234 SOILS AND FERTILIZERS 



action of the crop upon the mechanical condition of 

 the soil should be considered, otherwise the soil may 

 get into poor condition to retain water or become so 

 loose that heavy losses occur through wind storms. 

 Sandy soils are improved by those methods of cropping 

 which compact the soil, while heavy clays require the 

 opposite treatment. The rotation should be made to 

 conform to the requirements of the soil. 



320. Economic Use of Soil Water. The rotation 

 should not be of such a nature as to make excessive 

 demands upon the soil water. For example, after a 

 grain crop has been produced, it is best in regions of 

 scant rainfall to plow the land and get it into condi- 

 tion to conserve the water for the next year's crop, 

 rather than to attempt to raise a catch crop the same 

 year. During years of heavy rainfall catch crops can 

 be grown as green manure to increase the humus con- 

 tent of the soil. Crops removing excessive amounts 

 of water should not be grown too frequently. Sun- 

 flowers, for example, remove twenty times more water 

 than grain crops. Cabbage removes from the soil 

 more water than many other crops. With a good 

 rotation and systematic cultivation it is possible to 

 carry a water balance in the soil from one year to the 

 next, so that crops will be supplied in times of drought. 



321. Rotation and Farm Labor. The rotation of 

 crops should be planned so that an even distribution 

 of farm labor is secured. The importance of this 

 is so plain that its discussion is unnecessary. It is 

 one of the most important points to consider in 



