280 now CROPS feed. 



ily decomjiose, and cannot therefore themselves be consid< 

 ered as ingredients of the soil. 



Among- the proximate products of their decomposition 

 are organic acids (butyric, valeric, propionic) destitute of 

 nitrogen, and the amides leucin (C^ n,^ N0„) and tyrosin 

 (Cg H,, NO.,). These latter bodies, by further decompo- 

 sition, yield ammonia. As has been remarked, it is proba- 

 ble that the albuminoids, when associated as they are in 

 decay with cellulose and other carbohydrates, may at 

 once give rise to insoluble amide-like bodies, such as those 

 whose existence in humus is evident from the consider- 

 ations already advanced. 



Can these Organic Bodies Yield Nitrogen Directly to 

 Plants ? — Tliose nitrogenous organic compounds that exist 

 in the soil associated with humus, which possess something 

 of the nature of amides, though unknown to us in a pure 

 state, appear to be nearly or entirely incapable of feeding 

 vegetation directly. Our information on this point is de- 

 rived from the researches of Boussingault, whose papers 

 on this subject {De la Terre vegetale consideree dans ses 

 effets sur la Vegetation) are to be found in his Agronomie, 

 etc., Vols. I and II. 



Boussingault experimented with the extremely fertile 

 soil of his garden, which was rich in all the elements 

 needful to support vegetation, as was demonstrated by the 

 results of actual garden culture. This soil was especially 

 rich in nitrogen, containing of this element 0.26° |^, which, 

 were it in the form of ammonia, wonld be equivalent to 

 more than 7 tons per acre taken to the depth of 13 inches ; 

 or, if existing as nitric acid, would correspond to more* 

 than 43 tons of saltpeter to the acre taken to the depth 

 just mentioned. 



This soil, however, when employed in quantities of 40 

 to 130 grams (1^ to 4^ oz. av.) and shielded from rain 

 and dew, was scarcely more capable of carrying lupins, 

 beans, maize, or hemp, to any considerable development, 



