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LOW MOOR, 31st December, 1844.
HENRY BRIGGS, ESQ.
I duly received your obliging letter in reply to my pamphlet on the growth of wheat year after year on the same land, and now offer my rejoinder to your remarks. You seem to consider the expense is too great under the system pursued by me; and that it was more than was required by the crop, is proved in my opinion by the fact that the fertility of the land is very much augmented since the commencement of the experiment in 1841: as my first crop with 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


