160 HARNESSING THE EARTHWORM 



TABLE 1 



Properties of earthworm casts and of soil from cultivated field 

 Values given are means of six samples* with standard deviations 



* Each sample was a composite of individual samples collected at 5-pace intervals 

 on a line across the field. There were six lines, hence six samples. 

 t Composite samples from whole field. 



be significant. The total magnesium contents of casts and of 

 soil were virtually identical. 



In the forest soils (table 2) agreement among the four pro- 

 files was remarkably close, and differences between horizons are 

 obviously highly significant. The higher contents of nitrogen, 



