20 



SOILS AND FERTILIZERS 



Table 3. — Percentage Composition op Typical Residual 

 Soils from Virginia 



A striking feature is their low lime content, which is 

 characteristic of soils that have been long subjected to 

 leaching. Such soils would require applications of lime for 

 the profitable production of most crops. The low content 

 of lime in the soil derived from limestone illustrates the 

 fact that such an origin does not insure a satisfactory supply 

 of lime. 



19. Distribution of residual soils. — These soils are 

 widely distributed in the United States, being found in four 

 great provinces — the Piedmont plateau along the eastern 

 slope of the Appalachian mountains, the Appalachian moun- 

 tains and plateaus, the limestone valleys and uplands be- 

 tween and west of these mountains, and the Great Plains 

 west of the Mississippi and Missouri rivers. 



20. Cumulose soils. — Unlike residual soils, cumulose 

 soils are of very recent origin. They have been formed by 

 the growth of vegetation in and around lakes, ponds and 

 marshes, many of which were left by the retreating glaciers. 

 As the plants die they become immersed in water, which 

 shuts off the supply of air, and thereby arrests decomposi- 

 tion. The partly decomposed plant remains accumulate 



