NATURE OF A RYE SOIL. 1-21 



that after a very few liarvests its fertility would vanisli 

 speedily and for ever. 



That oiir corn fields should contain nutritive substances 

 in very great abundance is the necessary condition for a 

 contmuance of good crops, but it is not indispensable for 

 one rich harvest. 



A good rye soil is one which produces an average rye 

 crop, but less than an average wheat crop. 



From what we have seen, the reason why a wheat 

 plant, which requires fi'om the soil the same elements as 

 the rye plant, will not thrive as well as the latter upon a 

 rye soil, is founded on this, that during the same period 

 of time the wheat needs more of these nutritive sub- 

 stances than the rye, but cannot obtain this additional 

 quantity. Hence, a good wheat soil which yields an 

 average wheat crop, differs from a good rye soil which 

 produces an average rye crop, inasmuch as the wheat soil 

 in all its parts contains more nutritive substances, just in 

 proportion as the wheat crop needs and carries away 

 more than the rye crop. 



A good rye soil, which is able to give and does give 

 1 per cent, of its nutritive substances to an average rye 

 crop, would necessarily yield an average wheat crop, if 

 the wheat plants growing upon it could extract 1^^ per 

 cent, of its nutriment. But, in fact, this does not 

 take place : whence it follows that the absorbent root- 

 surfaces of the wheat cannot be half as large again as 

 those of the rye ; for, were this the case, the roots of the 

 wheat would come into contact with half as many more 

 earthy particles yielding nutriment, i. e. the rye soil would 

 necessarily produce an average wheat crop, which however 

 is not the case. 



The comparative returns, in corn and straw, from a 

 rye soil, which has been sown simultaneously half wiLli 



