34 FERTII.ITY AND FERTIUZER HINTS 



cay of roots leaves passages in the soil which aid in draining and 

 aerating it. Grass crops tend to make a soil compact, while al- 

 falfa, roots, grains and other cultivated crops tend to open up 

 the soil. 



A rotation should be selected to keep the soil in good physi- 

 cal condition. Sandy soils are improved by crops that compact 

 them while clay soils should be made more porous. 



ID. Rotation Saves Fertilizer Expenditure. — On some farms that 

 formerlv used 150 to 300 pounds of commercial fertilizer per 

 acre, as high as 1,500 to 2,000 pounds must be used now to give 

 the same yields. A proper rotation of crops will save the em- 

 ployment of such large quantities of commercial fertilizers. Farm 

 manure may be used and commercial fertilizer only applied to 

 those crops that are most in need of nourishment. 



11. Rotation of Crops Regulates the Humus Supply. — Some 

 crops furnish humus while others tend to deplete the soil of this 

 material. Single crop farming is very exhaustive on the humus 

 supply of the soil while a rotation of crops should be selected 

 to conserve the humus content of a soil. Grass crops tend to 

 increase the humus supply, while grain, cotton, tobacco, etc., have 

 the opposite efifect of consuming humus. The addition of farm 

 manure is helpful in supplying humus.* 



12. A Rotation of Crops Conserves Moisture. — In the arid 

 regions the conservation of moisture is an important considera- 

 tion in planning a rotation. Heavy moisture consuming crops 

 should not be planted in succession in sections of small rainfall, 

 but heavy consuming and light consuming moisture crops should 

 be so grown as to conserve the moisture supply.* 



System of Farming. — The loss of fertility sold from the farm 

 depends upon the kinds of crops produced and sold. When 

 live-stock, butter and milk are sold there is less fertility lost than 

 from common farm crops.* 



