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~.- [FROM THE AMERICAN JOURNAL OF SCIENCE, VOL. XXXII, SEPT. 1861.]

AGRICULTURAL CHEMISTRY—SOIL-ANALYSIS.

NOTICE OF THE AGRICULTURAL CHEMISTRY OF THE GEO-
LOGICAL SURVEYS OF ale nie ARKANSAS.*

t

‘ “\, » BY PROF. 8. W. JOHNSON.
4 a 4? OF YALE COLLEGE.
AY -

In no country has there been so much popular appreciation of

practical science as in the United States of America. Scarcely
one of the States is without its volume or volumes of Geological
and Natural History Reports, and though some of them have
been content to confine the work to the merest outline of the
general and industrial geology of their territory, and have ex-
pended but a few hundreds of dollars in the undertaking, others,
like New York, have embraced all the branches of Natural Sci-
ence in their survey, have prolonged the work of exploration or
| elaboration through many years, and have devoted money to
. these objects with unsparing hand.

The results of these surveys as they stand recorded in the
numerous volumes published by the States and by the General
Government, are of very unequal merit, as might be expected
from the wide range of country explored, from the various degrees
of interest and appreciation governing the many Legislatures
which have authorized these labors and from the exceedingly
unequal ability of the individuals charged with their execution.

These explorations have originated in all cases with our scien-
tificmen. It is their influence either brought toear immediately
upon the legislative bodies, or exerted less directly through
cultivated and public spirited persons to whom the possible
benefits of geological surveys have been explained—that has
accomplished this vast work.

The enterprises of which we speak being sustained pecuniarily
at the expense of the people, and depending from year to year
in many cases upon the popular vote, it has been not only politic
but right to exhibit at the outset the prospects of pecuniary
return for the required outlay of means, as an inducement to
support such undertakings. It has been no less proper in pre-
senting the results of the surveys, to lay stress on the discoveries
having industrial bearings which are the fruits of the work.

In those States where large quantities of metallic ores occur,
the interest of capitalists engaged in mining has often sufficed to

* Ist, 2d. 3d and 4th Reports of the Geological Survey of Kentucky 1854-60:
2d Report of the Geological Reconnoisance of Arkansas, 1860: Agricultural Chem-
istry and Geology by Dr. D. D. Owen, principal Geologist, and Dr. Ropert Petes,
Chemical Assistant.

Am. Jour. ScI.—SEconp SERIES, VoL. XXXII, No. 95.—SEprt., 1861.
| 30

a

ly

2 S. W. Johnson on the Soil-analyses of the [234]

inaugurate a geological survey. In other states the agricultural
sentiment has had to be operated upon.

Great results have been promised to agriculture from the appli-
cations of geology and chemistry, and a great deal of labor has
been performed in the attempt to satisfy the hopes that have
been thus excited.

The chief object.of the present notice is to inquire what has
been really accomplished for the good of the farmer, by the sci-
entific surveys that have been hitherto prosecuted in this country.

The labors of Dr. Peter in connection with the Kentucky and
Arkansas Surveys being the most recent and extended attempts
of this kind, we shall make them the basis of our inquiries.

If we except a few pages of general remarks on the theory of
vegetable nutrition, &c., which while useful to the practical readers
of the Report contain no new facts or principles,—the whole
effort of Dr. Peter has been concentrated on the analysis of soils,
marls, rocks and ashes. He publishes in the four Kentucky Re-
ports analyses of 375 soils, and in the Arkansas Report, 187, in all
562 soil analyses. Besides, we find the results of examinations
of 145 rocks, shales, &c., and of 88 ashes of plants, making a
grand total of 795 agricultural analyses.

The agricultural fruits of the surveys of Kentucky and Ar-
kansas are then to be sought in these analyses.

It certainly will strike all that the amount of work performed
by Dr. Peter is unusually great. It is now but six years since
the Kentucky survey was commenced and in that time the Dr.
has not only analyzed 795 soils, but has executed 516 analyses of
ores, slags, mineral waters and coals, making an average of two
analyses for every three days of this whole period. This labor
Dr. Peter states he has accomplished with the help of one intelli-
gent assistant, and by a special organization of his laboratory
and his operations whereby the utmost economy of time was
secured. We have had such experience of the advantages of a
similar system, that we are not prepared to doubt that the chemist
who adopts a plan of analysis which fully satisfies him, and from
which he never departs, may execute such an amount of work.
At the same time we must bear in mind that the only control
Dr. Peter offers for the accuracy of his results is, that the sum of
the weights of the separated ingredients equals their original
conjoined weight, no time being allowed to repeat a determina-
tion, or to prove the purity of a precipitate.

The Analytical Process followed in these analyses is not by
any means so minute and full as we should be warranted to
expect, when their author declares (4th Ky. Rep., p. 57) that
“such a work to be eminently useful must be thorough and
exhaustive ;” for soluble silica, chlorine, nitric acid and ammonia
are not at all estimated, and the condition of the iron, whether
protoxyd or peroxyd, is not noticed. It is worthy of notice that

[235] Geological Surveys of Kentucky and Arkansas. 3

carbonic acid and lime are always present in atomic proportions
in the soils latterly analyzed, no excess of either ingredient being
mentioned in the results. Carbonic acid however is not noticed
in the description of the analytical process, and that figuring in
the analyses does not appear to have been directly estimated,
but to have come from the oxalic acid of the reagent shelf.

If, as might easily happen, the contrary not being proved, a
portion of the lime dissolved by hydrochloric acid exists in these
soils as silicate, sulphate or phosphate, then the assumption that
it is united to carbonic acid introduces an error into the summing
up (which in many cases is exactly 100) and shows that a quan-
tity of some other ingredient has been overlooked.

For the estimation of phosphoric acid a highly modified form
of Sonnenschein’s process is employed, but our author does not
give the figures which prove that his changes are improvements.

Admitting however that the analyses are correct—we next
inquire what is their value—what useful deductions from them
appear in these Reports.

In the introduction to Vol. i, Kentucky Survey, page 18, Dr.
Owen says: “By consulting the numerous interesting results
obtained by the chemical analyses of the soils embodied in the
pages of this report, abundant evidence will be gathered of the
vital necessity of wide dissemination amongst the farming com-
munity, of the knowledge to be obtained by a correct insight
into their chemical constitution.” In the same volume, page
373, Dr. Peter remarks that he was impressed “that when the
composition of our Kentucky soils and minerals in general, is
once accurately established, their applications to our wants and
uses would be obvious to all well informed persons. He has
therefore consumed the time mainly in the analyses, and made
up his report principally of the results.”

In the agricultural section of the Arkansas Survey, p. 47, Dr.
Owen says:—“ principally from chemical soil-analyses can the
agriculturist form an intelligent opinion as to the comparative
fertility of soils, and their suitability to the growth of certain
plants, as well as judge what applications may be required in the
way of lime, bone earth, plaster of Paris, ashes, or salts of pot-
ash, soda, &c.”

Dr. Peter, in the same volume, page 166-7, observes :—“ It is
believed that by no other mode than by chemical analysis or by
the more tedious and laborious method of actual experience, in
cropping for a series of years and publishing a record of the
same, can the actual nature, capabilities and value of the various
soils of a State be presented to the public; and that by institu-
ting this Geologico-Agricultural Survey, the State of Arkansas
not only aids materially in the progress of the general science
of the civilized world, and that of the soil in particular, but
takes the most effectual mode of making known to the enlight-
ened immigrant her agricultural riches. In this she has followed

4 8S. W. Johnson on the Soil-analyses of the [236]

the wise lead of the older state of Kentucky, in which, since
the institution of her geological survey, the value of the land
in the regions examined and reported on has been very greatly
enhanced.”

In the Agricultural Geology of Kentucky, Report 2d, p. 9,
Dr. Owen says: “ Placing implicit reliance on the capabilities of
chemical science te indicate by the analyses of soils, the ingre-
dients removed by the cultivation and harvesting of successive
crops, it was hoped that by collecting samples of the virgin soil,
and of the same soil from an adjacent old field, that not only
the different substances assimilated out of the soil could be as-
certained, but also the exact proportion of these so that the far-
mer might know precisely what must be restored to the land to
bring back its original fertility.”

These quotations sufficiently show what were the opinions
which led our author to devote such an amount of labor to the
analysis of soils, and indicate in general, what results were ex-
pected.

In the 2d Arkansas Report, p. 49 et seq., Dr. Owen “ proceeds
to explain in what way soil-analysis becomes of value to the
farmer.” He desires ‘‘ to call particular attention to this subject,
because the opinion has been expressed even in this year (1860),
and by those having a high standing in the scientific world, that
chemistry is incapable of conveying any useful information to
the farmer by analyzing his soil.”

On the six following pages of the 2d Ark. Rep., and on page
80 of the 4th Ky. Rep., Dr. Owen gives the most complete résumé
of the teachings of soil-analysis which we are able to find in
the five volumes before us, and as these are his latest writings
on the subject, and as he then had the data of 389 analyses, viz.
of 187 Arkansas soils and 202 in the three volumes of the Ken-
tucky Report,—these being refrered to on the pages we are quoting
from,—we are warranted in considering what he has here pre-
sented, as embodying the strong points in favor of soil-analysis,
We will notice them separately as gathered from both Reports.

1st. ‘‘ Any one who will take the trouble to inspect the analy-
ses of the 187 Arkansas soils will see that the relative propor-
tions of the eleven mineral constituents of these soils is very
accurately given.”—2d Ark. Rep., p. 49.

If we admit fully that Dr. Peter’s analyses represent with
fair accuracy the composition of the two grammes of soil he ex-
perimented with in each instance, we do not therefore allow
that the composition of ‘these soils” considered as representing
geological formations, or large agricultural districts, or even
single fields, is “ very accurately given.”

Here at the outset the distinguished gentlemen who have con-
ducted the ‘geologico- and ‘chemico-agricultural’ part of the
Kentucky and Arkansas surveys have taken for granted, what

[237] Geological Surveys of Kentucky and Arkansas. 5

being an error, overturns their whole reasoning, and renders
their soil-analyses comparatively worthless.

Years ago, following the teachers of agricultural chemistry in
this country and England, we believed that soil-analyses were
adapted to be of exceeding use to farmers. Having practised
analytical chemistry sufficiently to undertake the work, we pro-
ceeded, when on a vacation visit, to collect some farm soils for
the purpose of applying our skill and knowledge. On putting
down the spade and post-augur into the drift overlying the low-
est Silurian of Northern New York, we were at once struck
with the difficulty of procuring an average specimen. The soil
for a depth varying from two to six inches was quite fine, but
below that depth largely mixed with gravel. On comparing
different samples taken from a small area, it was plain that the
soil was not a fit subject for analysis. The relative quantities
of organic matter as indicated by the color of the surface of small
stones,—some quartz and granitic, others slate and limestone
of several geological members,—were astonishingly variable.
Here we found the soil sandy, there. it was clay. To take a
sample from one place was to do obvious injustice to the sixty-
acre field. T'o take it from a dozen places would not render the
selection of a fair sample any more certain. Then as to depth
—was it proper to go down six inches, one foot, or how far?
Had the field been a bed of iron ore, assays of a dozen samples
taken from different parts would have indicated very satisfacto-
rily the general value of the deposit, would have served as data
for buying and selling the property, because the worth of an
unworked bed of such ore depends less upon its content of iron
than upon external circumstances which affect the extracting of
the metal. Had the field been covered with rich dressed copper
ore to the depth of six inches, it would have been necessary to
divide it up into small parcels of a few tons, average these care-
fully and as carefully assay each one. No one would risk pur-
chasing a hundred thousand tons of copper ore on the analysis
of one or of a dozen samples, because it is impracticable to in-
termix or average such a mass of material as that a dozen sam-
ples shall accurately represent it.

We hold it therefore as the first objection to soil-analyses that
to procure a specimen which accurately and certainly represent a
field or district, is practically impossible in the majority of cases,
and if possible, requires a series of andlyses to prove the fact.

This argument applies with the greater force when we con-
sider how small a proportion of the ingredients of a soil are of
any immediate use in feeding crops. The really active nutrient
matters of a soil are not reckoned by per cents nor by tenths of
per cents, but by the minutest fractions.

A heavy crop of thirty-seven bushels of wheat, grain and
straw included, removes from an acre of land but 300 lbs. total

6 S. W. Johnson on the Soil-analyses of the [238]

of mineral matters. According to Dr. Peter’s weighings on some
of the Kentucky soils, we may assume, that taken to the depth
of a foot, an acre of soil weighs 3,000,000 lbs. All that is re-
moved by the heaviest wheat crop then in one year is but 55,457,
or 0:0088+ per cent.

It follows that the annual removal of the heaviest crop of
wheat from a soil for 100 years diminishes its mineral matters
by less than 0-4 per cent. If then, in the selection of a sample,
the average composition is departed from to the amount of 4
parts in 1000, the analysis may misrepresent the soil, by the
value of 3700 bushels of wheat per acre, or by what represents,
so far as mineral ingredients can, the fertility of a century.

What freaks and accidents is not the soil-analyst the sport of?
A bird, squirrel, or dog relieving nature at the spot where he
collects his sample, innocently magnifies the phosphoric acid or
alkalies of the surrounding thousand acres a hundred fold.
The soil gathered toward the end of a long rain, whereby its
soluble matters are carried deep into the subsoil, is declared poor,
by analysis, whereas if taken after a fortnight of drought it
might appear extraordinarily fertile. Boussingauit found in his
rich garden soil in June, during wet weather, 0:00034 per cent
of nitric acid. In the following September, after a period of
dryness, it contained 0:0098 per cent, or twenty-seven times as
much asin June. This ingredient is indeed more liable to fluc-
tuation in amount than any other, both because it is formed in
the soil, and because it is not subject to the absorbent action
which the soil exercises over most other of its soluble constitu-
ents; but the same variation occurs among the other ingredients
according to the direction of the capillary movement of the soil-
water, though in less degree.

Independently however of all considerations and calculations
like the above, we have proof—evidence at least that supports
these considerations, and has never been publicly refuted—that
it is practically impossible to obtain average specimens of the
soil. I refer to investigations made as long ago as 1846-9 under
the direction of the Prussian ‘ Landes Oekonomie Collegium,”
and reported by the distinguished Magnus. The account of
these experiments is given in detail in Erdmann’s Journal fiir
Praktische Chemie, vol. xlvii, pp. 447 et seq.

The “ Landes Oekonomie Collegium” at that time carried on
systematic experiments in agriculture at fourteen distinct stations
scattered through the Prussian domain. The trials which we
now speak of, were made for the ostensible purpose of studying
the exhaustion of the soil by cropping. The plan was to analyze
the fourteen soils, the history of which for years previous was
accurately known, then crop them with rape until “exhausted,”
then compare together the original composition of the soils with
their composition after exhaustion, taking into account as well,

.

[289] Geological Surveys of Kentucky and Arkansas. 7

the composition of the crops removed. ‘The research began
with collecting and analyzing the soils. In order to meet as far
as possible the difficulties of securing average specimens, equal
portions of the soil of each field were taken with the spade at
ten or twelve different points, and thoroughly intermixed; each
sample was then passed through a sieve, the holes of which were
two square lines in area, so as to remove all coarser stones, then
again well worked over to complete the mixture. Of each sam-
ple three separate portions were analyzed, in most cases’ by dif-
ferent operators. The analyses were made by, or under the
guidance of, the ablest chemists of Germany. ‘They were made
according to a prescribed scheme, and that there should be no
reason to slight the work, the work was paid for. It is true that
analytical chemistry was not so advanced in 1846 as now. It is
true that the methods then practised for estimating phosphoric
acid and some other substances were not as perfect as they now
are; but for the most part the analyses then made are as accu-
rate as any that could be executed to-day. It cannot be sup-
posed for a moment that analysts like Rammelsberg, Bédecker,
Genth, Debus, Knop, Heintz, Krocker, Marchand, Weidenbusch,
Sonnenschein, Varrentrap, Weber, &c. &c., would by fault of
method or by carelessness return anything but results that were
accurate, as far as it was possible to make them such. We cannot
suppose that their determinations of lime, oxyd of iron, potash
and sulphuric acid, substances estimated then by the same meth-
ods that are now employed, would vary if they were supplied with
homogeneous material to operate upon. But let us look at some
of their figures. We tabulate a number of them taken at ran-
dom :

Soil of Lime. Potash. Sulphuric acid. Phosphoric acid.
a. 0°39 0:93 0:08 0:06
Eldena, db: +O"15 2°06 —— 0°17
} Car O25 0:12 0:02 0°40
a. 0°802 3°825 — 0:042
Beesdau, b. 0:039 0-490 — 0°046
ee net 5 0°792 0°004 0:007
a, 1:692 3°531 0°050 0051
Neuensund, <6. 0-614 1:289 0088 0-010
C. OheS 1°243 0°241 07121
G. 2312 1112 0:040 0:057
Turwe, db. .2:67 1:14 0:03 0°20
és) 3 a9 0:201 0:022 0:014
a. 0°420 1155 0:016 0:004
Frankenfelde, 4 6. 1:081 —.- 0°418
Cx Oral 1°456 0-015 0:071

If we run over these figures and those of the entire series of
analyses, we find that different determinations disagree to such
an extent as to make it the sheerest folly to base any calculation

8 S. W. Johnson on the Soil-analyses of the [240]

of the value of the soil upon analysis. Some of the analyses
agree sufficiently to show that accordant results are possible if
uniform material be taken; but the grand result of the investi-
gation is that the difficulties of getting a uniform material are
exceedingly great. Again, we must remember that in the case
before us, the three examinations of each soil were made upon
portions of one carefully mixed sample. What would have
been the result had each chemist received a sample collected
separately from all the others, and from different parts of the
field |

Dr. Peter mentions these analyses of the Landes Collegium,
and quotes a few of the results on page 187 of the 8d Kentucky
Report. He believes however that these discordant results do
not invalidate soil analyses when made as they may be made
with ‘means and appliances now at the service of the analytical
chemist” and thinks ‘this statement however hazardous it may
seem will be found to be sustained” in his Report.

In the Report before us however we do not find anything to
sustain Dr. Peter’s view. He gives, so far as we have discovered,
no duplicate analyses, to show what accuracy his methods admit
of on the same sample, much less does he prove by analyses of
specimens separately gathered from the same field, that it is easy
to procure an average material for analysis. Until this proof is
produced the evidence is in favor of our view.

Having shown how small an error in sampling may affect the
chemist’s estimate of a soil, it is not out of place to insist for a
moment, that a similar error in the analysis itself, must have the
same result. In running over 200 pages of Dr. Peter’s 4th Ken-
tucky Report, we find five analyses of soil in which there is a
gain of from five to eight tenths per cent; we find twenty-three in
which there is a loss exceeding five tenths per cent. In thirteen
of the latter the loss is eight or more tenths, in eight instances
the loss is one per cent or more, and in one case is one and eight-
tenths per cent. We should scorn to notice little matters like
these, errors which are inseparable from the best manipulation
and the best processes, were it not that in soil analysis it is pre-
cisely the small quantities which alone have any importance.

We find in Dr. Peter’s work, as in the work of all who have
preceded him in the analysis of soils from Davy and Sprengel
down, evidence that the best endeavors in this line of research
are entirely incommensurate with the desired results.

It may be objected to this criticism of the analyses that the
loss or gain must be distributed among the twelve ingredients
determined. It is true that there is a probability that such dis-
tribution would be just; but this is by no means certain, and it
is equally true that this being done there is still force in the
criticism—for the four-tenths per cent of the soil which a cen-

[241] Geological Surveys of Kentucky and Arkansas. 9

tury of wheat crops would remove, likewise consists of twelve
ingredients.

The 2d result of these analyses, according to Drs. Owen and
Peter, is what the former (4th Ky. Rep., p. 33) declares to be
“a general law” ‘now established,” viz., ‘that sozl-analysis 1s
capable of showing the exhaustion in land of the mineral food of
plants by continual cropping.”

To show the removal of soil-ingredients by cropping, the
plan was followed of collecting soils from contiguous fields, one
of which had been “cultivated” while the other was in its virgin
state. On comparing the analyses it was found that in seventy-
one* cases out of seventy-nine, a loss had occurred in the
soil which had been in use without manure from ten to fifty
years. In eight instances, however, the analysis failed to show
such a result, owing to local causes, the soil of the old field
being based on a sub-soil richer than was the virgin field, or the
old field having received washings of more elevated lands, &c.

The admitted richness of the old over the new soil in these
eight exceptional cases, is expressed by hundredths of per cent,
e.g., soil Nos. 982, virgin, and 983, cultivated, differ by 0°066 per
cent of potash. Soils 1144 and 1146 by 0:032 per cent of phos-
phoric acid. Soils 1204 and 1205 by 0:092 per cent phosphoric
acid. Soils 1207 and 1208 by 0:03 per cent potash. Similar
fractions likewise show the amount of deterioration in the other
seventy-one cases. We adduce two instances pointed out by
Dr. Peter in the 8d Kentucky Report, p. 207, and one given on
p. 176 of the 2d Arkansas Report:

Carb. of lime. Magnesia. Phosphoric acid. Potash.
Virgin soil, No. 557, 0°345 0°335 0-181 0°156
Old soil, No. 558, 0215 0°465 0'103+ 07101
Difference, 0°130 0:130 gain. 0:078} 0:055
Virgin soil, No. 738, 0°180 0°444 0179 0:256
Old field, No. 739, 0-145 0°388 0°163 0°179
Difference, 0:035 0:056 0-016 0:077
Virgin soil, No. 288, 0°121 0:371 0°127 0°116
Old field, No. 289, 0:021 0371 0:053 0:097
Difference, 0:100 0-000 0074 0:019

We were prepared to find these differences much larger. It
is seen at a glance that they fall within the errors of Dr. Peter’s
own manipulation, and when we assert that of ten analyses of
the most homogeneous material made by the same analyst under
the most favorable circumstances, five would differ among each
other by an amount equal to the quantities upon which this
“natural law” is supported, we assert what every competent

* Misprinted twenty-one, on p. 31, 4th Kentucky Report.

+ Misprinted on p. 207, 8d Ky. Rep, where the difference is made 0°045 instead
of 0078, as given above from the tabulated analyses.

Am. Jour. Sc1.—Sxconp Series, Vou. XXXII, No. 95.—Szpt., 1861.
31

10 S. W. Johnson on the Soil-analyses of the [242]

analyst knows to be true, and what moreover pronounces most
emphatically upon the value of such investigations.

It is therefore our conclusion, that while, as has long been
known, the soil loses in mineral matter what the crop gains, it is
doubtful if in any given case chemical analysis can indicate this
difference with certainty, for the reasons that the accidents which
affect analysis make the limits of inaccuracy, to cover more than
the loss by years of cropping. When we take into account the
changes that are constantly progressing in the soil when under
cultivation—changes by which the disintegration is hastened,
changes by which it is made in many instances more retentive
of soluble matters—when we remember that most cultivated
crops, although they carry off in seed, stem and foliage a quan-
tity of mineral matters, yet derive these in part from a depth
below the range of analysis, and in their roots or stubble, leave
upon the surface, salts brought up from a considerable depth—
we perceive that the problem is so complicated with compensa-
tions and variable quantities as to put it beyond the reach of
quantitative chemical analysis.

If, in any case, soil-analysis does show or appear to show the
exhaustion of the soil, it is however, the appeal to experience
which proves it, and as this is the first, most obvious, and an
entirely sufficient proof, we do not see the value of the “law”
that has 10 per cent (eight-seventy-ninths) of exceptions, the
existence of which like that of the rule itself, is only to be
established by comparison with the plain agricultural fact.

In short, if we admit the result as Drs. Owen and Peter would
have it—of what use or interest is it?

The 8d point, is that analysis shows ‘the peculiarities of the
soils derived from different geological formations.” Says Dr.
Owen, “these analyses most distinctly show that certain geolog-
ical formations impart to the soil more of the important mine-
ral fertilizers than others.” The reader will be able “to see
that it is those formations which are composed of easily disin-
tegrating materials, which, all other things being equal, yield the
soils richest in phosphoric acid, lime and potash; and at the
Same time contain the quantity of alumina and oxyd of iron
necessary to render them sufficiently retentive and attractive of
atmospheric water and ammonia; therefore these soils are the
best adapted for those grains and crops which require the largest
proportion of these ingredients.” ‘‘ He will moreover be able
to trace the gradual diminution in the proportion of the more
important mineral ingredients, down from these extraordinarily
fertile soils derived from the highly fossiliferous, argillo-calca-
reous beds of the lower Silurian, the Cretaceous and the Tertiary
systems of the West; through the silico-calcareous soils of the
upper Silurian, Devonian and Sub-Carboniferous limestone strata,
in which fossils are either more spariugly distributed or, in some

[243] Geological Surveys of Kentucky and Arkansas. 11

cases almost wanting, and which are far less easy of decomposi-
tion; thence through the argillo-silicious soils of the Coal meas-
ures with only locally organic remains, and these chiefly of plants,
down to the more purely silicious soils prevalent where the
non-fossiliferous sandstones of the Coal measures and of the
Millstone Grit, prevail to the exclusion of either shales or lime-
stones and which afford the most unproductive soils as yet an-
alyzed.” While it is to be expected that rocks of complex origin
rich in organic remains—which are evidences that the rocks them-
selves originally resulted from the deposition of the washings of
fertile lands—should yield richer soils than sandstones or lime-
stones, we do not see that analysis of the soil makes the fact
more evident. Knowledge of the composition of a rock enables
us to judge in a general way of the value of the soil, so far as
this depends upon chemical characters. We do not see what is
gained by further analyses of the scil. It would appear that the
cheap mental processes of deduction or inference may accomplish
here in a moment all that an expensive analysis can show.

We fail moreover to perceive that analysis shows “the pecu-
liarities of the soils derived from the different geological forma-
tions.” In a cretaceous or limestone soil we of course expect to
find much carbonate of lime, and in a sandstone or millstone grit
soil much insoluble silica or silicates, but the quantities of phos-
phorie acid, potash and sulphuric acid do not appear to bear any
definite relation to their geological origin. It is impossible to
represent the composition of the soil of any geological formation
by a typical statement of percentages, or to point out its pecu-
liarities further than by an undefinable more or less. Although
Kentucky and Arkansas lie mostly or altogether beyond the
influence of drift, yet the action of running water in its con-
stant passage from hill-top to valley has to a great degree oblite-
rated from the soils those peculiar differences to be found among
the rocks from which they have been derived.

A careful examination of the analyses recorded in the Arkan-
sas survey shows that the average composition of the eight soils
analyzed from the Lower Silurian and of the fourteen from the
millstone grit, compare as follows, in regard to the more im-

portant ingredients:
Phosphoric Sulphuric
c

Carb. lime. Magnesia. acid. acid. Potash.

Lower Silurian, average of 8 soils, 0°533 0°485 0184 0°052 0°355
Millstone grit, ¢ 14 “ 0215 0531 0180 0-057 0-148
Here we see that the soils of the poorest formation are inferior
to those of the richest only in carbonate of lime and potash. Of
the soils of the millstone grit, nine are richer in carb. lime than
the poorest of the Silurian, and five of the former contain more.
potash than the poorest of the latter. On the other hand but
two of the Silurian soils have higher percentages of either carb.

12 S. W. Johnson on the Soil-analyses of the [244]

lime or potash, than the richest soil of the millstone grit. If
these figures demonstrate anything, it is the fact, that no geolog-
ical formation has the absolute monopoly of either barren or
fertile soils. If the analyses of Dr. Peter show the “ peculiari-
ties” of the soils of any geological age, then certainly these
peculiarities are not remarkably peculiar!

On page 50 of the 2d Ark. Rep., Dr. Owen remarks as follows:

“With the table of the composition of the ashes of plants to
refer to, appended to this Report, and after becoming acquainted
with the usual proportions of mineral constituents in an average
soil, information which is easily acquired by looking over the
table of soil analyses in this Report, it is easy for any individual
to see, when he is provided with a reliable analysis of his soil,
not only to what crop it is best adapted, but what kind of min-
eral fertilizers, if any, it requires as a manure, and how it com-
pares in fertility to the various grades of soils from other farms
and other states. Is not this knowledge of some value to the
farmer ?”

The above, we are of opinion, proceeded rather from the
generous heart than from the critical brain of its lamented author.
Had he attempted to do the things which he believed to be so
easy, we are sure his statements would have lost somewhat of
their directness and would have appeared in a form highly modi-
fied from the above. “The usual proportion of ingredients in an
average soil.” What is an average soil? Our only way of
deciding what is such a soil consists in noting the average yield
of soils. But the yield depends not alone on the soil, but upon
climate, weather, tillage and various incidents and accidents. It
depends not on the composition of the soil—not on the “ propor-
tion of ingredients” alone, but likewise on the condition of
those ingredients, their state of combination, their solubility. It
depends also on the physical characters of the soil, which deter-
mine the relations of the crop to the essential conditions of reg- '
ulated heat and moisture. ‘The soil is not less important to the
plant in its function of home than in its function of food, the lodg-
ings are of equal influence with the board. It is a nice work to
balance these varying circumstances, many of which have as yet
in our science, no shadow of a numerical expression, and then to
say how many thousandths of a per cent of potash, lime, phos-
phoric acid, &c., belong to the “average soil.”

Dr. Peter has indeed attempted to show the degree of availa-
bility of the elements of the soil by the following process. “A
quantity, generally thirty grammes of the air-dried soil is
placed in an eight-ounce strong vial, with a close fitting stopper,
and the bottle is filled up with distilled water which has been
charged with pure carbonic acid gas, under a pressure of about
two atmospheres. The bottle is allowed to remain for about a

[245] Geological Surveys of Kentucky and Arkansas. 13

month at a temperature about that of summer heat.” The
matters thus dissolved were then analyzed as usual. These
results have this value, they show that the water of the soil is
capable of dissolving all the elements of the food of plants.
They furnish moreover a rough comparative view of the availa-
ble matters in different soils. Beyond this we cannot attach any
value to them.

We now come to Dr. Owen’s 4th result of soil-analyses,
embodied in the above quotation, and repeated on p. 30 of the
4th Ky. Rep., viz: its power of indicating “the suitability of
the soil for any particular crop.” Closely related to this is the 5th
item, viz., that analysis can show “ what addition any soil, either
uncultivated or cultivated, requires to render it productive and
remunerative for any given crop; and, of course, the deficiency
in the soil of one or more of the eleven elements determined by
chemical analysis.”

We cannot help feeling that the above assertions which are
here made unqualifiedly, were intended to be understood with a
large amount of reserve and subject to various conditions, Oth-
erwise we must regard them quite unjustified, if not absurd.
The chemical analysis of soil reveals nothing as to its tenacity or
lightness, its porosity or retentiveness for water, yet these phys-
ical and mechanical conditions more than anything else determine
the adaptation of a soil for any particular crop. The best grass
lands are not the best wheat lands—and although it would
scarcely be questioned that wheat requires a richer soil than
grass in order to produce an average crop, and although as we
know, it often happens that many successive hay crops may be
removed from a meadow without sensible diminution of the
yield, while uninterrupted cropping with wheat nearly always
reduces the capacity of the soil in a very few years below a
profitable point; yet each average hay crop removes from a field
more of every ingredient of vegetation than the grain and straw
together of an average harvest of wheat.

Such at least is the testimony borne by the most recent and
trustworthy data. Dr. Anderson of Glasgow basing his calcula-
tions on the best analyses and on the extensive agricultural
statistics gathered in late years by the Highland and Ag. Society
of Scotland, makes the following estimate of the amount of the
principal ingredients removed from an acre by average crops of
seven staple British farm products. See table on next page.—
Trans. Highland and Ag. Soc., 1861, p. 568.

On comparing the amount of matters removed from an acre
by the wheat and hay crops, we find that the latter requires four
times as much potash, lime and sulphuric acid; twice as much
silica and one-fifth more nitrogen.

Again we know that oats are raised on soils which are consid-
ered too poor for the profitable production of wheat, and the

[246]

S. W. Johnson on the Soil-analyses of the

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[247] Geological Surveys of Kentucky and Arkansas. 15

table shows us that an average crop of oats requires more of
every mineral ingredient than is needful for a corresponding
wheat crop.

In fact, wheat is the crop, to grow which continuously requires,
according to universal agricultural experience, land richer than
that needed for any other of the seven crops whose chemical
statistics are given in Dr. Anderson’s Table, and notwithstanding,
with exception of barley and the potato-tuber, it removes the
least from the soil.

The farmer knows that wheat delights in a deep, rather heavy
soil, one which holds moisture well, and yet is not wet. Barley
and oats flourish on soils that are too dry and light, and grass
on those which are too wet for wheat.

But how does the matter stand when these external conditions
are taken into account? Does not analysis aid us then in a
good degree? Let us take a case similar to what has repeatedly
occurred in actual practice. We have a soil which as the result
of long cultivation or from natural deficiencies, is incapable of
yielding a remunerative crop of wheat. Its texture is good, it
has produced wheat abundantly, and needs nothing but a little
of the right kind of manure to restore its power of giving a
crop. We put upon it Peruvian guano at the rate of 300 Ibs.
per acre, and the harvest isa good one. The entire addition to
the soil is but 5,32%,,ths = one hundredth per cent. The
amounts of phosphoric acid, of alkaline earths and nitrogen
added, are for each, but one six-hundredth per cent of the soil,
taken to the depth of a foot. These quantities are rather minute
for even the improved analysis of the present time to estimate
successfully.

Calculations like this show that the chemist cannot discrimi-
nate by his analysis between; 1st, a soil which is unproductive
from the temporary exhaustion of some of its available ingre-
dients; 2d, the same soil which is rendered fertile again for a
year by the use of 800 lbs. of guano; and 3d, the same, made
over-rich so that nothing will grow on it, by an application of a
ton of guano.

On page 18 of the 2d Ky. Rep., Dr. Owen remarks as follows:
“During last summer a soil was collected in Bullit county, from
an old field which had been fifty or sixty years in cultivation,
and which will now no longer produce clover. I venture to
predict that when the analysis of this soil shall be completed it
will be found to be deficient in some of these constituents,* and
the analysis will probably show what other green crop might
succeed better for the renovation of such land.”

On page 230 of the 8d Ky. Rep., Dr. Peter gives the analysis
of this soil, and says, ‘‘ The inability of this soil to produce clover

* The mineral ingredients of plants.

16 S. W. Johnson on the Sotl-analyses of the [248]

is explained by its very small proportion of lime, and rather
small amount of sulphuric and phosphoric acids. The addition
of plaster of Paris or some of the calcareous marls would prob-
ably restore it to the capability of supporting a clover crop.”

The percentages of the ingredients which Dr. Peter considers
deficient, are as follows:

Carbonate of lime, - - - 0:072 =lime 0°:040
Sulphuric acid, - - - 0:055
Phosphoric acid, - - - 0:070

Small as are these quantities, the smallest of them, viz., that
of lime, yet amounts to 1200 lbs. per acre, which is enough to
supply 10 clover erops of 3 tons each, and as by the analysis it
all exists in the form of carbonate, it must all be available. We
know from the vegetation experiments of Boussingault, Ville,
and Sachs, that plants are capable of absorbing from a limited
amount of soil the whole of any soluble nutritive substance pres-
ent, provided its quantity be no more than the plants require,
and the other elements of fertility are at hand in excess.

Twelve or thirteen years ago, Dr. Anderson in his capacity of
Chemist to the Highland and Ag. Society of Scotland, had occa-
sion to investigate two soils which had become “clover-sick,”
and he caused them, together with similar adjacent soils which
still produced clover, to be most minutely analyzed. Without
reproducing his figures, which may be found in the Trans. of the
Highland and Ag. Soc. for 1849-51, p. 204, we will merely
quote some of the remarks which accompany the analyses: “The
results of these analyses are certainly of an unexpected charac-
ter, and appear to me to indicate that, in this instance the failure
of the clover cannot have been dependent upon the chemical
constitution of the soil. In both cases the results of the analyses
of each pair do not present a greater difference than would be
obtained from the analyses of two portions of soil from different
parts of any field.”

In the present year, Stoeckhardt (Chemischer Ackersmann,
No. 2, 1861, p. 85), has published an account of several “clover-
sick” soils from Schlanstaedt, which reveal to analysis a greater
content of every nutritive mineral ingredient both soluble in water
and in acids, than exists in another soil from Frankenstein which

roduces clover and wheat as well. What proves beyond a
doubt that the inability of these svils to yield clover depends
upon something besides their chemical constitution, is the fact
that lucerne and esparsette still flourish upon them admirably,
and further, clover itself, if sown with one of these last men-
tioned crops, succeeds very well.

A great truth in agriculture is this: Each kind of agricultural
plant requires that its seeds be surrounded with certain conditions
in order that they may germinate readily and healthfully, so

[249] Geological Surveys of Kentucky and Arkansas. uf

that when the mother cotyledons are exhausted, the young plants
shall attack the stores of food in the soil with that vigor which
is needful in order to appropriate them without hindrance.

The fact that winter wheat is more delicate and fastidious in
its infancy than most other crops, is perhaps the main reason
why it does not succeed well on many good lands, and why it
cannot be continuously produced from the same soil, year after
year. It isa matter of experience that wheat requires a rather
firm seed-bed: beans, oats and mangold-wurzel approach wheat
in their requirements, while barley, peas and turnips are best
suited in a light tilth. On the other hand, climate, weather and
tillage so influence the character of the soil, that even on light
lands, wheat may find all the conditions of its growth. The bed
which is produced by inverting a clover sod, and allowing it to
consolidate by time and rains, or by passing a heavy roller over
it, is eminently adapted to wheat, even on a rather light soil.

The fact that in the cases given above from Stoeckhardt, clover
succeeded when sown with lucerne or esparsette, would indicate
that, possibly, the condition of the seed-bed was the cause of
failure.

These and other facts which might be adduced to almost any
extent, indicate sufficiently that chemical analysis alone, even if
we admit its full nicety and accuracy, can at the best furnish us
with a knowledge of but a few of many conditions which must
codperate in profitable agricultural production, and as a conse-
quence, its part in guiding the farmer is but very subordinate.
Taking into the account its evident uncertainty and clumsiness
when applied to estimating the minute quantities which affect
vegetable growth, the part it can play becomes still more subor-
dinate—we hesitate not to say, insignificant.

As we write, a fragment from a Scientific Journal brings to
our notice a discovery which if real, strengthens our views in
an unexpected manner. It is well known that iodine is so im-
mensely diluted in sea-water—the soil of marine-plants—that
none of our tests though they are among the most delicate, serve
to detect it directly, and it is doubtful if it has been detected
even in the highly concentrated mother liquors which remain
after separating the crystallizable salts, yet the fuci find and
accumulate it, and we must grant that it is present there for
them, in sufficient quantity.

Again, Prince Salm Horstmar several years since, in his ad-
mirable researches on the influence of the individual mineral
ingredients of plants on the development of oats and barley,
found that he could not by any possibility exclude chlorine from
his experimental plants. His soils and pots, the salts and water
he fed his plants with were so purified that he could not detect
this element in them, and yet he invariably discovered it in the

Am, Jour. Sor1.—SnconD SEeRies, Vou, XXXII, No. 95.—Sepr., 1861.
32

18 S. W. Johnson on the Soil-analyses of the [250]

ashes of the plants. So too he found titanic acid in the produce
grown on the most carefully purified soils. Now, it is mentioned
in the ‘Chemical News” that he finds a few hundredths of lithium
are indispensable to the ripening of barley. This element Bunsen
has but recently shown to be everywhere distributed, yet it has
been hitherto entirely unnoticed in all soil- and plant-analyses
because of its occurrence in almost infinitesimal quantity.

It must be well borne in mind that Agriculture herself—so-
called Practice—is able of her own resources to judge somewhat
of the value of soils, is able to know if a soil be fertile or poor,
is able to pronounce upon its adaptation to crops, and can to a
certain extent decide what is a good manure for this or that field.

We are free to assert that the knowledge which is now to be
gathered from experience, is able in ninety-nine cases out of one
hundred, to give a more truthful verdict as to the capacity of a
soil, that any amount of analysis, chemical, mechanical or other-
wise, can do. We would give more for the opinion of an old
intelligent farmer than for that of the most skilled chemist in
most questions connected with farming. Doubtless the farmer
would make some blunders from which chemistry might save
him, but the chemist would be likely to do more violence to
agriculture, than the farmer would to chemistry.

By these statements which may, but should not surprise some
of our scientific friends, we merely intend to express an opinion
as to the present relative position towards agriculture of those
who regard the art from a chemical, and those who see it from an
experimental point of view.

If any one has fuller and more inspiring notions of the import-
ance of science in its applications to agriculture than we have,
we desire to sit at his feet and share the higher aflatus. But our
inspiration, if it be of the sort that works enduring benefit, must
be based on clear ideas of the directions in which advance is
possible and on a full perception of the difficulties that lie before
us, and the means of overcoming them.

We have great faith that chemistry and that chemical analysis
have done and are to do a work for agriculture, that shall lay that
venerable art under everlasting obligations to the youthful sci-
ence. But not by soil-analyses alone or mainly is this to be
achieved. We do not assert that soil-analysis is worthless—we
believe that the probabilities of its uselessness in direct applica-
tion to practice are so great that we would rarely base any ope-
rations on it alone, and yet it may in many cases, promote science
and give us data for conclusions that are of practical use, But
for these purposes it must form part of a system of observations
and trials, must be a step in some research, must stand not as the
index to a barren fact, but as the revelator of fruitful ideas.

We hold that soil-analysis long ago played out the part which
Dr. Peter would have it perform. In the hands of Sprengel it

[251] Geological Surveys of Kentucky and Arkansas. 19

was fertile with new truth, but it must henceforth be a tool for
occasional use, and not an engine of discovery. With our aid-
vance in knowledge there must be an advance in methods of
finding out the unknown. Soil-analysis was indeed a means of
insight into the secrets of vegetable growth, but it carried with
it the measure of its limit. What we call telescopes do not ena-
ble us to see the end /

To study the soil in the hope of benefitting agriculture, we
must regard all its relations to the plant. We must examine it
not merely from those points of view which theoretical chemistry
suggests, but especially from those which a knowledge of prac:
tical agriculture furnishes, This is becoming more and more
the habit of agricultural chemists and the results are of the
happiest kind.

Let us remember what the illustrious Nestor of Agricultural
Science, Boussingault, has said as the summing up of his pro-
tracted experience and study.

“At an epoch not far distant it was believed that a strict
connexion existed between the composition and the quality of
arable soil. Numerous analyses shortly modified this opinion as
too positive. The sagacious Schiibler even sought to prove in a
research that has become classic, that the fertility of a soil de-
pends more upon its physical properties, its state of aggregation,
power of absorption, &c., than upon its chemical constitution.”

“The physical properties, in my opinion, do not enable us,
more than the chemical composition, to pronounce upon the de-
gree of fertility of the soil. ‘To decide this point with some meas-
ure of certainty, it is indispensable to have recourse to direct ob-
servation; it 1s necessary to cultivate a plant in the soil, and
ascertain with what vigor it developes there: the analysis of the
plant afterward intervenes usefully, to indicate the kind and quan-
tity of the elements that have been assimilated.”—(“ De la Terre

fegétale considerée dans ses Liffets sur la Vegetation,” page 288 of
“Agronomie, Chimie agricole et Physiologie, Tome premier, 1860.”)

There has been much progress made in our knowledge of the
soil during the last ten years. This advance has not consisted
in revealing to us the presence of new elements (lithia perhaps
excepted), nor in fixing with any more certainty the quantitative
limits which separate barrenness from fertility, it has not shown
what is the composition of a Silurian or a Sub-Carboniferous, a
Drift or a Tertiary soil, it has not defined the soil adapted to
wheat or that productive of clover, it has not indicated the ma-
nures which this or that soil needs; but content with the fact
that all soils which naturally support vegetation contain the
elements of vegetation, it has souglit to ascertain in what forms
these elements are assimilable, how they may be made available,
what changes or reactions in the soil affect its productiveness;
how fertilizers act indirectly (their influence often having no

20 S. W. Johnson on Soil-analyses, etc. [252]

relation to any supposable direct action), how the soil affects the
life of the plant otherwise than by feeding it, &c. &e.

We are approaching in fact by slow degrees to an understand-
ing of the physiological significance of the soil, a grand result
to which chemistry and physics cooperate.

We trust that in the future, the American people will not less
but more appreciate the value of science in its practical and es-
pecially its agricultural bearings; that here, as in Germany,
France and England, the labors of those who seek to unite Prac-
tice with Science may be fostered and sustained. But to this
end scientific men must be cautious that in endeavoring to heip,
however honestly and laboriously they may work, they do not
hinder.

Sheffield Scientific School, August 20th, 1861,

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