ith guano alone produced only 27 bushels per acre, whilst this
year from guano alone the produce was 42 bushels. But still I
think that your allowance of manure is far too little, and not
exactly what I should apply, and I shall frankly state my
objections and opinions, in the hope that they may elicit a reply
from you, as it will be from discussion and the experiments
instituted to test the various theories propounded, that
agriculture will be most materially benefited. You state that
Liebig's present theory is, that plants obtain the necessary
oxygen, hydrogen, carbon, and nitrogen from the rain and
atmosphere, and that the plants merely require the supply of
inorganic constituents, and that you are inclined to agree with
him. My copy of his work on the Chemistry of Agriculture is his
first edition; and I don't know how far he has since modified or
altered the opinions therein expressed, which are in some degree
at variance with each other. He states that it may be received as
an axiom in agricultural chemistry that the nitrogen of the
atmosphere is never assimilated by plants, except in the form of
ammonia or nitric acid. He certainly states that plants and
animals derive their nitrogen from the atmosphere; but why, if
this be true, does he attach so much importance to the excrements
(particularly urine), of men and animals being husbanded with so
much care? and he states that for every pound of urine wasted, a
pound of wheat is thrown away. But even if he said it was utterly
worthless, every practical farmer who has tried it knows how
exceedingly valuable it is. It may be said there are other
ingredients in urine besides ammonia, and these are what make it
valuable; and in reply to this I would ask what is it that makes
the ammoniacal liquor from gasworks so valuable? There are no
phosphates or alkalies there, and yet what a powerful stimulant it
is. Again, Liebig states that the carbon is derived from the
atmosphere; but to say nothing of the argument which might be
deduced from the advantage which is derived by plants from having
their soil loosened about their roots, the experiments of Dumas
and Boussingault prove that a tree which was cut off below the
branches expired a large quantity of carbonic acid. It may be
asked how I know this was not precipitated by the rain. I don't
know; but if the plant would assimilate this, why should it not
assimilate that which arises from the decomposition of the
carbonaceous