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THE

MANURES

MOST ADVANTAGEOUSLY APPLICABLE TO THE

VARIOUS KINDS OF SOILS,
AND THE CAUSES
OF
THEIR BENEFICIAL EFFECT

IN EACH PARTICULAR INSTANCE.

eseeesgeeeeAGoneus Patriz, sit Utilis Agris.
Fur. Sat. 14.

6; ae eaERT TG ance
) ae
A : =
“O93
“see | j BY

RICHARD KIRWAN, Esa F.R.8.& M.R.I. A.

Author of the Elements of Mineralogy, Gc.

FROM THE SIXTH LONDON EDITION.

PHILADELPHIA:

PriInTeD By KIMBER, CONRAD, anp CO.
No. 95 MARKET STREET, & 170 souTH SECOND STREEI

s.

1807
a

‘eof

Yea

ARR, otk 28) Beh et aie en ee
ie a ei i . titi %
er ae ot

10 aT “2
2

. WHAT ARE THE MANURES MOST ADVANTAGE-
° OUSLY APPLICABLE TO THE VARIOUS SORTS
OF SOILS;

AND,

WHAT ARE THE CAUSES OF THEIR BENEFICIAL
EFFECT IN EACH PARTICULAR INSTANCE.

—— =

smal Idoneus Patriz, sit Utilis Agris.
JUVEN, SAT. 14.

AGRICULTURE is the art of mak-
ing the earth produce the largest crop of
useful vegetables at the smallest expense.
It has often been remarked, that amidst
the various improvements which most of
the practical arts have derived from the
progress lately made in natural philosophy
and chemistry, none have fallen to the
share of agriculture, but that it remains
nearly in the same state in which it existed
two thousand years ago. I am far from
allowing the truth of this observation, taken

+h

im its totality ; to refute it, we need only
compare the writings of Cato, Columella,
or Pliny, with many modern tracts, or still
better, with the modern practice of our
best farmers. It must be granted, how-
ever, that vague and fortuitous experience
has contributed much more to the present
Hourishing state of this art than any gene-
ral principles deduced from our late ac-
quired knowledge, either of the process.
of vegetation, or of the nature of soils;
but the skill thus fortuitously acquired is
necessarily partial, and generally local;
the very terms employed by the persons
who most eminently possess It, are gene-
rally of a vague and uncertain significa-
tion. Thus Mr. Young, to whose labours
the world is more indebted for the diffu-
sion of agricultural knowledge than to
any writer who has as yet appeared, re-
marks, That in some parts of England,
where husbandry ts successfully practised,
any loose clay 1s called marl* ; 1n others,
marl is called chalk}+ ; and, in others, clay
is called loam t. Philosophic researches
have been made, but not yet sufficiently
noticed: muchi nformation may be derived
from. Monsicur Du Hamel, and much
more from the well-directed experiments of

* First Eastern Tour, 178.
+ 2 Bath Mem. 192, 220. + 2 Bath Mem. 137.

5

Mr. Tillet*. Immense strides have been
made in this career, by the illustrious Berg-
man; Dr. Priestley’s experiments have
thrown a new light on this, as well as on
every other object of natural philosophy.
Mr. Lavoisier’s new theory explains ma-
ny circumstances, before inexplicable ;
discoveries of great importance have been
made by Mr. Senebier and Dr. Ingenhouz:
even Mr. Young has not always confined
his attention to the mere practical part,
but sometimes happily extended it to ob-
jects of a more general and speculative na-
ture; but the fullest light, perhaps, has
been thrown on this subject by the late
discoveries of Mr. Hassentraz.t

If the exact connexion of effects, with
their causes; has not been so fully and so
extensively traced in this as in other sub-
jects, we must attribute it to the peculiar
difficulties of the investigation. In other
subjects, exposed to the joint operation of
many causes, the effect of each, singly
and exclusively taken, may be particularly
examined ; the experimenter may work in
his laboratory with the object always in his
view ; but the secret processes of vegeta-
tion take place in the dark, exposed to the
various and indeterminable influences of

* Mem. Par. 1772. * Annales Chymiques, Vul. 13, 14.

?

| 6

the atmosphere, and require, at least, half
a year for their completion. Hence. the
dificulty of determining on what peculiar
circumstance success or failure depends ;
the diversified experience of many years
can alone afford a rational foundation for
solid specific conclusions. It cannot there-
fore, be expected, that new, decisive, and _
direct experiments should be laid before
the Academy within the time prescribed
for answering this question. The resolu-
tion of the first part must be deduced from
a statement of facts long established by
multiplied experience ; and that of the se-
cond, by the application of more generai
principles to the explanation of those
facts. —But before we proceed to either
branch ‘of this question, the distinctions
and denominations, both of soils and ma- ©
nures, must be exactly settled and accu-
rately defined.

CHAP "1.

OF SOILS AND MANURES+»

ES ED SE

SECTION f.

OF SOILS.

LAND, considered as the basis of ve-
getation, is called soi.

Soils consist of different combinations of
two or more of the four primitive earths,
namely, the calcareous (which I some-
times call mild calx) magnesia, argill, and
the silicious. For a more accurate de-
scription of these I must refer to books of
mineralogy ; and shall only remark, that
by calcareous earths are meant chalk, and
all stones that burn to lime. They are
easily distinguished by their property of
effervescing with acids.

Magnesia is never found alone; its
distinguishing character consists in afford-
ing a bitter salt, generally called Epsom
Salt, when combined with the vitriolic
acid.

Argill is that part of clay to which this
ewes its property of feeling seft and unc-

8

tuous, and of hardening m fire; it is
difficultly soluble in acids, and scarce ever
effervesces with them. When combined
with the vitrolic acid, it forms alum.

S7licious Earth is often found in a stony
form, such as flint or quartz; and _ still
more frequently in that of a very fine sand,
such as that whereof glass 1s made. It
does not effervesce, nor is it soluble in any
of the common acids.

‘To these we may add Iron, in that im-
perfect state in which it exists when reduc-
ed to rust, and commonly called Calx of
Tron. |

The soils most frequently met with, and
which deserve a distinct consideration, are
clay, chalk, sand, and gravel, clayey loam,
chalky loam, sandy loam, gravelly loam,
ferruginous loam, boggy soil, and heathy
soil, or mountain, as it is often called.

Clay is of various colours ; for we meet
with white, grey, brownish red, brownish
black, yellow or bluish clays; it feels
smooth, and somewhat unctuous: if moist,
it adheres to the fingers, and if sufficiently
so, It becomes tough and ductile. If dry,
it adheres more or less to the tongue: if
thrown into water, it gradually diffuses
itself through it, and slowly separates from
it. It does not usually effervesce with
acids, unless a strong heat be applied, or

9

that it contains a few calcareous particles,
or magnesia. If heated, it hardens and
burns to a brick.

It consists of argill and fine sand, usually
‘of the silicious kind, in various propor-
tions, and more or less ferruginous. ‘The
argill forms generally from 20 to 75 per
ewt. of the whole mass; the sand and
calx of iron the remainder. ‘These are
perfectly separable by boiling in strong
vitrolic acid.

Chalk, if not very impure, is of a white
celour, moderate consistence, and dusty
surface, stains the fingers, adheres ‘slightly
to the tongue, does not harden when heat-
ed, but, on the contrary, in a strong heat
burns to lime, and loses about four-tenths
of its weight. It effervesces with acids,
and dissolves almost entirely therein. I
shail also add, that this solution 1s not dis-
turbed ‘by caustic volatile alkali, as this
circumstance distinguishes it from magne-
sia,—it prometes putrefaction.

Sand. By this is meant small loose
erains of great hardness, not cohering
with water, nor softened by it. It is gene-
rally -of the silicious kind, and therefore
insoluble m acids.

Gravel difiers from sand chiefly in size:
however stones of a calcareous nature,

10

when small and rounded, are often com-
prehended under that denomination.

Loam denotes any soil moderately co-
hesive : that is, less so than clay, and more
so than loose chalk. By the author of the
Body of Agriculture, it is said to bea clay
mixed with sand. Doctor Hill defines it
an earth composed of dissimilar particles,
hard, stiff, dense, harsh, and rough to the
touch, not easily ductile while moist, rea-
dily diffusible in water, and composed of
sand and a tough viscid clay. The defini-
tion I have given seems most suited to the
different species ] shall now enumerate.

Clayey Loam denotes a compound soil,
moderately cohesive, im which the argilla-
ceous ingredient predominates. Its cohe-
rence is then greater than that of any other
loam, but less than that of pure clay.
The other ingredient 1s a coarse sand, with
or without a small mixture of the calcare-
ous ingredient. It is this which farmers
generally call strong, stiff, cold, and heavy
. loam, in proportion as the clay abounds in
it.

Chalky Loam. This term indicates a
loam formed of clay, coarse sand, and
chalk ; in which, however, the calcareous
ingredient or chalk much predominates.
It is less cohesive than clayey loams.

Sandy Loam denotes a loam in which

i]

sand predominates : it is less coherent
than either the abovementioned. Sand,
partly coarse and partly fine, forms from
80 to 90 per cent. of this compound.

Gravelly Loam difters from the last only
in containing a larger mixture of coarse
sand, or pebbles. This and the two last
are generally called, by farmers, /7ght or
hungry soils; particularly when they
have but little depth.

Ferruginous Loam,or Till. This is
generally of a dark brown, or reddish co-
lour, and much harder than any of the pre-
ceding: it consists of clay and calces of
iron, more or less intimately mixed. It
may be distinguished not only by its co-
lour, but also by its superior weight: it
sometimes effervesces with acids, and
sometimes not; when it does, much of the
irony part may be separated, by pouring
it, when well dried, into spirit of salt ;
from which the iron may afterwards be
separated by alkalis or chalk. )

, Akin to this are certain vé¢rzolic
soils, which, when steeped in water, impart
to it the power of reddening syrup of vio-
lets. These are generally of a blue colour,
but. redden when heated.

Boggy Soil or Bogs, consist chiefly of
ligneous roots of decayed vegetables mix-

12

ed with earth, mostly argillaceous, and
sand, and a coally substance derived from
decayed . vegetables. Of bogs there are
two sorts : the black, which contain a
larger proportion of clay and of roots
more perfectly decayed, with mineral oil.
In the red the roots.seem less perfectly de-
cayed, and to form the principal part.

Heathy Soil is that which is naturally
productive of heath.

13

SECTION II.

OF MANURES.

Manure denotes any substance or ope-
ration by which a soil is improved. To
improve a soil 1s to render it capable of
producing corn, legumens, and the most
useful grasses.

The substances principally used as ma-
nures, are chalk, lime, clay, sand, mar},
gypsum, ashes, stable-dung, mucks, farm-
yard dung, pounded bones, sea- weeds,
sweepings of. ditches, old ditches. Other
manures or top-dressings, as they are em-
ployed chiefly to promote the growth cf
vegetables, and not merely with a view of
improving the soil, I omit.

The operations used to improve soils,
are fallows, draining, paring and burning.

Of chalk, clays, and sand, we have al-
ready treated.

Lime is a substance whose external
characters and mode of production are
well known. It differs from chalk and
powdered limestone chieily Van the absence
of fixed air, which is expelled from these
during their calcination. This air it gree-

14

dily re-absorbs from the atmosphere, and all
other bodies with which it comes in con-
tact, and which can furnish it; but it can-
not unite with the air unless it is previ-
ously moistened. 100 parts quick-lime
absorb about 28 of water. It is soluble
in about 700 parts of this fluid. To re-
gain its full portion of air from the atmos-
phere, it requires a year or more, if not
purposely spread out: it resists putrefac-
tion; but with the assistance of moisture,
it resolves organic substances into amucus.

Marl is of three sorts; calcareous, ar-
gillaceous, and silicious or sandy. All are
mixtures of mild calx (7. e. chalk) with
clay, in such a manner as to fall to pieces
by exposure to the atmosphere more or less
readily. :

Calcareous Marl is that which is most
commonly understood by the term Marl,
without addition. It is generally of a yel-
lowish white, or yellowish grey colour ;
rarely brown or lead coloured. It is sel-
dom found on the surface of land, but
commonly a few feet under it, and on the
sides of ‘hills, or rivers that flow through
calcareous couniries, or under turf in bogs.
Frequently of a loose texture, sometimes
mocerately coherent; rarely of a stony
hardness, and hence called stone-marl.
Sometimes of a compact, sometimes of a

15

lamellar texture ; often so thin as to be
called paper-marl. It often abounds with
shells, and then is called shell-marl ; which
is looked upon as the best sort. When in
powder, it feels dry between the fingers ;
put in water, it quickly falls to pieces or
powder, and does not forma viscid mass.
It chips and moulders by exposure to the
air and moisture, sooner or later, accord-
ing to its hardness and the proportion of
its ingredients : if heated, it will not form
a brick, but rather lime. It effervesces
with all acids. It consists of from 33 to
80 per cent. of mild calx, and from 66 to
2U per cent. of clay.

To find its composition. pour a few
ounces of weak, but pure spirit of nitre,
or common salt, into a Florence flask ;
place them in a scale, and let them be ba-
lanced ; then reduce a few ounces of dry
marl into power, and let this powder be
carefully and gradually thrown into the
flask, until after repeated agitation no ef-
fervescence is any longer perceived; let
the remainder of the powdered marl be
then weighed, by which the quantity pro-
jected will be known; let the balance be
then restored; the difference of weight
between the quantity projected and that
requisite to restore the balance will dis-

16

cover the weight of air lost during effer-
vescence ; if the loss amounts to 13 per
ewt. of the quantity of marl projected, or
from 13 to 32 per cwt. the marl essayed
is calcareous marl. ‘This experiment is
decisive, when we are assured by the ex-
ternal characters above mentioned, that
the substance employed is marl of any
kind; otherwise some sorts of the sparry
iron-ore may be mistaken for marl. The
experiments to discover the argillaceous
ingredient (being too dificult for farmers).
I omit. The residue left after solution, be-
ing well washed, will, when duly heated,
generally harden into a brick.
Argillaceou: Mart contains from 68 to
80 per cent. of clay, and consequently
from 32 to 20. per cent. of aerated calx.
Its colour is grey or brown, or reddish
brown, or yellowish or bluish grey. It
feels more unctuous than the former, and
adheres to the tongue : its hardness gene-
rally much greater. In water it falls to
pieces more slowly, and often into square
pieces: it also more slowly moulders
by exposure to the air and moisture, if of
a loose consistence : it hardens when he:t-
ed, and forms an imperfect brick. It effer-
vesces With spirit of nitre or common salt,
but frequentiy refuses to do so with vine-

hd

gar. When dried and projected into spi-
rit of nitre, in a Florence flask, with the
attentions above-mentioned, it 1s found to
lose from 8 to 10 per cwt. of its weight.
The undissolved part, well washed, will,
when duly heated, harden into a brick.

Silicious, or Sandy Marls, are those
whose clayey part contains an excess of
sand: for, if treated with acids in the
manner above-mentioned, the residuum,
or clayey part, will be found to contain
above 75 per cwt. of sand; consequently
chalk and sand are the predominant ingre-
dients.

The colour of this marl is brownish
eray, or lead coloured: generally friable
and flakey. but sometimes forms very hard
lumps. It does not readily full to pieces
in water. It chips and moulders by ex-
posure to the air and moisture, but slowly.
It effervesces with acids; but the resi-
duum, after solution, will not form a
brick.

Limestone-Gravel. This is a marl
mixed with large lumps of limestone. The
marl may be either calcareous or argillace-
ous ; but most commonly the former.
The sandy part is also commonly calcare-
ous.

B

is

Gypsum is a compound of auicarenes
earth and vitrolic acid: it forms a distinct
species of the calcareous genus of fossils :
of which species there are six families.

The general character of this species are,

1. Solubzlity in about 500 times its
weight of water, in the temperature of
60°.

2 Precipitability therefrom by all mild
alkalis, and also by caustic fixed, but not
by caustic volatile alkali.

3. Ineffervescence with acids, if the
gypsum be pure; but some families of this
species, being contaminated with mild
calx, slightly effervesce.

A. Insolubility, or nearly so in n the ni-
trous acid, in the usual temperature of the
atmosphere.

5. A specific gravity, reaching from,
2,16 to 2,31.

6. A degree of hardness, such as to ad-
mit being scraped by the nail.

7. When heated nearly to redness, it
calcines; and if then it be slightly sprink-
led with water, it again concretes and har-
dens.

8. It promotes putrefaction in a high
degree.

Of the six families of this species I shall
describe only one; namely, that which

19

has been most advantageously employed
as a manure. Descriptions of the other
five should be found in treatises of mine-
ralogy. It is called fibrous gypsum.

Its colours are gray, yellowish or red-
dish, or silvery white, or light red, or
brownish yellow, or striped with one or
more of these dark colours. It 1s compos-
ed of fibres or striz, either straight or
curved, parallel or converging to a com-
mon centre, sometimes thick, sometimes
fine and subtile, adhering to each other,
and very brittle: its hardness such as to
admit being scraped with the nail: com-
monly semi-transparent ; in some, often
ina high degree.

Ashes. Sifted coal-ashes, those of peat
and white turf-ashes, have been found
useful; red turf ashes useless, and gene-
rally hurtful. Wood-ashes have also been
employed advantageous ly in many cases ;
they contain either the four primitive
earths, as Mr. Bergman asserts; or cal-
careous earth chiefly, according to Achard;
or calcareous and magnesia, according to
D’Arcet. They also contain some pro-
portion of phosphorated selenite, z. ¢. cal-
careous earth united to the phosphoric
acid. Almost all co atain also a small and
variable propertion of common salt, Glau-

20".

ber’s salt, and terrene salts, which, when
in a small dose, all accelerate putrefition ; .
also small bits of charcoal.

Charcoal is a substance well known; it
has frequently and successfully been used
asa manure. Ist Young’s Annals, 152,
&e. &e.

S ap-boilers Waste forms an excellent
manure for some soils ; it contains, by
Mr. Ruckert’s Analysis, 57 per cwt. of
mild calx, 11 of magnesia, 6 of argill, and
21 of silex 3

Stable Dung. This is used either fresh
or putreficd ; the first is called /ong, the
other short dung; it abounds in animal
matter, easily runs into putrefaction, and.
when putrefied serves as a leaven to hasten
the decay of other dead vegetable sub-
stances; its fermentation is promoted by.
frequent agitation and exposure to the air;
yet it : shoul d be covered to prevent water
from carrying of most of its important
ingredients; or at least the water that 1 im-
bibes them should not be lost.

Farm-yard Dung consists of various
vegetables ; as straw, veeds, leaves, fern,
&c. impregnated with animal matter; it
ferments more slowly than the former ;

21

should be piled in heaps, and stirred, from
time to time. Fern putrefies very slowly.
The water that issues from it should be
preserved. |

Some of these manures have been ana-
lysed. |

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23

Hence they should be applied, not in-

discriminately, but according to circum-
stances, to be indicated in the sequel.
_ Pounded bones form also manure much
used in the neighbourhood of great towns.
They gradually deposit their oily part,
which contains a large proportion of ani-
mal! coal which 1s extricated by putrefac-
tion, and phosphorated calx. Hence Bone-
ash is also useful.

Sea-weed, particularly if mixed with
earth, soon putrefies, and makes a good
manure.

Sweepines of Ditches abound with pu-
trid matter from decayed vegetables, and
hence forma manure.

Old Ditches, exposing a large surface to
vegetation, contain, when destroyed, a
quantity of decayed vegetables, which
putrefy and make a good manure ; but in
this and the former case, it may be proper
to distinguish of what soil they are com.
posed, for reasons that will hereafter ap-
pear.

Fallowing, 1s the principal operation by
which exhausted lands are restored to fer-
tility ; its use seems to me to consist in ex-
posing the roots of vegetables to decay,
whereby food for a fresh growth is pre-

BA

pared ; the atmosphere also deposits fix-
ed air and carbonaceous substance on earth
long exposed to it.

Draining is an operation equally neces-
sary and well known, on which no more
need be said here.

Paring and burning reduces the roots of
vegetables to coal and ashes; and thus
prepares both a stimulant and nutriment
for plants, as will be seen hereafter.

Crt. hk

‘OF THE FOCD OF PLANTS, AND THE COMPO-
SITION OF FERTILE SOILS.

HAVING, in the preceding chapter,
explained the nature of the different soils
known in agriculture, and of the different
manures whose general utility has been
ascertained by long experience, we are
now to inquire which of those manures
are most advantageously applicable to
each of those particular soils, and what
are the causes of their beneficial effect in
each particular instance.

To proceed with order in this inquiry,
we must observe, that the general effect
expected from the apnlication of manure
is fertility; that is, the most copious pro-
duction of corn and grasses; and, since
fertility is itself the result of the due ad-
ministration of the food of those vegeta-
bles, we must first see what that food is,
and of what ingredients a soil ought to be
composed, in order to contain or adminis-
ter it; after which we shall indicate by

a0:
what manures each particular sort of soil
is brought into a fertile state (which is the
beneficial effect expected from them) and
how in each particular case they contri-
bute to the due adminstration of the vege-

table food, which is the cause of their be-
neficial effect.

SECTION I.
OF THE FOOD OF PLANTS.

To discover the food of plants, particu-
larly of those which form the object of
our present inquiry, we must examine the
nature and proportion of the substances in
which they grow, and of those which they
themselves contain : thus we shall be
enabled to see which of the latter are de-
rived fromthe former. —

First, All plants (except the subaque-
ous) grow in a mixed earth, moistened
with rain and dew, and exposed to the at-
mosphere. If this earth be chemically
examined, it will be found to consist of
silicious, calcareous, and argillaceous par-
ticles, often also of magnesia, in various
proportions, a very considerable quantity
of water, and some fixed air. The most

L 3 € > mehe at ~ ‘ Ty} “NT ats iy
fertile, also, centain 2 small proportion of
< A

27

oil, roots of decayed vegetables, a coaly
substance arising from putrefaction, some
traces of marine acid, and gypsum.* On
the other hand, if vegetables be analysed,
they will be found to contain a large pro-
portion of water and charcoal ;: also fat and
essential oils, resins, gums, and vegetable
acids: all which are reducible to water,
pure air, inflammable air and charcoal:
a small proportion of fixed alkali is also
found, some neutral salts, most commonly
eypsum, tartar, vitriolate, common salt,
and salt of sylvius. In corn, and pazticu-
larly wheat, phosphorated selenite is also
found.

Hence we see that, on the last analysis,
the only substances common to the grow-
ing vegetables and the soils in which they
grow, are water, coal, different earths, and
salts. These, therefore, are the true food
of vegetables: to them we should also
add fixed air, though, by reason of its de-
composition, it may not be distinctly found
in them, or at least not distinguishable
from that newly formed during fhezr de-
composition.

I shall now examine the separated func-
tions of each of these ingredients.

* Home, 15 Mem. D’Agriculture, Par. 1790. Encyclo-

\r r r - = > ¢
ped. Vezetation, p. 277.

28

OF WATER.

The agency of water in the process
of vegetation, has never been doubted,
though the manner in which it contributes
to it has not, until of late, been distinctly
perceived. Doctor Hales has shewn, that
in the summer months a sun-flower weigh-
ing three pounds avoirdupois, and regu-
larly watered every day, passed through
it, or perspired, 22 ounces each day;
that 1s, nearly half its weight. He also
found that a cabbage plant, weighing
1 lh. 9 oz. sometimes perspired lb. 3 oz.;
but at a medium about half its weight.*
Doctor Woodward found that a sprig of
common spearmint, a plant that thrives
best inmoist soils, weighingonly 28,25 gers...
passed through it 3004 grs. in 77 days,
between July and October ; that is, some-
what more than its own weight each day.
He did more; for he found that in that
space of time the plant increased 17 ers.
in weight, and yet had no other food but
pure rain water. But he also found that
it increased more in weight when it lived
on spring-water, and still more when its
food was Thames watert. From whence

Z pe ~7° 7 7
Litres; 9.10, 15. +2 Phil), Trang, Albro 7 2G.

25

we may deduce, that grasses and corn,
during the time of their growth, absorb
about one half their weight of water each
day, if the weather be favourable.

Secondly, that the water they thus ae
_ nourishes them merely as water, withou

taking any foreign substance into the ac-
count: for 3000 ers. of rain water, in
Doctor Woodward’s experiment, afford-
ed an increase of 17 grains; whereas, by
Mareraafi’s exper iments, 5760 ¢ ors. of tise
water contain only one third of” a grain of
earth*. But,

Thirdly, [t also follows, that water con-
tributes still more to their nourishment
when it conveys to them earthy and sa.
line particles, as spring and ‘Thames wa-
ters do.

The manner Yn which pure water con-
tributes to the nourishment of plants, be-
sides the service it renders them in distri-
buting,the nutritive parts throughout their
whole structure, and forming itself a con-
stituent part of all of them, may be un-
derstood from modern experiments. Doc-
tor Ingenhouz and Mr. Senebier have
shewn that the leaves of plants exposed
to the sun produce pure air: now water

* 2 Margr. 6, 70.

30

has of late been proved to contain about
87 per cwt. of pure air, the remainder be-
tng inflammable air. Water is then de-
composed by the assistance of light with-
in the vegetable ; its inflammable part is
employed in the formation of oils, resins,
cums, &c. its pure air is partly applied to
the production of vegetable acids, and
partly expelled as an excrement.

Many, indeed, have asserted, that water
is the sole food of vegetables ; and among
the experiments adduced to prove it, that
of Van Helmont, quoted by the illustrous
Mr. Boyle*, is by far the most specious.
He planted a trunk of willow, weighing
5lb. in an earthen vessel filled with earth
dried in an oven, and then moistened with
rain-water. This vessel, it appears, he
sunk in the earth, and watered partly with
rain-water, and occasionally with distilled.
After five years he found the tree to weigh
169 lb. and the earth in which it was plant-
ed, being again dried, to have lost only _
2 oz. of its former weight, though the
tree received an increase amounting to
164 Ib.

Before I proceed to the explication of
this experiment, 1 must remark some cir-

Ca. Coe ae Van OV
2c Shaw’s Boyle, 240i

~

ol

cumstances attending it: First, that the
weight of the earth contained in the ves-
sel at the commencement and at the end of
five years, could not be exactly compared,
because the same degrees of desiccation
could not be exactly ascertained, and be-
cause many of the fibrillze of the roots of
the tree must have remained in the earth
after the tree was taken out of the vessel,
and these must have prevented the true loss
of earth from being perceived. Secondly,
That the earthen vessel must have fre-

quently absorbed water impregnated with

whatever substance it might contain, from
the surrounding earth in which it was in-
serted ; for unglazed earthern vessels easi-
ly transmit moisture. (lst Hales 5, and
Tillet’s Mem. Par. 1772, page 298, 304,
8vo.) Thirdly, As it appears that the pot
was sunk in the earth, and received rain-
water, it is probable that distilled water
was seldom used.

These circumstances being considered,
it will easily be made to appear that the
rain-water, absorbed by the tree, contain-
ed as much earth as the tree can be sup-
posed to contain.

First, The willow ince eae in weight
164 lb. in five years; that is, at the rate of

2,7 Ib. nearly per month ; and it being an

32

aquatic, it cannot be supposed to pass less
than ‘its own weight of water each day
during the six vegetating months. In the
first month, therefore, ity absorbed and
passed 5x30=150 tb. and as each pound
of rain-water contains 1¢r. of earth, 50
grains of aad must have been deposited
in the plant; and allowing no more than
50 grains for ‘the deposit of each of the six
months. we shall have 50x6=300 for
the deposit of the first year : but at the
end of the first year the plant gains an ac-
cession of the 52lb. therefore, in each of
the six summer months of the succeeding
year, it passes 37X30=1110 Ib. of water,

and receives a deposit of 370 grains ; and
at the end of the second year the deposit
amounts to 2220 grains. At the com-
mencement of the thicd year, the tree
gaining a farther accession of 32 ib. must
weigh 69 lb. and pass in each of the sum-
mer months 69xX30=2070 lb. of water,
and receive a deposit of 690 ers.. which
multiplied into 6=4140 grains. At the
commencement of the fourth-year, the
tree still gaming 32 1b. must weigh 1C1 1b;
and if it passes i01x30 in each of the
summer months, it must gain a deposit in
each of 1010 ers. of earth, and at the enc
of the year, 6060

AS
JO

At the commencement of the fifth year
it weighs 133 Ib. and gains at the end of
the six months 23940 grains of earth.
The quantities of earth deposited each
year exceed 5 lb. avoirdupois, a quantity
equal to that which 169 Ib. of willow can
be supposed to contain; for the commis-
sioners employed to inspect the fabrica-
tion of saltpetre in France, having exam-
ined the quantities of ashes afforded by
trees of various kinds, found that 1000 Ib.
of sallow, a tree much resembling the
willow, afforded 28 Ib. of ashes, and con-
sequently 169 lb. should produce 4,7. I
do not give this calculation, however, as
rigorously exact. It is certain, that if the
deposit left at the end of every month
were exactly taken, the total would ex-
ceed the quantity just mentioned ; but that,
found even by this rude mode, sufficiently
proves that water conveys a portion of
earth into vegetables equal to any that the
experiments hithcrto made can prove to
exist in them.

As to the coal, or carbonaceous princi-
ple, which this willow must also have
contained, it is probable that much of it
existed in the earth in which the willow
grew. Some is contained in all moulds or

c

34

vegetable earth ; and as we are not told
what sort of earth Van Helmont used, we
may well suppose it was good vegetable
earth, its quantity amounting to 200 Ib.
This principle may also have been contain-
ed in the water, for the purest rain-water
contains some oleaginous particles, though
in an exceeding small proportion, as Mr.
Margraaff has observed* ; and all oil con-
tains coal. Some also may have pas-
sed from the surrounding vegetable earth
through the pores of the earthen vessel.
All the other experiments, adduced to
prove that water is the sole food of plants,
may be explained in the same manner.
Grains of wheat have been made to grow
on cotton moistened with water; each
produced an ear, but that ear contained but
one grain ¢. Here the carbonaceous sub-
stance was derived from the grain, and
afterwards diffused and transported through
the whole plant by the water absorbed ;
for it must be observed that grain, like an
ege, contains much of the nourishment of
its future offspring. It is thus that tulips,
hyacinths, and other plants, expand and
grow in mere water. |

The earth contained in rain-water is

* 2d Margr. 15,90. + 2d Young’s Annals, 487.

Sis,

united partly with the nitrous and marine
acids, as Margraaff has shewn, but far the
greater part only with fixed air; for the
feeble traces of the two former acids could
not hold in solution the 100 grains of earth
which he found in 300 lb. of rain-water.

By far the greatest proportion of vege-
table substances consist of water. Accor-
ding to Mr. Young and Ruckert, grass
loses about 2-thirds of its weight on be-
ing dried into hay*. Dr. Hales found a
sun-fower plant, which weighed 48 ounces,
to lose 36 ounces by drying in the air dur-
ing thirty davst, and consequently to
have lost 3-fourths of its weight. Even
vegetables to appearance thoroughly dry,
contain from 3-fifths to 3-fourths of their
weight of watert. This water is not all
in a liquid state, but, by the loss of much

of its specific heat, is in a great measure
solidified.

* 21 Young’s Ann. 26.. 2d Ruck. 1397
ft 1st Hales, 8.
¢ Ruckert, 28. Seneb. Encyclop. Vegetation. 5%.

56

OF COAL, OR THE CARBONIC SUBSTANCE.

To Mr. Hassenfraz we owe the dis-
covery, that coal is an essential ingredi-
ent in the food of all vegetables. Though
higherto little attended to, it appears to be
one of the primeval principles, as ancient
as the present constitution of our globe:
for it is found in fixed air, of which it
constitutes above one-fourth part; and
fixed air exists in lime-stones and other
substances, which date from the first ori-
gin of things.

Coal not only forms the residuum of all
vegetable substances that have undergone
a slow and smothered combustion, that is,
to which the free access of air has been
prevented, but also of all putrid vegetable
and animal bodies : hence it is found in
vegetable and animal manures that have
undergone putrefaction, and is the true
basis of their ameliorating powers : if the
water that passes through a putrefying
dunghill be examined, it will be found of
a brown colour; and if subjected to eva-
poration, the principal part of the residuum

37

will be found to consist of coal*. All soils
steeped in water communicate the same
colour to it in proportion to their fertility ;
and this water being evaporated, leaves
also a coal, as Mr. Hassenfraz and Four-
croy attest}. They also observed, that
shavings of wood being left in a moist

place for nine or ten months, began to re--

ceive the fermentative motion, and being
then spread on land, putrefied after some
time, and proved an excellent manuret.
Coal, however, cannot produce its benefi-
cial effects but in as much as it is soluble
in water. ‘he means of rendering it so-
luble are not as yet well ascertained ; ne-
vertheless, 1t is even now used as a ma-
nure, and with good effect).. In truth,
the fertilizing power of putrid animal and

vegetable substances were fully known.

even in the remotest ages, but most specu-
latists have hitherto attributed them to the
oleaginous, mucilaginous, or saline parti-
cles then developed, forgetting that land is
fertilized by paring and burning, though

the oleaginous and mucilaginous particles

are thereby consumed or reduced to a coal,
and that the quantity of mucilage, oil or
salt in fertile land is so small, that it could

*14 Ann. Chym. 56, + Ibid.
t Ibid: § Young’s Annals.

38

not contribute the 1000th part of the
weight of any vegetable; whereas coal is
supplied not only by the land, but also by
the fixed air combined with the earths,
and also by that which is constantly set
loose by various processes, and’ soon pre-
cipitates by the superiority of its specific
gravity, and is then condensed in, or me-
chanically absorbed by, soils, or contained
in dew. Lands which contain iron ina
semicalcineci state, are thereby enabled to
decompose fixed air, the iron, by the help
of water, gradually attracting the pure air,
which enters into the composition of fixed
air, as Mr. Gadolin has shewn* : a disco-
very which appears to me among the most
important of these later times ; but these
calces of iron may again be restored to
their former state by union with oleagin-
ous substances, as Mr. Beaume has no-
ticed ; and this is one of the benefits re-
sulting from the application of dung be-
fore it has fully putrefiedy. Hence we
may understand how soils become effect-
ed and exhausted, this effect arising, in
great measure, from the gradual loss of
the carbonic principle deposited by vege-

* Ist Chym. Ann. 1791, 53. :
+ The affinities of coal and iron to pure air, vary with the
temperature.

39

table and animal manures, and from them
passing into the growing vegetables; and
also from the loss of the fixed air contain-
ed in the argillaceous part of the soil,
which is decomposed by vegetables ; and
from the calcination of the ferruginous
particles contained in the soil. I say
in great measure, because other causes
contribute to the diminution of fertility ;
which shall presently be mentioned. Hence,
also, we see why lands pastured remain
longer fertile than those whose vegetable
crop is carried off, as much of the carbo-
naceous principle is restored by the ex-
crements of the pasturing animals: why
some crops exhaust more than others;
because corn, and particularly wheat, con-
tains more of the carbonic principle than
grasses, and very little of its exuvie are
left behind: why fallows are of some
use; as the putrefaction of the roots of |
weeds and the absorption of fixed air by
clays, are thereby promoted : why vege-
tables thrive most in the vicinity of towns;
because the carbonic principle is copious-
ly dispersed by the smoke of the vari-
ous combustibles. consumed in inhabited
places: why soot is so powerful a ma-
nure : why burning the clods of grassy
land contributes so much to its fertility,

40

‘and then only when the fire is smothered
and coal produced; besides many other
agricultural phenomena, too tedious to re-
late : but I must not omit that the phos-_
phoric acid is found in coal; and this en-
ters into the composition of many vegeta-
bles.

The quantity of coal in vegetables is
various, according to their various species,
age, and degrees of perfection : wood and
corn contain most, grasses least. Weig-
leb found dry beech-wood to contain one
fifth of its weight of coal*. Westrumb
found trzfolium pratense, a sort of clover,
to contain about one seventh. Hence,
after water, it is the most copious ingre-
dient in vegetables. :

OF EARTHS.

The next most important ingredient to
the nourishment of plants is earth: and
of the different earths the calcareous seems
the most necessary, as it is. contained in
rain-water: and, absolutely speaking, ma-
ny plants may grow without imbibing any
other. Mr. ‘Tilletfound corn would grow

* Uber cie alkalis, p, 76.

Al

in pounded glass*; Mr. Succow m pound-
ed fluor spar, or ponderous spar, or gyp-
sumt+: but Tillet owns it grew very ill;
and Hassenfraz, who repeated this experi-
ment, found it scarcely grow at all when
the glass or sand were contained in pots
that had no hole in the bottom, through
which other nutritive matter might be
conveyed. It is certain, at least, from
common experience, that neither grasses
nor corn grow well either in mere clay,
sand, or chalk ; and that in vegetables
that grow most vigorously, and in a pro-
per soil, three or four of the simple earths
are found. Mr. Bergman, on the other
hand, assures us he extracted the four
earths, the silicious, argillaceous, calcare-
ous, and muriatic, in different proportions
from the different sorts of cornt. Mr.
Ruckert, who has analysed most species
of corn and grasses, found also the four
above-mentioned earths tn various pro-
portions in all of them. Of his analysis
I shall here give a specimen, comprehend-
ing, howeve ry the calcareous and muria-
tic in the same column, as this last scarce-
ly deserves particuiar notice :
* Mem. par. 1772, 301, 8vo.

+ ist Chym. Ann. 1784.
¢ 5 Bergman, 94,98, Scheffer Warles, s2c. 172.

£7

42

One hundred parts of the lixiviated

ashes of
contained of Silex. Calx. Argill.

Wheat---f - 48pts. 37 15

Oats <jceae | -. '68 26 6
Barley---} - 69 16 15
Bere <i.) oa Oo 25 10
See a oe Ny 32 oy ee XG)
Potatoes - | ay} 66 30
Red Clover... -, .37 33 30

Mr. Ruckert is persuaded that earth
and water, in proper proportions, form the
sole nutriment of plants; but Mr. Gio-
bert has clearly shewn the contrary ; for,
having mixed pure earth of alum, silex,
calcareous earth, and magnesia, in vari-
ous proportions, and moistened them with
water, he found that no grain would grow
in them; but when they were moistened
with water from a dunghill, corn grew
in them prosperously*. Hence the ne-
cessity of the carbonic principle is appa-
rent.

The absolute quantity of earth in ve-
getables is very small. Dr. Watson in-
forms us that 106 avoirdupois pound
=1696 ozs. of oak, being carefully burn-
ed, left but 19 ozs. of ashes; and from

* Encyelop. Vegetution, 274.

43

these we must deduct 1,5 for salt, then
the earthy part amounts only to 17,5;
that is, little more than one percwt. The
commissioners appointed to inspect the
saltpetre manufactory, found nearly the
same result; namely, 1,2 per cwt. in
beech 0,453, and in fir only 0,003. Hence
we need not wonder at trees growing
among rocks where scarce any earth is to
be seen: but in the stalks of Turkey-
wheat, or maize, they found 7 per cwt.
of earth, in sun-flower plant 3,7* ; so that,
upon the whole, weeds and culmiferous
plants contain more earth than trees do.
Mr. Westrumb found trifolium pratense
to contain about 4,7 per cwt. of earth, of
which 2 per. cwt. was mild calx, nearly
2 more silex, 0,7 argill, together with a
small proportion of phosphorated iron,
calx of iron, and manganesey.

Since plants derive some proportion of
earth from the soil on which they grow,
we cannot be surpised that these soils
should, at length, be exhausted by crops
that are curried off; such as those of corn
and hay, particularly the former: even
lands pastured must at last be exhausted,
as the excrements of animals do not re-

* See 3 Trans. Royal Irish Academy.
f Ist Chym, Ann. 187,

44

store the exact quantity that the animals.
have consumed ; and hence the utthty of
mucks, as the restoration 1s performed by
more animals than have been employed in
the consumption. ence also a succes-

sion of diferent crops injures. land less

than a succession of crops of the seme

kind, as different proportions of the differ-

ent earths are taken up by the different

vegetables. Finally, we may hence de-

rive the utility of marling land. as the de-

ficient earths are thereby replaced. ‘This

subject admits of more lagi than has

been hitherto imagined, and may even be

subjected to calculation. The absolute
quantity and relative proportions of the

various, earths in an acre of land may be

determined, so may that in the crops. of
different vegetables ; and by comparing

both, the z2me also may be found in which

the land must be exhausted, unless reno-

vated by various manures: thus the ne-

cessity of marling. ‘The kind of marl or

other manures, and the quantity necessa-

ry to an acre of land, may be very nearly

ascertained. }

Earths cannot enter into plants but m a
state of solution, or at least we when sus-
pended in water in a state of division as
minute as if they had been really dissolvy-

45

ed. That silicious earth may be suspend-
ed in such a state of division appears from
various experiments, particularly those of
Mr. Bergman, who found it thus difiused
in the purest waters of Upsal; and it is
equally certain that it enters copiously into
vegetables. Both his experiments, and’
especially those of Mr. Macie, establish
this point beyond contradiction*. Argil-
laceous earth may also be so finely diffused
as to pass through the best filters ; so also
may calx, as appears from the quantity
Margraait found in the purest rainwater.
This earth is even soluble by means of an
excess of fixed air in about 1500 times its
weight of water. It may also be, and
most frequently is converted into gypsum
by the vitriohc acid which most clays con-
tain, as Mr. Morveau has shewny, and
then it is soluble in 500 times its weight
of water.

Vegetables not only require food, but
also that this food be duly administered to
them ; a surfeit is as fatal to them as ab-
solute privation. Doctor Hales observed,
that a young pear tree, whose roots were
set in water, absorbed a smaller quantity
of it every day, the sap-vessels being sa-

* Phil. Trans. 1791.
¢ Ast Encyclop. Chym. 123.

A6

turated and clogged by it ; and Mr. Mil-
ler found that too much water rotted the
young fibres of the roots as fast as they
pushed out*, Saturated solutions of dung
appeared to Mr. Du Hamel equally hurt-
fult. Now the preservation and due ad-
minstration of this liquid food is effected
by due proportions of the simple earths
and their loose or condensed state. Their
situation in other respects being the same,
those that abound in the argillaceous prin-
ciple are the most retentive of water ;
those that abound in the coarse silicious,
least; the calcareous being intermediate
between both; various species of vegeta-
bles requiring various quantities of water
and other food: hence it is that every
sort of soil bears vegetables peculiarly
adapted to it, while others do not grow at
all, or but ill init. By the experiments
of Mr. Bergman, we find that
Argill takes up 2,5 times its weight of
water when saturated so as to let none
drop.

Maenesia - - 1,05
Chalk ae ne (ager 4
Silictous Sand - 0,25

* Ist Hales, 17.
t Mem. Par. 1748.

FIXED AIR.

That plants do not thrive, but most fre-
quently perish, when surrounded by an
atmosphere of fixed air, has long been ob-
served by that great explorer of the
most hidden processes of nature, Doctor
Priestly ; but that fixed air imbibed by
the roots is favourable to their growth,
seems well established by the experi-
ments of Dector Perceval, of Manchester,
and fully confirmed by those of Mr.
Ruckert. This last-mentioned philoso-
pher planted two beans in pots of equal
dimensions filled with garden-mould. The
one was watered aimost daily with distil-
led, the other with water impregnated with
fixed air, in the proportion of half a cu-
bic inch to an ounce of water; both were
exposed to all the influences of the atmos-
phere, except rain. The bean treated
with aerated water appeared ever ground
nine days sooner than that moistened with
distilled water, and produced 25 beans ;
whereas the other pot produced only 15.
‘The same experiment was made on stock-
July-flowers, and other plants, with equal

A8

success*. ‘The manner in which fixed air
‘acts in promoting vegetation, seems well
explained by Mr. Senebier: he first dis-
covered that fresh leaves exposed to the
sun in spring-water, or water slightly im-
preguated with fixed air, always produce
pure air as long as this impregnation lasts ;
but as soon as it is exhausted, or if the
leaves be placed in water out of which
this air has een expelled by boiling, they
no longer afford pure airt: from whence
he infers that fixed air is decomposed, 1

carbonic principle retained by the plant,
and its pure air expelled. It appears to
me, also, by acting as a stimulant, to help
the decomposition of water. Mr. Has-
senfraz, indeed, denies its decomposition ;
but his arguments do not appear to me
conclusive, for reasons too tedious and
- technical to mention here. ‘he vitriolic
acid contained in various clays brought into
multiplied contact with calcareous earth
by the agitation of soils in agricultural
operations, and the motion of the roots,
eradually sets loose the fixed air contain-
ed in this last-mentioned earth ; that por-
tion a'so of this earth, which is by water
introduced into the plant, is decomposed,

* 21 Chym. Ann. 1708, 399.
t+ Sur influence de la Lumiere, & 41 Roster, 206,

A9

and its air set loose by the vegetable acids
of the plant.

OF SALINE SUBSTANCES.

Saline substances (gypsum and phos-
phorated calx excepted) seem to serve ve-
getables (as they do animals) rather as a
condimentum, or promoter of digestion,
thanasapabulum. This idea is suggested
by the smallness of their quantity, and the
offices they are known to perform. Their
quantity is always smaller than that of
earth; and this we have already seen to
be exceeding small.

Thus one thousand pound of ib

Oak gives of saline matter only 1,5
Elm = - ee la 3,9
Beech - - - . 1,27
Fir - - . - 0,45
Vine branches - - 5,5
Fern - - . - 4,25
Stalks of Turkey wheat 17,5
Wormwood - - 73
Fumitory - : . 79
Trifolium pratense - x20, 78
Vetches* - - 2 ie

Beans with their stalks* ? - BO

* 3 Ruck. 49.
De

50.

In all the experiments hitherto made,
the proportion of saline matter to the ear-
thy has been found smallest in woods. In
other plants, generally as 1 to 1,3, 1,5, or
2; however, Mr. Ruckert has marked.
some exceptions, which I shall mention as
worthy of notice.

PROPORTION OF SALINE SUBSTANCES TO THF

EARTHY.

InHemp - as 1 to 8.

Flax sh 5 1a to) Liew
ue arsnips: =)" TP tore.

Potatoes |) 1 eno iS

eParnips . 7" tO; 3338

Wheat = ae LO tees

Rye SOE) ie ie Cy.

Wats Bi a eee

_These proportions have some analogy
with the quantity and sort of manure pro-
per to be employed in the cultivation of
these plants and the succession of crops.
But I shall enter no farther into this sub-
ject as 1t would lead me too far from the
present object of enquiry.

The salts generally extracted from the
ashes of vegetables, are tartar vitriolate,

51

Glauber’s salt, common salt, salt of Syl-
vius, gypsum, phosphorated calx, and
fixed alkalis. |

Alkalis seems to be the product of the
vegetable process, for either none or scarce
any is found in the soils, or in rain-water,
while in the vegetable they are, most prob-
ably, neutralized, partly by vegetable acids
which are decomposed in the process of
combustion, and partly by the vitriolic and
marine acids. Westrumb found tartar
vitriolate and digestive salts in the juices
of trifolium.

Gypsum probably exists in greater quan-
tity in plants than it appears to amount to
after combustion and lixiviation ; much of
it must be decomposed during the combus-
tion, and still more during lixiviation, by
the alkalis existing in the solution. Thus
the apparent quantity of tartar vitriolate is
increased.

Phosphorated Calx is found in greatest
quantity in wheat, where it contributes to
the formation of the animal gluten. Hence
in rainy years the quantity of gluten in
wheat has been observed to be smaller.*
Hence the excellence of bone- ashes as a
manure for wheat; and hence wheat

* 2d Witwer’s Dissertations, 103.

piety

succeeds best after clover, if the clover be
fed off, but not if it be mowed,* as much
of the phosphoric acid is communicated by
the dung of animals.

The chief use of tartar vitriolate seems to
be, that it promotes the decomposition of
water, as Mr. Senebier has observedt.

* 2d Young’s Annals, 36, 37.
’ + Sur la Lumiere, p. 130.

SECTION ff.

OF THE CONSTITUTION OF FERTILE SOILS, ANDY
THE METHOD OF ESTIMATING THEIR FER-
TILITY.

The most fertile soil is that which con-
tains the greatest quantity of the food of
those vegetables that nourish men and use-
ful animals, and administers it to them
with due economy.

The first essential requisite, therefore,
to a fruitful soil is, that it contain a suf-
ficient quantity of the three or four simple
earths above mentioned, and of the solu-
ble carbonaceous principle. The other
requisites are, that the proportion of each,
and general texture of the soil be such as
‘to enable it to admit and retain as much
water as is necessary to vegetation, and
no more.

Now we have already seen, that the re-
tentive powers of moisture are very differ-
ent in the simple earths: therefore the
proportions in which the fertility of a soil
requires them to be mixed, must be dif-
ferent in climates and countries that differ

54

considerably in moisture: in the drier,
they must be such as are most retentive :
in the mozster, such as suffer it to pass
or evaporate more easily.

The same remark extends to situation.
Lands on a plain should be so constituted
as to be less retentive of water than those
situated on a declivity ; as is very evi-
dent.

So lands that have a retentive or im-
permeable sub-soil, should be differently
constituted from those that have one less
retentive or more permeable. ‘The time
of the year in which rain most abundantly
falls may also be worthy of notice.

These circumstances must, undoubt-
edly, modify the conclusions that may be
drawn from the experiments I shall now
relate.

ANALYSIS OF A FERTILE SOIL IN A VERY RAINY

CLIMAT Se

Mr. Giobert has communicated to the
public, the analysis of a fertile soil in the
vicinity of Turin, where it rains yearly
above 40 inches on the square foot. He
found 1 1b of it to contain from 20 to 30
grains of extractive matter which flamed

55

and burned, and therefore was a coal solu-
ble in water; 26 lb. of it contained 1808
grains of water. The simple earths were
in the following proportion per cwt.*

mMex. irom. —— 77% .to. 79
Argill — —'-—s«Wdws é9)9 — jj
Calx —— §—]2

Hence the pound should contain, +

ors.
Carbonic matter — 25
PRCT ry ae
Silex, from 4362 to 4475
Anew 809 = 703
Cae eg —— O79

He also found it to contain a great deal
of air (about 19 grains) of which one-third
was fixed, and the remainder heavy inflam-
mable air: but no volatile alkali.

The weight of a cubic foot of this soil
does not appear, nor is its specific gravity
given; hence neither its texture, nor the
quantity of each ingredient, can be di-
rectly ascertained ; yet, from the necessity

* Encvclop. Vegetation. 276.
7 The Twin medicin:1 pound is divided Ike the troy, and
contains the same number of grains.

56

of its being, in some degree, open, and the
weights of good soil found by Mr. Fa-
broni,* I conclude its specific gravity can-
not exceed 1,58: then a cubic foot of it
should weigh about 120 lb. troy, or 100
avordupois.

In less fertile soils, Mr. Giobert found —
the proportions of |

Silex, from 48 to 80
Argill — fk, an
Calx 6- = 1

Hence the troy pound contained, of

Silex, from 2716 to 4528
Argill — 396 — 1245
Calx — 339 — 662

allowing 100 grains for moisture, as either
the calx or argill exceeds the proportions in
more fertile lands.

The specific gravity of these soils is not
given ; but it probably exceeds or falls short
of that of the more fertile soils.

* 8 Young’s Annals, 174.

57

IN BARREN SOILS,

The proportions of Silex, from 42 to 88
Argil — 20 — 36
Calx — 4 —20

Hence the troy pound contained, allow-
ing for water 120 grains,

Silex, from 2368 to 4963
Argill — 1128 — 162
ANS yes OR ee :

The specific gravity of these soils is not
given; but it probably is either much
above or much below that of the former,
as they are either too close or too open.
Mr. Fabroni found that of barren sandy
land 2,21.

Note also, that if the proportion of
water be different from that here suppos-
ed, the contents of the troy pound will
also be different; but may be easily recti-
fied.

ANALYSIS OF A TERTILE SOIL, WHERE THE FALI
OF RAIN IS 24 INCHES.

Mr. Bergman found that a fertile soil,
situated on a plain, where the yearly fall of

4

58

rain amounts to 15 Swedish (that is 23,9
English) inches contained four parts clay,
three of silicious sand, two of calcareous
earth, and one of magnesia (in all ten parts; )
but the last not being of absolute necessity
may be annexed to the calcareous.

The composition of the clay he does not
expressly mention, but we may suppose it
such as most frequently occurs, contain-
ing 66 per cwt. of fine silicious sand, and
34 of mere argill : consequently 0,40 of it
contain nearly 0, 14 of mere argill: and 0,26
of fine silicious sand.

The silicious sand, mentioned by Mr.
Bergman, is what we call gravel (consisting
of stone from the size of a pea, or less, to
that of a nut ;) and thus he himself explains
it.* This amounts to SO per cwt.

Hence we may state the proportions thus :

Coafse piex |... =". ae

Finer .— nih hes) oe Tiers
—7—56 parts

Argil — = hae Bene 14

Calx ake hy scape ie 30

100

oe

* 5 Bergman, 102, 163.

59

The use of the gravel is to keep the soil
open and loose : a circumstance absolute-
ly necessary, as I have before observed.

The specific gravity is not given, but
should not much exceed, I suppose, 1,600.
Muschenbroek found that of garden-mould
1,630. ‘Fhe carbonic matter was not
known to Mr. Bergman.

The proportion in a troy pound, sup-
posing the quantity of water and coal not
to exceed 100 grains, stands thus, omit-
ting fractions :

Gravel 3 : 1698

Fine Sand - 2 1471
an) L169

Arenk t=) <9 3a: - 792

alee tee) ve “ 1698

Here we see the quantity of calx much
greater than in the soil of Turin, where the
fall of rain is greater: for inthe drier climates
there isa necessity to retain the rain, and the
argill if increased would retain it too long
and too much; and, besides enters very
sparingly into the constitution of plants.

The following experiments were made
by Mr. Tillet, at Paris, where the fall of
rain amounts to 20 inches at an average.

60

He filled with mixtures of different
earths a number of pots twelve inches in
diameter at the top, ten at the bottom, and
seven or eight deep. It appears also, that
they were so porous as to absorb moisture,
and that they were perforated at the bot-
tom. These he buried up to the surface
in a garden, sowed in each some grains of
wheat, and then abandoned them to na-
ture.

FERTILE MIXTURES.

ist. The first mixture he found fertile,
consisted of three-eighths of the potters
clay of Gentilly=0,375, three-eighths of
the parings of lime-stone, and two-eighths
of river sand =0,25. In this, the corn
crew very well for three years; that is, as
iong as the experiment lasted.

As potters clay is not pure argill, and
as Mr. Tillet does not mention the pro-
portion the mere argillaceous part bore
to the silicious, [ must supply this defect,
by supposing this clay to contain near one
half of its weight of pure argill, as it is clay
of this sort that potters generally chuse ;
and that of Gentilly is esteemed one of the
best. Both the clay and lime-stone, he
tells us, were pulverized, that they might

61

more exactly incorporate when mixed.
Then the centesimal proportions will
stand thus :

Coarse Silex 7 a) BS
Finer — A ees |
—— 46
i : 2 16,5
OY a rg ‘ : S755
100

The quantities in the troy pound, sup-
posing the water, &c. to amount to 100
grains, are, :

Coarse Sand - - J4}5
Finer — : ~ i. LSS
—— 2603
Pare - a 934.
Calx —_ - : 122
5659

Sere

2d. This contained two-eighths of pot-
fers clay, three-eighths parings of lime-

62

stone, and three-eighths coarse sand.
The centesimal proportions are,

Coarse Sand -
Finer — r

Argill — i
Calkx — i

In the troy pound, supposing the quan-
tity of water to amount to 100 grains, the
quantities of the three earths will be,

Coarse Silex -
faner.

Argill —
Calx RASS

2122
792
—2914
622
2122
5658

Hence we see that in the drier coun-
tries, where the fall of rain 1s but 20 itl
ches, the soil, to be fertile, must be closer,
and the quantity of calcareous earth much
increased, and that of the silicious much

65

diminished. Thus, m ‘thé’ climate’ of
Turin, where the fall of rain exceeds 40
inches, the proportion of silicious earth is
from 77 to 80 per cwt. and that of calca-
reous, from 9 to 14, to suffer this excess
of rain more easily to evaporate. In the
climate of Upsel, where the fall of rain is
24 inches, the proportion of silex is only
56 per cwt. but that of calx is 30 ; and in
the climate of Paris, which is still drier,
the proportion of silex is only from 46 to
51, and that of calx 37,5 per cwt. and
hence we may perceive the necessity of at-
tending to the average quantity of rain to
judge of the proper constitution of fertile
lands on fixed principles. The quantity
of rain differs much in different parts of
the same kingdom ; but in general in Ire-
land, I believe it to be between 24 and 28
inches on an average.

In the two last mixtures the proportions
vary considerably : The first may serve as
a model for the heavier soils, and the se-
cond for the lighter. In these and the fol-
lowing experiments, the carbonic princi-
ple seems to have been extracted from the
surrounding garden-mould with which the
pots communicated, by means of their per-
foration, at bottom.

64,

BARREN MIXTURES.

FIRST.

\

Mr. Tillet, in his sixth and eighth ex-
periments, mixed three-eighths of potters
clay with three-eighths of parings of lime-
stone and two-eighths of jie sand; the
only difference between this mixture and
that of the first experiment was, that in the
first experiment coarse sand was used,
and in this jie, yet the former was fruit-
ful in the highest degree; but in this the
grain prospered indeed the first year, but
sickened in the second, and failed in the
third: the proportions have been already
stated. Here we have a clear proof of the
necessity of an open texture in soils, with-
out which the best proportions are use-
less.

SECOND.

In his thirteenth experiment he employ-
eda mixture of two-eighths potters clay,
four-eighths coarse sand, and two-eighths
marl. The corn grew well the first year,
poorly the second, and decayed the third.

65

“The composition of the marl is not men-
tioned ; but supposing it to contain 70 per
ewt. of calx, and 30 of clay, of which the
one-half is argill, it would form one of the
richest sorts of marls. The centesimal
proportions of this mixture should be,

Silex : 4 50x14=64
Argill < 3 lly 8=19
Calx J : : 17

x5, TOO

And in, the troy pound, supposing the
water, &c. to amount to 100 grains, the
quantities will be, |

Silex ‘ 3622

Argill A ru 1075
Calx “ ! 962
5659

The sterility of this mixture seenis to
proceed from a defect of calcareous earth,
{f we suppose the marl poorer in that
earth, the defect will be still sreater. The
retentive powers of the different earths

y i
4 |
|

¥

66

with respect to water, being expressed by
the quantities which each can retain with-
out suffering any to drop, as above said,
and the quantities retained by the mixed
mass of these earths being proportional
to the respective quantities of each, it
should scem that in fertile soils, where the
fall of rain is from 20 to 30 inches, this
power should not exceed 70, nor fall short
of 50 per cent. It were of great conse-
quence to settle this point with precision ;
but to do this would require more nume-
rous experiments. ‘Toexplainmy mean-
ing, I shall give one example.

Of the retentive Power of the Fertile Soils,
mentioned by Mr. Bergman.

This soil contains, as we have already seen,

Silex - 56
Argill -" 14
Calx - 30
Now the retentive power of 100 parts
Silex =. 25
Argill -= 250
Calx = 50
*onsequently the retentive power of
56 parts Silex = 15
4, - relly 3p
30 ° Calx =—- 15

snnsimasiom (} 3

67

The constitution of the Irish fertile
soils has not been ascertained, nor has the
average annual quantity of rain been de-
termined here. Indeed, the solution of
the question proposed by the Academy,
does not strictly require it should, not
having been limited to any particular coun-
try : but I should suppose its best soil to
approach to the nature of that of Upsal,
the fall of rain being probably between 24
and 28 inches. In 1792, which was
reckoned remarkably wet, it was 302 in-
ches in Dublin.

Before I quit the experiments of Mr.
Tillet, it will be proper to mention a few
made by him, which seem to invalidate
the necessity of the presence of the. three
simple earths in fertile soils.

1™° In his 26th experiment he tells us,
he employed: only pure sand, such as 1s
used for making glass, yet corn grew well
in it the first year, indifferently the second,
and nearly failed in the third.. Mr. Has-
senfraz having repeated the experiment
in pots unperforated, did not find it to
succeed even the first year, therefore, the
success. of Mr. Tillet was owing to the
perforation at the bottom of his pot,
through ‘which’ water, impregnated with
the different earths, and coal: must have

68

passed. In fact, Mr. Tillet’s conclusion
is contradicted by universal experience.
In his 28th experiment, in which
powdered lime-stone only was employed,
the corn sown prospered exceedingly du-
ring the three years. ‘To the cause men-
tioned, in treating of the 26th, I must add,
that the lime-stone he used was that of St.
Leu, which contains clay, and consequent-
ly silex and argill; it is so porous as to
admit from 3- 19ths to 1-5th of its weight
of water, as Mr. Brisson has shewn; and
thus 1s easily decomposed. The coarse
powder to which it was reduced answered

the same purpose as coarse silex ; and the »

finer might nourish the plants.

3° In his 30th experiment he employed
nere potter’s. clay ; the grain grew tolera-
bly well the first year, but perished the se-
eond; on the third it flourished most. It
is hard to draw any specific conclusion
from this experiment, for it 1s plain that if
the texture were not much looser than that
cf clay, the corn could not grow at all, as

vas the case in his 6th and 8th experi-

ments, already mentioned, and as Mr.
ilassenfraz, who repeated this experiment,

observed. Rain-water might however
supply a small quantity of calx sufficient
tor a small produce of corn.

;

69

I pass over his experiments on old mor-
tar, as the three earths were evidently con-
tained in it, though in unknown propor-
tions. |

Soils on the declivity of hills ought to
be more retentive of water than those on
plains as is evident.

70°

CHAP. III.
TO DETERMINE THE COMPOSITION OF A SOIL»

j™> IN. dry weather, when the soil is.
not over moist nor dry, let a surface of 16
square inches. be cut through to the depth
of 8 inches ; this may be effected by a right
angled spade, formed for ‘this particular
purpose. Of the parallelopiped thus dug
up, the two inches next the surface should
be cut off to get rid of the grass, and the
greater part of the roots; we shall then
have a solid 6 inches long, and 16 square
at the end=96 cubic inches. Let this be
weighed ;* its weight will serve to find the
specific gravity of the soil; for if 96 cubic
inches weigh 2 pounds, 1728 (a cubic
foot) should weigh x» pounds, and x divid-
ed by 75,954 will express by the quotient
the specific gravity of the soil. To render
this and the subsequent operations more

* Troy weights are generally more exactly made than
avoirdupois, and therefore should be preferred. A cubic
foot of pure water weighs 75,945 troy, very nearly, or 62,5
avoirdupois pounds, at the temperature of 62°.

71

intelligible, I should illustrate each by an
example: Suppose the 96 cubie inches to
weigh 6,66 pounds, then 1728 cubic inches
| 120
should weigh 120 lb. and—
75,945

9° The earth being weighed, is next to
be broken down and freed from all stony
‘substances above the size of a pippin, and
the remainder well mixed together, to ren-
der the whole as homogeneous as possible;
then weigh the stones that were picked out,
and find the proportion belonging to each
pound of the residuary earth ; cali this the
stony supplement, and denote itby S. ‘Thus
if the stones weigh 1 lb.=12 oz. the re-
mainder, or mere earth, must weigh 5,66:b.
and if to 5,66lb, there belong 12 oz. of
“stone, to 1 lb. must beiong z4,12014 ozs. or
2 ozs. 57,66 grains = 1017,66 grs. This
then is the stony supplement of each suc-
-ceeding pound =.8.

3° Of the earth thus-freed from stony
‘matter, take lib.-—S. (that 1s the above
-ease 1lb.—2 oz. 57 two thirds grs.) heat
it nearly to redness in a flat vessel, oiten
stirring it for half an hour, and weigh it
again when cold. Its loss of weight will
indicate the quantity of water contained
an | Ib. of the soil. Note this loss, and

= 1.579.

2

cali tt the watery supplement=W. Suppose
it in this case 100 grains.

4° “jake another pound of the- above
mass ireed from stones, deducing the
stony and watery supplements; that is
1 1b.—S—W, or in the above case 1 1b.—
202. 57 two-thirds grs. for stone, and—
100 grains for water; consequently 1 lb.
—2Zoz. 157 two-thirds ers. reduce it to
powder : boil it in four times its weight of
distilled water for half an hour; when cool,
pour it off, first into a coarse linen filtre
to catch the fibrous particles of roots, and
then through paper, to catch the finer
clayey particles diffused through it: set
by the clear water, add what remains on
the filtre to the boiled mass: if it be insipid,
as I suppose it to be, then weigh the fibrous
matter, and call it the #drous supplement=
f. Suppose it in the example in hand to
weigh 10 ers.

5° Take two other pounds of the mass
freed from stony matter, No. IT. subtract-
ang from them the weight of the stony,
watery, and fibrous substances already
found; that is, 2ib—-2 S29 W—9 F >;
pour twice their weight of warm distilled
water on them, and let them stand twenty-
four hours or longer; that is, until the water
has acquired a colour; then pour it of,

73

and add more water as long as it changes
colour ; afterwards filtre the coloured water
and evaporate it to a pint, or halfa pint;
set it in a cool place for three days, then
take out the saline matter, if any be found,
and set it by.

6° Examine the liquor out of which the
salts have been taken ; if it does not effer-
vesce with the marine acid, evaporate it
to dryness, and weigh the residuum ; if it
does effervesce with acids, saturate it with
the vitriolic or marine, and evaporate it to
one fourth of the whole; when cool, take
out the saline residuum, evaporate the re-
mainder to dryness, and weigh it: this gives
the coaly matter, which may be tried by
projecting it on melted nitre, with which
it will deflagrate. The half of this coaly
matter call the coaly supplement of 1\b.
I shall suppose it to amount tol2 ers. and
denote it by C.

7° The filtred water, No. IV. is next to
be gently evaporated to nearly one pint,
and then suffered to rest for three days in
a cool place, that it may deposit its saline
contents, if it contains any ; and these be-
ing taken out, the remainder must be eva-
porated nearly to dryness, and its saline
and ether contents examined. How this

G

74

should be done, I shall not mention, the
methods being too various, tedious, and of
too little consequence : few salts occur ex-
cept gypsum, which is easily distinguish-
ed. The water may be examined as to
its saline contents when it is evaporated
to a pint; if any salts be found, call them
the saline supplement, and denote them by
S. I shall suppose them here = 4 grains.

8° We now return to the boiled earthy
residuum, No. IV. which we shall sup-
pose fully freed from its saline matter, as,
if it be not, it may be easily rendered so,
by adding more hot water: let it then be
dried as in No. III. is mentioned. Of
this earthy matter thus dried, weigh off
one ounce, deducting one- twelfth part
of each of the supplements 5. W. F. C.
and .S’; that is, in this case

T0177, 66 100 10
———-———- = 84,405 + —— = 8 ,333+—=
12 12 12
12 A.
8,333 +— =] +—=0,5333=95 ers. in all
12 12

—then 480—95=385 grains will remain,
and represent the mere earthy matter in an
ounce of the soil.

9° Let this remainder be gradually
thrown into a Florence flask, holding one

75

and an half as much spirit of nitre as the
earth weighs, and also diluted with its own
weight of water {the acids employed should
be freed from all contamination of the vi-
triolic acid ;) the next day the flask with
its contents being again weighed, the dif-
ference between the weights of the ingre-
dients and the weights now found, will ex-
press the quantity of air that escaped dur- —
ing the solution. Thus, in the above
case, the earth weighing 385 ers. the acid
577,5 grs. and the water 577,5 gers. in all
1540 ers. the weight after solution should
also be 1540, if nothing escaped; but if
the soil contains calcareous matter, a loss
will always be found after solution. . Let
us Suppose it to amount to 60 grains.

The weight of air that escaped, furnishes
us with one method of estimating the quan-
tity of calcareous matter contained in the
earth essayed ; for mild calx generally con-
tains 40 per cent. of air; then if 40 parts
air indicate 100 of calcareous matter, 60
parts air will indicate 150.*

10° The solution is then to be carefully
poured off, and the undissolved mass wash-
ed and shaken in distiiled water ; the whole

* I take no account of magnesia, as in agricuiture I be-
lieve it of little importance. ‘

76

thrown on a filtre, and sweetened as long
as the water that passes through has any
taste. The contents of this water should
be precipitated by a solution of mild mine-
ral alkali: this precipitate also being wash-
ed and dried in a heat below redness,
should then be weighed. Thus we have
another method of finding the weight of
the calcareous matter.

11° The undissolved mass is next to be
dried in the heat already mentioned, and
the difference between its weight and the
weight of the whole earthy mass before
solution should be noted, as it furnishes a
third method of discovering the weight of
the calcareous matter of which it 1s now
deprived. Supposing this to amount to
150 grains, the weight of the undissolved
residuum should in the above case be 383
—150=235 grains.

12” Reduce the dried mass into the
finest powder, throw it into a Florence
flask or glass retort, and pour on it three
times its weight of pure oil of vitriol, di-
gest in a strong sand heat, and at last raise
the heat so as to make the acid boil; after-
wards let it evaporate nearly to dryness :
when cold, pour on it gradually six or
eight times Its weight of distilled water,

17

and, after some hours, pour off the solu-
tion on a filtre; the filtre should previous-
ly be weighed, and its edges soaked in
melted tallow ;* the substance found on
the filtre being weighed (subtracting the
weight of the filtre) gives the quantity of
silicious matter ; and this weight subtract-
ed from that of the dried mass, gives that
of the argill. In this case I will suppose
the silicious mass to weigh 140 grains, then
the argillaceous should weigh 95 grains.

Then the composition of one pound of
the soil is as follows :

Stony matter - 1017,66
Water =s_—i= = 100
Fibres of roots” - 10
Soluble coal 2 12
Saline matter ~ 4,
Silex 140 x 12 = 1680
Argill 95 x12=1140

Mild calx 150 x12 =1800

ES 6 SE EES SS

5763,66+

* An ingenious contrivance of Dr. Black.

+ An error of 3,66 grains for decimals omitted in sub-
tractions.

78

{Stony matter 18
Fine silicious 29

3 ——47

And in centesi- | Argill 22
mal proportion } Mild calx 31
100

L netic

Its retentive power is 82,25: hence I
should judge it to be unfertile in this cli-
mate unless situated on a declivity, with
an unimpeded fall. It may be called a
clayey loam.

Mr. Young discovered a remarkable’
circumstance attendant on fertile soils : he
found that equal weights of different soils,
being dried and reduced to powder, afford-
ed quantities of air by distillation some-
what corresponding to the ratios of their
values. This air was a mixture of fixed
and inflammable airs, both proceeding,
most probably, from the decomposition of
water by the coaly matter in the soil. ‘The
distillation should be made from a retort
glazed on the outside. He found an ounce
of dry soil, value five shillings, produced
ten ounce measures ;

79
Of value of from 5 to 12s. produced 280zs.

12—20 42
above 20 66

This appears to be a good method of esti-
mating the proportion of coaly matter in
soils that are in full heart ; that 1s, not ex-
hausted, and freed from roots, &c. An-
other mark of the goodness of a soil is the
length of the roots of wheat growing in It;
for these are an inverse proportion to each
other, as, if the land be poor, the wheat
will extend its roots to a great distance im
quest of food; whereas, if it be rich, they
will not extend above five or six inches ;
but of these and some other empyrical
marks, I shall say no more, as they do not
tell us the defects of the soils.

80

CHAP. IV.

OF THE MANURES MOST ADVANTAGEOUSLY AP-
PLICABLE TO THE DIFFERENT SOILS, AND OF
THE CAUSES OF THEIR BENEFICIAL EFFECT
IN EACH INSTANCE.

THE solution of the first part of this
problem can only be derived from general
practice of the most skilful farmers, cor-
rected, however, and improved by the more
precise determinations and restrictions of
theory. That of the second, I shall en-
deavour to deduce solely from the theory
established in the two last chapters. The
whole is grounded on this simple propo-
sition—That manures are applied to sup-
ply etther the defective ingredients of a
soil, or improve its texture, or correct its
VICES.

I now proceed to consider each soil in
particular,

81

OF CLAYEY SOILS.

The best manure for clayey soils is
marl: in this all the books of agriculture
are unanimous ;* and of the different sorts
of marl, that which is most calcareous is
best; the silicious next best; limestone-
gravel best of all; and argillaceous marl
least advantageous. +t

Clayey soils are defective both in con-
stitution and texture; they want the cal-
careous ingredient and coarse sand. Cal-
careous marl supplies the calcareous in-
gredient chiefly: limestone gravel both.
The other marls supply them in a lesser
degree. If the clay be analysed, and its
proportion of sand and argill known, the
species of marl most advantageously ap-
plicable may be determined still better.
For instance, if the argill notably exceeds
or even amounts to the proportion of 40
or 50 per cwt. calcareous marl or lime-
stone-gravel are the best improving ma-
nures, as they contain most of the calca-

* 4th Young’s Eastern Tour, 404. 1st Body of Agricul.
gure, 104, 108,
t Ibid, 108.

H

82

.reous ingredient ; but if the silicious in-
gredient amounts to 75 or 80 per cwt. as
it sometimes does, argillaceous marl is
most suitable.

A mixture of marl and dung is still
more advantageous,* because the dung
supplies the carbonaceous ingredient. But
the marl must be used in the same quan-
‘tity as if dung had-not been applied, other-
wise the operation must be more frequent-
ly repeated. How the quantity of marl or
other ‘manure can be estrmated, I shall
presently shew.

If marl cannot be ‘had, a mixture of
coarse sand and lime perfectly effete or
extinguished, or chalk, will answer the
same purpose, as it will supply the defec-
tive ingredient, and open the texture of
the clay; so also sand alone,:or chalk, or
powdered limestone, may answer, though
less advantageously. Lime alone.appears
to me less proper, as it is apt to’cake, and
does not sufficiently open the soil.

Where these ‘manures cannot be had,
coal ashes, chips of wood, burned clay,
brick-dust, gravel, or even pebbles, are
useful;+ for all these improve the texture,

* 4th Young’s Eastern Tour, 404.

+ 5 Bergman, 107; and Young’s Irish Tour, 129, 136,
949, ,

85

andthe former supply alsothe carbonaceous
ingredient,

Before I advance farther, to prevent
superfluous repetition, I shall lay down a
second general maxim: which is, That
dung is a proper ingredient in the appro-
priated manures of all sorts of soils, as it.
supplies the carbonaceous principle.

OF CLAYEY LOAM.

This soil is defective either in the cal-.
careous ingredient, or in the sandy, or in.
both: if in the first, the proper manure is
chalk :* if-in the second, sand ; if in both,
silicious marl or limestone-gravel, or effete
lime and sand.

The quantity of chalk that should be
employed, considered abstractedly, should
be directly proportional to the defect of
calcareous matter ; but as such a quantity
cannot be added without diminishing the
proportion of one of the other ingredients, .
a much smaller quantity must be employ-
ed, or else a substance which may convey.

* Ist Young’s Eastera Tour, 395.

84,

some proportion of the other ingredient.
The same observation holds also with re-
spect to sand. Thus we have seen, in
the last chapter, a clayey loam, in which
the sandy ingredient was defective, and the
argillaceous superabundant, but the calca-
reous exact. Its composition stocd thus :

Sand and Gravel - - 47
Arell: ve" eee
Mild Cals oe ae eae

Here the sandy part wants 10 per cwt.
the argill is superabundant ; but we can-
not increase the proportion of sand with-
out diminishing that of calx. Hence
we must either use a smaller propor-
tion of sandy ingredient than its defect
requires, or apply a substance that
would supply some proportion of the cal-
Careous ingredient also: such are lime-
stone-gravel, silicious marl, effete lime,
mixed with sand, or pounded limestone.
Suppose the proportion of the substance
to be employed were six per cwt. ; that is,
six pound for every hundred pounds of
the soil, then the quantity requisite for an
acre may be calculated thus: a square
foot of this soil, cut down to the depth of
fourteen inches, and paring off the two up-

85

permost, as consisting chiefly of roots, &c.
weighs, as we have seen, 120 lpesand If
100 Ib. requires six of the manure, 120]b.
will require 7,2; therefore every square
foot of the soil will require 7,2 of the ma-
nure : now an English acre contains 45560
square feet ; and consequently 43560 mul-
tiplied into 7,2 of the manure =313632)b.
or 208 cart loads, reckoning 1500 lb. to
the cart load.

CHALKY SOILS.

This soil wants both the argillaceous
and the stony, sandy, or gravelly ingredi-
ents; therefore the best manure for it 1s
clayey loam, or sandy loam;* but when
the chalk is so hard, as it frequently is in
England, and so difficultly reducible to
impalpable powder as to keep of itself the
soil sufficiently open, then clay is the best
manure,t} as in such cases the coarse sand
or gravelly ingredients of loams are of no
use. Some think, it is true, that pebbles
ina field serve to preserve or communi-

* 5 Bergman, 107.
+ Young’s Eastern Tour.

86

cate heat. This use, however, is not suf-
ficiently ascertained.

CHALKY LOAM.

The best manure for this soil is clay,
or argillaceous marl,* if clay cannot be
had; because this soil is defective princi-
pally. in the argillaceous ingredient. In
Ireland, chalky soils or loams seldom oc-
cur, but light limestone soils frequently,.
and these do not differ essentially from
chalky loams poor in argill: clay, there-
fore, and often the soil of bogs, shouldserve:
as.a manure for them.

SANDY SOILS.

The best manure for these is calcerous-
marl,+ which exactly corresponds with our
theory ; for these soils want both the argil-.
laceous and calcerous ingredients; and
this marl supplies both: the next best is
argillaceous marl; and next to these, clay,
mixed with lime, or calcareous, or clayey

* 4th Young’s Eastern Tour, 404.
t Ibid. 491, 412.

87

loams. In Norfolk, they seem to value
clay more than marl, probably because
their sandy soils already contain calcareous
parts; possibly, also, they misname marl,

ealling mere chalk by that name. Lime
or chalk are less proper, as they do not give
suficient coherence to the soil; however,
when mixed with earth or dung, they an-
swer well,* because they form a sort of
marl or compound, comprehending the de-
fective ingredients.

SANDY LOAMS.

These are defective chiefly in the calca-
reous ingredient, and, in some degree, also
in the argillaceous; their texture too Is im-
perfect, as they abound both in fine and
coarse sand; chalk or lime would supply
the first detect, but would leave the texture
unamended. Hence they are used when
better cannot be had;+ yet calcareous or
argiliaceous marls are most proper.t
Clay, after land has been chalked, answers,

* Young’s Eastern Tour, 397.
+ 4th Young’s Eastern Tour, 398.
+ Ibid. 402.

88

as we are told, remarkably well, because
it remedies the texture. *

GRAVELLY LOAMS.

These soils are benefited by the appli-
cation of marl, whether argillaceous or
calcareous,t for reasons which I suppose
are now apparent: if the gravel be calca-
reous, clay may be employed.f A mix-
ture of effete lime and clay should answer
in all cases.

TILL AND VITRIOLIC SOILS.

These necessarily require the calcareous
ingredient to neutralize their peccant acid:
hence chalk, limestone-gravel, lime and
calcareous marl, are most advantageously
applied to them.

Home, 35.

BOGS, OR BOGGY SOILS.

When these are well dried by sufficient

* 4th Young’s Annals, 413.
+ 4th Young’s Eastern Tour, 404, 406.
z Ist Eastern Tour.

89

drains, the nature of their soil should be
explored by analysis, and an appropriate
manure applied. In general, they should
first be burned, if capable of that operation,
then gravelled. If their upper parts con-
tain a sufficiency of the carbonaceous prin-
ciple, as often happens, they need not be
burned. Limestone-gravel will answer
best, or lime mixed with coarse sand or
gravel, because in general they are of a
clayey nature; if more sandy, lime may
answer well, or calcareous marl. The
preference in these cases must be decided ©
by analysis.*

HEATHY (SOLES.

These should first be burned, to destroy
the heath and increase the carbonaceous
principle: they should then be analysed,
and the defective principles supplied.
Lime is said to destroy heath, and so is
limestone-gravel :+ this is fittest when the
soil is clayey; lime when it is gravelly. 7
Gypsum also answers remarkably well
when the soils are dry.

* Young’s Ivish Tour, 233, 22
2

o
. ? ys
T 4th Young’s Eastern LP. ur, 396.
may
a

7

4 Pe ak bo
Hi Irish He Oe ear eee

4

90

“OF SOME PARTICULAR MANURES.

We have now stated most of the known
soils, and mention the manures which
tend most to their improvement: there
are, however some others whose mode of
action is not generally understood, and

whose nature it will therefore be proper
to explain. )

‘OF PARING AND BURNING.

This ‘mode of improvement is not par-
ticular to any species of soil, though poor
soils that have few vegetables growing in
them, will certainly profit least by it.

Its advantages are,

First, that it converts vegetables and
‘their roots into coal. Hence it is that ag-
ricultural writers tell us, though without
; knowing the reason, that all violence of
fire is to be avoided, and that a slow
smothering fire is best.*

Secondly, That it destroys the old sickly
‘roots, and thus leaves room for others
“younger and.more vigorous.

* Ast Body of Agriculture, 210, 211.

91

Many have imagined that it diminishes
and consumes the soil; but repeated ex-
perience has shewn the contrary. I need
only mention that of Colonel St. Leger,
in Yorkshire, related by Mr. Young in
the Ist volume of his Eastern Tour, p.
182. It is well known that clays and
loams are rather hardened than consumed
by heat. However, unless fresh seeds be
committed, the soil will be unproductive
for a number of years ; the coaly principle
may also be exhausted by too many crops..

OF GYPSUM..

This manure was discovered by Mr.
Mayer, a German clergyman of uncom-
mon merit, in the year 1768 : it has since
been applied with signal success: in Ger-
many, Switzerland, France, and America.

Ifin England it has not been so much
approved of, it must be because the calca-
reous principle prevails there almost uni-
versally : clayey lands are most improved
by it.. The time for spreading it is Fe-
bruary er March, and then it is. to be
thinly strewed on the land at the rate of '
xbout eight bushels to the acre: more
would be hurtful... The rationale. of. its

92

effects may be deduced from its extraordi-
nary septic power, for it is found to acce-
lerate putrefaction in a higher degree than
any other substance ;* and hence it is not
ploughed in like other manures, but bare-
ly strewed on the surface of the land; and
in the month of February, to convert the
old grass quickly into coal, to nourish the
young growth.

2dly. From its being itself no inconsi-
derable part of the food of many plants,
particularly of clover, pulse, and corn, but
the land on which it is strewed must be
dry, such as would naturally suit clover,
&c. otherwise it would be useless.

Thus far I have endeavoured to illus-
trate the important subject proposed by
the Academy, collecting and reflecting
upon it the scattered rays resulting from
the latest chemical researches. ‘The inti-
mate connexion between many of these,
seemingly the most abstract and remote,
with the hidden process of nature, may
now be clearly perceived. These grand
and complicated operations, like a well
fortified town, cannot be mastered by storm
or a coup-de-main; the approaches must
be made at a distance, and almost unseen.

* Histoire de la Putrefaction, 36.

95:

Hence we may infer how little can be ex-.
pected from agricultural societies that do.
not unite chemistry and meteorology with
their principal object.

With respect to the question at present
before us, the great desiderata seem to be,
flow to render charcoal soluble in water
Sor the purpose of vegetation : and, to dis-.
cover that composition of the different
earths best suited to detain or exhale the
due proportion of the average quantity
of moisture that falls in each particular
country. On this relation, or adaptation,
we have seen that the fertility of each es-.
sentially depends : we must also have per-
ceived, that to a regular and systematic
improvement of soils, a knowledge of their
defects, and of the guantum of their de-
fects, is absolutely necessary.. This in-
formation can be conveyed only by a che-
mical analysis. Country farmers (at least
as long as the present absurd mode of edu-
cation prevails) cannot be expected to. pos-.
sess sufficient skill to execute the necessary.
procesess: but country apothecaries cer-
tainly may. The profit arising from such
experiments (should the public encourage
them) would sufficiently excite them to.
acquire a branch of knowledge so nearly.
allied with their profession. In the mean

94

time, soils might be sent to some skilful
persons in the capital by country gentle-
men; who would thus be enabled to as-
certain and appreciate the advantages at-
tending such researches, and enlighten and
encourage their more ignorant and difh-
dent neighbours. Many of them might,
perhaps, themselves feel a taste for occupa-
tions of this nature: occupation swhich not
only fully suffice to fill up the many vacant
hours and days which the solitude of a
country life must frequently leave them,
but are, moreover, sweetened by the plea-
sing recollection, that, of all others, they
tend most directly to the general happi-.
ness of mankind..

AGRICOLA..

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