170 



THE GE1!?ESEE FARiflER. 



farmers sliould be the accumulation of nitrogen (or 

 ammouin) on the farm. 



Tlie practical bearing of the question is easilj^ 

 perceived. Some of our correspondents have pro- 

 posed to increase the fertility of the soil by grow- 

 ing crops of Indian corn, Chinese sugar cane, rye, 

 oats, etc., and plowing them in as manure. Now, 

 if these plants destroy nitrogen during their growth, 

 it is clear that such a practice Avould not accom- 

 plish the object. We must grow plants Avhich do 

 not destroy nitrogen, or, in other words, plants 

 which contain at least as much nitrogen as they 

 remove from the soil. The same remarks are 

 equally true, so far as increasing the fertility of the 

 soil is concerned, whether these crops are plowed 

 luider or consumed on tlie farm by stock, and the 

 manure returned to the soil. We can not pursue 

 this subject further at the present time. "We allude 

 to it for the purpose of showing that it is not 

 merely a scientific question, but one of great prac- 

 tical importance — one, in fact, that lies at the 

 foundation of all judicious systems of rotation and 

 manuring. 



Mr. Lawes' experiments on barley prove most 

 conclusively that, like wheat, it destroys nitrogen 

 during its growth. This most extensive series of 

 experiments show that, "within certain limits, 

 nitrate of soda, ammoniacal salts, and rape cake, 

 a U increase the producs of iarley^ approximately in 

 proportion to the amounts of nitrogen they rcspect- 

 i'jely sxqyplied.'''' But while this is the case, in no 

 one instance has the increase contained anything 

 like as much nitrogen as was supplied in the manure. 

 There was a loss of at least one half the nitrogen. 

 How this loss takes place we know not at present; 

 science will doubtless discover the cause ere long. 

 The fact of such a loss can not be doubted, and it 

 is one of the most important facts which the appli- 

 cation of science to agriculture has yet discovered. 



SPECIAL MAFUHES. 



"When chemical analysis first demonstrated that 

 dlfterent classes of plants yield an asli of different 

 composition, the idea of special manure had its 

 origin. By special manures, were meant mixtures 

 containing just the quantity of each ash ingredient 

 removed from the soil by an average yield of each 

 crop. But investigation has demonstrated that 

 there are in general no practical advantages in 

 these attempts to feed the plant by ration. Lat- 

 terly, Lawes & Gilbeiit, of Rothainsted, England, 

 believed to have established, by a multitude of field 

 experiments, that ammonia is specially suited to the 

 production of wheat, and phosphoric acid to the 

 growth of turnips ; but there are other equally au- 

 thentic trials which as fully prove just the reverse." 



The above is an extract from the article on Agri- 

 cultural Chemistry in. the New American Gyclopce- 

 dia^ written by Prof. S. W. Johnson}— au article 



which,, as a whole, though somewhat hastily writ- 

 ten, we can not too highly commend. We are 

 glad to see a writer of such great ability and of 

 such eminent scientific attainments, speak out sc 

 distinctly against the utih'ty of ordinary soil- 

 analyses, and against the doctrine of special ma- 

 nured ; for these two ideas have done much to 

 retard agricultural improvement, and are now, 

 wherever entertained, diverting the attention of 

 scientific men from a line of inductive investiga- 

 tion which would in all probability lead to the 

 discovery of many of the hidden laws of vegetable 

 growth. 



We fear, however, that the paragraph above 

 quoted is likely to convey a wrong impression. 

 We can not think that Prof. Joknson intended to 

 class Messrs. Lawes & Gilbert among the advo- 

 cates of special manures^ for he well knows tliat it 

 was precisely the " invastigations " that have been 

 instituted by these gentlemen that have "demon- 

 strated" the unsoundness of the special manure 

 theory. We accept Prof. Johnson's definition of 

 the meaning of special manures — "mixtures con- 

 taining just the quantity of each ash ingredient 

 removed from the soil, by an average yield of each 

 ci'op." In other words, the ash of wheat contains 

 five times as mnch phosphoric acid as the ash of 

 turnips, and, therefore, tbe soiL or manure, best 

 adapted for the growth of wheat must contain 

 four times as much phosphoric acid as a soil or 

 manure suited to the growth of turnips. This 

 was the fundamental idea of the doctrine of spe- 

 cial manures. We are pleased to hear the Trans- 

 lator of Leibig's- criticism on Lawes & Gilbert's- 

 experiments assert that these very experiments 

 have ^'•demonstrated " the fallacy of the pet theory 

 of the great German chemist, for assuredly he must- 

 have had these investigations in view when he 

 penned this sentence. 



If the experiments of Lawes & Gilbert prove 

 anything, — if they have " demonstrated " that the 

 special manure theory is unsound — that wheat 

 does not require more phosphoric acid in the soil 

 than turnips, — they certainly indicate that "ammo- 

 nia is specially suited to the production of wheat, 

 and phosphoric acid to tlic growtli of turnips." 

 If these experiments are to be held of no more 

 authority than others Hohich prove just the reverse^''' 

 then they are incapable of demonstrating the un- 

 soundness of the special' manure theory. If they 

 have been made with sufficient accuracy to " dem- 

 onstrate " that there is no advantage in attempting 

 to feed plants with, manures compoxmded according 

 to the composition of their ashes, then they are 

 equally good authority for showing that "ammonia 

 is specially suited to the production of wheat, and 

 phosphoric acid to the growth of turnips." 



