A decade of conservation agriculture in intensive cereal systems: Transitioning to soil resilience and stable yield trends in a climate crisis

Climate change jeopardizes the food security gains achieved in India since the Green Revolution, especially by impacting the productivity of the rice-wheat system in the Indo-Gangetic Plain, a region that serves as the 'breadbasket' of South Asia. In this study, we characterized the potential of long-term conservation agriculture (CA) based management practices (i.e., no-tillage, residue retention, and diversified rotations) to stabilize and enhance crop yields in Northwest India. The study consisted of six different production scenarios (Sc) namely Sc I: conventional rice-wheat system; Sc II: partial CA-puddled transplanted rice-zero till wheat-zero till mung bean (TPR-ZTWMb); Sc III: CA-based zero-till direct seeded rice-zero till wheat-zero till mung bean (ZTDSR-ZTWMb); Sc IV: CA-based zero till maize-zero till wheat-zero till mung bean (ZTM-ZTWMb); Sc V: Sc III + subsurface drip irrigation (SSDI); and Sc VI: Sc IV + SSDI. Long-term yield analysis indicated that the CA-based maize-wheat-mung bean system with SSDI (Sc VI) produced approximately 12%, 27% and 35% higher rice equivalent yield (REY), wheat yield and overall system yield, respectively, over to Sc I. Our study examines Wricke's ecovalence index (Wi²) and the sustainability yield index (SYI) to gauge long-term yield stability and sustainability. Consistently higher wheat yields with lower Wi² and higher SYI were recorded in CA-based scenarios (Sc V: Wi² = 0.82, SYI = 0.81; Sc VI: Wi² = 0.85 and SYI = 0.82). CA-based scenarios also demonstrated stable REY over time. The soil physical properties were influenced by CA systems and compared to Sc I, bulk density was -5.89% in Sc V, followed by -3.62% in Sc III and -1.73% in Sc VI. Moreover, CA systems, Sc IV, Sc VI, and Sc V exhibited positive responses by +106%, +99 % and +72%, respectively for water infiltration rates. Overall, soil organic carbon was +83% and +69% with Sc VI and Sc V, respectively than in Sc I. By substantially enhancing soil health and crop productivity, as well as boosting resilience, CA emerges as a promising solution for meeting the increasing food demand in Northwest India and beyond.