DENITRIFICATION IN SUNUGHT AND ITS RETARDATION PART IV.

Experiments show that when ammonium sulphate in solution is mixed with substances like titanium oxide, zinc oxide, silica, sterile or unsterile soil, there is appre­ciable nitrification and loss of nitrogen even in the dark, under completely sterile conditions: The nitrification and nitrogen lost increase in light. Before the formation of nitrate there is always the production and decomposition of ammonium nitrite in the process of nitrification. In all cases the actual amount of nitrate present is small in comparison with the loss of nitrogen. Hence, the amount of nitrate actually present in a soil after the addition of nitrogenous manure is not a true measure of nitrification which has to be determined by the difference in the total nitrogen before and after the process rather than on the actual amount of nitrate present.

Very little ammonia is lost from the soil as free ammonia although considerable amount of nitrogen loss takes place from soils.

Very little loss of nitrogen is observed when a nitrate is mixed with glucose and exposed to sun light.

Under field conditions on the addition of blood, urea and gelatin there is more lass in light than in dark. Molasses readily conserve the total nitrogen in the soil, and that is why organic substances are useful in preserving and increasing the soil nitrogen.