Incubation Studies on Nutrient Release Pattern of NPK and Enzymatic Activities in Inceptisol of Andhra Pradesh, India

Incubation experiment was conducted with the initial bulk surface soil sample from experimental field to study the nutrient release pattern of available N, P, K and activity of soil enzymes (urease, alkaline phosphatase and dehydrogenase activity) under NPK alone, IPNS (NPK+FYM), Farm Yard Manure (FYM) alone and absolute control. As compared to all other treatments, IPNS recorded relatively higher available N, P and K status. In case of NPK alone treatments, the available N content increased up to 90 days of incubation and decreased thereafter. In case of IPNS treatments, the status has shown an increase up to 120 DAI. Both under NPK alone and IPNS, the available P showed an increase up to 90 days after incubation and thereafter declined gradually up to 120 DAI while soil available K showed a gradual increase up to 120 DAI. Irrespective of different stages of incubation, STCR-IPNS treatments recorded comparatively higher enzymatic activity (urease, alkaline phosphatase and dehydrogenase) than STCR-NPK alone. These findings derived from the incubation experiment brought forth the fact that the release pattern of N, P and K and enzymatic activities under NPK alone, IPNS, FYM alone and absolute control paved way for understanding the beneficial effects of IPNS on crop productivity, efficiency and economy in fertiliser application and soil fertility sustenance throughout the period of crop growth.