The effect of certain inorganic salts on the nitrification rate of two South Australian soils.

Abstract

The nitrifying capacities of two virgin soils, Urrbrae clay loam (Adelaide) and Seddon sandy gravelly loam (Kangaroo I.), were determined by the soil perfusion technique. Nitrification was low in both soils and a lag of 10-15 days was recorded before nitrate nitrogen accumulated in the Seddon soil perfusate. The addition of calcium carbonate, either alone or with phosphate and trace elements, increased the nitrifying capacity of both soils but phosphate or trace elements alone had little effect on the soil nitrification rate. Calcium carbonate, with or without phosphate and trace elements, reduced the lag in nitrification of the Seddon soil by up to 50 per cent. The addition of carbonate, phosphate, and trace elements was followed by maximum nitrification in both soils. A transient increase in nitrite nitrogen was recorded with soils enriched with calcium carbonate, and ammonia nitrogen was removed from the perfusate in a number of "stages".