Changes in Total and Available Soil Nitrogen Status under Integrated Nutrient Management of Rice

A pot experiment with an Udic Ustochrept was conducted to test the changes in soil nitrogen forms, uptake and grain yield due to integrated nutrient management of rice through conjunctive use of fertilizer urea with FYM, biogas slurry, poultry manure and greenmanures viz. glyricidia and azolla. Growth of rice and N uptake was slow in vegetative phase but rapid during reproductive phase. Azolla application significantly enhanced grain yield followed by glyricidia over 100 per cent N as urea. Nitrogen uptake by rice was in the order of azolla > glyricidia > poultry manure > biogas slurry. None of the organic sources had any specific positive influence on total or available N contents of soil at any stage. The contents had increased at 45 and 60 DAT due to soil nitrogen transformations and later decreased at harvest due to plant utilization.