ABSTRACT
In laboratory experiments under three moisture levels [50, 200 and 400% whc] with sandy, sandy loam and clay loam soils, the ammonification and subsequent nitrification of 200 ppm biuret-N was studied. Ammonification was more rapid in heavy than in light textured soils. Mineralization percentages of biuret-N were 25, 27 and 30.2 at 400% whc, in sandy, sandy loam and clay loam soil, respectively, and most mineralized-N was in the form of NH4 +. The corresponding figures at 50% whc were 15, 16 and 21% and most nitrogen was in the NO3 form. NO-2-N accumulated in considerable amount only at 200% whc, and persisted longer in soils which reflect the relative sensitivity of Nitrobacter to anaerobic conditions. Whc, of 400%, inhibited both Nitrosomonas and Nitrobacter and no NO-2 or NO-3 was detected in the soils. Biuret, by itself, at 200 ppm-N had no effect on nitrifying bacteria