560 



INTERRELATIONSHIPS OF ORGANISMS 



patches and streaks of soils that have not yet reached the typical end 

 condition for that climate. 



In general the soils east of the Mississippi River have a low content 

 of soluble salts, because precipitation is greater than evaporation. West 

 of the Mississippi evaporation becomes greater than rainfall (except for 

 restricted areas in the mountains and along the Pacific Coast). In the 

 humid regions east of the Mississippi the soils generally contain less of 



PRAIRIE 

 SOILS. DE- 

 GRADED 

 CHER- 

 NOZEM 



CHER- 

 NOZEMS 

 AND 

 REDDISH 

 CHESTNUT 

 SOILS 



DARK GRAY CHESTNUT. 



ANO BLACK BROWN 



SOILS OF AND 



TROPICAL REDDISH. 



SAVANNAS BROWN 



SOILS 



SIEROZEMS. PODZOLS. GRAY- 



DESERT AND WITH MUCH BROWN 



RED DESERT BOG PODZOLS. 



SOILS BROWN 



FOREST 

 SOILS 



LATOSOLS. 

 RED-YELLOW 

 PODZOLS. 

 ETC 



SOILS OF 



MOUN- 

 TAINS ANO 

 MOUNTAIN 

 VALLEYS 



ALLUVIAL 

 SOILS 



Fig. 32.11. The great soil groups of the world. {From Charles E. Kellogg, courtesy Scientific 

 American.) 



the soluble calcium and magnesium salts than did the parent materials, 

 and since iron and aluminum compounds are less soluble than the calcium 

 salts, the soil is chiefly composed of aluminum and iron compounds. In 

 the less humid areas west of the Mississippi, on the other hand, the soluble 

 calcium and magnesium tend to accumulate near the surface, and the 

 soils contain a higher concentration of calcium and magnesium salts and 

 a somewhat lower proportion of aluminum and iron compounds than the 

 parent material. 



The Chernozem, Chestnut, Brown, and Sierozem soils are all examples 

 of the calcium-rich groups (pedocals); the Podsol, Gray-brown Forest, 

 Prairie, and Red and Yellow soils are examples of the calcium-poor group 





