liquid annulled, they could be nitrified more easily. Ex- 

 cessive alkalinity is inimical to the process of nitrification. 



830. The practical lessons to be deduced from these 

 principles are : (i) Cattle should be fed in stalls where the 

 manure should rot and be trodden upon. (2) The urine should 

 be removed fresh and used separately as manure mixed with 

 ashes and water. (3) If no provision is made for removing the 

 urine, gypsum should be freely used in the stall. (4) Lime 

 (slaked) should be occasionally spread in the stall. (5) The floor 

 of the stall should be about 18 inches deeper than the surround- 

 ing level of the land. (6) Straw should be freely used for litter as 



^ it leaves openings for air to act on the manure. In other words, 

 cowdung and litter may be utilized the basis for nitre-beds. 



831. Nitrates are partially de-oxidized in swampy rice 

 fields where the process of reduction occurs resulting in the 

 formation of marsh gas. Even in soils rich in humus, nitrates 

 are easily destroyed in the absence of O, quickly in high 

 temperature and slowly in low temperatures. The nitrates 

 are reduced and free N. gas escapes. 



832. Nitrates in soils are probably chiefly derived from 

 oxidation of ammonium compounds, resulting from organic 

 matter coming in contact with lime ; also from various orga- 

 nic nitrogen compounds. It is not a purely chemical process 

 which can be represented by chemical formulae. In the labora- 

 tory, of course, nitrates could be evolved by treating nitrogen 

 compounds with strong oxidizing agent e. g., when caustic 

 ammonia is boiled with potassium permanganate, or subjected 

 to the action of peroxide of hydrogen. But in the soil the 

 intervention of bacteria is the determining agent in the for- 

 mation of nitrates ; but how these bacteria work is not yet 

 known. That they live on nitrogenized organic matters and 

 on ammonia compounds is known, and also that they give 

 rise to nitrates. 



833. Urine does not nitrify unless it has been diluted 

 with water and mixed up with a great deal of earth. Very 



NNN 



