Agricultural Clicmistry. 
437 
which the ordinary means of farm-yard manure, fallow, or green 
cropping would attain ; and, if it be really so, there surely has 
been some light thrown, upon the important question of the 
source of the efficacy of these well-recognised practices, so far 
as the growth of grain is concerned. 
The object of this inquiry really was, to determine by what 
constituents of manure the produce could be raised from the 
normal amount of its agriculturally exhausted state — no matter 
whether this was 17 bushels or 0 — up to the point of which 
it was capable by the ordinary means of intelligent and successful 
farming. This is the practical question, the question for agri- 
culture. And we repeat, that, inasmuch as by the means that 
were employed we obtained an increase per acre of 10 to 15 
bushels or more, with its equivalent of straw, over the produce 
of the unmanured land, whatever this last might he — we say that, 
as this was the case, our soil was in a fit and proper state to 
elucidate the important agricultural question as to what was the 
nature of the exhaustion suffered by a course of agricultural crop- 
ping, and as to what constituents it was necessary to provide 
before the produce of grain could again be raised, from that of the 
practically exhausted, to that of the -practically fertile condition 
of the land. 
But Baron Liebig has said that, because we obtained an 
average produce of 1125 lbs. of grain and 175G lbs. of straw, 
during seven consecutive years, that this was a sufficient proof — 
" that the soil was naturally so rich in available mineral constituents, of the 
kinds required by plants, that manuring with 4 cwt. of mineral manure per 
acre, a quantity which, S])read over the ground and mixed with the soil 
to the depth of 12 inches, gives 1 grain to 20 cubic inches of soil, could most 
certainly produce no effect, or, at the utmost, a very tritling one. For, in the 
first year, the soil contained seven times, or about 85 per cent, more of 
these substances thanVas required for one crop." — FrincijAes, p. 58. 
Now, if it really were so, that our " soil was naturally so rich 
in available mineral constituents of the kinds required by plants," 
as Baron Liebig admits, is it not the strongest condemnation 
which could possibly be conceived of the doctrine presented in so 
many forms to the farmer, namely, that "if only the soil contain 
a sufficient supply of the mineral food of plants," then " the 
ammonia required for their development will be furnished by 
the atmosphere " ? Is it not, we ask, the strongest possible con- 
demnation of such a view that, with the soil in this supposed 
naturally rich condition, the produce should still be less, by many 
bushels of corn, and their equivalent of straw, than that ob- 
tained on the simple addition of available nitrogen to the soil ? 
And, when Baron Liebig now informs us that — 
" no one but Mr. Lawes himself can be surprised that, under such circum- 
stances, by manuring with ammoniacal salts only, without any addition of 
