Influence of Slow Release Nitrogenous Fertilizers on Soil Enzyme Activity and Microbial Population under Laboratory Condition

An Incubation study under laboratory condition were conducted during 2015-16 with a view to study "Influence of slow release nitrogenous fertilizers on soil enzyme activity and microbial population under laboratory condition" The laboratory incubation experiment was conducted in completely randomized design.In incubation study, the urease enzyme activity was increased with an increased period of incubation in all the treatments.Dehydrogenase enzyme activity was significantly higher in treatment GRDF at 7, 21, 45 and 90 DAA (1.41, 1.55, 1.69 and 1.56 µg TPF g -1 soil hr -1 respectively).It was increased upto 45 DAA and decreased at 90 DAA.The treatment GRDF significantly recorded the higher population of Nitrosomonas at all the period of incubation and on par with treatment RDN-SCU, NCU and CDU at 7 and 14 DAA.The use of NCU and SCU recorded less Nitrobacter population in early period of incubation.The application of nitrogen through slow release fertilizers as CDU, NCU and SCU and their combination with urea and among the organic sources release the soil available nitrogen with advanced incubation period.It was decreased in treatment GRDF and RDN-CDU at 90 DAA.The release of ammonical nitrogen in all the treatments showed the similar trend to that of soil available nitrogen at all the period of incubation.The slow release nitrogen fertilizer treatment @ 50 % RDN-urea + 50 % RDN either through CDU, NCU or SCU were beneficial for release of nitrate nitrogen in soil.