38 
TABLE V.—Denitrification by Soil and Manure Bacteria 
Source of 
bacteria 
Medium 
Gas 
Formation 
Nitrites 
Nitrates 
Soil A 
Soil B 
Horse 
manure 
Denitrifying 
organism 
Sterile 
control 
(i) How do conditions for denitrification come about in agricul¬ 
tural practice? 
