528 AGRICULTURE. 



origin ; in greater part, the result of the nitric ferment, acting 

 upon the organic matter of the soil. The action of the fallow 

 crop, therefore, results in the considerable increase in the soil of 

 combined nitrogen, available for the nutrition of future crops. 

 The carbon, hydrogen, and oxygen of plants, which in connection 

 with nitrogen constitute the organic parts of all plants, are, as 

 far as is at present known, of atmospheric origin. 



The fallow crop cannot, of course, produce ash minerals of 

 plants ; nevertheless, its effects upon the condition and position 

 of such minerals in the soil may be, and are, very important. In 

 the first place, the roots of the legumes, as a rule, penetrate the 

 subsoil, whence they draw their mineral food, from depths far 

 below the portion of the soil reached by the plow, or drawn upon 

 by the roots of cereal crops to any great extent. The effect of 

 this is that the fallow plant brings up from the subsoil, and de- 

 posits near the surface, within reach of succeeding cereal crops, 

 a large store of mineral food, in precisely that condition easiest 

 of assimilation by the cereals. Moreover, it appears that the 

 legumes possess a much greater power for the absorption and 

 assimilation of the crude and less soluble forms of minerals than 

 is possessed by cereals. The obvious importance of this fact 

 has, I think, been too much overlooked by writers on scientific 

 agriculture. Suppose, for example, we desire to manure a wheat 

 crop with insoluble and crude raw phosphate. Experience estab- 

 lishes the fact that phosphates of that sort are assimilated by 

 wheat with difficulty, and to a limited extent. Let us apply 

 such phosphates to clover, which assimilates them greedily, and 

 brings them into a condition, and into a position in the soil 

 where they are readily reached and assimilated by the wheat 

 which succeeds the clover in rotation. Such a treatment of 

 crude raw phosphate is, in my opinion, more scientific, more 

 economical, and more effectual than chemical treatment of it by 

 the ordinary manipulations with acid and drier, as practised in 

 the manufacture of so-called soluble, or dissolved, or super-phos- 

 phates of commerce. 



Attention is particularly invited to the point here made. It 

 is believed that herein is disclosed a function of the fallow crop, 

 by no means the least important. In British agriculture, phos- 

 phates are not applied to cereals in any form, but only .to crops 



