Mineralization and Nitrification in Soil Amended with Urea and Enriched Greenmanures in Submerged Soil System

Mineralization pattern of three greenmanures, viz. dhaincha, cowpea and guar were evaluated along with the effect of their enrichment and compared with that of urea in a submerged soil system. Inorganic N in soil was found to decrease after 42 days after transplanting (OAT) rice. Mineralization of urea amended soil was on par with enriched guar. Cumulative mineralization from greenmanures followed the order: guar > dhaincha > cowpea. Rate of mineralization attained peak after 35 DAT. Relationship between net ammonification and mineralization was found to be significant. Cumulative mineralization from greenmanures was positively correlated with total N, whereas negative correlation existed with lignin content and CIN ratio. Lignin was found to be the best predictor of mineralization which can explain 80 per cent of total variations.