Intensification of Rice-Fallow Agroecosystem of South Asia with Oilseeds and Pulses: Impacts on System Productivity, Soil Carbon Dynamics and Energetics

Rice-fallow systems in South Asian countries play a pivotal role in increasing agricultural production. However, the productivity of these system is largely challenged by deteriorating soil health and limited residual soil moistures in dry-periods, precluding the possibility of winter and/or spring season crops after rice harvest. This investigation explores the possibilities of including winter and/or spring crops through conservation agriculture (CA)-based management practices and evaluates its effect on soil carbon dynamic, system productivity, energy and carbon budgeting. Field experiments were conducted at a farmer's field in participatory modes at Chene Village, Jharkhand, India, and had five treatments comprising (1) fallow-land [FL]; (2) transplanted puddle rice (TPR)-fallow (winter)-fallow (summer), a typical cultivation practice of this region [RF]; (3) TPR-conventional-till mustard-conventional-till blackgram [CP]; (4) CA with zero-till transplanted rice (ZTTR)-ZT mustard-ZT blackgram [CA1]; (5) CA with zero-till direct seeded rice (ZTDSR)-ZT mustard-ZT blackgram [CA2]. Results revealed that CA2 comprising full CA practice of growing direct seeded rice, mustard and blackgram under ZT increased total soil organic carbon (TSOC) of 0-0.6 m soil layer by 14.3% and 10.3% over RF and CP, respectively. The C-sequestration rate was higher in CA treatments and varied from 0.55 to 0.64 Mg C ha(-1) year(-1). The system rice equivalent yield in CA2 during the initial four years was lower than CP but it was 23.7% higher over CP in fifth year. The CA-based system (CA2) enhanced the water productivity of rice, mustard and blackgram by 7.0%, 23.6% and 14.1% over CP, respectively. The CA2 treatment, having higher system productivity, better C-sequestration potential, lower C-footprint, higher energy and water productivity has very good potential for sustaining soil health and crop yield of rice-fallow systems.