KINETICS OF CARBON MINERALIZATION IN MOLLISOLS UNDER BENTONITE AND NON BENTONITE SYSTEMS UNDER VARYING MOISTURE REGIMES

An incubation study was conducted to evaluate kinetics of carbon mineralization in bentonite and non bentonite systems under varying moisture regimes in Mollisols of Tarai region of Uttarakhand with eight treatments viz. control (soil), nitrogen , wheat straw, FYM , wheat straw + nitrogen , FYM + nitrogen, rice straw and rice straw + nitrogen. Rice and wheat straw were applied @ 6 t ha -1 , while FYM was applied @ 10 t ha -1 . Nitrogen @120 kg ha -1 was used as starter dose. All these treatments were incubated at 30 0 centigrade in BOD incubator for 90 days in triplicate using two bentonite (0% and 10%) levels and two moisture (field capacity and saturation) regimes. Decomposition rates of rice straw, wheat straw and FYM under varying moisture regimes in bentonite and non bentonite systems have been monitored periodically for 90 days on the basis of carbon dioxide evolution .The first order kinetics models gave good fit over the zero order models in describing organic matter decomposition. Both half-lives (18.38%) and turnover times (22.28%) were increased in 10% bentonite compared to 0% bentonite concentration. Similarly, longer half-lives (143.06%) and turnover times (139.14%) were recorded at saturation compared to field capacity. To, get immediate effect of added bentonite ,(within 90 days of incubation) a higher amount of clay (10%) was used in this study. Though application of 10% clay under field conditions (224000 kg/ha ) seems to be impractical, data generated from this lab incubation study gives a scope for further field research using different possible lower concentrations of bentonite in eroded soils alone or with other potential amendments like biochar which may give a better result for carbon sequestration.