I duly received your pamphlet on the use of lime, for which I am
much obliged, and am delighted to perceive that you confirm the
idea (expressed in my pamphlet on the growth of wheat every year
on the same land) that the excessive use of lime is ultimately
injurious to the fertility of the soil to which it is applied.
This, coming from a gentleman of your reputation and experience,
will, I hope, induce someone capable of performing the experiment
to endeavour to ascertain with precision how much lime it is
desirable to apply to an acre to give the best results, and with
the least waste, assuming that the land contained little or none
previous to the experiment; and it would also be desirable to
ascertain whether it is better, in an economical point of view, to
apply a small quantity every year, or a larger quantity every
third or fourth. My own opinion is in favour of the former method,
except that it is difficult to get it ploughed in, particularly in
wet weather, immediately after spreading (which is essential where
you grow wheat on the same land every year) without injuring the
feet of the horses. You speak of ten days or a fortnight being
necessary to neutralize caustic lime, but our horses had their
feet injured by it six weeks after it had been spread on the land,
last year, although the weather had been wet almost the whole of
the time, say from the beginning of February to the middle of
March. You appear to think that lime will replace silica in the
wheat plant. Whose authority have you for this? It will be very
important to establish this supposition, but I fear it is too good
news to be true. On referring to your letter, I find you don't say
what I supposed you did, but that the lime liberates the soluble
silicates, potash, &c. This may be, and certainly the beneficial
effects of lime in growing wheat are not to be explained by any
other hypothesis with which I am acquainted. I am this year trying
some experiments to ascertain (if I can) the cause of clover-
sickness, and I hope to be in a position to say whether your
supposition that lime, gypsum, &c. will prevent it, is correct. My
experiments so far are opposed to this theory, but it is not very
safe or philosophical to draw conclusions from one or two
experiments only. I doubt the possibility of making silicate of
soda by merely mixing lime, sand, and salt together, as my
chemical friends tell me this cannot be accomplished unless the
silex and the alkali are fused together. If a soluble silicate of
soda can be made in the way you mention, it will be a great saving
of expense. Has it been tried? You have no doubt seen a report of
the enormous crop of wheat grown in a field in Norfolk last year
(90 bushels to the acre), and that the Royal Agricultural Society
have determined to have the soil analyzed by Dr. Playfair. This is
very desirable, but as Dr. Playfair is more of a lecturing than an
analyzing chemist, I think it is very necessary that his analysis
should be checked by another, made by the most eminent chemist
that Europe can produce, for 90 bushels is so unheard-of a crop,
that no expense should be spared which would enable us to
ascertain what the soil contained to enable it to produce such a
crop, which is the more remarkable as the field seems to have been
a good many years under the plough. As your Wakefield Farmers'
Club has many wealthy members in it, allow me to hint the
desirableness of your undertaking this analysis, which, if
properly performed, will be worth a thousand times more than its
cost. When you are aware that even Davy missed 16 per cent. of
alumina in one of his analyses and that the chemists of the
present day don't seem to have detected the potash which exists so
abundantly in potato-tops, you will, I think, agree how
exceedingly important it is that such analysis should be checked
by others, made without any communication between the parties. You
speak of an original letter of Liebig's appearing in the "Farmer's
Journal." On what subject is it? as I have no means of referring
to the periodical in question. Does it throw any light upon the
new manure for which he is said to be taking out a patent? You
speak of humus and humic acid. What do you understand by humus?
as, according to Liebig, humus sometimes means one thing and
sometimes another, and he appears to treat it very much as modern
chemists treat phlogiston, as something which they don't
comprehend, but which they need to explain the phenomena of
vegetation. If you are a believer in humus, what is it composed
of, and how does it act in forwarding vegetation? I suppose you
will reply, By combining with oxygen and forming humic acid. But
would not the theory of the decomposition of carbon do quite as
well? I don't perceive the injurious effects of quicklime upon
grass land which you anticipate in your paper, but the contrary,
and the more caustic it is the more beneficial is its action, so
far as I can judge from my own experiments; and it is my practice
in liming grass land to spread it as soon as I can get it into the
state of flour. I shall be glad to hear the result of your
electrical experiment--at present I am rather sceptical on the
subject.
P.S.--Am I to suppose that you have abandoned the idea of manuring
an acre of wheat for thirteen shillings?
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