CORN SOLD IS MANURE LOST. 179 



of the same quality, may yet have a very dissimilar 

 value for the cultivation of corn. If in one heap the 

 ash-constituents of corn are twice as many as in the 

 other, the former has double the value of the other. 

 By the removal of the mineral constituents of the corn, 

 which were derived from the manure, the efficacy of 

 the manure with regard to future corn crops is con- 

 stantly diminished. 



From whatever point of view, therefore, the aliena- 

 tion of corn or other field produce may be regarded, the 

 farmer who does not replace the mineral constituents 

 taken away in the crops, will find that the inevitable 

 result is exhaustion of the soil. Continued removal of 

 the corn crops makes the ground unproductive for clo- 

 ver, or deprives the manure of its efficacy. 



In our exhausted fields the roots of cereals no longer 

 find, in the upper layers of the soil, sufficient nutriment 

 for the production of a full crop : the farmer, therefore, 

 grows on these fields clover, turnips, and other plants 

 of the kind, which, with their wide-spreading and deep 

 roots, penetrate in all directions through the soil, open 

 up the ground by their large root-surface, and appro- 

 priate the constituents which are needed by cereals for 

 the formation of seed. In the residue of these plants, 

 in the constituents of the stalks, the roots and the 

 tubes, which the farmer puts upon the arable surface in 

 the form of manure, he restores to the land, in a con- 

 centrated form, the corn-constituents for one or several 

 full crops : what was below and scattered, is now above. 

 The clover and the fodder-plants did not engender the 

 conditions of richer corn-crops, any more than rag- 

 gatherers produce the conditions for paper-making : 

 they are mere collectors. 



From the foregoing remarks it is evident that the 

 cultivation of plants exhausts the fertile soil, and ren- 

 ders it unfruitful. In selling the produce of his fields, 

 which serves as food for man and beast, the farmer re- 

 moves a portion of his soil, and indeed the constituents 

 most efficient for the production of future crops. In 

 course of time, the fertility of his fields will decrease, 



