SOILS CLASSIFIED 75 



In the hilly sections farmers are compelled to face the problems 

 of soil erosion. The natural efforts of running water to carry 

 away the surface soils of fields should be prevented so far as pos- 

 sible (Figs. 61 and 62). This is done by the use of cover crops on 

 fields; by the use of the steep hillsides for wood lots; by terracing- 

 cultivated fields; by plowing and cultivating along level lines at 

 right angles to the slopes, instead of up and down the slopes. 



Wind is a mighty force in the movement of soils, particularly 

 in dry climates or during dry seasons in the humid climates. Crops 

 are sometimes blown out by the roots. Hills may be removed in a 

 single day and others as quickly constructed. The influence of 



r 



FIG. 61. Hillsides may often be prevented from erosion by throwing up furrow-slices 

 to form dams or "balks" along the meandering contour lines of the hill. Water follows these 

 so slowly that no erosion occurs. (Fights of the Farmer.) 



the wind is greatest upon such soils as do not retain moisture 

 readily and those which do not have much binding material. For 

 just these reasons sandy soils are more frequently blown by winds 

 than clayey soils. To prevent the blowing away of the surface 

 soil fields should be kept well covered with a growing crop, par- 

 ticularly in dry seasons when the danger is greatest. Sheltered 

 belts of growing timber will be helpful. Such are strongly recom- 

 mended for use in the prairie states. The addition of humus to 

 soils will cause them to hold moisture better and thus prevent 

 blowing. When fields are plowed late in the fall they may be left 

 rough and thus be less damaged by plowing than when harrowed. 

 Soils Classified. Many kinds of soil are in use by man in the 



