The Sun.
London, England, 1855-10-19 00:00:00

THE LATE MEETING OF THE BRITISH
ASSOCIATION AT GLASGOW.

The following paper, "On sonic points connected with
Agricultural Chemistry," by J. B. Lewes, F.R.S., and Dr.
J. 11. Gilbert, F.C.S., was read at the late meeting of the
above association :
The author explained that their subject was necessarily
somewhat controversial, for Baron Liebig had recently
published a criticism on their experiments and opinions,
which had been circulated very freely in England, France,
Germany, and America : and, from the well-merited re-
putation of that distinguished chemist, his statements and
opinions had been echoed almost unexamined by ninnerous
writers, both in the technical and general press. To those
statements and opinions, therefore, the authors now pro-
posed to address themselves. They would first call atten-
tion to the unfairness of an article on the question at
issue, in a recent number of the "Journal of the High-
land Society of Scotland,"* as by so doing they would be
naturally led to a proper definition of the subject before
them. They explained that it was agriculture, not nor-
mal vegetation—that is, the growth of plants, under culti-
vation, and nut their growth in circumstances under which
every element necessary for their development had to be
specially provided. In other words, they pre-supposed,
as the preliminary conditions of their inquiry, a soil under
ordinary cultivation and an atmosphere—each yielding,
unaided, their quota to the result. Indeed, Baron Liebig
had defined the province of agricultural chemistry to be
that of producing more corn and more meat, and not sim-
ply corn and meat, which had been produced for centuries
without her aid.
Looking at the subject in this point of view, the authors
maintained, as a fundamental fact, that the composition of
agricultural vegetable produce was no direct guide in the
choice of manure for the various crops grown in rotation—
that which was required being simply the resultant deficit
for the artificial production of that margin of produce
which distinguished agriculture, as practised in this coun-
try, from natural vegetation, or from produce obtained
for the purposes of export, without any return to the laud
by home manures.
Those of their experiments which had been passed under
criticism by Baron Liebig were taken, with others by their
side, to illustrate the conclusions to which the authors had
arrived. They first brought a summary of the results of
their experiments on the growth of wheat, by different
chemical manures, during many consecutive years, and
they maintained that, inasmuch as by means of such ma-
nures they could raise the produce by from 10 to 20 bushels
per acre over the unmanurod produce, and, indeed, far ex-
ceed the result obtained by the annual supply of farm-yard
manure; that this being the case, the objection of Baron
Liebig that their soil was naturally so rich as to be unfit
for experiment, must be considered to be entirely without
foundation. They then illustrated by tables and diagrams
of results, by reference to which Baron Liebig had endea-
voured to prove the contrary :—l.st, " That the mineral
constituents of wheat cannot by themselves increase the
fertility of land ;" and 2d, " That the produce in grain and
straw is rather proportional to the supply of ammonia."
So far as it went they fully accepted the above definition
of their conclusions as given by Baron Liebig—subject, of
course, to the qualifications which their own papers would
indicate. But they utterly repudiated that definition
when understood in the manner assumed by Baron Liebig,
when summing up and giving his verdict on their opinions
at the conclusion of his treatise. They next showed by
reference to tables that nitrogenous manures, whether ap-
plied in the form of ammouiacal salts, nitrate of soda, or
rape-cake, had a great effect in the increase of produce of
barley also the next in importance of the cereal grains.
Turning to turnips, the type of the root crops grown in
alternation with the cereals, they submitted that Baron
Liebig's statement, that the phosphates were the only
Manures which they had found to increase the growth of
the turnip, was directly contrary to the whole tenour of
their papers on the subject, in which they bad maintained
the absolute necessity of matters yielding both assimilable
carbon and nitrogen within the soil, for the production of
a full amount of the crop in question. They did main-
tain, however, that phosphoric or phosphatic manures had
an action on the development of the underground fibrous
fee era of the plant, and, consequently, on its rapid growth
and development, which could not be accounted for by the
mere supp isition of supplying the actual constituents of
the crop to be grown and removed from the land. They
illustrated that in their experiments, they had the very
circumstances provided which hat been demanded by.
Baron Liebig as necessary for the support of their conclu-
sions; and thus it was proved that even where existed in
the land a residue of phosphates from previous manuring,
more than would be contained in many heavy crops,
still an annual additional supply gave annually a consider-
able increase of produce. They further pointed out that
Baron Liebig had endeavoured to substantiate his objec-
tions by comparisons, which they showed to be quite inad-
missible, whilst one main argument he had founded upon
a mere misprint, which reference to the succeeding tables
would at once have explained. His argument on the point
in question was therefore simply reversed.
They next illustrated by a collective table the action of
manures on some of the most important crops of rotation,
including wheat and barley as cereals, turnips as a root
crop, and beans and clover as leguminous crops. From this
table it appeared that, whilst mineral manures alone had
little or no effect in increasing the produce of wheat and
barley grown respectively in succession, nitrogenous ma-
nures, on the other hand, yielded most striking results.
And hero attention was called to the fact that these manures
bad a similar effect on a corn-exhausted soil on the farm of
the Earl of Leicester, at Holkham, of which the surface
soil was poor and light, but the subsoil somewhat rich and
loamy; and, also, at the farm of the Duke of Bedford at
Woburn, on a soil and subsoil naturally of the poorest pos-
sible description. And they further maintained that these
results of direct experiment on different soils wore perfectly
in accordance with the general experience of practical far-
mers all over the country, as to what was the predominant
characteristic of corn exhaustion. In the experiments quoted
mineral manures were, of course, found to give a further
increment of increase when the nitrogenous manure em-
ployed was in excessive quantity.

With turnips, again, superphosphate of limo had given
an average increase during a series of years of more than 7
tons of the bulk ; the addition of alkalis to this had even
diminished the amount of increase. Ammonia salts alone,
on the other hand, had only given a few hundredweights
of increase, instead of more than as many tons, by the
phosphatic manure. The mixture of both mineral and
ammoniacal manures bad, however, given a better produce
still ; though not equal to that which would have been ob-
tained had there been also a liberal supply of carbonaceous
organic matter within the soil. Turning to beans and
clover, nitrogenous manures which had been so beneficial
to the cereals, and phosphates which had been so much so
to the turnips, had here comparatively little effect. The
constituent of manure which acted in the most charac-
teristic manner with these leguminous crops was the
alkali potass, which, when used as a direct manuro to soil of
a similar description, had comparatively little effect on the
increase of growth of the cereals or turnips.
In these remarkable facts, though the experiments cited
were by no means to be taken as examples of manuring,
the authors considered there was afforded an interesting
clue to the principles involved in manuring, fallow, and
the rotation of crops.
They next called attention to the analysis of three actual
rotLltions • the course in each case being turnips, barley,
clever, and wheat. In one instance, the rotation com-
mencing without manure; in the second with super-
phosphate of lime alone ; and in the third, with a mixed
and pretty full manuring. It appeared that, in each
case, the clover grown between the barley and the wheat
(the intervention of which, instead of the immediate suc-
cession of the wheat, would greatly increase the produce
of the latter), removed from the land very much mere of
phosphoric acid, of potass, of lime, and of magnesia—in
fact, of every important mineral constituent except silica
—than either the preooding barley or the succeeding wheat.
Hence it was maintained that the effect of this leguminous
crop, in rotation as a preparation for wheat, could not be,
according to the theory of Baron Liebig, to increase the
available supply of, or to conserve within the soil, the im-
portant mineral constituents of the crop. Unless, indeed,
i❑ the case of silica; which, however, Baron Liebig had
himself maintained would never be wanting in sufficient
quantity in any soil provided there were a sufficiency of
available alkalies present. Taking these facts, together
with those indicating the most important manuring for the
cereals, as well as with others relating to the composition
and known circumstances of growth of the leguminous
crops, it could only be concluded that the clover had accu-
mulated from the atmosphere within the soil—a supply of
available nitrogen to a great extent exhausted by the
growth of the previous cereal, barley, and so essential for
the succeeding cereal, wheat.

Finally, attention was called to the fact, that but a
comparatively small proportion of the nitrogen supplied in
manure for the growth of cereals, was recovered in the
increase produced. They showed by a table that the loss
of nitrogen was greater or less according to the amount of
it supplied in manure, and to the condi ions favourable or
otherwise as to mineral supply, character of the season, &c.
Under the most favourable supplied conditions—that is,
with a full supply cf minerals and a limited supply of
nitrogen, they had only recovered in the increase about
half the nitrogen contained in the manure. But when
nitrogen was supplied in quantity sufficient to yield a full
crop for any given season, they had only obtained about
one-third of the supplied nitrogen in the increase. And,
inasmuch as, when the amount of nitrogen employed was
not very great, the one-half or two-thirds which was not
recovered in the increase obtained in the year of the ap-
plication of the manure had little or no effect on the next
crop, it could not be supposed that the excess of nitrogen
still remained within the soil. It was worthy of remark
that vegetable physiologists had frequently observed the
evolution of nitrogen from the leaves of plants during their
growth, beyond that which was due to the atmosphere with
which they had been supplied. But as it had not yet been
clearly shown that the cereals gave off more nitrogen in
this way than the leguminous crops of rotation, further
experiment was needed before the loss in question, and
consequently the varying characters in this respect of the
different plants in rotation, could with full confidenc;b_.
be
explained by reference to the functional action in quest
The only explanation which had been suggested asspe'_! special
to the cereals was that proposed by Kr. Way, "Toe double
the silica required by these plants is taken up:
silicate, of which ammonia is one of the basthe and that
this alkali or its constituents is evolved
¢t least not in
of the silica within the plant. was fa-
vour
of the view that the authoirts had
less silica than pure
containing salts of ammonia dissolved en
ftound that water
bulk of soil. It
water when percolated through g?
must be admitted, however, thateaearletnevlosuithigthhte
rexplanation
of this loss of nitrogen with
etheeuth
ors had hoped to devote
then investigation, which th
of other crops, they had recovered
to it, yet, as in the vas©, proportion ogbfuletehnoteriostyeepooluiveladd.
in a series of years a muche la'
nitrogen, they consider
;ofbuatftuhilatertehpe
not be wholly due eitherdttohdatirsaitenhfaegnelioirfssionlu
he producotgioeini
poration of volatilbelecolmeepsoiunnti
fact of a considers
; list be looked uen
of the cereal gra-9 ra • thep as
au
important
and fundamental item in stud ying rationale of agricul-
tural practicwesolo
h they concluded-
-lU.PTabsit"t-he manure indicated by the resultant require-
n3ents of British agriculture has no direct connection with
composition of the mineral substances collectively
the
found in the ashes of the produce grown on or exported
from the farm ; and that the direct mineral manures which
are required are not advantageously applied for the direct
reproduction of the exportable corn, but it should be used
for the green or fallow crops, the office of which it is to
collect from the atmosphere., or to conserve on the farm,
nitrogen for the increased growth of the saleable cereal
grains.
2. That the nitrogen required to be provided within the
soil for this purpose is far greater than that contained in
the increase of produce obtained by it.
3. That the effects of fallow in increasing the growth of
the saleable cereal grains, chemically considered, are not
measurable by the amount of the additional mineral food

* Professor Anderson, on the part of the Highland Society,
repudiated its responsibility for the article in question, :lid
Mr. Robt. Russell, of Kilwiaiss, also digs:Lamed all connection
?rah 45 authorship.