4 BULLETIN 512, U. S. DEPAETMENT OF AGRICULTURE. 



soil will absorb 2 inches of rainfall. The incorporation of organic 

 matter or humus in a soil adds materially to its moisture-holding 

 capacity. This is best accomplished by plowing under deeply, ma- 

 nure, stubble, stalks, and various cover crops. This organic matter, 

 in a decomposed state, is capable of absorbing considerable water and 

 forms a richer and deeper top soil. 



USE OF COVER CROPS. 



Vegetation or cover crops will protect the soil in four ways: (1) 

 by holding rain Avater on the surface for a time, thus giving the 

 soil a better opportunity to absorb the water; (2) by keeping the soil 

 open through the growth of the roots, which form passages for the 

 water to reach the subsoil; (3) by holding the soil particles together 

 through the binding power of the roots; and (4) by reducing the 

 movement of soil particles through diminishing the velocity of sur- 

 fajce water. Cover crops usually are grown during the winter or 

 when the land is not being used for other crops. Their importance 

 as a means of protecting land from erosion at such times can not be 

 emphasized too strongly. Vetch, clover, cowpeas, wheat, and rye are 

 used commonly for this purpose. It can be said generally that good 

 farming and the use of cover crops go hand in hand. 



PRACTICE OF LEVEL CULTURE. 



Contour plowing and the following in general of practically level 

 lines in farm operations tend to check the surface flow down a slope 

 and to retain the water where it falls. In cultivating crops each 

 row is banked up and a shallow depression which holds the surface 

 water is left between the rows. Thus the absorption by the soil of 

 this impounded water is facilitated and the rapid run-oif down the 

 slope, with its destructive eroding power, often is entirely eliminated 

 in case of ordinary rains. Contouring contributes also in a consider- 

 able degree to the conservation of moisture on hill lands. The very 

 apparent benefits of this practice merit its universal use on lands sub- 

 ject to erosion. 



PASTURING AND FORESTING. 



Often it seems impossible to prevent erosion on lands with exces- 

 sive slopes. No attempt should be made to cultivate such areas but 

 they should be seeded to meadow or pasture and usually retained as 

 such. In well-sodded land the soil is not exposed directly to the 

 erosive action of the water, so that erosion is much less destructive 

 than in cultivated fields. 



In many sections of the country timberland on excessively steep 

 slopes has been cleared for cultivation, and in many instances after 



