SOIL COMPOSITION 89 



ports data showing 31,000 pounds of total potassium in the same 

 stratum. The average of 161 soils from various parts of Ohio 

 shows 960 pounds of acid-soluble phosphorus in 2 million of soil. 

 As a general average about 85 per cent of the phosphorus in such 

 soils is soluble in the acid used, so that the total phosphorus 

 probably amounts to about noo pounds. 



The average composition of three samples of surface soil from 

 the loess-covered uplands at the Missouri Experiment Station at 

 Columbia, in central Missouri, shows 2710 pounds of total nitro- 

 gen, 690 pounds of total phosphorus, and 28,500 pounds of total 

 potassium, in 2 million pounds of soil (Schweitzer, Missouri Bul- 

 letin No. 5). These amounts correspond closely with the average 

 composition of the most common upland soils of southern Illinois; 

 and the more highly productive corn belt soils of north central and 

 northwest Missouri are more nearly comparable with the brown 

 silt loams and black clay loams of the middle Illinoisan glaciation. 



An analysis * of the worn upland soil near St. Louis, Missouri, 

 shows 1160 pounds of nitrogen, 700 pounds of total phosphorus, 

 and 35,200 pounds of potassium in 2 million of soil. This is about 

 the average composition of the subsurface soil of the deep loess area 

 in Illinois, and indicates previous loss of surface soil by washing. 



Professor Keyser has kindly furnished the author with some 

 unpublished data concerning the soils of Nebraska, showing that 

 the glacial silt loam of eastern Nebraska, which has been formed 

 evidently from the weathering of the till of the Kansan glaciation, 

 contains, in 2 million pounds of the surface, 3940 pounds of nitro- 

 gen, 660 pounds of total phosphorus, and 23,000 pounds of potas- 

 sium; while the ordinary loessial soil representing the most common 

 corn belt type in the southeast part of the state (and probably of 

 northeast Kansas as well) contains 5160 pounds of nitrogen, 1060 

 of total phosphorus, and 29,000 pounds of potassium, correspond- 

 ing very closely to the brown silt loams in the loess-covered middle 

 and upper Illinoisan glaciation. The common silt loam of the less 

 humid region of central Nebraska contains 3680 pounds of nitrogen, 

 1520 of phosphorus, and 48,000 of potassium. 



A preliminary general soil survey of Iowa (Stevenson, Iowa 



1 Reported by Doctor R. O. Graham, Bloomington, Illinois, as a commercial 

 analysis. 



