Conservation Agriculture for Enhancing Crop Productivity, Energy Use Efficiency, Carbon Stock, Soil Health and Reducing GHG Emissions

Conservation agriculture (CA) is believed to improve the soil properties. The question whether transplanted rice adapts to CA alike is not answered. Furthermore, the role of genotypes/varieties in CA is not clearly established. We compared two CA-based cropping systems i.e. ZT-direct seeded rice (DSR) followed by ZT-green gram (GG), (ZT-DSR-ZT-GG) and ZT-transplanted rice (TPR) followed by ZT-GG, (ZT-TPR-ZT-GG), vis-à-vis. conventional tillage (CT) system, (CT-DSR-CT-GG) with respect to soil structure, nutrient status, carbon sequestration potential, GHG emissions, energy saving and yield. Additionally, relative performance of green gram varieties under CA was evaluated. After five years, OC, N and P increased significantly in ZT-DSR-ZT-GG system. The increase in TOC was 16.90% and 11.86% in ZT-DSR-ZT-GG and ZT-TPR-ZT-GG, respectively, over CT-DSR-CT-GG. Similarly, in ZT-DSR-ZT-GG, the MBC, DHA, FDA, acid phosphatase and alkaline phosphatase were 2.7, 1.9, 1.4, 1.03 and 1.07 fold higher over CT-DSR-CT-GG. The cumulative seasonal emission of N2O was 73% and 35% higher in CT-DSR-CT-GG over ZT-DSR-ZT-GG and ZT-TPR-ZT-GG, respectively. Overall energy saving was 32% and 25% in ZT-TPR-ZT-GG and ZT-DSR-ZT-GG cropping systems, respectively, compared to CT-DSR-CT-GG. The system productivity was at par in CA (ZT-TPR-ZT-GG)- and CT-based cropping system. The interaction between the CA practices and the crop variety was non-significant for most of the tested parameters indicating flexibility in choosing a variety for crop cultivation under CA. It may be concluded that the associated benefits of CA without compromise in yield are highly recommended to sustain soil and environmental health in rice-pulse cropping system.