AGEICULTUEE. 



147 



VI. 



The growth of crops on, and their removal from, the 

 land, and the pasturing of sheep, cattle, &c. and their 

 removal or slaughter, withdraws from the soil certain 

 proportions of its fertilising or mineral matters ; and each 

 succeeding crop grown and removed diminishes the power 

 of the soil for reproduction, in a definite proportion accord- 

 ing to the crop. The same result follows from the con- 

 tinuous rearing and removal of animals, as they carry away 

 with them in their flesh, blood, wool, hair, and bones, 

 mineral constituents derived from the herbage on which 

 they feed, which in its turn derived them from the soil. 



This is made perfectly manifest by a comparison of the 

 analyses of soils, vegetation, and animal matters. A single 

 series or table of these wiU suffice to make this clear. 



1,2 



