322 MAN'S USE AND CONSERVATION OF SOILS 



rainfall is insufficient 

 or so unevenly dis- 

 tributed that these 

 plants are unable to 

 grow. This is true 

 over a large area of 

 the United States, 

 and the same condi- 

 tions often prevail 

 over the usually well- 

 watered part of the 

 country in times of 

 drought. The ques- 

 tion of increasing 

 MUD CRACKS the water-holding 



Showing the way clay cracks when it dries. Capacity and of pre- 

 venting the loss of 

 water by evaporation or in other ways is a very important one. 



PRAIRIE SCENE 

 Showing modern methods of harvesting the crop from fertile silt soil. 



