404 FARM MANAGEMENT 



rapid destruction of humus. The clovers and grass crops 

 usually increase the humus. The control of weeds, in- 

 sects, and fungi, and the maintenance of the humus 

 supply are the chief reasons for rotating crops. 



(3) If crops are rotated, the other benefits that come 

 from growing legumes and grass may be secured for each 

 field. 



(4) Labor is often saved by crop rotation. Grasses 

 are sown in small grain, so that one fitting of the land 

 does for two crops. In some parts of the country winter 

 wheat is sown after potatoes or beans, so that one plowing 

 of the soil does for three crops the tilled crop, the wheat 

 crop, and the grass crop seeded in the wheat. In most 

 of the Middle West, oats are disked or cultivated in on 

 corn ground without plowing. In some parts of this region, 

 the yields are better on disked than on plowed land. In 

 other parts, plowing is better. Cowpeas may be grown 

 between the rows of corn without additional fitting of 

 the soil. 



(5) By crop rotation, the land may be occupied more of 

 the time. Wheat may follow oats and grass follow wheat, 

 so as to keep the soil in use. If the season is long enough, 

 it is possible to grow more than one crop a year. 



(6) Deep and shallow rooted crops may be alternated, 

 thus making use of the deeper soil. 



(7) Formerly it was thought that the chief reason for 

 rotating crops was because plants use the plant foods in 

 different proportions, so that when the soil became ex- 

 hausted for one crop, it might contain the kind of food 

 that the other crop required. As a matter of fact, the 

 increased yields resulting from rotation cause the removal 

 of more of each kind of food than is removed by the 

 smaller yields that are secured if one crop is grown con- 



