International Journal of Plant & Soil Science

Management of soil organic matter (SOM) in arable lands has become increasingly important in many areas of the world to combat land degradation, increase food security, reduce carbon emissions and/or mitigate climate change. Soil carbon cycling and composition are essential components of comprehensive agricultural and ecological impacts and forecasting. Soil Organic Matter (SOM) plays keys to developing drought-resistant soils (i.e., water conservation, evaporation and erosion control and soil water infiltration ease) and ensuring sustainable food production. This study was conducted during 2018 (March) after harvesting of mustard at Instructional-cum-Research Farm, Assam Agricultural University, Jorhat-13, to determine the temporal effect of different tillage practices on soil carbon stock in Rice (Oryza sativa)-Mustard (Brassica juncea)-Sesbania (Sesbania rostrata) cropping system under conservation agriculture system. The soil was acidic (pH- 5.4), sandy loam in texture with CEC-6.28 cmol(p⁺)/100 g, organic carbon-0.92%, available  N-260 kg ha^-1, available P-19 kg ha^-1, available K-86 kg ha^-1. Tillage practices can potentially affect soil organic carbon (SOC) accumulation in agricultural soils. SOC stocks of the 0-15 cm, 15-30 cm and 30-45 cm soil layers for each treatment were calculated by multiplying bulk density (g/cc), organic carbon (%) and depth of the soil (cm). Significantly lower bulk density was observed in CT and the control over the MT. While soil organic carbon was recorded significantly higher in MT over the CT and the control. The SOC stocks in MT were also higher than those under CT and Control (P < 0.05). The order of SOC stocks in the 0-45 cm soil layer was MT >CT.