Tillage and residue management strategies enhance crop yields, soil health, and profitability in the rice-wheat system of Nepal’s Western Terai

Inappropriate agronomic management practices and poor soil health contribute to low yields in the rice-wheat (R-W) systems of Nepal. Findings from other South Asian countries reveal that appropriate management practices have the potential to improve soil health, increase soil sequestration, and enhance rice and wheat yields in the R-W systems. Hence, a field experiment was conducted at the National Wheat Research Program (NWRP) in Western Terai, Nepal, from 2018 to 2020 to assess the effects of various tillage methods (conventional, reduced, and zero) and residue management levels (removal and retention) on crop growth and yields, soil health, and soil carbon sequestration. A strip-split plot design with three replications was employed. Three seed rates in wheat (80, 120, and 160 kg ha⁻¹) were evaluated to identify the optimal seed rates under different tillage and residue management practices. Data on growth, yield, and yield attributes, and soil properties and soil carbon sequestration were collected and analyzed using R statistical Software. Zero tillage (ZT) and residue retention (RR) significantly reduced bulk density and increased soil carbon levels. Tillage didn’t affect the number of days to flowering and maturity, but they were delayed with lower seed rates. Wheat root mass decreased with depth, with ZT enhancing root development in the upper soil layers. Seed rate influenced root distribution, with lower rates promoting shallow roots and higher rates favoring deeper roots. RR under conventional tillage did not significantly affect growth, yield, phenology, and root distribution in either crop. ZT improved wheat growth, reduced sterility, and increased yield and yield components. In rice, however, tillage or residue management didn’t significantly influence yield and yield components. The sustainable yield index for wheat was significantly higher under ZT and with a higher seed rate. ZT wheat, followed by ZT direct-seeded rice, significantly enhanced profitability, while residue management practices had no notable effect. Results suggest the potential advantage of ZT combined with RR in terms of crop and system yields, soil carbon sequestration, and soil health. Implementing ZT, retaining residues, and using a seed rate of 120-160 kg ha⁻¹ in wheat can improve the yields of individual crops in the R-W systems while maintaining soil health and carbon sequestration in Nepal’s Western Terai, with such potentials in other parts of Nepal and other South Asian countries where these systems are practiced on a wide scale.