280 THE CULTURE OF FARM CROPS. 



tion for wheat. The same facts apply to peas and beans, 

 and explain the advantages which follow the growth of 

 wheat after these crops. 



But another point is to be considered. We have dwelt 

 often and particularly upon the necessity for thorough cul- 

 ture of the soil; the effect of the atmosphere; of moisture; 

 and of heat; and the oxidizing and nitrifying effects of por- 

 ous soils upon organic substances contained in them. Hence 

 it is a great advantage for the farmer to grow crops which 

 require cultivation in alternation with other crops; both for 

 the purpose of destroying the weeds and cleaning the land; 

 and of gaining all the benefits from the repeated stirring of 

 the soil during the summer. Hence it is that the practice 

 of a rotation of crops became customary in the infancy of 

 agriculture, and has always prevailed, although the farmers 

 who followed it could not explain the reason for it, but 

 simply followed it because experience had taught them its 

 value. ("Sic quoque arva requiescent, fetibus mutatis." 

 "Thus also the fields rest, the produce being changed." 

 Virgil). 



But if a rotation of crops is advantageous and profitable, 

 it follows that the best rotation; that which will confer the 

 most of these beneficial results upon the land; will be the 

 best for the farmer to follow. And we would suggest the 

 consideration, whether or not, the present rotation common- 

 ly followed, of four crops or ''four courses," viz : wheat, 

 grass, corn, and oats; might not be very much improved, 

 and a corresponding advantage be secured by the farmer. 



The present ordinary rotation is based upon one green 

 crop a grass and clover sod plowed under; one cultivated 

 crop corn; and one manured crop wheat. But three 

 exceedingly exhaustive crops are grown, one after the other, 

 viz: corn, oats and wheat; and it is questionable if the gen- 

 eral low average yield of wheat is not due in a great meas- 

 ure to the exhaustion of the soil by the two previous exact- 

 ing crops. Corn is a gross feeder, and oats pick up very 

 eagerly what the corn leaves behind it. Thus the wheat 

 meets with decidedly unfavorable circumstances, when from 



