Yield comparison of tillage and irrigation regimes in a rice–wheat production system in the Indian mid-Himalaya

Background Meeting the increasing food demand under changing land use, constrained water resources, and rising climatic variability requires resource-conserving management of the rice–wheat (R-W) system in the Indian mid-Himalayas. Zero tillage (ZT) and improved irrigation scheduling may maintain crop productivity, while reduce cultivation cost and improve water-use efficiency. Objectives This study evaluated the long-term response crop and system productivity, water-use indices, economic performances, and yield sustainability to contrasting tillage practices and irrigation regimes. Methods A 19-year field experiment (2001–02–2019–20) to compared zero tillage (ZT) and conventional tillage (CT) under four irrigation regimes: These comprised pre-sowing irrigation only (IR1); pre-sowing plus active tillering in rice/crown-root initiation in wheat (IR2); IR2 plus panicle initiation in rice/flowering in wheat (IR3); and IR3 plus irrigation at grain filling (IR4). Results Rice yield declined significantly over time across tillage practices and irrigation regimes, indicating that long-term reduction in system productivity was largely associated with declining rice yield. Mean wheat yield under ZT showed a modest upward trend (+18.7 kg ha −1 year −1 ), whereas the corresponding trend under CT was negative. Irrigation significantly influenced the mean yields of both crops and overall system, with IR4 producing the highest productivity. However, increasing irrigation frequency reduced wheat and system water-use efficiency (WUE), demonstrating a trade-off between yield maximization and efficient use of irrigation water. ZT wheat WUE from 10.2 to 10.6 kg ha −1 mm −1 and increased system net returns by 68.8% while reducing cultivation cost by 14.9% relative to CT. Conclusion and Implications Irrigation regime exerted a stronger influence on long-term R-W system productivity than tillage. IR4 was most suitable for maximum productivity, profitability, and yield sustainability where irrigation water was adequate. Under limited water availability, IR3 offered a more balanced option because it maintained relatively high productivity and water-use performance with a stable sustainability trend. Although ZT did not significantly increase mean system yield, it maintained productivity comparable to CT while lowering cultivation costs and improving economic and water-use performance. These findings support the selection of tillage and irrigation practices according to water availability and production objectives in the Indian mid-Himalaya.