LOSS OF NITRATES 



155 



as 100 per cent, and that of the imirrigated as 100 per cent., the 

 manured and irrigated soils then become with 5 tons of manure, 147 

 per cent.; with 15 tons of manure, 188 per cent.; 5 inches of water, 

 106 per cent.; 10 inches of water, 117 per cent.; 20 inches of water, 



2060 



500 



480 



200 



180 



160 



no 



120 



100 



80 



60 



40 



20 



D 



EXPLANATION \ 



PER CENT OF GRAIN 



PER CENT OF STOVER 



PER CENT OF BACTERIA 



PER CENT OF BACTERIA (FALLOW) 



PER CENT OF AMMONIA 



PER CENT OF AMMONIA (FALLOW) 



PER CENT OF NITRIC NITROGEN 



PER CENT OF NITRIC NITROGEN (FALLOW) 



NO MANURE 



5 TONS 

 OF MANURE 



FIG. 23. Diagram showing the influence of manure on the yield and bacterial activi- 

 ties of a soil. The unmanured soil is expressed as 100 per cent. 



108 per cent. Large quantities of irrigation water produced the 

 greatest depressing effect in the presence of 15 tons of manure to the 

 acre. 



Fewer organisms develop on synthetic agar from a cropped than 

 from a fallow soil. The application of manure to a cropped soil 



