162 



HARNESSING THE EARTHWORM 

 TABLE 2 Continued 



*WF valves are on a water-free basis. 



organic carbon, and exchangeable calcium in the casts were even 

 more pronounced here than they were in the field soil, particu- 

 larly when the A^ horizon is considered. The AI and A3 together 

 correspond roughly to the 0-6-inch layer of the cultivated soil. 

 On the other hand differences in available phosphorus and ex- 

 changeable potassium and magnesium were distinctly smaller than 

 in the field soil. Total magnesium content was actually lower in 

 the casts than in Ax. There was no essential difference in 

 either the total colloids or the clay content of the casts as com- 

 pared with the AI horizon, but both were considerably lower in 

 the A 3 . 



In comparison with the cultivated soil, the forest soil casts 

 were much higher in nitrogen, carbon, exchangeable calcium, and 

 moisture-equivalent values. The higher proportion of exchange- 

 able calcium to exchangeable magnesium in the upper horizon of 

 the field soil was not observed in the forest soil, nor was there 

 any such relation between total calcium and total magnesium in 



