422 THE PRINCIPLES OF SOIL MANAGEMENT 



Under ordinary farm conditions, denitrification is 

 of no significance in the soil where proper drainage 

 and good tillage are practiced. Warington showed that, 

 if an arable soil be kept saturated with water to the 

 exclusion of air, nitrates added to the soil are decom- 

 posed, with the evolution of nitrogen gas. As lack of 

 drainage is usually most pronounced in the early 

 spring, when the soil is likely to be depleted of nitrates, 

 it is not likely that much loss arises in this way unless 

 a nitrate fertilizer has been added. Of the many diffi- 

 culties arising from poor drainage, denitrification of 

 an expensive fertilizer may be very considerable item. 



The addition of a nitrate fertilizer to a soil receiving 

 stable manure is not likely to result in a loss of ni- 

 trates unless the dressings of manure have been ex- 

 tremely heavy. Hall states that at Rothamsted, where 

 large quantities of nitrate of soda are used every 

 year in connection with annual dressings of farm 

 manure, the nitrate produces nearly as large an in- 

 crease when added to the manured as when added 

 to the unmanured plat. There appears, in other words, 

 to be no loss of nitrate by denitrification. 



It is possible to reach a point in manuring where 

 denitrification may take place. Market gardeners 

 sometimes reach this point where fifty tons or more 

 of farm manure, in addition to a nitrate fertilizer, 

 are added to the soil. Plowing under heavy crops 

 of green manure may produce the same result. In 

 either case, the best way to overcome the difficulty is 

 to allow the organic matter to partly decompose 

 before adding the fertilizer. The removal of the easily 



