! :: '."X"-""-"-

' VI 1

-_ -.ztj^ii/ ~--^-'- -

■ r - - -

5::::::::::: ::: :-;?!!: +

x

2 "IS 'i^.X^^^xl____

----^'--:--T!T-rT^rrr-^"-

>•■••'

t ■ 2.

■

i 1 --h

_u U ]-i-\ ! 1 i i i ; 1 1 n

+-T^-4^4-Tr^!iM'- ' +

^Si-±^==ff=f=Tff==+ =

\. -

Jan. Feb Mar. April May June July Aug Sept. Oct. Nov. Dec.

Fig. 45.— Rainfall, Percolation, and Nitrogen as Nitrate in Drainage through
20 inches of Soil. Rothamsted. 26 years (1878-1903).

soil the drainage from the 60-inch gauge is more uniform in
concentration throughout the year, the main discharge also
comes a little later in the year.

Inspection of the curves shows how great is the variation

NITRATES IX DK'AINACK WATKIJS -u

from month to month in ])oth tlic (.-oiicvnt ration ..ftli.' <iiaiMa<:<'
water and the loss of nitrat(\ Tlic (•(•nccntratioii is at it>
lowest in February, a tinu^ of ycai- when tlic s(.il is still at a
very low temperature and lias Immmi thorouLihly washed |.\
the winter's rains. In April the cdnccntration has iiurrasiMl
but little, and this combined with a smaller jiercolatioii
resuhs in the minimum loss of nitrates t'nr the veai- in
this month. The rise in concentration is still slow until
July, when there is a considerable juiiip, the concent rat inn
reaching its maximum in Septemltcr. The niaximnm lo>-
of nitrates comes as soon after this [)oinL as the rain
fall is abundant enough to wash through the soil; on the
average the greatest annual loss of nitrates takes place in
November, from which time onwards both concentration
and total loss diminish. All these results refer to soil
which is kept bare and uncropped, \\here in consequence
the percolation is at a maximum, and where also there
are no growing crops to take up the nitrates as they are
produced. The effects to be seen under more ordinary condi-
tions can be followed in the analyses of the drainage water>
from the Broadbalk wheat field, under each phjt of which runs
a tile drain at a depth of from 2 feet to 2 feet 6 inches. The>e
<lrains all debouch into a cross trench at the bottom of the field,
and a record is kept of the occasions upon which there is an\
flow from the drains. Determinations of the nitrates contained
in the waters are also made, but as it is im]iossil)le to with
draw an ahquot sample of the whole How of the drain. an<l a-
also during any particular running the concentration is ah\ay>
changing, the earlier discharge being sometimes .stronger and
sometimes weaker than the later, it is impossil)le to make any
exact account of the quantity of nitrogen removed by each
drain. By coml)ining, however, the results obtained over the
whole period of the determinations, an aj)proximate i<lea of the
concentration of the discharge will be ol)taiiie(l. ()th"r cnn
siderations lead one to .suppose that the (lischar<:e fmni the
drains does not represent, either in ((uantity or concentration.

232

NITRIFICATION

the water that may be supposed to pass into the subsoil at the
depth of the drain. The resuh-s, however, are probably com-
paratively true from plot to plot.

Table LXXXII. shoAvs the average concentration of the
nitrates in the drainage water from four of the wheat plots, and

Table LXXXII.

-Xitrogen 2)61' million i^cirts of Broadhalk Drainage
Water

Plot 3.

Plot 7.

Plot 9.

Plot 15.

September ... .3-9

7-8

10-5

7-8 i

October

5-0

8-8

12-8

16-9 '

November

7-0

17-7

14-7

44-0 i

December

.'.•9

20-5

17-7

50-3

January

4-2

12-7

9-0

23-7 i

February

4-0

8-1

9-2

17-7

March .

2-6

9-4

12-2

12-9 \

April .
May .

1-7

14-3

30-5

9-6

0-7

8-4

9-1

6-5 t

June

0

8-8

6-8

1-3 i

July .

0-5

3-2

8-0

2-5

August .

0-9

7-4

I 4-3

2-7 [

1

Table LXXXIII. the average number of days in each month
on which the drains of the same plots run.

Table LXXXIII. — Xumbcr of Days with Drainage, Broadhalk Field.
Average over 36 years.

Plot 3.

Plot 7.

Plot 9.

Plot 15.

September .

16

12

14

8

October

64

.51

53

35 1

November

: 94

84

86

54

December

107

10:^

107

58

January

103

111

116

60

February

69

73

77

45

March .

f.O

43

56

23

April

1 21

21

18

9

May .

16

12

17

9

June

17

10

9

6

July .

15

9

9

7

August .

' 13

11

10

6

Considering first the unmanured plot, Init Httle drainage
takes place dtmng the summer months, May to August, because
of the drying action of the crop upon the land. At the same
time the concentration of such water as does find its way

BROADBALK FIELD DlJAlNAdi: W ATFKS -j?,:)

tliroiigh into the drain is vciv low, ^o iIk.iou'jIiIv liavc ihc
nitrates been removed l)y tlic m'owinu croj). From Srjitcnil.fr
onwards, however, to FrFmarv, the (•(.iiccntratioii ..I" tlir \\;itcr
is comparatively high, and as tlie (h-ains Ix-gin to lun tncly
(hu'ing this period wlicn tlie crop is ofV tlic i^rouiid. mrat I<»»(v
of nitrate are Hkely to occnr. Nilrifuatioii goes on thronghont
the winter; even in years when the rainfall of the early antinini
is so excessive as to wash the soil clean ol'all nitivitcs pi-oduccd
(luring the first nitrification following t lie icnioval of the cinp.
yet fresh nitrates are still produced in considerahle (inantily,
and find their way into the drains in Deceml>er and January.
Nothing, in fact, short of the absolute freezing of the ground
stops the production of nitrate and its consequent loss when
ever the rainfall is heavy enough to wash through into tin-
subsoil.

If the results obtained on the drainage water fioni the
manured plots be examined, it will be seen that nitrification
of manures like ammonium-salts is extremely rapid ; if there is
Any percolation, nitrates begin to appear in the drainage water
immediately after the application of the mamu'e. Even in
autunm an application of anunonium-salts is converted into
nitrate in a very short time, a.s may be seen from the followinu'
series of analyses of the water running from tln^ drain below Plot
1.'), in October 1880.

On October 25th of that year, mixed anunonium-salts citn-
taining 86 lb. of nitrogen and 110 lb. of chlorine per acre
were applied to Plot 1 ') and plougluMl in. Heavy rain followed,
so that on October 27th the drain l)eneath the pl(»t was
running; other rain fell at short intervals, and yielded ilie
series of samples set out in the table. It uill be noticed
tliat in the first runnings, taken within forty iiours of tin-
application of the manure, some anunonia was to be found.
Tliis is a very exceptional oecuri-ence, but the large excess in
which the chlorine was present in the w, iter show e.l th.it ilie
decomposition of the annnonium chloride and retention ot
the anunonia by the soil had progressed considerably.

234

NITRIFICATION

Nitrification had also set in, since the earhest running con-
tained nearly twice as much nitric nitrogen as was found in
the sample taken a fortnight earlier, before the application
of the manure. The proportion of nitrate continued to
increase, and reached its maximum in the discharge three
weeks later, by which time the nitrification of the ammonium-
salts must have been far advanced towards its completion.

Table LXXXIV. — Nitrogen and Chlorine in Drainage Water from
Plot 15. Parts 2Der million.

Nitrogen
as Ammonia.

as^ffis. ' Chlorine.

Nitrogen
as Nitrates ,

to
100 Chlorine. :

1880
1880

1880
1880
1880
1880
1880
1880
1881

October 10 ....
October 27, 6.30 A.M. .
October 27, 1 p.m.
October 28 ....
October 29 .
November 15, 16 .
November 19, 26 .
December 22, 29, 30 .
February 2, 8. 10.

None

9-0

6-5

2-5

1-5
None
None
None
None

8-2
13-5
12-9
16-7
16-9
50-8
34-6
21-7
22-9

22-7
146-4
116-6
95-3
80-8
54-2
47-6
23-2
19-4

37-0
9-2
11-1
17-5
20-9
93-7
72-7
93-5
118-0

The last column of the Tal)le shows the relation between
the nitric nitrogen and the chlorine in the drainage water.
The chlorine is derived from the ammonium-salts of the
manure, and as it is in no way retained by the soil its
appearance in the drainage indicates the movements of
soluble salts in the soil independently of the production of
nitrates. In the earlier runnings the chlorine was present in
great excess, being immediately derived from the manm^e ; in
the later months the proportion fell as it became washed out,
and by December it had again reached the normal level it
had showed before the manm-e was put on. Meantime the
proportion of nitrate was being maintained by constant nitri-
fication in the soil, so that the ratio of nitric nitrogen to-
chlorine in the drainage water rose rapidly towards the end
of the winter.

When ammonium -salts are applied as a top-dressing in the-

LOSS OF MTKWTKS \\\ l»i:\INA(;K

spring, as is now more m'luTally ihc ca^i'. ilic l.)»c> ol' nil r.ii cs
are very much reduced; nt»t only is ilic tcuiiMTutiin' ol" tlir soil
lower, so that nitritieation lako place inure slowly. I.iit the
growing crop both diniinislies ihe juMc.ilalion and i.ikr> iqi ilie
nitrates as fast as they are produc-ed. Tlie li^ures. liouever.
for Plot 7 and Plot 9, Table LXXXII., show some ris.- in il.r
concentration of the drainage wMvv in (he earh s|)rin'_;. follow-
ing the application of manure.

By combining the figures obiained for the eoneenliaiinii of
the water flowing from the Broadltalk field dr,nn> witli ilh-
amounts of water percolating through tlie drain-gauue eon
taining 60 inches of bare soil (see p. '22), an estimate can

Table LXXXV. — Nitrir Nitroncn in Draliiri/jc JFatrr. Lh. ]hr tirtr.

Plot.

Mamiriiig per acre.

1879-80.

188041.

Spring

Harvest

Spring

Harv.!«t

Sowing

to

Sowing

to

to

Spring

to

Spring

Harvest.

Sowing.

Harvest.

Sowing.

3

Unmanured

1-7

10-8

0-6

171

5

Minerals only

1-6

l.'f.t

0-7

17-7

fi

Minerals + 200 lb. Ammonium-salts .

10-1

12-6

2*2

lys

7

Do. +400 lb. do.

18-3

12-6

4-3

21-4

9

Do. ^550 lb. Nitrate ot Soda .

40-0

15-6

If.-O

41-0

10

400 lb. Ammonium-salts alone ....

42-9

14-3

7-4

3.-. -2

11

400 lb. do. 4 Superphos])liate .

400 lb. do. do. and Sulph. Soda

28-3

17-7

3-4

29 •«

12

21-2

n-.l

3-3

27 "2

l;i

400 lb. do. do. and Sulph. Pot.

19-0

16-4

3-7

'2'< -.1

14

400 1b. do. do. andSulpi). Mag.

26-0

16-8

4-2

2'. -9

ir.

Minerals - 400 lb. Amm.-salts in Autunui

Estimated Drainage— Inches

9 6

59-9

3-4

7 1 •'.»

11-1

4-7

1-8

be formed of the losses to the land l»y drainauv iindci- ce h
sy.stem of manuring, an estimate rendereil erroneous beeau-e
it does not take into account the drying effect of the crop.
However, the figures thus obtained, tlioiigli iinperfeci. are
i Instructive, and are set out in Tabic LXXW. for two year.s,
each divided into two periods; liist, from tlic dale <.f >owiiig
the nitrogenous manures u[) to harvest ; .seeondly. fiom harvest
round again to the sowing of the manures in sJ)rill.u^

The sea.sons were rather exceptional, the summei- rainfall

23f) NITRIFICATION

and drainage in 1879 and the winter rainfall in the following
year being both above the average. It will be seen that the
loss was greatest from Plot 9, receiving 550 lb. of nitrate of soda,
and this excess of loss was chiefly in the summer drainage
water : the figures are, however, exaggerated by the fact that
half the nitrate plot received no mineral manures, and therefore
grew but a scanty crop. The losses during the winter months
are more nearly the same for all plots, and represent to a large
degree the nitrification of the organic residues in the soil. The
losses from the plots receiving minerals and varying amounts of
ammonium-salts (Plots 5, 6, and 7) increased with each applica-
tion of nitrogen ; the losses from the plots receiving ammonia
and various mineral manures (Plots 10, 11, 12, 13, and 14)
diminished as the mineral manure l)ecame a more complete
plant food, because the greater growth of crop which resulted
I'emoved more of the nitrates as they were formed, besides
hindering nitrification by drying the surface soil.

Perhaps the most striking result that emerges from these
analyses of the drainage waters is the rapidity with which
nitrification takes place of such substances as the salts of
ammonia ; even in the colder autumnal and winter soils
nitrification is so active that great losses of nitrogen are sure to
occur if such manures are applied in the autumn, hence the
justification for using ammonium-salts only as a spring dressing.
It also serves to show that any differences in the effectiveness
of the nitrogen of nitrate of soda and of ammonium-salts is
most likely to be due to the differences in habit of growth
of the plant induced by the two manures, since the conversion
of the ammonium-salts into nitrate is so easily and completely
effected except in such soils as are short of the base necessary
for nitrification. Only in the wheat experiments is there
any indication that a wet and cold year may so check
nitrification as to make the ammonium-salts a less valuable
source of nitrogen than usual. Again, we see how cereals, and
especially wheat, are specially dependent on artificial supplies of
nitrogen, and have earned the character of being exhausting

COMPOSTTION ()!• 1 )1:AI N A( ; i; W A ri:K':

crops. Their growth is ahnost coiuijlcicd l.ctmv ninirKalioii
has reached its greatest activity (from tldwcriiiL: limc ^.Il^vanl.>^
the cereals take no more nitrogen tVoiii the xtil). ami hciim'
harvested in August or (\irly Scptcinltci-. thcv leave the i^niun.l
bare at a time of rapid nitrate formation, thus exposini: it to
all the risks of washinu' awav l>v tlu' autunmal raiu>.

VI. OtHKH C(»NST1TI KNIS oK DllAlNAi.l. W \l 1 i;s.

Complete analyses of the mineral constituents of the waters
draining fi*om the various Broadltalk plots were ma<le at vaiioii>
times by the late Dr Voelcker and by Sir Edward Frankiaiid ;
these analyses still constitute ahnost our only information as to
direct losses of the land by drainage.

Table LXXXVI. gives an average of the tiv(> analy>e>
made during the years 1866, 1867, and 1868.

Table LXXXVI. — Comj'osition of Drainagr Waters from the BroddbaU:
Mlieat Plots, in parts 2)cr million (Dr A. Voclvkrr). Mean of Jive (or
fewer) Collections — December 6, 1866; May 21, 1867; Jamcri/ \'^.
April 21, a7id December 29, 1868.

As refjards constituents of

Nitrogen ok ,

i

•3

!H

i

.2

£

■5
■<

<

.

Plot.

1

1

1
1

1

^

1

i

1
1

106-1

1

35-7

i

1
1

0-16

Nitric Acid

2

2-6

147-4

4-9

5-4

1
13-7 20-7

16-1

3-4

5-7

98-1

5-1

1-7

6-0 10-7

24-7

6-63

10-9

0-12

3-9

! 5

4-4

124-3

6-4

5-4

11-7 11-1

66-3

0-91

15-4

0-13

5-1

1 6

2-7

143-9

7-9

4-4

10-7 120-7

73-3

1-54

24-7

0-20

8-5

! 7

8-1

181-4

8-3

2-9

10-9:26-1

90-1

0-91

17-0

0-07

14-0

! 8

2-7

197-3

8-9

2-7

10-6139-4

89-7

0-17

20-9

0-27

16-9

9

5-1

118-1

5-9

4-1

56-1112-0

41-0

10-6

0-24

IS -4

10

4-0

154-1

7-4

1-9

7-1 ! 32-0

44-4

1-44

13-7

0-08

13-9

11

3-4

165-6

7-3

1-0

6-6 131-6

54-3

1-66

11-3

0-17

15-3

12

3-6

191-6

6-6

2-7

24-6

30-9

96-7

1-26

17-9

0-30

15-1

13

3-7

,201-4

9-3

3-3

6-1

36-6

1 86-9

1-09

28-3

0-16

17-4

14

3-7

1 226-7

11-6

1-0

5-6

39-4

99-7

1-01

14-0

0-09

19-2

1.0

3-4

201-1

7-9

5-3

14-3

24-6

123-9

1-54

22-1

0-11

24 -2

16

3-0

117-1

5-3

2-4 I .'■.-I '11-4

1 !

21-9

0-91

17-0

0 09

1 '•»

= .E

77-4
«7-7
fiO-1
84-6
92 -rt
110-7
99-7
87-0
83-9
96 -«
100-1
121-6
87-6
75 -I

U

476-1
246-4
326-0
407-6
492-4
54 s -4
4 •_'.■»-!•
406-9
425-9

530 P
544-3

5»H-rt

585-3

'_'>Ml-7

it lia> aliva<l\

been noted that practically no niti-ogenous compountU oecm-
except tlic nitrates; phosplioiie acid i>

in drainage watei

238 NITRIFICATION

also present in but small amounts, even in the plots receiving
a great annual excess of this substance, while potash was
found in sHghtly greater quantities. The mean annual loss,
however, cannot be estimated at more than about 2 lb. of
phosphoric acid and 10 lb. of potash per acre, both of which
in normal cases Avould be arrested in the subsoil below the
drains. Dr Bernard Dyer's analyses of the Rothamsted soils
and subsoils would also indicate that all the excess of phos-
phoric acid, applied as a manure and not removed in the
crop, still remains in the soil very near the sm-face, the potash
having sunk a little further, and being present to some degree
in the third depth of 9 inches below the surface.

The chief constituent of the drainage water from the
unmanured plots consists of calcium carbonate, the amount of
which is increased in the water from the dunged plot, owing to
the greater production of carbonic acid from the decay of the
dung and crop residues. Where ammonium-salts like the
sulphate and chloride are applied as a manure the soil suffers a
great loss of calcium carbonate, the calcium being removed in
the drainage water combined with the sulphuric or hydrochloric
acid of the manure. This reaction is the necessary precedent
to the arrest of the ammonia in the soil and its subsequent
nitrification. In the absence of a sufficiency of calcium
carbonate in the soil to bring about this reaction, ammonium-
salts become injurious to plant life. The salts of potassium,
like the sulphate and chloride, may also increase the loss of
calcium carbonate to the soil, for they react with it in the same
way as do the ammonium-salts, forming calcium sulphate and
chloride, which are no longer retained by the soil.

Since the healthy condition of the soil depends on a due
proportion of calcium carbonate being present, these losses
caused by the use of natural and artificial manures are of the
greatest importance ; many of om- fertile soils may easily lose
much of their power of producing crops unless their proportion
of calcium carbonate is restored by judicious liming at intervals.

Determinations of the calcium carbonate in samples of the

EEMOVAL OF LLMK L\ 1 )KA1 N ACi: W ATi:i:s SM

suil taken at various intt'i-vuls l>L't ween ISO,") and \\h\\ iiKlicaie
that on the unmanured plots tlie nonnal l(».s ol calciiim
carbonate in the drainage water aiiumiits to aliout looo ll..s.
per acre. When aniinoniuni-salts are used as a manurf. the
loss is increased by the amount re(|uired to eoinl)iiif with tlie
combined acid in the manure. Tlie calcium carbonate. In.w-
ever, which is required for nitrification, gets returned lo thr
soil by the growth of the plant itself, and by ilu- decay ot
calcium compounds in the crop residues.

Hkkkhk,N( ES

•' On Nitrification " (R. Warington). Trans. Chew. S,„:, 33 (1S7S). J I.

"On Nitrification," Part II. (U. Warington). Trans: (hem. Sue., 35 (1879).

429.
"On Nitrification," Part III. (R. Warington). Trans, ('hem. S,,,-.. 45 (lSS4),

637.
*' On the Distribution of the Nitrifying Organisms in the Soil " (R. Warington).

Trans. Chem. Sue., 51 (1887), US.
"On Nitrifieation/' Part IV. (R. Warington). Trans, ('hem. .Sor., 59 (IsOl),

484.
•' On the Amount and Composition of the Rain and Drainage \N .iters cnl-

leeted at Rothamsted." Jour. Roi/. Ag. .S'oc, 42 (1881), L'41 and ".11 :

and 43 (1882), 1. Rothamsted Memoirs, Vol. \'., No. 18.
•• Determinations of Nitrogen in the Soils of some of the Experiment.il

Fields at Rothamsted, and the bearing of the Results on the (Question <>f

the Sources of the Nitrogen of our Crops." Report of the .\meriean

.Association for the Advancement of Science, 1882. Rothamsted .Memoirs,

Vol. v., No. 19.
"On the Productive Powers of Soils in Relation to the Loss of Plant -fcM.d

by Drainage" (A. Voeleker, Ph.D., F.R.S.). Jonr. Chem. .So... 24

(1871), 276.
••'Six Lectures on the Investigations at Rothamsted Experimental Station.

delivered under the provisions of the Lawes Agricultural Trust, by R.

Warington, F.R.S., before the .\.ssociation of American .Agricultural

Colleges and Experiment Stations, at Washington, D.C., .Aug. 12- Is.

1891." Experiment Stati<.n Bulletin. No. 8, I'nited States Department

of Agriculture.

CHAPTER XII

THE FEEDING EXPERIMENTS

I. Relative Value of Nitrogenous and Non-nitrogenous Constituents of Food.
II. Relation of Nitrogenous Food to Work.

III. The Source of Fat in the Animal Body.

IV. Relation of Food Consumed to Live Weight Increase.

V. The Composition of Oxen, Sheep, and Pigs, and of their Increase during

Fattening.
VI. The Manure Value of Foods.
VII. Miscellaneous Feeding Experiments.
References.

I, — Relative Value of Nitrogenous and Non-nitrogenous
Constituents of Food.

At the date of the inception of the Rothamsted Experiments
even less was known about the laws of the nutrition of animals
than of crops, though the question had excited more interest on
the Continent than in England. Here attention had been in the
main concentrated upon the animal ; it had been the object of
breeders and graziers to develop races of stock that would give
the least waste and the largest proportion of useful meat to live
weight. To this end early maturity had also been successfully
sought, thus economising the food used merely in keeping the
animal alive without, increasing its weight. On the Continent,
however, even in the eighteenth centmy, attention had l^een
rather directed to the character of the food, and especially to
obtaining a measure of the comparative value of different foods,
with the view of ascertaining how far one could replace
another.

As an example of what was going forward, Thaer's " hay

EARLY THEORIES OF M'TIMTIoN -JH

values " may 1)6 instanced ; in ls()«> lie puLlislicd a ial)l.' ot all
the recognised cattle foods, ranged in order and marked lo slntw
how much of each was equivaliMit to 100 parts of hay taken a>
a standard. Timer's hay values were Itascd parhv on liis own
experience as a practical man and partly on attempts, very
imperfect in the then state of ehemieal kiiowlrd^p, to estimate
by analysis the nutritive constituents of the foods, liou.ssiniiault's
investigations were the earliest serious attempts to apply .scien-
tific principles to the feeding of animals ; the importance of the
nitrogenous constituents of food had now become clear, so his
first work consisted in determining the proportion of nitrogen
present in a large numljer of feeding materials. C'areful
practical trials were then made with a few selected foods, and
as a result he published a revised table of hay values, ])ased on
the amount of nitrogen the foods contained, and checke(l to
some extent by his practical experience. His experiments led
Boussingault to bring into prominence the non-nitrogenous
constituents of food, but in general his conclusions were that
the comparative values of food-stuffs are determined rather by
their nitrogenous than by their non-nitrogenous constituents.
In this subject Boussingault's was the pioneer work, and
Liebig, who in many respects must be regarded as the
originator of any general theory of animal nutrition, in the
main arrived at his deductions fi'om Boussingault's results.
Liebig also, and perhaps even more strongly than Boussingault,
looked at the nitrogenous matter as the most im])ortant
con.stituent of food for the production of both increase and ••!"
work.

In this position was the science of animal nutrition uln'ii
Lawes and Gilbert began their experiments on fce(lin<:. .nid
natm-ally the direction their experiments took was maiidy
determined by the views then prevailing. The most notable
characteristic of the Rothamsted experiments on animals was
that from the first they were concerned with animals increasing
in weight rather than with animals whose food rations wen-
adjusted to maintain them in a ccaistant condition. Ihr

242 THE FEEDING EXPERIMENTS

practical side Avas thus prominent : they were trying to give a
scientific basis to the work of the grazier by ascertaining to
what source the increased weight of an animal was due, and
how it might be produced most rapidly and economically.

The first set of feeding experiments at Rothamsted dealt
with the relation between food consumed and live weight
increase produced. Selected pens of the various animals were
fed upon specified rations of different foods, one of which was
always fed ad libitum, so that the exact composition of the
ultimate ration was determined by the animal itself. The
nitrogen and dry matter in the food was determined, and the
weight of manure produced both in a fresh and dry condition
was ascertained. In all, about 600 sheep w^ere employed in
the experiments, 160 pigs, and 200 oxen, many of the latter
being fattened on the Duke of Bedford's farm at Wobm-n.

The experiments with sheep came first, and tended to shoA^-
that the prevaihng impression of the special importance to be
attached to the nitrogenous constituents of food was not
correct, but that it was rather the supply of non-nitrogenous-
food which regulated both the amount of food consumed
by a given live weight in a given time and also the
increase in five weight produced. Of course, at that time
it was not possible to distinguish between the digestible and
the indigestible portions of the food, nor was any attempt
made to estimate in the different foods the relative proportions
of albuminoid nitrogen and of such nitrogen compounds as the
amides, etc., which are abundant in roots, but of whose feeding-
value nothing was known. That the exactitude of their
experiments was Umited by these considerations, was pointed
out by Lawes and Gilbert ; at the same time, the corrections
necessary would not invalidate the soundness of the general
conclusions they drew. The experiments on pigs indicated
still more clearly that the carbohydrates were chiefly concerned
in both the maintenance and in the increase in five weight of
the pigs, also that very great variations in the amount of
albuminoids consumed were without much effect on the result.

VARYING PROrOUTIONS Ol' A I.i;i M I \( )i i . -n;

when once the necessary ininiiiuim of nitrou'cnou^ inaiirr in tlir
ration had been passed. Tlio rations trd to the vari<.n> lots of
pigs were so arranged as to supply vcrv .litVcivnt pn.pc.rtions
of nitrogenous and starcliy food. In sonic cases the lood was
mainly highly nitrogenous bean or lentil meal, in others veiv
starchy barley meal or maize was employed; in another set

lb

-1 r

,c . 1

^
^

i

1

i

i

i
1

2. 3.

Nitro^enousSubstance.

1 Non-nitrogenous Substance

Fig. 46.— Dry Matter and Nitrogenous Substance consumed per 100 lb. Live-weighl
per week. Pigs.

1. Bean and Lentil Weal, ad lil>.

2. Maize Meal, limited. Bean and Lentil Meal, ad W>.

3. Bean and Lentil Meal, limited. Maize Meal, ad l\l>.

4. Bran, limited. Maize Meal, ad lil>.

5. Barley Meal, ad UK
*5. Maize Meal, ad lil>.

of experiments, actual starch or su;;ar wa,-. addcil i
rations. In all cases the pigs had an (id lihltuni supply (
food or other, so that they could regulate the amount ;
some extent the composition of their diet.

.f on.
md'tn

244

THE FEEDING EXPERIMENTS

The diagrams, Figs. 46 and 47, show, from some of these
results obtained with pigs, the amomit of dry organic matter
required to produce 100 lb. of increase, and also the proportion
of it which can be reckoned as nitrogenous matter.

It will be seen from these diagrams that, speaking broadly,
neither the amount of dry food- stuff* required for maintenance

lb,

400

R^

Ratio

Nitrogenous
Substance

~|Non-nitro|enous
J Substance

^ Ratio of non-nltro^enous
'to nitrogenous matter in food

Fig. 47. — Nitrogenous and Non-nitrogenous Matter in Food required to produce
100 lb. Live-weight Increase. Pigs.

1. Bean and Lentil Meal, ad lib.

2. Maize Meal, limited. Bean and Lentil Meal, ad lib.

3. Bean and Lentil Meal, limited. Maize Meal, ad lib.

4. Bran, limited. Maize Meal, ad lib.

5. Barley Meal, ad lib.

6. Maize Meal, ad lib.

per 100 lb. live weight of the animal nor the amount required
to produce 100 lb. increase in the live weight varied very widely,
whatever the character of the foods consumed. The amount
of nitrogenous substance did, however, show a very wide range
of variation, hence whatever was consumed above a certain
minimum could have been replaced without loss by pm^ely non-

NITROGENOrs Toon and \\n\:w «ji.-,

niti'Dgenoiis organic inatlci-. In oilier \v<>r<l>. tlir ii(»iMiiin.;^'riinu>
c'oiiiponnds aiv \\w main items to lu« taken into account in
making up tlic value of a cattle food, wliicli value camn.t In-
estimated on a basis of its nitrogen content onlv.

11. — Relation of Xi'ri!o(;KNoi s 1''ooi> io W'okk.

The very special im[)oi'tance that was originalK attaclie(l to
the nitrogenous constituents of food was also seen in the vie\N> of
J.iebig with regard to the source of tlie work, either external or
internal, performed l)y an animal. He put forward tin- \iew
that the amount of work done was determined by the amount
of nitrogenous material transformed in the body, and therefore
that it could he measured by the amount of nitrogen appearing
in the urine, since the albuminoids and other nitrogen com-
pounds in food which are digested and undergo change in
the animal are excreted as urea. Lawes and Gilbert, by their
studies of human dietaries, were led to conclude that this
view w\as mistaken, and that the fats and carbohydiates.
which are oxidised and leave the body in the respiration
products, supply the energy for the work performetl in and
l)y the body. Two experiments with pigs, carried out in lsr)4
and 1862 respectively, were adduced as further evidence. The
pigs w^ere confined in a frame ; the nitrogen in the food and the
nitrogen excreted in urine and fieces respectively were
determined. The food was so adjusted that one pig received
about twice as much nitrogen as the other (Table LXXW'II.).

The animals were obviously under equal conditions a>
regards exercise, both being at rest, yet in each experiment the
animal receiving the highly niti-ogenous diet excri'ted rather
more than twice as nuich nitrogen as urea. Thus the amount
of nitrogen in the urine, which measinv> ihr amount of
allmminoids oxidised, could hardly be taken as a measure of
the amount of w^ork performed by the respective animals.

The question was afterwards sy.stematically attacked in
various directions ])y other investigators, and diivct j)roof
was obtained that the energy require<l to cany on work is

246

THE FEEDING EXPERIMENTS

derived from the oxidation of the food constituents, either
albuminoids, fats, or carbohydrates being available for the
purpose, though as a rule the two latter are utilised. The

Table LXXXVII. — Experiments at Rothamstcd ivith Pigs in 1854 and
1862. Quantities per head per day.

Period.

i SS

1

Urea Voided.

Nitrogen
in Urea.

June to August 1854.

Days.
3

10
10

No. 1.
No. 2.

No. 1.
No. 2.

Lentil Meal
Barley Meal

Lentil Meal
Barley Meal

Grams.

123-0

58 -9

120-6
51-2

Grams.

134-0

61-5

141-0
52-1

Grams.
62-6

28-7

65-8
24-3

August to September 1862.

10
10

5

5

No. 1.
No. 2.

No. 1.
No. 2.

Barley and Bran
Beans and Bran .

Barley and Bran
Beans and Bran .

41-6
66-0

46-2
82-0

43-6
89-6

52-3
116-6

20-4
41-8

24-4
54-4

amount of energy obtainable from each food can be directly
measured by the heat it will generate when burnt, and provided
the animal receives enough nitrogenous material to repair the
norm.al waste of tissue, the energy required to do work can be
wholly derived from the combustion of non-nitrogenous
materials. However, when the output of work has to be rapid
and at high pressure, it has been found advisable to include a
fairly high proportion of easily digestible and concentrated
albuminoids in the food ; as Lawes and Gilbert put it in 1852,
"a somewhat concentrated supply of nitrogen does, however,
in some cases, seem to be required when the system is over-
taxed."

III. — The Source of Fat in the Animal Body.

The source of the fat stored up in animals, or given out as
milk, was also for a long time a matter of considerable contro-

FAT DERIVED rivM).M ( ' A IM'.i )| I VI )|:aTK

-'»:

versy. It was dear that tlic tat »iii.j.li.'.l in tlir CmmI wa> in
many cases, especially with herhivora. insiillicient to supjily all
the fat produced by the animal, and thouL^h Lichi^ on <4('ncral
grounds argued that the starch, sni^^ar, and other carhohydnites
of the food could be ela])orated into fat, for some time the view
Avas held that the extra fat could only come from tlie trans-
formation of albuminoids. This view was strongly opposed bv
Lawes and Gilbert, whose experiments upon tlie fattenim; of
pigs showed that the animals put on far more fat tlian conld be
made up from the whole of the fat and albuminoids in the foods.
To take one example, pigs were fed upon maize meal or b.irlrv
meal ad Jih., with the following results : —

Table LXXXVIII.

Iteriay
Meftl.

Number of Animals
Duration of Experiment
Original Live Weight per head
' Increase in Live Weight

Weeks

Lb.

Lb.

144
73

149
97

Per 100 increase in Live Weight.

(1) Albuminoids in Food

(2) Albuminoids in increased Live Weight .

(3) Leaving Albuminoids available for Fat Formation

(4) Fat in increased Live Weight
5) Fat in Food ...

51-7

79-0
2«-S

(6) Fat formed during the Experimnit

Relation of last item to the Carbon of Fat forim-d during tl>e KxiK-riiii.iit

64
6-5

57-5

71-2
12-4

Carbon in Fat formed (ti) ; • ■**^'*' i '*^**

Carbon in Food Albuminoids (3), less Carbon excreted in Una . 24*7 27'4

Carbon in Fat formed during Experiment, not derivable from Fat or

Albuminoid •I.''.'.' 17"9

5%

Thus, after crediting the fat put on by the animal .hiring the
experiment with the whole of the fat in the food, and with the
maximum that could by any po.ssibility be generated out of the
albuminoids in the food, there still remains abont 40 j)er cent.

248

THE FEEDING EXPERIMENTS

of the fat formed which could only have come from carbo-
hydrates in the food. Similar but less decisive evidence wa&
adduced from the sheep-feeding experiments, and the view
which Lawes and Gilbert maintained on these grounds has-
since been amply confirmed by the experiments of Klihn and
others.

TV. — Relation of Food Consumed
Increase.

TO Live Weight

Taking the ordinary foods available on the farm, Lawes and
Gilbert found that oxen, sheep, and pigs differed greatly in
their powers of consuming food, and in the rate at which their
live weights would increase. During the whole fattening period
oxen will consume per 1000 lb. of live weight 120 to 150 lb. of
dry food per week {e.g., in the experiments, 25 lb. cake, 60 11).
clover hay, and 350 lb. Swedes), and should produce about 10
lb. live weight increase per week. Sheep, per 1000 lb. live
weight, will consume in the same time about 150-160 lb. of dry
food (44 lb. cake, 52 lb. clover hay, and 70 lb. Swedes) for a
production of 17-18 lb. increase per week. The same live
weight of pigs, consuming 260-280 lb. of dry food (300 lb. barley
meal), will produce 50-60 lb. increase.

These results may be expressed in a table as follows : —

Table LXXXIX.

Number

of
Experi-
ments.

Number

of
Animals.

Dry Substance of Foo<i
consumed.
Average
duration : ,

of Per To produce
Experi- 1 p.-Hpar! ' WOO lb. lib.
ment. 1 frJilT i Live Increase
per week. height in Live
per week. Weight.

1
'""^^^'^ j ManSe*

Weight ^IJXf
per week. 1 J^^^^l

Oxen . 1 27
Sheep . 19
Pigs . 33

112
307
104

Bays.

'87

143

58

Lb.

146i

20i

48"

Lb. ; Lb. Lb. Lb.
121 13-0 9-4 50
159 9-2 17-2 54
270 4-8 56-2 63

* Dr>- JIatter of Solid Excrement and Urine exclusive of Litter.

These estimates, drawn up from a very large number of
trials carried out in the ordinary way of farming, have been
generally verified by the later exact work of the German experi-

FOOD KEQrilM'.l) ]\\ STocK

•_'}<»

nienters. if allowaiici- he lu.-ulc Wm ili,. Mip.-ri.)!- tatiniiip^'
(|ualities of the English .stork. I'rol.al.ly at thr prcsmt day
l)()tli the e.stiiiiates c)f the amount of food refpiinMl per (hCm and
tlie rate of increase should he raised, liccausc of the ininrc.vc-
ments that have been effected in the hrccils of onr sheep and
cattle. The modern farm animal is in fact a more ellicient meat
producing machine than it was fifty years ago. capal.le of
dealing with more food and of growing more rapidly to
maturity, thus shortening the time during which food has to he
consumed for purposes of pure maintenance only. It i> in t In-
direction that new experiments and additional data are geiieralh
needed, for we know nothing of the relative capacities of
modern breeds of farm animals as meat producers or of their
digestive powers for various foods. Due economy in feeding i.-
only possible if the practical man can check his opinitius by
reference from time to time to exact determinations of the re-
([uirements of different animals at various stages of their growth.

Others of the pig experiments showed how much less (jf
the food is utilised for increase as the fattening advances,
partly because as the animal increases in size it consumes more
food for purposes of warmth and internal work than before,
partly also because the increase made during the latter period is
more fatty and therefore drier than in the earlier stages.

The following tal)le shows the rates of increase of pigs fed

Table XO. — Fattening I'ujs. Weekly Consumption of Food, nnd rati-
of Increase.

FoodConsumo<l. ... Llve'^ghl.

Pood

otlnmum.

Per Head.

Per 100 lb.
Live Weight.

Per Head.

Per 100 lb.
UTeWelgbt.

First Fortnight
1 Second Fortnight .
Third Fortnight
Fourth Fortnight .
Fifth Fortnight

Lb. ' Lb. 1 Lb.
60-1 39-7 I.'--.''.
67-.-. 36-7 17 -J
66--1 30-9 13-2
66 0 27-4 12 9
69-6 1 26-3 11-3

Lb.

10-3
9-1

»5-2

r.-i

.3S9 1

.'ill

«J21

Mean

65-9 1 3J-

I'.V

-250

THE FEEDING EXPERIMENTS

on an unlimited supply of barley meal together with a fixed
ration of 1 lb. per head of pea meal per diem.

V. — The Composition of Oxen, Sheep, and Pigs, and of
THEIR Increase during Fattening.

The most important work carried out at Eothamsted on
the nutrition of animals was the determination of the composition
of ten farm animals in different stages of growth and fattening.

Store Half-fat Fat Very fat Store Fat

Sheep. Sheep. Sheep. Sheep. Pig. Pi|

^^1 Mineral Matter .' ^^^NitrogenousSubstance A' ^^^ fat Z \ |Water .

Fig. 48.— Percentage Composition of the Whole Bodies of Oxen, Sheep, and Pigs

For this purpose the following animals were selected — a fat
calf, a half-fat and a fat ox ; a fat lamb, a store sheep, three
others in the half-fat, fat, and very fat condition ; a store and a
fat pig. These animals after slaughter were carefully divided,
and the weights of the carcass and different parts of the offal
were determined. Afterwards the proportions of water, fat,
nitrogen, and ash in each part were determined, the composition
of the ash of each part being determined later. A summary of
the results is set out in Table XCL, while the diagram (Fig.
48) shows graphically the composition of the entire animals.

PERCENTAGE ('( ).M l^osiTloN

:.'."» 1

Table XCI. — Percentaiic Composition of the Carcasses, th> Offal, >ind the
Entire Bodies of ten Animals of different descriptions, or ■■■ f-fr--'
conditions of Matwity.

Koscription of Animal.

Mineral Matter
(Ash).

NitrogenouH
SnbataDce.

Per cent, in Carcass.

Fat Calf
Half-fat Ox .
Fat Ox .

Fat Lamb
Store Sheep .
Half-fat Old Sheep
Fat Sheep
Extra Fat Sheej) .

Store Pig .

Fat Pig. . . .

Mean of all

4-48 ; 16-6 16t5
5-56 17-8 22-6
4-56 15-0 34-8

3-63 10-9 36-9
4-3() i 14-5 23-8
4-13 1 14-9 ' 31-3
3-45 • 11-5 ' 45-4
2-77 0-1 55-1

2-57 14-0 -JS-l
1-40 10-5 i 49-5

37-7 .vj-:;
4()-0 54-(»
54-4 I5r,

51-4 4v.i
42-7 57-.'!
50-3 49-7
60-3 39-7
67 0 33-0

44-7 55-3
61-4 3.^-fi

3-69 13-5 34-4 51-6 48-1

Per cent, in Ofial (excluding Contents of Stomachs and Intestines).

Fat Calf
Half-fat Ox .
Fat Ox .

Fat Lamb
Store Sheep .
Half-fat Old Sheep
Fat Sheep .
Extra Fat Sheep .

Store Pig
Fat Pig.

3-41
4-05
3-40

2-45
2-19
2-72
2-32
3-64

3-07
2-97

17-1 14-6
20-6 15-7
17-5 2ti-3

18-9 20-1
18-0 , 16-1
17-7 18-5
16-1 1 26-4
16-8 i 34-5

14-0 15-0
14-8 1 22-8

35-1 G4-9
40-4 i 59-6
47-2 52 -S

41-5 5S-:.
36-3 •i.<-7
38-9 61-1
44-8 55-2
54-9 45-1

32-1 67-9
40-6 j 59-4

1

Mean of all

3-02

1
17-2 1 21-0 41-2 5SS

1 1

Per cent, in the Entire Animal (Fatted Live Weight).

[

Fat Calf

Half-fat Ox .

FatOx ....

Fat Lamb
Store Sheep .
Half-fat Old Sheep
Fat Sheep .
Extra Fat Sheep .

Store Pig
Fat Pig .

3-80 15-2
4-66 16T,
3-92 14-5

2-94 12-3
3-16 14-8
3-17 14-0
2-81 12-2
2-90 10-9

2-67 13-7
1-65 10-9

1

14 8 33-3 C3'0
19-1 JO-3 51-6
.'iO-l 48-5 15-5

2S-5 43-7 47-8
18-7 3ti-7 57-3
23-5 40-7 50-2
35-t) 50-6 43-4
45 -S 59-6 35-2

23-3 .'tg-" 55-1
42-2 54-7 41 t

S-17
8-19
.•4-98

S-54
«I-00
9-05
6 02
5-18

'>-n

.«U7

Mean of all

3 17 18-6

28-2

44-9

25!> THE FEEDING EXPERIMENTS

It is obvious that from these results a great deal of evidence
can be obtained as to what goes on during the fattening process,
if we can assume that the particular animals selected for
analysis are typical of the ordinary run of live stock and
represent the normal change in composition of fattening
animals. It is obvious, for example, that the fattening process
is properly so called ; even animals in the store condition
contain rather more fat than nitrogenous substance, but as the
fattening process advances the proportion of fat to albuminoid
rises until it becomes two or even three times as great.
Of course the gross amount of albuminoid in the animal
continues to increase somewhat, but the increase in the fat is
so nnicli greater that the proportion of albuminoid in the
finished animal has been reduced. It will be seen also that the
fat animal contains less water than the same animal in the
store condition ; lean meat possesses, in fact, a considerably
higher proportion of Avater than fat does, so that the accumula-
tion of fat tends to reduce the proportion of water in the whole
body.

From the figm^es obtained in these experiments the composi-
tion of the live-weight increase during fattening can be deduced.
This is set out graphically in the diagram Fig. 49, from which
it will again be seen how much of the weight put on by an
animal during fattening is made up of fat itself. In oxen, when
the fattening process begins while they are young, as is generally
the case noAvadays, the increase of weight will consist of about
one-third Avater and tAvo-thirds dry substance, the latter being
made up of about 15 per cent, of nitrogenous matter and 75-80
per cent, of fat. For the final fattening stage, Avhen the animal
is full groAvn, about three-quarters of the increase will be dry
matter, containing only about 10 per cent, of nitrogenous
matter and 90 per cent, of fat.

In the case of sheep, rather more mineral matter is contained
in the fattening increase, because of the large content of avooI
in alkaline salts ; but despite the nitrogenous natm^e of wool, the
amount of nitrogenous matter in the increase is less for sheep

COMPOSITION OF IXCHKASK IN WKHilir :.':>:{

100 ,

€0

AO

20

^

^

Ash %

% m%^

\\\\\

Oxen. Sheep. Pi^;

^^^^ Nitrogenous Substance X

Fat 7.
Water X

Fui. 49.-Oxen, Sheep, a.ul I'igs. C..n.p<..sitioM of imrea.ve in Fattrn.i.K.

254 THE FEEDING EXPEEIMENTS

than fur oxen, the balance being made up by an extra proportion
of fat, which may amomit to 75 per cent, of the increase. In
the case of really fat pigs the increase will contain about 70 per
cent, of fat and 7 per cent, of nitrogenous matter, being even
less nitrogenous and more fatty than with sheep.

These experiments on the composition of whole animals,
which form the fundamental basis of om* knoAvledge of the
nature of the animal's body and of the changes taking place
during growth and fattening, have never been repeated.

VI. —The Manure Value of Foods.

In order to form any estimate of the value of different cattle
foods, it is of much importance to know how far their various
manurial constituents — nitrogen, phosphoric acid, and potash —
find their way into the manure heap, and so back to the
farm.

In the experiments previously described it is seen how
small a proportion of the nitrogenous constituents of food is
retained in the increased live weight of the animal dming
fattening, by far the largest portion being passed undigested
into the f?eces, or excreted as urea in the urine. When the
animal is producing milk, however, a much larger proportion of
the nitrogen will be removed in the milk than is retained in
fattening increase, and the manm'e made will be correspond-
ingly poorer. At the other extreme is the case of a working
horse or a store beast not gaining in weight, when the whole
of the nitrogen supphed in the food will be voided in the
faeces or the lu-ine.

As regards the mineral matters of the food, after the animal
has withdrawn a certain small proportion for increase or for
milk, the remainder must find its way into the manure ; but in
the case of the nitrogenous compounds there is always the
possibility of loss, because some of the nitrogen may pass into
volatile ammonia, or even into gaseous nitrogen, during the vital
processes.

The question of the existence of this loss was investigated

LOSS OF NITIJOOKN DlIMNir !• I'Kl )I \( ; i.>r.:»

at Rotliamsteil in IS7A with n'uj^s, ihc aiiiinals l.rin^ ciiirmrd in
a frame resting upon a sloping' zinc hottoni. Tlicy were \vatclic(|
(lay and night diu-ing the experinu'Ulal period, .md ih.- vnidinu'-
were collected as soon as passed, and analvsiMl ai ic^nlar
intervals for dry matter, ash, and nitrot^cn. The results wen-,
however, not satisfactory ; there was a considci-al.Ii' iK.ition <.r
the nitrogen of the food unaccounted for in eitlicr tljc increase
of weight or in the excrements. The results seenjed to show
that the loss was probably due to the difhcuhies of j»roj)er
collection and analysis of the excreta, so that the experiment
was repeated with greater precautions in 1862. This time the
losses of nitrogen were much reduced, and when allow aiiet' wa>
made for the many unavoidable sources of error, tlie results
supported the idea that the whole of the nitrogen of the food
not stored up as increase passed over into tlu^ maiun-e. ( )tliei-
experiments were made with sheep; but again it was impossible
to avoid some mechanical losses, and to eliminate the une(M-tainty
due to lack of exact knowdedge of the composition of the
animal at the beginning and close of the experiment.

Later experiments on the Continent have indeed set the
point at rest, and shown that there is ncj decomposition of
nitrogenous matter of the food into nitrogen gas during the
vital processes, but that the whole of the digested nitrogen
which is not utilised for increase, milk, etc., is voided in the
urine.

The practical question which greatly occupied the attention
of Lawes and Gill)ert was that of tlie manure value (.f the
many purchased cattle foods commonly used in ihi> country,
and particularly the compensation t(j be paid to an ouiLroini:
tenant for their consumption in the latter years of his tenancy,
liefore he could be supposed to have ol)tained a return from
them in the shape of the crop. Lawes and (Jill)ert fiierefon-
prepared a table showing the composition of most of the cattle
foods commonly in use, and calculated wiiat proportion of the
nitrogen, phosphoric acid, and pc^tash present would under
normal conditions be retained bv fattening stock consunn'n.u' tin-

256 THE FEEDING EXPERIMENTS

food. Thus when stock consume linseed cake, Lawes and
Gilbert calculated that every 6 lb. of food produced 1 lb.
increase in live weight containing 1 "27 per cent, of nitrogen ; so
that if 1 ton were consumed, out of the 106*4 lb. of nitrogen in
the cake the animals would retain 474 lb., and pass on to the
manure 101 '66 lb. The same ton of linseed cake would contain
44*8 lb. of phosphoric acid, of which the fattening animal would
only retain 3"21 lb., and 31*4 lb. of potash, of which the animal
would only retain 0*4 lb.

When dealing, however, with less concentrated foods the
amount required to produce 1 lb. of increase would be much
greater and the toll taken by the animal of the nitrogen in the
food would also increase. For example, 1 ton of oat straw
contains 11*2 lb. of nitrogen, of which the animal would retain
1*6 lb. and pass on 9*6 lb. to the manure — only 86 per cent, of
that wdiich had been fed instead of over 95 per cent., as in the
case of linseed cake.

From data of this kind Lawes and Gilbert were able to
calculate for each of the named foods the amount of nitrogen,
phosphoric acid, and potash which would go to the manure.
The experiments before mentioned had gone to show that there
is no loss of nitrogen during the actual feeding pi'ocess.
However, it had been ascertained that even under the best
conditions (as in the cattle-feeding experiments at Woburn
before alluded to) there were great losses of nitrogen in making
the dung before the manm-e reached the land, these losses being
due in the main to the volatilisation of ammonia resulting
from the rapid fermentation of the urea. Such losses, too, fall
upon the urea, the most valuable part of the excreta, since the
undigested food residues in the faeces decay so slowly in the
ground as to have a lower manm^e value. Very few data
•existed from which to determine how large these losses are
under ordinary farming conditions, but Lawes and Gilbert felt
safe in assuming that at least one-half of the manurial material
voided by the animal is lost during the making and storage of
the dung, and does not come back to the land in the manure.

MANURE VALrES (W CAT'l'li: I'oops 'j:,:

The compensation taMr ihcy di-cw up >li(.\\.-«l (l) tli.-
amount of nitrogen, plujsphoiic acid, ami pnia^h in tin- food
itself; (2) the amomit passed l)y tlic animal alter takin;^ nnl
what it required for its own fattenini^^ increase ; (:J) [\w vahie of
this voided material at the current i)i-ic-es of tliesc constituents
in manures, or as they called it, tlie "original maiune vahie" of
the food. They then proceeded to arrani^'e a (-onipensation
tal)le on the basis of allowing tlie outgoing tenant half tlii>
original manure value, i.e., assuming that only iiall' of the
manure material voided by the animal would lie louud by the
incoming tenant in the manure heap he was taking over, '^lli•^
compensation value was further diminished by one-third fi>i-
each additional year between the date when the food was con
sumedand the expiration of the tenancy ; thus the com|)ensatioii
value of food consumed in the last year of the tenancy would
1)6 half of the original manure value, and it would l»ecome
(me-half less one-third of itself (or one-third of the original
manure value) for food consumed in the second year before
the tenancy ended, and so on by steps of one-third less foi-
each earHer year. These tables were based on the composition
of the fattening increase as ascertained in the previous experi-
ments. Other tables were drawn up for milch cows, wln\-li
take a much greater toll of the food consumed.

These compensation tables never passed into general use.
partly because of the somewhat complex character of tip-
argument and the long period previous to the expiration of the
tenancy over which tliey allowed compens<ition to l)e claimed
for the consumption of purchas.-d food. Tliey liave, however,
brought into prominence the gieat errors introdn'--' '- ♦^"
common custom of paying half fl^e purchase price •
consumed during the last year idy of the lenancy, .si;
manure value of a food is quite m.lependeiit nf its fo,..|
and price in the market. Decorticated cotton eake. for example.
has the highest manure value of any >ub>taiice .nnuiionly used
for food, yet it can be purchased more cheapl\ than linseed wike.
which has a much lower manure value. Maize, again, however

R

258 THE FEEDING EXPERIMENTS

valuable as a food because of the carbohydrates and fat it
contains, has but a low manure value, since it is comparatively
poor in nitrogen and ash constituents. Thus the custom of
paying half the last year's cake bill would result in paying too
highly for linseed cake and maize and too little for cotton cake
consumed on the farm.

As an appreciation of these facts gradually spread among
practical men in consequence of the Rothamsted pubhcations,
and as recently legislation rendered it imperative to put this
question of compensation due to the outgoing tenant on a sound
scientific basis, the matter has latterly received more attention
from farmers and professional valuers. More data have also
been accumulated as to the nature and extent of the inevitable
losses of nitrogen in manure making, so that it has been possible
to construct a modified version of the original compensation
table, which now seems to be generally accepted in principle by
the valuers chiefly concerned.

VII. — Miscellaneous Feeding Experiments.

The above summary by no means exhausts the many
experiments upon animal feeding which were carried on at
Rothamsted. One set of trials, for example, was arranged to
test the relative values of starch and sugar as foods, with the
result tliat they were found to l^e sensibly equal, as we should
nowadays expect in the light of the equal calorific value and
similar chemical composition of these foods.

Other trials chiefly dealt with jDractical points, as for
example the long series of trials on the comparative fattening
qualities of different breeds of sheep — Hampshires, Southdowns,
Cots wolds, Leicesters, and crossbred Leicester- Southdowns
being selected for the purpose.

Experiments on the use of condiments in cattle feeding
proved of great practical value, as they showed the exaggerated
nature of the claims which were being advanced by the
manufacturers of some of the patented cattle foods.

Other feeding experiments dealt with the comparative value

('()\(M.rsi()xs I'.vj

of sewage-irrigatod and t.rdinnrv meadow ,i:ra>s. wiih iiirus.'..r
malted foods, with tlic valiir of ensilage ; l.m iIm-s.. ujl) )„.
dealt with separately.

JSpeaking generally, these feeding expcrimriits ni" l.awcs .uid
Gilbert, while they will not l>oar the exact analysis to which
later experiments carried out in respiration chamltcrs can )>.•
subjected, so that the digestibility of the foods and thf p<ii-tion>
which go to maintenance, increase, and work respi-ctivcly can
be ascertained, yet gave a somul general idea of the broad
principles of animal nutrition as they affect the farmer. Tin \
are noteworthy for the intuition with which correct opinions o|
the general processes were deduced ])y statistical means from
experiments carried out in the main under onlin.uy farming'
conditions, opinions which have in all cases l»een .ilinndantlv
verified l:)y later and more accurate research.

Refkuences

" Aivricultural Clu-mistry : l>i.^•-Fel■di^i,^" Jour. Ifoi/. .Ig. S,,,:, 14 (lf*.')3),

459. RotJunnsted Memoirs, \o\. II., No. •").
-'Experimental Enquiry into the Composition of soiiu- ot" the Aniin.ils I'cd

and Slaughtered as Human Food." Phil. Tnuis., 149 (IS.-.'.I), I '.».;.

Roihamstcd Memoirs, Vol. III., 4to, No. 1.
■"On the Composition of Oxen, Sheep, and Pigs, and of their Iiicreasr

wliilst Fattening." Jour. Uoij. Ag. Soc, 21 (ISGO), I'M). liutlmmsUd

Memoirs, \o\. 11., No. 12.
"The Feeding of Animals, for the Prothutidii of Mt-it, Milk, .iiid Manur. .

and for the Exercise of Force." Jour. Jioi/. .Ig. .Soc, 56 (i>'.i'>\ IT

Rotham.sted Memoirs, Vol. \TI., No. 13.
'^'The Royal Commission on Agricultural Depressittn and tht- \alti ition

of Unexhausted Manures." Jour. Roi/. .ig. Soc, 58 (1S"J7), 'm I

Rotham.sted Memoirs, Vol. VII., No. 9.
■"The \'aluation of the Manures obtained by the ( oiisumptioii of F«mmI>.

for the Production of Milk." Jour. Ro>,. Ig. S,n:, 59 (ISI)S). |n;!

Rothmihsted Memoirs, \(A. VII., No. 10.
^'The Value of Unexhausted Manures obtained by th.- (Musumplion of F«mmIs

bv Stock." by J. A. Voelcker and A. I). 11., ,/./.'. /.V, 63 (19()2), 70.

CHAPTEE XIII

MISCELLANEOUS ENQUIRIES

I. Experiments upon Sewage Irrigation.
II. Experiments upon Malt and Barley.

III. Experiments upon Ensilage.

IV. The Composition of Wheat Grain and its Mill Products.
References.

I. — Experiments upon Sewage Irrigation.

From time to time the Eothamsted investigators were called
upon for work dealing with various debatable questions of
public importance more or less connected with agriculture.
For example, Lawes was appointed a member of the Royal
Commission which was charged in 1857 "to inquire into the
best mode of distributing the sewage of towns, and applying it
to beneficial and profitable uses." The application of sewage
to land was. naturally one of the subjects of enquiry, and was
entrusted to a sub-committee consisting of Lawes and Way^
who carried on during 1861-64 experiments at Rugby on the
growth of grass Avith and without sewage treatment, and on
the value of the sewage-irrigated grass for feeding stock. The
experimental station at Rothamsted was much occupied ^vith
the suiDerintendence of these experiments and with the analytical
and statistical work involved. The general conclusion from the
experiments was that broadcast irrigation on grass land was
the best way of dealing with sewage, the highest returns being
obtained when large quantities of sewage, as much as 9000
tons per acre, were employed.

VALUE OV MAIT IN I-|:i:i >! \( ; -j,-,!

As to tlic grass — that grown in sewage was tniiiid to I.e
more watery tlian tlie unsewaged grass ; lieiiee. of efjiial wei<,'lits
of green grass, tlir uiisewaged produced tlie most increase in
fattening oxen. But calculated on a ])asis ctf equal weights
of dry matter, the sewage-irrigated grass gave the Letter
results. The best returns were, however, obtainecl when the
grass was fed to milking cows; sewage ii-rigation wa> fdund
to mcrease the amount of milk which could he produeed
from 1 acre of land three- or four-fold. The herl)a"e of the
sewage-irrigated meadows was found to change rapidlv ; ihr
Leguminosa) disappeared, as did most of the miscellaneous
i^pecies, while the grasses became restricted to two or three
vigorous species, which constituted the whole vegetation,
j^uch as rough-stalked meadow grass, couch grass, cocksfoot,
Yorkshire fog, and rye grass.

II.— Experiments upon Malt and Baiji.kv.

In 1863, at the request of the Board of Trade, experiments
Avere undertaken to ascertain the relative feeding value of malt
and of the barley from which it was made, so as to see if any-
thing was gained by the process of malting. It had often l)een
asserted, and was the opinion of many practical graziers, that
even if there were some loss in the process of converting barley
into malt, yet the superior digestibility of the malt and its
action upon the other items of the whole food more than
compensated for this loss.

The investigation was divided into two stages— (1) an
encjuiry into the natiu-e and amount of the losses dming th'*

malting process; (2) a comparison of the t 1 value ..f the

resulting malt and of the original barley.

Two lots of barley were selected for the .'xperinient. • a

malting l)arley of fair (piality, the other a tiiinner, more nitro-
genous barley, such as would only be used for feeding. The
malting was done in tlie ordinaiy way, at Hertford, and .siiujples
of 25 lb. each were taken of the grain l.cfore steeping, when
thrown out after .steeping, at intervals .luring growth, and

262 MISCELLANEOUS ENQUIRIES

finally after drying and screening ; these samples being sent to
Rothamsted for analysis.

The results are summarised in the following ta1)le, which
shows for each sample the changes during the various stages,
as calculated back to 100 parts in the original material.

Table XCII. — Loss of Constituents at certain Stages, and at the conclusion
of the Malting Process. Proportion to 100 before Steeping.

2

II
If

^•

.

Final Products sent

5 o

II

to the Kilu.

II

?1

^2

S5

1

=«

X

Barley No. 1.

As Sampled ....
Total Dry or Solid Matter .
Non-nitrogenous Organic Matter
Nitrogenous Matter
Mineral Matter .

100

143-2

135-4

78-93

2-20

1
81-13

100

99-6

95-9

89-45

2-35

91-80

100

99-9

95-7

89-66

1-74

91-40

100

99-6

99-0

90-61

6-45

97-06

100

90-3

89-4

77-68

7-94

85-62

18-87
8-20
8-60
2-94

14-38

Barley No. 2.

As Sampled

Total Dry or Solid Matter .
Non-nitrogenous Organic Matter .
Nitrogenous Matter
Mineral Matter ....

100
100
100
100
100

98-3
100-0

138-7

74-62

3-21

96-1

87-78

3-41

95-8

88-19

2-62

97-1

85-52

7-14

102-5

84-76

12-02 !

77-83 22-17
91-19 8-81
90-81 I 9-19
92-66 } 7-34
96-78 ' 3-22

For example, dealing with sample No 1, we see that 100
parts of grain yielded 79 parts of malt and '2'2 of malt dust, a
loss of weight of nearly 19 per cent. This loss was, however,
largely water, for the next row of figures shows that of 100
parts of dry matter in the original material 91*8 were recovered
in the malt and malt dust. During steeping 0*4 per cent, of dry
matter was lost, consisting of mineral matter (largely dirt
washed ofi" the grain), a little nitrogenous matter, and the ready-
formed sugar in the barley. During the process of growing on
the floor something over 4 per cent, of dry matter is lost ; the
table, for instance, shows a fall from 99*6 parts of the original
dry matter to 95-9 parts, by the eighth day. This loss is due to
the respiration process accompanying growth, and represents

LOSSES DI'IMNC MAITINC ^iVA

the combustion of a certain ainmint of starch into carlMmic acid
and water, which escape into the .dr. During ilic kilnin-,' and
drying process there is a furtlicr loss ot (h-v matter, tins lime
mainly a mechanical loss due to mah dust, whicli fails throuL'li
the wire floor into the flre.

The further figures show that of the nitrogenous materials
there is a Httle loss by solution in the stce[)- water, but little or
none upon the floor, where there will be no production ol'
free nitrogen as long as the germination process is proceedim:
properly. The chief loss of nitrogenous material is mechanical,
in the drying and screening process. Similarly with the
mineral matter : after the first loss in the steep no otheis are
possible save those of a mechanical nature. It should be
noticed, however, how much of the nitrogen and mineral matter
passes into the malt dust ; the young shoots of the barley plant
are comparatively far richer in nitrogen and mineral matter
than the whole grain. The other changes, which take place
(Imping malting and are not shown in this table, would be thi'
incipient conversion of some of the starch into malt sugar (it is
well known that malt possesses a comparatively sweet taste) and
the migration of a large portion of the all)uminoids of the grain
into soluble nitrogenous compounds, chiefly anii<les and amino
acids, the nutritive value of which is certainly less than that
of the allumiinoids from which they were derived. The malt
also contains large amounts of diastase, the ferment which
converts starch into sugar during "mashinir." the next brewim:
process.

The figures thus ol)tained foi- the changes during the
malting process agree with those generally accM'pted by
maltsters to-day, who expect to lose 10-11 per cent, of material
(dry weight), distributed as follows: —

Loss in steep ... 1 P'"'' '•'''^^•

Loss by respiration 4.)

Malt dust . . . *

Waste . . . . I ••

The waste has been (Umini.shed bv the cmph.yni.-nt of tiled

264 MISCELLANEOUS ENQUIRIES

floors to the kiln instead of woven wire, but the great loss by
respiration is a necessary part of the process.

The problem then remaining was to ascertain if the
inevitable loss thus produced in the dry matter of the original
barley would be compensated for by an increased digestibihty
of the malt. Experiments with stock were made as follows :—

(1) Milch cows, two lots often, each animal receiving either

3 lb. of l^arley or its equivalent in malt per diem. The
experiment lasted for 10 weeks, and the amount of milk
produced and the live weight of the cows were recorded.
The general ration to which the barley or malt was
added consisted of 2 lb. rape cake, 2 lb. bean meal, 14
lb. clover chaff, 7 or 8 lb. straw chaff, and 50 lb. Swedes
per head per diem.

(2) Two lots of three-year-old bullocks were fattened,
receiving respectively either 4 lb. barley No. 2 or its
equivalent in malt, in addition to a general ration of
clover chaff, cake, and Swedes ad lib. The experiment
lasted 20 weeks.

(3) Five lots of twelve Hampshire Down wether lambs mider

cover. Lot 1 had for 16 weeks J lb. and for 4 weeks
1 lb. barley No. 1, per head per diem. Lot 2 had an
equivalent in malt from barley No. 1. Lot 3 had
similarly f and then 1 lb. of barley No. 2. Lot 4 had
the equivalent in malt. Lot 5 had the same weights of
a mixture of two parts unmalted and one part malted
barley No. 2. The general ration was 1 lb. of clover
chaff, and cut Swedes ad lib.

(4) Six lots of eight pigs for 10 weeks. Lot 1 had unmalted

barley No. 1 ad lib. Lot 2 had the malt from the same
barley, also ad lib. Lot 3 had both barley No. 1 and its
malt separately ad lib. Lots 4, 5, 6 were similar, save
that barley No. 2 and its malt were substituted. All
the pigs in addition had 1 lb. each of pea meal per
diem.
In all these trials the final differences in the weights of the

NO (;AIX DTK TO M AI.hm; 26:)

comparative lots, reccivinu oil the ( lilt" hand liarl.y aii.l on tlir
other an equal (iiiaiitity turned into malt, wore sjnall. and ntit
mueli removed from the inevital)le erntr in exprrimcnts of thi>
kind. But, as a rule, the ditterenees wvw in faNonr of ilir
barley, so that Ave may eonelude that iiothinic had Itrm ^'aincd
by the changes which the malt had mideru^.nc whieh would
compensate for the loss of dry matti'r. This is indccil what wr
should have expected; we now know that the whole of ih.-
l)arley is easily digestible except a certain amount of hn>k.
This husk is unaffected by the malting process, and i> not
rendered thereby more digestible. The malting changes, in
fact, consist in a destruction of some of the most soluble and
readily digestible carbohydrates, together with a tiansforniati(ni
of albuminoid into amides and other nitrogen coin})ounds of
less nutritive value. Thus the general conclusion may be drawn
that it is not economical to malt grain l)efore using it as food
for stock; since, putting on one side the cost of the malting
process, the result is only a loss of some of the most valuable
parts of the grain.

It has, however, been pointe<l out by Dr H. T. Brown that
there may still be some foundation for the graziers' high opinion
of a little malt in a mixed diet.

The greater part of the kernel of the grain of cereals consists
of starch-containhig cells, which are invested by a thin
cellulosic membrane. As long as this membrane remains intact
it c(mstitutes a formidable barrier to the free action of the
starch-dissolving enzyme of the pancreatic fluid, which plays
isuch an important part in the dissolution of the solid staich-
granules when once the food has passed the pyloric orifice.

There does not appear to be any provision in tlu- dige>ti\e
tract of the herbivora for the secretion of an enzyme capable of
attacking this investing membrane, the dissolution of which
under ordinary conditions is l)rought about in the stomach by an
enzyme pre-existent in the grain. Cnder eeriain (•<»nditi..n> ihi-
enzyme, cytase, may either be absent from the foo<l-grain or
present only in minimal quantity, in wJiich case the addition to

266 MISCELLANEOUS ENQUIRIES

the food of a material rich in cytase may be expected indirectly
to aid tlie more ready dissolution and assimilation of the starch.
Such a material is malt, provided it has not been kiln-dried at
too high a temperature, for, during the process of germination to
which it has been subjected, there is a considerable production
of cytase in the grain. But the rations used in these experi-
ments were not rich in cellulose material, consequently there
was no real test of whether the extra cytase l)rought in by the
malt would have any beneficial effect.

III. — Experiments upon Ensilage.

During the early eighties in the last century, owing to a
succession of wet summers, the question of ensilage came
prominently before the agricultural public, and farmers were
urged to convert their grass and forage crops into silage instead
of running the risks of loss and of Avasted time incident to the
operation of hay-making. Silos were built on various prin-
ciples all over the country, but before the system had made any
real headway, the cycle of dry seasons, which began with 1887,
set in, and farmers no longer felt the want of the process.
Latterly, with the growth of forage maize in the drier districts
of the country, the making of silage has been re\dved some-
what, the idea being to utilise maize silage instead of roots, as
is so largely done in the eastern states of America.

Experiments on silage were begun at Eothamsted in 1884
with the construction of two rectangular tanks calculated to hold
about 100 tons of silage each. These were filled — one with red
clover, l3oth first and second crop, and the other with meadow
grass ; the materials were chaffed and weighed as put in, and a
number of samples were taken from which to ascertain the
average composition of the mixtm^e entering the silo. The silos
were emptied between December and the following April, when
in the same way the material leaving each silo was weighed
and sampled. The analytical results were not wholly satis-
factory as far as the determination went of the loss of dry
matter during the making of the silage. Such material, both

LOSSES IN MA K INC SIl.ACi: •_'♦;:

as put in and as taken out. i> .siil.jcct to sucli vari;iti(.ii> in
water-content that a vcrv l.ir-c iimnlxT of samples arc nMiiiirctl
from which to obtain a fair avcrauv for the comiit^itioii of tlir
whole.

The resuhs indicated that the losses ueie not so j^Mvat as
was then commonly supposed; not more than .'> per cent, of
the total dry matter of the clover, and alnait 1.") pci- eein. (.f the
dry matter of the grass appeared to be lost. Tlie analyses also
indicated a certain loss of nitrogenous matter ; the chief change,
however, consisted in a conversion of a large proportion of the
albuminoids into nitrogenous compounds of lower grade, aniide>
and kindred bodies. The loss of dry matter chiefly fell npon
the non-nitrogenous constituents, but the evidence was all
against the idea that any of the woody fibi'(> was convert e(l into
a more soluble and digestible form.

The next step in the experiments consisted in testing the
feeding value of the silage produced, and for this pnrpnsr
experiments were made both with fattening oxen and with
cows in milk. Two lots of five oxen were picked ont an<l fed
with 6 lb. cake and 4^ lb. l)arley meal each per diem. In
addition, the beasts in one lot received 65 lb. of clover silage, and
the beasts hi the other k)t 12 lb. of clover chaff and .")() II.. of
Swedes. The experiment lasted 114 days.

The final result was .shghtly in favonr of the sila-v ; the
beasts receiving silage made an average increase of 1 ■)■«') lb. p'T
week per 1000 lb. mean live-weight, as again.st a corresponding
increase of 14-8 11). made by the bea.sts receiving roots an<l
chaffed hay.

In the other experiment with milch cows, two lots each of I'O
cows were selected, .so as to o1)tain them as nearly as po.s.^ibh-
with equal milk yioMs and (Mjnally advanced in the lactation
period in each lot. This could hardly be realise. 1 with exact it nde.
especially as fresh cows had to be brought in during the
experiment. Of concentrated food each cow receivc.l \ lb.
cake, 4 lb. bran, and 10 lb. chatt{hay and .straw mixed). The
silage lot got from 42 to r)0 lb. of ch)ver .silage, the other> 7:» to

•268 MISCELLANEOUS ENQUIRIES

90 lb. uf mangels, quantities arranged to supply each lot with
equal amounts of dry matter. The experiment lasted 13 weeks,
and was immediately continued for another 6 weeks with
meadow-grass silage, a reduction being made in the chaff from
10 to 7 lb., because of the larger amounts of woody fibre intro-
duced by the grass silage.

The results seemed to show that the cows on the clover
silage tended to fatten rather more than those on the mangels ;
though giving slightly less milk they gained in live weight,
while the mangel-fed cows lost slightly in weight.

With meadow-grass silage, however, there was not the
same tendency to fatten, the cows losing weight ; the milk
yield was practically equal from the two lots of cows. When
analysed, the milk of the mangel-fed cows always showed a
higher percentage of both total solids and of butter fat than
that of the silage-fed cows.

The general conclusions reached were, that good food would
make good silage without much more loss of dry matter than
usually takes place hi hay-making, etc. ; also, that good silage is
a useful food for both fattening oxen and cows in milk. It did
not seem likely, however, that it Avould pay farmers to grow
crops specially for silage rather than to grow roots.

IV. — The Composition of Wheat Grain and its Mill
Products.

The question of the food value of the various materials
grown on the expei'imental plots was one always before Lawes
and Gilbert. Particularly they were preoccupied with anything
relating to the production of wheat and its variations in
composition due to soil, season, or climate. The original plan
of their investigations included a study of the influence of
season and manuring upon the composition of the wheat grain,
and a further study of the varieties of wheat and their adapta-
tion to various climates and localities in the great range of the
earth's surface over which wheat is grown.

COMPOSniON ()|- will. AT lion: n.;-.

In a paper puMislud in ls:,7 ih,.y uavc tlir rr>iilts of a

series of experimental niillinus of wheat <,M-ain from tlin f tlir

plots — the uiiinaiuired plot, that which receives nitn><:en i»nly in
the shape of annnoniuni-salts. .iikI one that is c(.nijilc!rl_\
manured with both minerals and annnoninm-salts. '{'he <,'rind
ing was done by an ordinary millstone, then the only method
of grinding- wheat. Figures wei-e obtained >li(.\\iie^' the rrlati\e
weights of the nine mill products -tlonr ot \arious grades oC
fineness, tails, sharps, poHard, and bran figures which
are unfortunately of little interest nowadays since the i-<.ller-
milling which has become universal has introduced (juite a
ditierent series of separations, lioller-milling, also, no longer
bruises the bran in the way that was inevitable with >tone
grinding, so that the composition even of the finest j)roducls
has been to some extent altered. Further determinations were
then made of the dry matter, ash, nitrogen, and pIio>|)lioric acid
in the various products, as had previously been done for several
seasons with the whole grain. The results showed that the
percentage of nitrogen was lowest in the products at the hea<l
of the dressing-machine, i.e., in the Hour itself, but inci-eased
considerably in the more branny portions, being at its highest
in the sixth product, the so-called "coai'se sharps." 'fhe ash
increased to a still greater degree in the coarser portions, being
ten times as great in the coarsest l)ran as in the finest flour, and
the percentage of phosphoric acid augmented ^vith the increase
in the percentage of ash.

But Law^es and Gilbert protested most strongly auMin>t th.-
idea which was then l)egimiing to be held, and which has nevei-
ceased to be promulgated as a sort of creed — that the whole
meal of the wheat grain is the most nutritive food, and that
ordinary white bread is deprived of niucli ojit^, value because of
the removal of the bran.

For example, Gilbert wrote in l^^l : -'ni'' hi-h'-r |)er
centage of nitrogen in bran than in lin<' Hour ha> freciuently
led to the reconunendaticai of the coarser brea«ls as moiv
nutritious than the finer. We have already seen that tlie

270 MISCELLANEOUS ENQUIRIES

more branny portions of the grain also contain a much
larger percentage of mineral matter. ... It is, however, we
think, very questionable whether, upon such data alone, a
valid opinion can be formed of the comparative values, as food,
of bread made from the finer or coarser flours from one and
the same grain. . . . Again, it is an indisputable fact that
branny particles, when admitted into the flour in the degree of
imperfect division in which our ordinary milling processes leave
them, very considerably increase the peristaltic action, and
hence the alimentary canal is cleared much more rapidly of its
contents. It is also well known that the poorer classes almost
invariably prefer the whiter l:)read ; and among some of them
who work the hardest, and who, consequently, would soonest
appreciate a difference in nutritive quality (navvies for example),
it is distinctly stated that their preference for the whiter bread
is founded on the fact that the l^rowner passes through them
too rapidly, consequently before their systems have extracted
from it as much nutritious matter as it ought to yield them.
It is freely granted that much useful nutritious matter is, in the
first instance, lost as human food, in the abandonment of 15 to
20 per cent, of our wheat grain to the lower animals. It
should be remembered, however, that the amount of food so
applied is by no means entirely w^asted. And further, w^e
think it more than doubtful, even admitting that an increased
proportion of mineral and nitrogenous constituents would be
an advantage, whether, unless the branny particles could he
either excluded, or so reduced as to prevent the clearing action
above alluded to, more nutriment would not be lost to the
system by this action than would be gained by the introduction
into the body, coincidentally with it, of a larger actual amount
of supposed nutritious matters. In fact, all experience tends
to show that the state, as well as the chemical composition of
om^ food, must be considered ; in other words, that its digesti-
bility, and aptitude for assimilation, are not less important
qualities than its ultimate composition.

"Of course, if the branny portions were reduced to a

FOOD VALUE OF DIFFKKKNT II.()ri:> jn

perfect state of fnieiu'ss. ami it were tniiinl that iliis prevent i'« I
the aperient aetiun, aiul that oiIut i-vils wt if not induced, <.r
better still, if more of the food niaicrial can he separated from
the bran, and in either ease without more eost than the sjivin;;
would be worth, there might be some advautau'f. Hut. to
suppose that whole wheat meal, as ordinarily prepared, is. as
has generally been assumed, weight for weight, more mitritiou-
than ordinary bread-tiour, is an utter lallaey, founded on
theoretical text-book dicta : not oidy entirely unsupportefj by
experience, Init inconsistent with it. Tn faet, it i> ju>i \\i'-
poorer fed and the harder working that should have the
ordinary flour bread rather than the whole-meal bread as
hitherto prepared, and it is the over-fed and the sedentary that
should have such whole-meal bread. Lastly, if the whole
grain were finely ground, it is by no means certain that the
percentage of really nutritive nitrogenous matters would be
higher than in ordinary bread-Hour, and it is quite a (iue>tion
whether the excess of earthy phosphates would not then be
injurious."

The persistent idea that the branny portions of the gi-aiu
possess a higher nutritive value comes from trusting in the
crude chemical view of a centmy ago, that the percentage of
nitrogen alone measures the value of a food, without tidving
any account of its digestibility and the amount of these
nitrogenous materials which can be assimilated by the body.
As to the extra value of the phosphoric acid, there is no
evidence to show that the ordinary dietaries are in any \Nay
deficient in phosphates. The whole subject has, during t In-
last few years, been elaborately tested experimentally in the
com-se of the nutrition investigations of the United States
Department of Agricuhure, with the result that I^iwes and
Gilbert's opinion of the superior nutritive value of white bread
has been fully confirmed.

The other question raised l)y Lawes and Gill)ert in tht- \s:>7
paper, that of the effect of the difierent systems of mamn-ing
upon the baking quality of the wheat and the differeneo in

272 MISCELLANEOUS ENQUIRIES

composition between English and foreign-grown wheat, is
again at the present time being made the subject of investiga-
tion at Rothamsted.

References

•'On some Points in the Composition of Wheat Grain, its Products in the

Mill, and Bread." Jour. Chcm. Soc, 10 (1857), 1. Rothamsted Memoirs,

Vol. I., No. 10.
"Bread Reform." Jour. Soc. Arts, January 21, 1881. Rothamsted Memoirs,

Vol. v.. No. 16.
"On the Sewage of Towns (Third Report and Appendices 1, 2, and 3, of

the Royal Commission, presented to Parliament), 1865." Rothamsted

Memoirs, Vol. IV., No. 2.
"Report (presented to Parliament) of Experiments undertaken by Order

of the Board of Trade to determine the Relative Values of Unmalted

and Malted Barley as Food for Stock, 1866." Rothamsted Memoirs, Vol.

IV., No. 3.
"Experiments on Ensilage conducted at Rothamsted, Season 1884-5." Agric.

Gazette, April 27 to Aug. 10, 1885. Rothamsted Memoirs, Vol. IV.,

No. 12.

APPENDIX I

The Authors are indicated by initials as foUows : —

J. B. L. = the late Sir John Beiinet I jiwes.

J. H. G. - the late Sir J. Henry Gillx-rt.

R. W. = R. Warington.

A. D. H. = A. D. Hall.

N. H. J. M. = N. H. J. Miller.

ii*. Mer/i. (Rothanisted Memoirs) refers to the ten bound volumes of reprints whi. Ii
were distributed in 1S90 and since to the chief Libraries, Agricultural Colleges, aii<l
Experiment Stations, both at home and abroad.

J.R.A.S. = Journal of the Royal Agricultural Socieltj of l^iu/lmnl.

J.C.S. = Journalof the Chemical Society.

T.C.S. = Transactions of tlie Chemical Society.

P.C.S. = Proceedings of the Chemical Society.

I.— LIST OF PUBLICATIONS ISSUED FROM THE RO IH AMS I KI>
EXPERIMENTAL STATION, 1843-190n.

1. "Experiments at Rothamsted Farm, Herts, in lSi:5 and Is 11. on tin-

Growth of Turnips" (by J. B. L., Gard. Chron., June IfSto).

2. "Agricultural Chemistry" (by J. B. L., J.Ii.A.S.,8, 1847,22(5). /•'. .Mnn..

Vol. I., No. L

3. "Agricultural Chemistry, Turnip Culture" (by J. H. I.., ././i'../..V. 8, 1>I7.

494), R. Mem., Vol. I., No. 2.

4. "On the Sources of the Alkalies in Agriculture " (by .1. H. I... 77/f Finmcis'

Magazine, 29, 1848, 178).

5. " Agricultural Chemistry, Sheep Feeding, and .Manure," Part I. (by .1. H. I. .

J.R.A.S., 10, 1849,27G),/«*. Mem., Vol. II., No 1.

6. "Experimental Investigation into the Amount of W.ilcr given ulfby Plants

during their Growth" (by .1. B. L., Jour, llnrl. Soc. lAtnd., 5, iSfiO,
38), R. Mem., Vol. I., No. 3.

7. " Report of some Experiments undertaken to ascertain the Conipnrativr

Evaporating Properties of Evergreen and Deciduous irees " (by
J. B. L., Jour. Hart. Soc. Lnnd., 6, 1S.-,1, 227). U. Mrm., \'<.l. I.. No. 4.

274 APPENDICES

8. "Agricultural Chemistry, especially in relation to the Mineral Theory of

Baron Liebig " (by J. B. L. and J. H. G., J.R.A.S., 12, 1851, 1), R.
Mem., Vol. I., No. 5.

9. "' Report of Experiments on the Comparative Fattening Qualities of Different

Breeds of Sheep" (by J. B. L., J.R.A.S., 12, 1851, 414), R. Mem., Vol.
II., No. 2.

10. " Report of Experiments on the Comparative Fattening Qualities of

Different Breeds of Sheep " (by J. B. L., J.R.A.S., 13, 1852, 179), R.
Mem., Vol. II., No. 3.

11. "On the Composition of Foods" (by J. B. L. and J. H. G., Rep. Brit.

Assn., 1852), R. Mem., Vol. II., No. 4.

12. "Agricultural Chemistry; Pig Feeding" (by J. B. L., J.R.A.S., 14, 1853,

459), R. Mem., Vol. II., No. 5.

13. " On the Amounts of, and Methods of Estimating, Ammonia and Nitric

Acid in Rain-water" (by J. B. L. and J. H. G., Rep. Brit. Assn., 1854),
R. Me7n., Vol. I., No. 6.

14. "On the Equivalency of Starch and Sugar in Food" (by J. B. L. and

J. H. G., Rep. Brit. Assn., 1854), R. Mem., Vol. II., No. 6.

15. "Experiments on the Comparative Fattening Qualities of Different Breeds

of Sheep" (by J. B. L., J.R.A.S., 16, 1855, 45), R. Mem., Vol. II., No. 7.

16. "On the Sewage of London" (by J. B. L., Jour. Soc. Arts, 1855), R. Mem.,

Vol. II., No. 8.

17. "Report on the Experiments on the Growth of Wheat at Holkham Park

Farm" (by J. B. L., J.R.A.S., 16, 1855, 207), R. Mem., Vol. I., No. 7.

18. "On some Points connected with Agricultural Chemistry; being a reply

to Baron Liebig's Principles of Agricultural Chemistry " (by J. B. L.
and J. H. G., J.R.A.S., 16, 1855, 411), R. Mem., Vol. I., No. 8.

19. " On the Growth of Wheat by the Lois-Weedon System " (by J. B. L. and

J. H. G., J.R.A.S., 17, 1856, 582), 7^. Me?n., Vol. I., No. 9.

20. " On some Points in the Composition of Wheat Grain, its products in the

Mill, and Bread" (by J. B. L. and J. H. G., J.C.S., 10, 1857, 1), R.
Mem., Vol. I., No. 10.

21. "On the Growth of Barley by Different Manures continuously on the

same Land" (by J. B. L. and J. H. G., J.R.A.S., 18, 1857, 454), 7?.
Mem., Vol. I., No. 11.

22. " Letter on the Utilisation of Town Sewage " (by J. H. G., Report

ordered by House of Commons, 1857, Appendix, 12, 1857, 477), R.
Mem., Vol. II., No. 9.

23. "Experimental Inquiry into the Composition of some of the Animals Fed

and Slaughtered as Human Food" (by J. B. L. and J. H. G., Abstract,
Proc. Roy. Soc, 9, 1858, 348), R. Mem., Vol. II., No. 10.

24. "Observations on the recently introduced Manufactured Foods for

Agricultural Stock" (by J. B. L., J.R.A.S., 19, 1858, 199), R. Mem.,
Vol. II., No. 11.

25. "On the Annual Yield of Nitrogen per acre in Different Croi>s " (by

J. B. L. and J. H. G., Chemical Gazette, Nov. 1, 1858, 413).

apim:m)|\ I

276

26. "Report of Kxperinients with ilillcivnt Manures on IVriimnrnt Mr«.l..w

LjuuI" (by J. H. L. and J. 11. C, ././,•./., v., ig. Ik:,h, :,;,••• ,„„i 20
1859, 228 and 398), h\ Mmi., \'ol. I., N„. 1 -j.

27. "On a New Method for the (Quantitative Ksliniatinn ..f Niiri.- \.i.|",l.v

E. Pujrh, J.C.S., 12, 18r)9, 30).

28. "Experimental Inquiry into the Coni|i(.sili..ii ..f.sonie .if Ih.- .\i(iiii.»U 1 .,1

and Slaughtered as Human rood'- ^l.y .1. H. L. and .1. II. O., I'hil
Tram., 149, 1859, 493), li. Mm,., NCI. III. (.|t„). N... I.

29. "On the Composition of Oxen, Slit<|., and I'i^rs. and d ih.ir InercjiHc

whilst Fattening" (by .1. B. I,, and .1. II. (1.. J.li. I.S., 21, Isr.o, 1;J3)
R. Mew/., Vol. II., No'. 12.

30. "On the Composition of the Animal Portion of our ImmkI, and on itx

relations to Bread" (by J. II. (;., Ahslrait, ./.r.\., 12, Isf.o, 54), U
3/(v«., Vol. II., No. 13.

31. "Report of Experiments on the (irowth of Red (lover bv ditfrrenl

Manures" (by J. B. L. and J. H. G., ././i'../..S., 21, IsOd, ITS), li M,-,,,
Vol. I., No. 13.

32. "On the Application of different Manures to different Crops, and on th«-ir

proper Distribution on the Farm " (bv J. B. L., 18()1), li. Mrm., \o\.
I., No. 15.

33. "On some Points in connection with the Exhaustion of Soils " (In .1. H. I..

and J. H. G., Abstract, /iV/;. nril. .I.smi., 18(31), A'. Mrm.', \\,\. \ ,
No. 16.

34. "On the Sources of the Nitrogen of N^egelation, with special reference to

the Question whether Plants Assimilate Free or Uncombined Nitrofjeii "
(by J. B. L., J. H. G., and E. Pug^ ^'/"/- Trans., 151, ISGl, 431), Ji.
Me?n., Vol. I. (4to), No. 1 (also J.C.S., 16, 1863, lUd), li. .Mn,,., \'ol.
III., No. 1.

35. "Fifth Report of Experiments on the Feeding of Sheep " (bv .1. H. I., and

J. H. G., J.R.A.S., 22, 1861, 189), R. Mn,,., Vol. II . No. 'i I.

36. " Report of Experiments on the Fattening of Oxen at \\'ol)uni Park I'arnj "

(by J. B. L. and J. H. G., ./.li. I.S., 22, 1861, 2U(l). /.'. Mrm. \\,\. II .
No. 15.

37. " Report of Experiments made ;it Rodniersham, Kent, on the Growth of

Wheat" (by J. B. L. and J. H. G., J.R..I.S., 23. 1S62, 31). R. .Mn,,.,
Vol. I., No.' 17.

38. "Experiments on the Question whether the I'sc of ConclinK iils jncrensc'ti

the Assimilation of Foods by Fattening .\nini.ils " (l>y .1. M. I... I.tiitt.
Vet. Reiinr, 1862), R. Mnn.,'Vo\. II., No. 16.

39. "Supplementary Report of Experiments on the Feeding of Slurp " (by

J. B. L. and J. H. C;., J.R..I.S., 23, 1862, 191). li. .Mn,,., Vol. II.,
No. 17.

40. "The Utilisation of Town Sewage" (by .1. M. I... ././.'. /.V. 24. 1863,65),

R. Mem., Vol. II., No. 18.

41. "Effects of different Manures on tli<- Mix..! Il.rbage of (irass I..iid' (by

J. B. L. and J. H. G., J.R..I.S., 24. Is6.i. 131 and 501). li. .Mr,,,., Vol.
I., No. 18, and Vol. III., No. 3.

276 APPENDICES

42. " Report of Experiments on the Growth of Wheat for Twenty Years in

Succession on the same Land" (by J. B. L. and J. H. G., J.R.A.S., 25,
1864, 93 and 449), R. Mem., Vol. III., No. 4.

43. "On the Selection of Artificial Manures for the Sugar-Cane " (by J. B. L.,

1864), R. Mem., Vol. III., No. 5.

44. "On the Chemistry of the Feeding of Animals for the Production of

Meat and Manure" (by J. B. L., Jour. Roij. Dublin Soc, 1864, 256),
7?. Man., Vol. IV., No. i.

45. "On the Sewage of Towns" (by J. B. L. and J. T. Way, Royal Com-

mission, Third Report, and Appendices 1, 2, and 3, 1865), R. Mem., Vol.
IV., No. 2.

46. " On the Accumulation of the Nitrogen of Manure in the Soil " (by

J. B. L. and J. H. G., Rep. Brit. Assn., 1866), R. Mem., Vol. III., No. 6.

47. " Report (presented to Parliament) of Experiments undertaken by Order

of the Board of Trade to Determine the relative Values of Unmalted
and Malted Barley as Food for Stock" (by J. B. L., 1866), R. Mem.,.
Vol. IV., No. 3.

48. "On the Composition, Value, and Utilisation of Town Sewage" (by

J. B. L. and J. H. G., J.C.S., 19, 1866, 80), R. Mem., Vol. IV., No. 4.

49. " Food in its Relations to the various Exigencies of the Animal Body ""

(by J. B. L. and J. H. G., Phil. Mag., Fourth Series, 32, 1866, 55),
R. Mem., Vol. IV., No. 5.

50. "On the Sources of Fat of the Animal Body" (by J. B. L. and J. H. G.,

Rep. Brit. Assn., 1866; Phil. Mag., Fourth Series, 32, 1866, 439),
R. Mem., Vol. IV., No. 7.

51. '^'' On the Home Produce, Imports, and Consumption of Wheat " (by

J. B. L. and J. H. G., J.R.A.S.,29, 1868, 359), R. Mem., Vol. III., No. 8.

52. "Exhaustion of the Soil in relation to Landlords' Covenants, and the

Valuation of Unexhausted Improvements " (by J. B. L., London Farmers"
Club, 1870), R. Mem., Vol. III., No. 9.

53. " Scientific Agriculture with a view to Profit " (by J. B. L., Maidstone-

Farraers' Club, 1870), R. Mem., Vol. III., No. 10.

54. "Effects of the Drought of 1870 on some of the Experimental Crops at

Rothamsted" (by J. B. L. and J. H. G., J.R.A.S., 32, 1871, 91), R. Mem.^
Vol. III., No. 11.

55. " Notes on Clover Sickness" (by J. H. G., Jour. Roy. Hort. Soc, 3, 1871,

86), R. Mem., Vol. III., No. 12.

56. " Report of Experiments on the Growth of Barley for Twenty Years in

Succession on the same Land" (by J. B. L. and J. H. G., J.R.A.S., 34,
1873, 89 and 275), R. Mem., Vol. III., No. 13.

57. "Unexhausted Tillages and Manures, with reference to the Landlord and

Tenant (Ireland) Act, 1870" (by J. B. L.), R. Mem., Vol. III., No. 14.

58. " On the more frequent Growth of Barley on Heavy Land " (read before

the London Farmers' Club, 1875, by J. B. L.), R. Mem., Vol. V., No. 1.

59. " On the Valuation of Unexhausted Manures " (by J. B. L., J.R.A.S., 36,

1875, 1), R. Mem., Vol. V., No. 2.

AlM'KXhIX 1 077

€0. "Note on the Occurreiur of F.iiiv HiM-s- (|,v .1. II. ( ; . ./oi/r I „„, S,^
Botany, 15, 1875, 17), li. Mmi., W.l. \\, No. .'i.

61. "On some Points in connection with Vt-f^ctation " (Addnss (hliv.rnl nt

South Kensinj^ton Science ConfcnMncs, is"!"., hv .1 H (; ) l{ Mm,
Vol. v., No. 4. . • .

62. "On some Points in coinicction with Animal Nutrition" (by .1. H. C...

Address delivered at South Kensington Science (\)nfcrcnrrs lS7r.)
7?. Mem., Vol. IV., No. 9.

63. "On Rainfall, Evaporation, and Percolation" (l.v .1. 11. (J.. I'nu-. Inst ( I

45, 1876), li. Mem., Vol. V., No. 5.
6-i. "On the Use of Germinated Barlev for Feeding,'" (hv .1. H. I... laru-. (in:rllr.

May 1876).
6-3. "On the Quantitative Determination of Nitric .Acid h\ Indi^io" (l»y

R. W., C/iem. Xeirs, 35, 1877, 45, 57).

66. "The Rothamsted Allotment Club" (by .1. H. I,.. ./..'i'../..S., 38. 1S77, 387).

67. " Freedom in the Growth and Sale of the Crops of the Farm " (by .1. M. I .

Jour. Soc. Arts, Dec. 12, 1877), li. Mem., Vol V., No. 0.
G8. " On the Formation of Fat in the Animal Body " (by J. B. I., and .1. H ( ■ .
Jour. Anat. and Phijs., 11, 1877), R. Mem.,\o\. \\ ., N... 1(>.

69. " Composition of Potatoes " (by J. H. G., Note, Jour. lim/. Hort. .Sm-., 5,

1878), R. Mem., Vol. v., No. 7.

70. "On Nitrification " (by R. W., T.C.S., 33, 1878, 44).

71. "Is Higher Farming a Remedy for Lower Prices" (by .1. B. L., Lecture

delivered before the East Berwickshire Agricultural .Association, May .'<,
1879 ; Berwick, 1879), R. Mem., Vol. V., No. 8.

72. "On Nitrification," Part II. (by R. W., T.C.S., 35, 1879, 429).

73. " On the Determination of Nitric Acid, as Nitric Oxide, by means of it.s

action on Mercury" (by R. W., T.C.S., 35, 1879, 375).

74. "On the Determination of Nitric Acid by means of Indigo, with

special reference to Water Analysis" (l)y U. U ., / .CS., 35.
1879, 578).

75. "On some Points in connection with Agricultural Chemistry " (by .1. 11. (> .

Abstract, Rep. Brit. As.sn., 1879), R. Mem., Vol. V., No. lit)-

76. "Our Climate and our Wheat Crops" (by J. B. L. and .1. U. G., J. HAS.,

41, 1880, 173), R. Mem., Vol. V., No. 11.

77. "Agricultural, Botanical, and Chemical Results <.t Kxpcrinunts on tlir

Mixed Herbage of Permanent .Meadow— I'nrt I., The Agriiultunil
Results" (by J. B. L. and .1. H. i).. Hn/. Tnou., 171. iHhO. 2^9),
R. Mem.,Vo]. II. (4to), No. 1.

78. " Sketch of the Progress of Agricultural Chemistry "( by .1. H. (i, /''•/'

Brit. Assn., 1880), R. Mem., Vol. V., No. 13.

79. "On the Determination of Nitric Acid as Nitri.- Ox-ie. by n.eans ..f .t«

reaction with Ferrous Salts" (by K. W.. Part I . TCS, 37. IH.HO, 468;
Part II., T.C.S., 41, 1882, 345).

80. "On the Determination of Carbon in Soils" (by K W. ,.nd U A IVakr,

T.C.S., 37, 1880, 617).

278 APPENDICES

81. "On the Home Produce, Imports, Consumption, and Price of Wheat, over

27 (or 28) Harvest-years, 1852-3 to 1879-80" (by J. B. L. and J. H. G.,
J.R.A.S., 41, 1880, 337), R. Mem., Vol. V., No. 14 ; see also Jour. Stat.
Soc, 43, 1880, 313.

82. "Letter on Bread Reform" (by J. H. G., Jour. Soc. Arts, 1881), R. Mem.,

Vol. v., No. 16.

83. "On the Amount and Composition of the Rain and Drainage Waters

collected at Rothamsted " (by J. B. L., J. H. G., and R. W., Parts I.,
II., and III., and Appendix Tables (J.R.A.S., 42, 1881, pp. 241 and
311 ; 43, 1882, 1), R. Mem., Vol. V., No. 18.

84. "Letters on Fertility" (by J. B. L., Agric. Gazette, Feb. 21 to May 9,

1881), R. Mem., Vol. V., No. 17.

85. " On the Formation and Decomposition of Carbonic Acid " (by J. B. L.,

Phil. Mag., 1881, 206).

86. "On Increasing the Fertility of Pastures" (by J. B. L., Jour. Amer. Agric.

Assn., 1, 1881, 67).

87. "On Alterations in the Properties of the Nitric Ferment by Cultivation "

(by R. W^, Rep. Brit. Assn., 1881, 593).

88. " Note on the Appearance of Nitrous Acid during the Evaporation of

Water" (by R. W., T.C.S., 39, 1881, 229).

89. " Some Practical Aspects of recent investigations on Nitrification " (by

R. W., Jour. Soc. Arts, April 7, 1882).

90. "Determinations of Nitrogen in the Soils of some of the Experimental

Fields at Rothamsted, and the bearing of the results on the Question
of the Sources of the Nitrogen of our Crops" (by J. B. L. and J. H. G.,
American Assn. for the Advancement of Science, Montreal, August
1882), R. Mem., Vol. V., No. 19.

91. "Agricultural, Botanical, and Chemical Results of Experiments on the

Mixed Herbage of Permanent Meadow. Part II., The Botanical
Results " (by J. B. L., J. H. G., and M. T. Masters, Phil. Trans., 173,
1882, 1181), /?. Mem., Vol. II. (4to), No. 2.

92. " On the Determination of Nitric Acid in Soils " (by R. W., T.C.S.,^1,

1882, 351).

93. " The Future of Agricultural Field Experiments " (by J. B. L., Agric.

Students Gazette, 4, 1882, 33).

94. " On some of the Changes which Nitrogenous Matter undergoes within

the Soil" (by R. \W, Lecture delivered at South Kensington, April 16,
1883).

95. " Contribution to the Chemistry of Fairy Rings " (by J. B. L., J. H. G.,

and R. W\, T.C.S., 43, 1883, 208), R. Mem., Vol. V., No. 20.

96. " New Determinations of Ammonia, Chlorine, and Sulphuric Acid, in the

Rain-water collected at Rothamsted " (by J. B. L., J. H. G., and R. W.,
J.R.A.S., 44, 1883, 313), R. Mem., Vol. V., No. 21.

97. "The Nitrogen as Nitric Acid, in the Soils and Subsoils of some of the

Fields at Rothamsted" (by J. B. L., J. H. G., and R. W., J.R.A.S., 44,

1883, 331), R. Mem., Vol. V., No. 22.

AIMM'ADIX I 279

98. Supplement to foniur jKiper . ntillcd " K\|.iTiinrnt»l Iii(|iiiry into thr

Composition of some of llu- Aiiim.ils I .-,1 and SlaufjIUrrrd nn liumnii
Food" — Cumposilion of' !/„■ ./.v// ,;/' //„• Inlirr Amttmls and of crrtititt
Separated Parts (by J. M. I., and .1. N. (;.. /'/»/. Trans., 174. iMs.J, SGa),
R. Mem., Vol. III. (4to), No. l'.

99. "Compensation for Unexhausted Mamires" (l)y J. H. I, . I...iidnii. 1883).

100. "An Attempt to explain the Aetion of Manures" (|.\ .1. \\ F... Jomr.

Neircastle Farrncrs' Club, 1883, iii.).

101. "Introduction to the Study of the Scientific I'limipies of .X^riiidlurr "

(by J. H. G., Inaufjural Lecture, delivered May <-, Issj, ,,t il„- Ini-
versity Museum, Oxford), R. Mem., Vol. VI., No. 1

102. "On the Composition of the Ash of Wheat-Crain and Win il-Slniw

grown at Rothamsted " (by J. B. L. and J. U. (;.. 'J'.C.S.. 45. 1SS|.
305), R. Mem., Vol. VI., No. 2.

103. " Presidential Address to the Chemical Society" (l)y .1. H. (i., March

30, 1883, T.C.S., 43, 1883, 224).

104. " Report of Experiments on the Growth of Wheat for the second periinl

of Twenty Years in Succession on the same Land" (by .F. H. L. and
J. H. G., J.R.A.S., 45, 1884, 391), R. Mem., Vol. VI., No. 3.

105. "On Agricultural Investigation; being a Lecture delivered at the

Michigan State Agric. College, Lansing, Mich., Oct. 14. ISSt ; and
at Rutgers College, New Brunswick, N.J., Oct. 27, 1884 " (i)y J. 11. (. .
Proc. Soc. Promoting Agric. Science, 1885, 73), R. Mem.. \ ..]. \ I .
No. 5.

106. "Further Remarks on the Action of Manures " (l)y .1. H. I... Jour.

Xeu-castle Farmers' Chib, 1884, 77).

107. "On Nitrification," Part III. (by R. W., T.C.S., 45, 1884, 037).

108. "On some Points in the Composition of Soils; with Results illu.strating

the sources of the Fertility of Manitoba Prairie Soils" (by J. B. L. and
J. H. G., British Assn., Montreal, 1884, '/'.f '..S., 47, 1S85, 3S0), R. Mr„i .
Vol. VI., No. 4.

109. "Note on the Behaviour of Nitrates in Kjeldahl's Process for the

Determination of Nitrogen " (by R. W., Cliem. Snrs, 52, 18sr., 102).

110. "Note on some Conditions of the Development, and of the Activity, of

Chlorophyll" (by J. H. G., Abstract, Rep. Rrit. Assn., 188.".). /^ Mem,
Vol. VI., No. 6. "

111. "On the Valuation of Unexhausted .Manures " (by .1. H. I., and .1. IL O ,

J.R A.S., 46, 1885, 590), R. Mem., Vol. VL, N... 7.

112. "Experiments on Ensilage, conducted at R.ithamsted, Sra.s^ui lSf<4-.'i'

(by J. B. L. and J. H. G., Agric. dazelte, .April 27 to Aug. 10. 1885).
R. Mew., Vol. IV., No. 12.

113. "Notes on the Detection of Nitrous and Nitric .\ci.l " (l)y U NN .

('hem. Nen-s, 51, 1885, 39).

114. "On the Action of Gypsum in I'roon.tin;; N.lr>r..ati..n " (by II. U .

y.C.S'., 47, 1885, 758).

115. "Sugar as a Food for Stock" (by J- H. I... .//.'../V. 40. 1>'.-., - 1 ).

280 APPENDICES

116. " Remarks on the Products of the Cow" (by J. B. L,., Agric. Sfiideiilx'

Gazette, 2, 1885, 129).

117. " Mangels as a Milk-producing Food " (by J. B. L., Agric. Students' Gazette,

2, 1885, 147).

118. "On the Necessity for some Change in the Law in regard to the

Adulteration of Milk " (by J. B. L., British Dairy Farmers' Assn.,
Oct. 7, 1885, Vol. II., 1886, 197).
119 "Results of Experiments at Rothamsted on the Growth of Barley for
more than Thirty Years in succession on the same Land " (by J. H. G.,
Agric. Students' Gazette, New Series, 3, 1886, 1), R. Mem., Vo\. VI.,
No. 8.

120. " Remarques sur la relation qui existe entre les .sommes de tempera-

ture et la production agricole " (by J. H. G., Archives des Sciences
Physiques et Natiirelles, 3' periode, 16, 1886, 421), R. Mem., Vol. VL,
No. 9.

121. " Shall we Import, or Breed.'" (by J. B. L., Lire Stock Journal Almanac,

1886).

122. "Selling Live Stock by Weight" (by J. B. L., Jour. Xe/rcastle Farmers'

Club, 1886, 3).

123. "On the Distribution of the Nitrifying Organism in the Soil " (bv R. W.,

7'.C.^'., 51, 1887, 118).

124. "Succulent Food" (bv J. B. la., Jour. Bath and W. ofEng. Soc, Series

III., 18, 1886-7, 299).

125. " What is an Average Turnip Crop? " (by J. B. L., Jour. Bath and W. of

Eng. Sac, Series III., 18, 1886-7, 301).

126. "The Home Produce, Imports, Consumption, and Price of Wheat in the

United Kingdom, 34 Harvest-years, 1852-3 to 1885-6 " (by J. B. L. and
J. H. G., The Field, Feb. 12, 1887), R. Mem., Vol. VI., No. 10.

127. " A Contribution to the Study of Well Waters" (by R. W., T.C.S., 51,

1887, 500).

128. "On the present position of the Question of the Sources of the Nitrogen

of Vegetation — Preliminary Notice" (by J. B. L. and J. H. G., Proc.
Roy. Soc, 43, 1887, 108), R. Mem., Vol. VI., No. 11.

129. " Results of Experiments at Rothamsted on the Growth of Root-ci-ops for

many years in succession on the same Land " (by J. H. G., Agric. Student.s'
Gazette, New Series, 3, 1887), R. Mem., Vol. VL, No. 12.

130. " Nature of Nitrogenous Organic Matter in Soils" (by R. W., Chem. News,

55, 1887, 27).

131. "Some Remarks upon Foods " (by J. B. L., Agric. Science, 1, 1887, 99).

132. "Food in Relation to Milk" (By J. B. L., Jour. Brit. Dairy Farmers'

Assn., 3, 1887, 7).

133. "The Relative Value of Store and Fat Stock " (by J. B. L., Scottish Agric.

Gazette Almanac, 1887)

134. "Tables for Estimating Dead Weight and Value of Cattle froiii Live

Weight" (by J. B. L., 1888. Published by Roy. Agric. Soc).

APPENDIX I 281

135. " Results of Experiments at Hoth.imstrd on tin- ( Jmulh of IN.laliM-H for

Twelve Years in succession on the same Land ' (hy .1. H. (i., .Igrir.
Sliidoits' Ga-i'dc, New Series, 4, 188S), li. M,-,,,., \ol.'vi.. No. 13.

136. "The Permanent Wheat and Barley Kxperinients in SUckvard Field.

Woburn " (J. B. L., J.K.A.S., 49, 188S, 1).

137. " The Chemical Actions of some Micro-or^ranisms " (hv U. \\ ., /Vrx . i'hrm.

Soc, 4, 1888, 69 ; T.C.S., 53, 1888, 727).

138. "On the Present Position of the Question of the Sources of Nitrofrt-n ».f

Vegetation" (by J. B. L. and J. H. (;., P/iil. Trans., 180, H. issg, 1),
li. Mem., Vol. I. (4to), No. 2.

139. "The History of a Field newly laid down to IVnu.iiirnt drass " (l.v .1. H. I...

J.R.A.S., 50, 1889, 1), li. Mc»,., Vol. VI., No. 14.

140. "The Amountof Nitric Acid in the Rain-water at Uoliianistcd, with notes

on the Analysis of Rain-water" (by R. W., T.C.S., 55, 1889, TtM).

141. " Results of Experiments at Rothamsted on the Growth of Leguminous

Crops for many years in succession on the same Land" (by J. H. CI.,
Agric. Students' Gazette, New Series, 4, 1889, 137: and 4. 1890, 179),
R. Mem., Vol. VI., No. 15.

142. "The Food of our Agricultural Crop.s '" (hy .1. B. 1.., ./.h'.I.S.. 51, 1890,

69), R. Mem., Vol. VI., No. 17.

143. "Results of Experiments at Rothamsted on tlie (Question of the I'ixation

of Free Nitrogen" (by J. H. G., Agric. Student.^!' Gau-tte, New Series, 5,

1890, 33 ; and 5, 1891, 62), R. Mem., Vol. \'II., No. 1.

144. "Condiments" (by J. B. L., The Farmer and SloMrrrdrr'.s Ynir-lMtok,

1890,25).

145. " The Market Value of the Different Samples of Wheat and Barley grown

in 1889 on the Experimental Plots at Rothamsted " (by Lawes Agric.
Trust Committee, J.R.A.S., 51, 1890, 432).

146. "Observations on Rainfall, Percolation, and Flvaporation.at lU.thamstcd ;

with Tabular Results for Twenty Harvest-years, 1870-1 to l.'<89-9(l
inclusive" (by J. H. G., Pruc. ItJ. Civil Eugiucrrs, 105, 1S91, Part III.).
R. Mem., Vol. VIL, No. 2.

147. " Results of Experiments at Rotham.sted on the Question of the Fixnticm

ot Free Nitrogen" (by J. H. G., Nature, Nov. 12, 1891). R. Mem.,
Vol. VIL, No. 3.

148. " The Sources of the Nitrogen of our Leguniin<.iis Crops" (hy .'. B. L.

and J. H. G., J.R.A.S., 52, 1891, 057), R. Mem., \o\. \II., No. 4.

149. "On Nitrification," Part IV. (by R. W., P.C.S, 7. 1S91. 927 : T.C.S., 60.

1891, 484).

150. "Six Lectures on the Investigations at U..llianist.-d i:\perimrntnl

Station, delivered under the provisions of the Uwes .Vgrirultural Tru.Ht
before the Assoc, of American Agric. C.Ueges and Kxpt. Stations, nt
Washington, D.C., Aug. 12-18, 1891 " (by R. W.. C.S. D.pl. ..f .\grir..
Office of Expt. Stations, Bui. No. 8, Washington, 1^92).

151. " Allotments and Small H<.ldings " (l.y .1. B. L. an.l .1. H. <• . .rUA.S.,

53, 1892, 439), R. Mem., Vol. VIL, No. 5.

282 APPENDICES

152. "Nutritive Ratios" (by J. B. L., Agric. Students' Gazette, New Series, 6^

1892, 1).

153. "Small Holdings" (by J. B. L., Farming World Year-book, 1893).

154. "Home Produce, Imports, Consumption, and Price of Wheat, over 40

Harvest-years, 1852-3 to 1891-2" (by J. B. L. and J. H. G., J.R.A.S.,
54, 1893, 77), R. Mem., Vol. VII., No. 6.

155. "Rotation of Crops" (by J. B. L. and J. H. G., J.R.A.S., 55, 1894, 585),.

R. Mem., Vol. VII., No. 7.

156. "Upon some Properties of Soils, which have Grown a Cereal Crop and a

Leguminous Crop for many years in Succession " (by J. B. L., Agric.
Students Gazette, New Series, 7, 1895).

157. "The Agricultural Investigations at Rothamsted, England, during a

period of Fifty Years " (by J. H. G., United States Dept. of Agric.,.
Office of Expt. Stations, Bui. No. 22, Washington, 1895).

158. "The Rothamsted Experiments; being an account of some of the

Results of the Agricultural Investigations conducted at Rothamsted, in
the Field, the Feeding-shed, and the Laboratory, over a period of
Fifty Years " (by J. B. L. and J. H. G., Trans. Highland and Agiic. Soc. of
Scotland, Fifth Series, 7, 1895, 1).

159. "The Feeding of Animals, for the Production of Meat, Milk, and Manure,

and for the Exercise of Force " (by J. B. L. and J. H. G., J.R.A.S.,
56, 1895, 47), Vol. VII., No. 13.

160. "The Depression of Corn Prices; and the Production of Wheat in some

of the chief exporting Countries of the World " (by J. B. L. and J. H. G.,
J.R.A.S., 57, 1896, 723), 7^. Mem., Vol. VII., No. 8.

161. " The Lawes Agricultural Trust Committee. Brief Summary of Proceedings

during its first Five Years of Office" {J.R.A.S., 57, 1896, 324).

162. "Soil Inoculation" (by N. H. J. M., J.R.A.S., 57, 1896, 236).

163. "The Royal Commission on Agricultural Depression and the Valuation

of Unexhausted Manures" (by J. B. L. and J. H. G., J.R.A.S., 58,

1897, 674), R. Mem., Vol. VII., No. 9.

164. "Production of Milk Rich in Fat" (by N. H. J. M., J.R.A.S., 58, 1897,

655).

165. "The Valuation of the Manures obtained by the Consumption of Foods

for the Production of Milk " (by J. B. L. and J. H. G., J.R.A.S., 59,

1898, 103), R. Mem., Vol. VII., No. 10.

166. "The Growth of Sugar-beet, and the Manufacture of Sugar, in the United

Kingdom" (by J. B. L. and J. H. G., J.R.A.S., 59, 1898, 344), R. Mem.,
Vol. VII., No. 11.

167. "The World's Wheat Supply" (by J. B. L. and J. H. G., The Times,

Dec. 2, 1898), R. Mem., Vol. VII., No. 12.

168. "Agricultural, Botanical, and Chemical Results of Experiments on the

Mixed Herbage of Permanent Grass Land, conducted for many years in
succession on the same Land. Part III. The Chemical Results — Section
I." (by J. B. L. and J. H. G., Phil. Trans., 192, B, 1900, 139), R. Mem.,
Vol. II. (4to), No. 3.

APPENDIX I 2H:j

169. "Wheat ♦jrownycMraftti Vf.non tlusai.u- Land, at l{nt himstril. KiiKlainl ;

without Mamn-c, with Farmyard Mamirt-, aiul with various Artifinnl
Manures" (by J. B. L. ami ,1. H. (1., London, 1900).

170. "Experiments at llothamsted <>ii the Cliaiipe.s in tlu- ('«Mn|Nisiti<)n »»!'

Mangels during Storage" (by N. II. .1. M., ././i'../..S., 61, ll»iK», r>7 ; and
63, rj02, 135).

171. "The Amounts of Nitrogen as .Annnonia and as Nilrie A«id. nnd n(

Chlorine in the Rain-water eollected at Uothanisted " (l)v N. II. .1. M .
P.C.S., 18, 190l>, 88).

172. "The Amounts of Nitrogen as Nitrates, and (hiorine, in the Dniinnfjr

through Uncropped and Unmanured Land " (by N. H. .1. .\I.. I'.C.S., 18,
1902,89).

173. "Results of Investigations on the Rotliamsli-d Soils; being tlu- L«-itureN

delivered under the provisions of the Lawes Agrieultural Trust" (by
B. Dyer, U.S. Dept. of Agric., Office of Kxpt. Stations, Bui. No. 106,
Washington, 1902).

174. "The Amounts of Nitrogen and Organic ("arbon in some Clays and

Marls" (by N. H. J. M., Quart. Jour. Geul. Soc, 59, 1903, 133). '

175. "The Continuous Growth of Mangels for 27 years on the .same Land,

Barnfield, Rothamsted " (by A. D. H., J.It..l.S.,63, 1902, 27).

176. "The Value of Unexhausted Manures obtained l)y the Consum|)tion of

Foods by Stock" (by J. A. Voelcker and A. " i). 1 1, ././.'. /.V, 63.
1902, 76).

177. "The Manuring of Grass Lands" (by A. D. H., J.li.l.S., 64. 1903, 7G).

178. "The Mechanical Analysis of Soils and the Composition of the Fractions

resulting therefrom" (by A. D. H., T.C.S., 85, 1904, 950).

179. "The Effect of the long-continued use of Sodium Nitrate on the

Constitution of the Soil" (by A. D. H., T.C.S., 85, 1904, 9f,t).

180. "The Comparative Nitrifying Power of Soils" (by S. F. Ashby, T.C S .

85, 1904, 11.58).

181. "The Analysis of the Soil by Means of the Plant " (by A. i). II , Jnur.

Agric. Science, 1, 1905, 65).

182. "Note on Calcium Cyanamide " (by A. 1). H.. ./""'•. 'A'"'- V"-""-. L

1905, 146).

183. "The Effect of Plant Growth and of .Maimres upon the Soil ; the Reten-

tion of Bases by the Soil " (by A. 1). H. and S.U. .1. .M.. Pnn. liny. Soc.,
190.5).

184. "On the Accumulation of Fertility by Land allowed to run Wild" (by

A. D. H., Jour. Agric. Serine. 1, 1905, 211).

IL-PUBLICATIONS BY OTHER INVESTIG.VrORS. 1)EAL!N(;
WITH MATERIAL FRO.M ROrHAMSIED

1. " On the Composition of the Waters of Land Drainag. and of Rain" (by

J. T. Way, J.n.A.S., 17, 1856, 1 23).

2. "On the Quantity of Nitric Acid and Annnoma in Rain water" (by .1 'L

Way, J.R.A.S., 17, 1S56, 6 is).

284 APPENDICES

3. " Oh the Productive Powers of Soils in Relation to the Loss of Plant Food

by Drainage" (by A. Voelcker, J.C.S., 24, 1871, 276).

4. "Bodenstatik und Bodenanalysen " (by H. von Liebig, Zeits. landw.

Vereines, Bayern, 1872).
5 "On the Composition of Waters of Land Drainage" (by A. \'oelcker,
J.R.A.S., 35, 1874, 132).

6. "Sixth Report of the Rivers Pollution Commission, London, 1874" (see

results by Dr E. Frankland, pp. 58-68).

7. "The Analytical Determinations of probably available Mineral Plant Food

in Soils" (by B. Dyer, Pror. C.S., 10, 1894, 36; and Trans. C.S., 65,
1894, 115).

8. " Manurial Conditions affecting the Malting Quality of English Barley"

(by J. M. H. Munro and E. S. Beaven, J.R.A.S., 58, 1897, 65).

9. " Denitrification and Farmyard Manure" (by R. W., J.B.A.S., 58, 1897,

577).
10. "On the Analysis of Soil as a Guide to its Fertility" (by B. Dyer, Trans.

Highland and Agric. Soc. of Scotland, Fifth Series, 10, 1898, 26).
11 ["Analyses of Rothamsted Soils"] (by A. Goss and H. Snyder, U.S.

Dept. of Agric, Division of Chem., Bui. No. 51, 1898, 73).

12. "Some of the Principles which should Determine Compensation for the

Use of Foods and Manures " (by R. W., Lecture to Newcastle Farmers'
Club, Vinton, London, 1898).

13. "Various Conditions affecting the Malting Quality of Barley" (by J. M.

H. Munro and E. S. Beaven, J.R.A.S., 61, 1900, 185).

14. "Results of Percolation Experiments at Rothamsted, Sept. 1870 to Aug.

1899" (by R. H. Scott, Quart. Jour. Roi/. Met. Soc, 26, 1900, 139).

15. " The Comparative Value of Nitrate of Sodium and Sulphate of Ammonium

as Manures" (by R. W., J.R.A.S., 61, 1900, 300).

16. "A Chemical Study of the Phosphoric Acid and Potash Contents of the

Wheat Soils of Broadbalk Field, Rothamsted" (by B. Dyer, Proc. R.S.,
68, 11 ; P/iil. Trans., 194, B, 1901, 235).

17. "The Determination of Available Plant Food in Soils by the use of Weak

Acid Solvents " (by A. D. Hall and F. J. Plymen, Proc. C.S., 1901;
and Trans. C.S., 81, 1902, 117).

18. "Sur les phosphates du sol solubles a I'eau " (by Th. Schloesing, ju)i.,

Co7npt. rend., 134, 1902, 1383).

19. "Lost Fertility: The Production and Loss of Nitrates in the Soil" (l)y

R. W., Trans. Highland and Agric. Soc. of Scotland, Fifth Series, 17,
1905, 148).

III._OTHER PUBLICATIONS DEALING WITH THE
ROTHAMSTED EXPERIMENTS.

1. "The Rothamsted Agricultural Experimental Station" (^Gard. Chron., Sept.

22, 1877).

2. "Rothamsted — Trente Annees d'Experiences Agricoles de MM. Lawes

et Gilbert" (par A. Ronna, Paris, 1887).

APPENDIX I 2h:>

•Notes sur Hotliamstcd" (par H. (in.sj,;..,. /,/;,. /„./. \nl. Unw , 3,

1878-9).
' Die Resultate iler hauptsachliclisteii I'elddim^un^s-vrrsuche. von I..iwrs

uiul C.ilbert in Knjrland iind ilirt- Hedeutun^r fur die driitsdir Laiid-

wirthschaft " (von I)r Paul Ik-hrend, Berlin. ISSl).
•The Rothamsted Kxperiments on the (irowth of Whtat, liarlev. and th«-

Mixed Herbage of Grass Land" (by W. Kreani. London, ISSH).
•Le Ble a Rothamsted" (par Ku-r«iie Marcliand. ./n„r. d' .Icricullurr

Prathiiie, Paris, 1888-90).
• Le Ble I'Avoine et I'Orge a Rothamsted" (par Kug. nc M.inhai.d. Jmir.

d' Agriculture PratUjue, Paris, 1889-90).
' L' Azote dans la Culture du Ble" (par Eugene Marchand, .Umr. d'.hni-

culture Pratique, Paris, 1890.^).
•Lessons afforded by the Rothamsted Experiments" (I'.S. Dipt, of

Agriculture, Expt. Station Record, 7, 1896, 343; also J.U.A.S., 57,

1896, UO).
' Die Rothamsteder \'ersuche nach dem Standc des .lahres, 1S94" (von

K. Bieler, Berlin, 1896).

II. ''Concise Review of Principal Data on Rothamsted Kxperiments as

carried out by Sir J. B. Lawes and Prof. J. H. (Hlbert, based mainly
on Prof. W. Fream's Book" (by Gustav Kottmann, Ph.D.. Svdnev.
1897).

III. '"The Rothamsted Experiments and their Practical Lessons for I'arnu-rs "

(by C. J. R. Tij)per, London, 1897).
i;i. •' Forsoksverksamheten vid Rothamsted i PLngland " (H. von I'lilitztii.

Jonkoping, 1900).
14. "Rothamsted — Un Demi-siecle d'Experiences Agronomiques dr .NLM.

Lawes et Gilbert" (par A. Ronna, Anuales de la Science Agrnnoiuitjur

fraiK^aise et ctrangrre, 2' si'rie, 6' anni-e, Paris, 1900).
1"'. '• Du Role des Elements de Cendres dans la V^egetation " (par .\. Ronna.

Jour, d' Agriculture Pratique, 25 avril et 2 mai, Paris, 1901).
IG. "The Geological Survey in Reference to Agriculture, with Re|H>rt on the

Soils and Subsoils of the Rothamsted Estate " (by Horace B. Woodward.

Summary of Progress of the Geological Survey for 1903. .Appendix L.

1904, 143).

lu

Xote. — It should be mentioned that Nos. 54, 56 (Sec. 4), 65, 71, 77 (part).
83 (part), 90, 97, 102, and 162, of Series L, were translated into French by
iNL P. P. Deherain, and published in the Aimalcs Agrontwiiqucs.

APPENDIX II

Trustees.
The Rt. Hon. Lord Aveburv, D.C.L.
The Rt. Hon. Lord Walsingham.
Sir J. Evans, K.C.B., D.C.L.

Commitlec.
Sir J. Evans (Cliainuan).
H. MuLLER, LL.D., F.R.S. (Treasurer).
H. E. Armstrong, LL.D., F.R.S.
H. T. Brown, LL.D., F.R.S.
W. Carruthers, F.R.S.
Sir M. Foster, K.C.B., D.C.L., M.P.
Sir C. B. Lawes-Wittewronge, Bart.
Sir J. H. Thorold, Bart.
J. A. Voelcker, M.A., Ph.D.

Former Memberi

W. Wells, M.P. {Trustee).

The Rt. Hon. the Earl Cawdor (Member of Committee).

Sir W. T. Thiselton Dyer, K.C.M.G. (Member of Committee).

C. Whitehead (Member of Committee).

Secretary.
H. Rix, B.A.

APPENDIX III

AST OF PAST AM) PRESENT WOItKKUS A I I 111
ROTH AMSTED EXPERIMENTAL STATION

1. Present Staff.

A. D. Hall,

M.A

Director, 1902.

N. H. J. MiLLEH,

Ph

.1).

Clu-mist, 1887.

J.J. Willis

Hotanic.il and Gciu-r

tl Assi.stant,

.*<•■) J.

G. T. DUNKLEY

Secretary, 1878.

W. Wilson

Clerk, 1883.

E. GUEY

Chemical and Gener

\\ Assistant,

S7I.

C. Bigg .

General Assistant an

d Laboratorx

.Man,

is-'j

A. Oggelsby

Chemical and Gener

\\ Assistant,

IH)1.

2.

Former Members of thr Si

"ff-

Na.mk.

Date.

PosnidS.

F. A. Manning

1849-1858

. Chemist.

W. SiMCOE

1850-1859

Ciiemist.

— Masters .

1856-1858

Chemist.

R. RiCHTER

1862-1902 .

. Chen)ist.

Has been responsible for the analyses of tlie ash of Rothanistcd crops,

etc., some 900 in all, of which only a portion have been publislu-il.

This work, begun in the Rothamsted Laboratory, was continued up to

1902 in his laboratory at Charlottenbur^.
P. Cathcart .
W. A. Peake .

Died 1883 (see Trans. CIn
D. A. Louis .
T. Wilson, B.A.

— Churchill

— Sanders .

(i. GlKKINS

W. Smith

M. DoMAGALSKI

W. Christy .

H. Archer

H. O. Williams

C. B. Kaye .

A. Hall

F. G. Abbott .

C. Barnett .

ibout 1878

Chemical .\ssistant

1878-1882

Chemist.

.S'oc.,45, 1884,

617)

1882-1887

Chemist.

1882-1893

'iVanslal..r. tt«-.

1850-1852

Clerk.

1851

Clerk.

1852-1893

Clerk.

1852-1854

Clerk.

1855-1860

Clerk.

1860-1805

Clerk.

1872-1883

Clerk.

1872-1875

Clerk.

1873-1878

Clerk.

1889-1892

. Clerk.

1892-1899

( l.rk.

1899-1901

( Urk.

290

INDEX

Calcium carbonate — continued.

Removed in drainage waters, 238.
Carbohydrates, in root crops, 96.

Required for fixation of nitrogen, 140.
And fat in animals, 247.
Carbon, accumulation of, in Rothamsted
soils, 139.
In plant, source of, 1.
In Rothamsted soils, 28.
Cellulose dissolved during malting, 265.
Centaurea nigra, 155, 160, 181.
Chalk, eifect of on grass land, 158.

In Rothamsted soils, 2S, 140.
Changes in herbage following changes
in manuring of grass land, 168, 170,
261.
Chlorine in rain, 19, 21.

In drainage water, 233.
Clay-with-flints, 24.

Clover, accumulation of nitrogen by, 8,
137, 147.
Continuous growth on garden soil, 144.
Effect of, on succeeding crops, 200,

207.
Experiments on, 141.
Grown in rotation, 194, 200.
Sickness, 133, 148, 194.
Compensation tables for purchased

foods, 257.
Competition of grasses, etc., in meadow,

153, 162, 171.
Composition of, animal carcasses, 250.
Mangel crop, 115.
Rothamsted soil, 27, 145, 214, 222.
Wheat flours, 268.
Condiments in cattle feeding, 258.
Condition of land, 90, 212.
Continuous barley, maintenance of yield,
72.
Oats, 92.
Root crops, 95.

Wheat, maintenance of yield, 36.
Cytase in malt, 265.

D

Dactylis glomerata, 162, 175.
Denitrification, 115, 210, 219.
Diastase in malt, 263.
Diffusion of nitrates in soil, lack of, 228.

Diminishing returns, law of, 46, 102,
Drain gauges, 15, 22, 229.
Drainage water, compositioii of, 237.

Losses in, 50, 232.

Nitrates in, 229.
Drains in Broadbalk field, 231.
Drought of 1870, 163.
Dry matter in mangels, 116.
Dyer, B. , analysis of Rothamsted soils,.
27, 54.

E

Ensilage, experiments on, 266.
Evaporation of rainfall, 22.

F

Fallow, accumulation of nitrates during,
63, 222.
Effect of, on wheat, 62.
And leguminous crop in rotation, 200.
Farmyard manure, accumulation of, in
soil, 220.
Effect on barley, 77, 85.
Effect on grass land, 156, 165.
Effect on potatoes, 125.
Effect on wheat, 39, 55.
Losses of nitrogen in making, 256.
Recovery of nitrogen of, 54, 113.
Residues left by, 78, 156.
Value for mangels, 97, 108.
Fat formed from carbohydrates, 247.

In fattening animals, 250.
Fattening animals, change in composi-
tion of animals during, 252.
Food required by, 248.
Feeding experiments, 240, 258, 264, 267.
Feeding roots on the land, effect of, 206.
Fertility of land, maintenance in equi-
librium, 39, 212, 221.
Festuca ovina, 154, 157, 158, 175.
Fixation of nitrogen, by bacteria, 140,
210.
By leguminous plants, 11, 143, 159,

200.
Experiments on, 6, 8, 13.
Flour, food value of different grades, 270.
Food value, of malt, 261.
Of sewage-irrigated grass, 261.

INDFA

•Jl»l

Foods, for stock, -J 10.
Manure value of, '254.
Required by fattening animals, 'J 1>^.
Fr.uikland, analyses of drainat;e waters,

19. 20, 237.
Fungoid disease as affected by manur-
ing, 102, 126, 10"..

G

Oarden clover plot, 144.
Geescroft field. 92, 134.
Geology of Rothanisted soils, 24.
Glucose in mangels, 115.
Grain, ratio of, to straw, 55, S J, ?

Stability of composition, 62.

Weight of barley, 84.

Weight of oat, 93.

Weight of wheat, 55.
Grasses, separation of, 154.
Grass land, experiments on, 150.

Signs of impoverishment, 154.

H

Hay, experiments on, 150.
Haymaking, losses during, 266.
HeUriegel and Wilfarth, 11.
High farming, 46.
Holcus lanatus, 162, 173.
Hoos field, 62, 70, 95, 141.
Humus, 39, 63, 198.

Value in growing mangels, 97.

Value of, in grass land, lOri.

Lathyrus pratensis, 137, 159, 179.
Lawes, description of Rothamsted soil,
24.
Origin of Rothamsted experiments, 4.
Leaf and root, proportion of, in mangels
and sugar beet, 112, 129.
Proportion of, in turnips, 119.
Leguminosae, fixation of nitrogen by.

11, 133, 143, 159,210.
Leguminous crops, will not grow con-
tinuously, 133, 145.
Effect of mineral manures on, 197.

I.<pinilnou.n rrt>p» r„mtimt4t,i.

C'Hiwn in rotntion. HM.

Injuri.msiy ftffcirtl by nHn.K»-n«».
innnurfs. I its.
I^gmiiinous pl.mU in ^ntM Und. l.'.O.
Leonlmlon hispuius. I5i, MO. l""!.
Liebig. tlicory of nninwl nutrition. J41,

Theory of plant nutrition. J. H. 33.
Lime, efrc«t of, on jfm-vs Uiml. 1«7.
Little Hoos ful.l. It.
Lotus cornieulatuH. 1.'.,'., I'.p, 17".
Lucerne, S. 141.

Kffeet on succ«Tiliiu' croi.'., i 1 1

M

Magnesium salts in manure, rlTret of,
48, 105.

in Soil, 27.
Maintenanie of yield without nuinun*,

36, 65. 72, 154, 192.
Maize for silage, 20'').
Malt as food, 261.
Malting, losses during, 262.
Mangels, cannot draw upon the nitrofirn
of the air, 99.

Composition of, 115.

Dependence on farmyard nuinurr, 97.

Grown continutmsly. 95. 96.

Value of potash for, 115.
Manure value of fo<Hls. 254.
Manures, composition of, as u»«*tl at
Rothamsted, 31.

I'sed for wheat plots, 34.
.Manurial constituents g]iini-<l or lost by

the land, 20'.'.
Mechanical analysis of Uolhnnistrd mHI*.

2'5.
Mediiago lupuluui, on rotation plot*. IM.

Weed on whe-at plots. S«.
Meteortdogieal obsrrvatioiu. li.
.Mill pnHhicts of whrnt. •.'«•*.
Minenil nianun-s, 5, H.

Klfect of. on Itrtfley. SO.

KfTeet of. «>n crops in nit«tU»n. l»«.

KfTect of. on jfmss land. \!>^.

KfTect of. on Irjruiiiimju* crop*. 197.

FfTwt of. on nianjfcU. 103.

F.fTe«-t of. on potatort, 124.

292

INDEX

Mineral manures — continued.
Eifect of, on Swedes, 120
Effect of, on wheat, 48.

Nodules on roots of leguminous plants,

11.
Nutrition of animals, 240.

N

Nitrate of soda, comparison with ammo-
nium-salts, 44, 59, 60, 76, 82, 85,
107, 131, 157, 161, 163.
Nitrates, distribution in soil and subsoil,
224.
Due to fallowing, 63, 222.
Formed by bacteria, 218.
In drainage waters, 229.
In mangels, 118.
Lost by drainage, 51, 63, 223.
Nitric acid in rain, 18.
Nitrification, 52, 196, 217, 236.

Of ammonium-salts, 225.
Nitrifying organisms, distribution of, 221.
Nitrite-forming bacteria, 218.
Nitrogen, accumulated by clover, 147.
Added to the soil by rain, 20.
Effect of, on quality in barley, 89.
Experiments on fixation of, G, 8, 11,

99.
Gain or loss to the soil, 38, 210.
Gained or lost during feeding, 254.
In barley grain, 84, 89.
In plant, sources of, 3.
In soil, accumulated by wild herbage,

139.
Of manure recovered in crop, 54, 112.
Nitrogenous constituents of food, and
fat, 247.
In fattening animals, 250.
And increase, 242.
And work, 245.
Nitrogenous manures, comparative effect
on barley, 76.
Effect on grass, 161.
Effect on mangels, 97, 116.
Effect of successive increments on

yield of wheat, 45.
Effect on wheat, 42.
Injurious effect on leguminous crops,

198.
Injury caused by excess of, 102, 126,
162.

o

Oats, experiments on, 92.
Oxen, composition of, 250.
Organic matter in rain, 20.

In Rothamsted soils, 28.

In manures, value of, 165.

In soils, effect of on bacteria, 220.

Peas, 141.

Percolation of rainfall through bare soil,

22, 61.
Phosphoric acid, function of, 59, 80, 87,
120.

Importance to barley, 80.

Importance to Swedes, 120, 196.

In Rothamsted soils, 29, 54.

Removed from soil by crops, 38, 212.

Removed in drainage waters, 238.

Value of, in wet seasons, 59, 87.
Pigs, composition of, 252.

Experiments upon, 242.
Plantago lanceolata, 160, 181.
Poa pratensis, 162, 175.
Potash, and carbohydrate formation,
56, 117, 125.

Diminishes incidence of fungoid
disease, 103, 165.

Effect of, on grass land, 160, 164, 170.

Effect on leguminous plants, 159.

Effect on turnips, 120.

Function of, 56, 59, 87, 105, 117, 125,
129.

In Rothamsted soils, 29, 54, 214.

In soils^ set free by lime, 168.

Lost in drainage waters, 238.

Removed from the soil by crops, 38,
212.

Value of, for beans, 134.

Value of, in dry seasons, 59, 87.

Value of, with mangels, 105, 111.
Potatoes, continuous growth of, 95, 123.
Poteriura sanguisorba, 155, 160, 179.

INDKX

'J1»:j

Practical conclusions : —

Barley, 90.

Grass land, 185.

Mangels, 119.

Potiitoes, 126.

Rotation, 214.

Sugar beet, 132.

Turnips. 122.

Wheat, 68.
Pugh, experiments on nitrogen
tion. •■,.

Quality of barley crops, 83, 88.

Wheat crops, 55.
Quotient of purity in mangels and
beet, 115. 131.

fixa-

Kil>rninjr. rffrct of phmphoiic acid. »0.

Of itmngrl*, lOrt, 11'.'.

Of sugar bcrt, I'JJ*.
Ilool crops, frtl on the Und, 'Ml.

Grown c<>ntinuou<ily. J»l.
Rmits, habits of rooln indurrd b\ Mi»iiur
ing, 82, 107. 120. lrt.1. li*..

Root to leaf, proportion of.
129.
Kotation. Iviriry grown m, T.'i. h><. ii»|.

Beans or ilovor gn>wn in, 104. 200.

Kxperiment.s on crops grtjwn in. 1*>0.

Removal of manure ronstitucnti by
crops grown in. 2U.

Wheat grown in. 6.'>, 194.
Rumex acetosa, IT.S, 159, 181.

R

Rainfall, effect of, upon barley, S7.
Effect of, upon grass land, 1S5.
Effect of, upon wheat, 60.
Proportion evaporated, 23.
Records, 15.

Wet and dry year, 58, 85.
Rain gauges, 15.

Ranunculus acris and bulbosus, 160, 179.
Rape cake, as manure for barley, 76.
Character as manure, 101.
Recovery of nitrogen of, 114.
Residue left by, 205.
Recovery of manure nitrogen, 112, 209.
Removal of manure constituents in crop,

209.
Residues, left by ammonium-salts, 52,
226.
Left by farmyard manure, 78, 156.
Left by feeding roots on the land, 206,

207.
Left by leguminous crops, 143, 203.
Left by nitrogenous manures, 198,

22(i.
Left by rape cake, 76, 205.
Nitrogenous, effect of, on quality of
barley, 89.
Respiration, losses by, during malting.
262.

S
Sainfoin, 141.

Salt as manure for mangels, 105.
Saussure, De. 1.
Schloesing and Miintz on nitrificntion.

217.
Sclerotinia trifoliorum, 148.
Season, effect of, u|>on l>arlcy, 85.

Effect of, upon grass crops, 183.

Effect of, upon nitnfication, 222, 231.

Effect of, upon wheat. 5i'>.
Sewage, experiinents with, 2'5m.
Sheep, breeds, coni|«irativc fultrnrng
power, 25>.

Composition of, 250.

Experiments upon, 242.
Silicate of soda, manuriul effect of, 182.
Soda salts a.s econoniiscr. of |M>t*«h. 82,

108. 158.
Soil, analyses of Ruthanistcd, 26. 27.

Description of Hothani.'ktcd, 24.

Nitrifyinj; orgnnisni* in, 221.
Starch, as fj>od, 25s.

Change during malting. 2»53. 2«J.

In potiitcK's. 125.
Stones in Rothnmstinl soil. 26.
Straw chaff on grajw lami. I'".'
Straw to grain, ratio of,
.Sugar l>cft. W, 127.
Sugar, OS fiKxl, 2.'''.

In nuUt, 2'5.J.

294

INDEX

Sugar — continued.

In mangels, 115.

In sugar beet, 129.
Sulphuric acid in rain, 21.
Sunshine records, 17.
Superphosphate, effect on grass land,
160.

Effect on turnips, 120.
Swede turnips, 119.

Grown in rotation, 192.

Importance of phosphatic manures,
120, 196.

Specially dependent on manure, 193.

Temperature records, 17.

Texture of the soil as affected by manure,

95, 97, 108, 120, 134.
Thaer's hay values, 240.
Torula on mangels, 103.
Trifolium pratense and repens, 141, 159,

177.
Turnips, Norfolk white, 94, 119.

Swede, 95, 119, 192.

u

Unraanured plots, 37, 72, 154, 192.
Uromyces betae, 103.

Variety tests of wheat, 66.
Vergil on enriching effect of leguminous
crops, 10.

Vertical movement of nitrates in soil,

228.
Vetches, 141.
Voelcker, analyses of drainage waters,

237.
Nitrogen in clover crop, 10.

w

Warington on nitrification, 217.

On denitrification, 219.
Way, experiments on sewage, 260.
Weeds, accumulation of, 32, 41, 63.

Competition of, with wheat, 41.

Sign of impoverishment in grass land,
154.
Weight, per bushel of barley, 84, 89.

Wheat, 55.
Wheat, allowed to run wild, 41.

And fallow alternatelj-, ^Yi.

And fiour, 268.

Effect of winter rainfall on yield, 60.

Experiments on, 31.

Grown continuously, 36.

Grown in rotation, 65, 193.

Valuation of crop, 55.

Variety tests, 66.
White bread, food value of, 270.
Wild vegetation, after clover and beans,
137.

After wheat, 41.
Winogradsky, on nitrification, 218.
Winter rainfall, effect of. on wheat, 60.

Effect on fallowing, 64.
Woodward, description of Rothamsted

soil, 24.
Work in relation to nitrogenous food,
245.