On continuing my attempts to grow wheat on the same land year after year, I observed that the crop of 1845 was very seriously injured by the deficient drainage--the old drains having been destroyed by the subsoil plough. It was therefore necessary to replace them: they were accordingly put in four feet deep. This occupied so much time that the season for sowing wheat had gone by, and the ground was cropped with potatoes, which were got up in September, and the wheat might have been got in early in October. But seeing in your paper that sowing too early was not advisable, and also being carried away by the arguments of the thin-seeders, I deferred sowing until the middle of November, and then put in little seed; and the winter proving very unfavourable, when the wheat was coming up, there was not half plant enough in the spring, and I hesitated whether to plough up the ground or drill in barley. I determined to do the latter, which was done on the 18th April, and wheat and barley grew up together, and when cut and threshed, proved to be equal to 48 bushels to the acre. * * * * * 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