Nitrogen Mineralization from Urea Enriched Greenmanures as Influenced by Water Management Practices

Nitrogen mineralization of enriched greenmanures in relation to soil water contents was investigated in an incubation experiment. Cumulative mineralization and rate of mineralization of nitrogen was significantly higher at soil water content at field capacity than that under submerged condition. Mineralization rate was highest after incubation of 35 days. Net ammonification under submerged condition and net nitrification at field capacity soil water regime can be taken as an index of net mineralization. N release from greenmanures increased by enrichment with urea and individual contribution followed the order: Guar > Dhaincha > Cowpea. Cumulative mineralization was positively correlated with total N and negatively with lignin content and C/N ratio of greenmanures. Lignin was better index to predict cumulative mineralization than C/N ratio or N content of greenmanures.