Conservation agriculture improves soil physical properties and crop productivity: a long-term study in middle Indo-Gangetic Plains of India

Abstract

Context Conservation agriculture (CA) can potentially arrest deteorating soil fertility and improve crop production in the middle Indo-Gangetic Plains of India. Methods A field experiment (ICAR RCER, Patna, India; 2009–2016) tested four common farming practices: S1, a wheat–rice fallow rotation with complete removal of crop residues; S2, best management practices (BMPs) with puddled transplanted rice, drill-seeded wheat in no-tillage (NT), and drill-seeded mungbean in conventional tillage (CT) in a wheat–mungbean–rice rotation where residues were retained on surface in rice and wheat, and residue incorporated in mungbean; S3, CA system in a wheat–cowpea–rice rotation; and S4, BMP intensified and diversified cropping system in a potato + maize–cowpea–rice rotation (unpuddled transplanted rice with dribbled maize + potato, intercropped) in CT and relayed dibbling of cowpea in NT. Full residues of potato and cowpea were incorporated and one-third portion of rice and maize residue were retained on soil. Key results After 7 years, S2, S3 and S4 systems lowered soil bulk density and penetration resistance compared to S1. S3 resulted in higher soil macro-aggregates (>0.125 mm) and lower soil micro-aggregates (<0.125 mm). Avoiding tillage in wheat and including a food legume in rotation in S2 increased annual rice equivalent yields by 30.5–34.4%. S4 had the highest water productivity (1.04 kg rice equivalent grain m−3) and S1 had the lowest (0.64 kg rice equivalent grain m−3). Conclusions and implications NT and retention of crop residues have potential to improve soil health and monetary gains.