Integrated Nitrogen Management With Vermicompost on Soil Nitrogen Fractions in Onion-Radish Cropping System

A field experiment was conducted on a sandy loam soil during Kharif (onion) and Rabi (radish) seasons of 2007-08 with a view to study the effect of integrated use of nitrogen (0, 60, 90 and 120 kg N ha^-1) and vermicompost (0, 5 and 10 t ha^-1) on soil nitrogen fractions in onion-radish cropping system. Among the treatments tried, higher buildup of all the N fractions could be observed in integrated application of vermicompost @ 10 t ha^-1 along with 120 kg N ha^-1 (V₃N₃) in soil after harvest of onion over their initial status. At the end of onion-radish cropping system, residual effect of vermicompost and nitrogen applied to preceeding onion crop and cumulative application of 75 per cent recommended dose of fertilizers to succeeding radish showed significant effect on all the inorganic and organic N fractions in soil. Among the cumulative treatments, all the inorganic and organic forms of N showed build up of soil status over their initial status. In case of residual treatments, exchangeable NH₄⁺, fixed NH₄⁺, total hydrolysable N, acid insoluble N showed depletion of soil status while build up of NO₃-N, hydrolysable NH₄⁺, hexosamine N and amino acid N over their initial soil status.