288 



SOIL EROSION 



cultivation can be done around or across the slope rather than with 

 the slope. When furrows run up and down the hill washing is 

 greatly increased. This precaution may well be observed in sowing 

 grains as well. 



Crops May be Alternated on Hillsides. — On long slopes it is 

 good practice to lay out the field into comparatively long and 

 narrow strips, and crop them alternately with corn, grain and 

 grass. In this manner the distance down hill through which the 

 accumulation of water may occur is shortened, thus greatly pre- 

 venting the formation of tiny streams. ^ > < 



Fia. 189. — Depressions through fields which serve as surface runs should be kept sodded. 



(Iowa Station.) 



Grassing and Cover Crops. — On many steep slopes it is well 

 to keep the ground well protected by a good grass cover. Depres- 

 sions which serve as surface-runs should be kept sodded. The 

 growing of winter cover crops like rye and clover should be encour- 

 aged. The roots of such crops help to bind the soil and the vegeta- 

 tive growth protects it (Fig. 189). 



Terracing. — Terracing is the most effective method of prevent- 

 ing soil washing, and it is doubly effective when other methods 

 of controlling erosion are practiced in connection with it. Terrac- 

 ing consists primarily in reducing the slope over which the water 

 moves, or in stopping the flow of water down the slope by forming 

 balks or breaks which gradually rise into banks separated by 

 belts of plowland. 



