Influence of organic residue addition on CO2 evolution and N mineralization in soil

A combination of pot culture experiment and incubation study was conducted at the soil science and agricultural chemistry section, college of agriculture, nagpur to assess the decomposition potential and rate of mineralization of nitrogen of different organic residues. Initially, the rate of CO2 evolution was near constant during 10 days of incubation peaking on 3rd day after incubation. There was a steep increase in CO2 evolution in all the treatments after 10 days, attaining its peak at 70 days after incubation thereafter it began to decrease in a non-uniform pattern upto 120 days. Cummulatively, maximum CO2 evolution was recorded in green gram stalks followed by sugarcane trash and lowest was found in control pot. Nitrogen mineralization in pot culture experiment was analysed at 4 monthly intervals viz. 30, 60, 90 and 120 days. There was a sharp increase in the rate of N mineralization at 60 days interval and altogether, there was a decreasing trend of nitrogen mineralization after 60 days of experimentation. The peak amount of mineralization was observed at 90 days in near about all the treatments. Subabul leaves mixture (T7) recorded maximum ammoniacal nitrogen (48.98 mg kg-1, 52.66 mg kg-1, 56.99 mg kg-1 and 44.99 mg kg-1) and nitrate nitrogen (26.25 mg kg-1, 38.02 mg kg-1, 30.01 mg kg-1 and 20.83 mg kg-1) throughout the experimentation. The results highly indicated that addition of all residues produced a significant increase in soil organic carbon and nitrogen but, leguminous residues showed a higher response.