SOIL COMPOSITION 



TABLE 16. FERTILITY IN ILLINOIS SOILS Continued 



TIMBER UPLANDS, FLAT 



SAND, SWAMP, AND BOTTOM LANDS 



subsoils are also well supplied with potassium, or may be by deep 

 plowing; whereas broad_ areas of deep peat or of shallow or medium 

 peat on sand are as a rule deficient in potassium. 



Most of the older soils (chiefly in southern and western Illinois) 

 are markedly acid in the surface and subsurface, and exceedingly 

 acid in the subsoil. The rolling or hilly timber uplands and the 

 sand soil are very deficient in nitrogen, while the undulating prairie 

 lands (except in the late Wisconsin glaciation), the undulating 

 timber lands, and even the flat prairie lands in the oldest forma- 

 tion, are only moderately well supplied with nitrogen. The black 

 clay loams (especially in the more recent formations) are rich, and 

 the peaty soils exceedingly rich, in humus and nitrogen. 



In the main the soils of central and northern Illinois are com- 

 parable with similar soil types in Indiana and Ohio on the east, 

 and with Iowa and eastern Nebraska soils on the west; and the 

 soils of southern Illinois are comparable with similar types in 

 Missouri and eastern Kansas on the west, and also with the loess- 

 covered areas in southern Indiana, Kentucky, Tennessee, and 

 northwest Mississippi; while some of the same soil types that are 



