May as» 1914 
Transformations of Soil Nitrogen 
113 
opinion, however, this appears to be without significance, as both good 
and poor soils usually contain rather large quantities of insoluble nitro¬ 
gen. The control of the rate of nitrification is, on the other hand, of 
fundamental importance. In pot experiments a normal rate of nitrifi¬ 
cation is shown to be possible with a green crop turned under, and it 
seems reasonable to recommend this practice in the field for maintaining 
the humus supply of the soil. The evidence of the above experiments 
suggests that the extensive use of mature straw is to be avoided, though 
light applications of straw to fields too high in nitrate, probably also 
with the liberal use of ground limestone, might be advantageous. 
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