156 CORN CROPS 



(c) Land in cultivated crops erodes more than (6). 



(d) Cultivated land not in crops erodes most. 



110. Preventing erosion. — Since the character of the 

 crop and the grade of the land both have a marked effect 

 on the degree of erosion, they are the two principal means 

 of preventing the same. 



Land subject to severe erosion should be kept principally 

 in grass crops and small grain, and never left longer than 

 necessary without a growing crop. If a good supply of 

 vegetable matter is maintained and deep plowing practiced, 

 cultivated crops can often be grown on rolling land with 

 little loss by erosion where otherwise the loss would be 

 severe. It is often noted that new land just brought under 

 cultivation does not erode, but as the humus supply 

 decreases, erosion increases. Also, the plowing undsr of a 

 heavy coat of barnyard manure or a green manure crop 

 will often stop erosion where it is otherwise serious. Deep 

 plowing enables the soil to take up water readily and give 

 it up slowly, and in many cases deep plowing alons has 

 been found to entirely prevent erosion. 



The second method of preventing erosion is by decreas- 

 ing the grade. This is usually done by terracing, causing 

 the water to follow the contour of the hills at a low grade. 

 The same effect is secured in some degree by plowing and 

 planting with the contour of the hills. 



To summarize : Erosion is better controlled when the 

 land is in grass or small grain than when in a hoed crop. 

 Sufficient organic matter and deep plowing decrease erosion. 

 The land should not be left bare. The grade can often be 

 decreased by terracing. 



The most serious loss due to erosion is the constant re- 

 moval of the accumulated organic matter of the surface 

 soil. 



