Work

Long-term yield dynamics of rice-rice and rice-wheat systems in South Asia: Evidence from 39 experiments

Year: 2026

Type: article

Abstract: We assessed long-term yield trajectories in rice-rice (RR) and rice-wheat (RW) in South Asia, using multi-decadal records from 11 RR and 28 RW experiments under Control, NPK, and NPK+farmyard manure (FYM). Trends were classified as positive or declining using site-level regressions (slope ≠ 0, P ≤ 0.05). In RR, positive system productivity trends occurred at 10% (Control) vs. 46% (NPK) and 60% (NPK+FYM), while declines fell from 40% to 9-10%. In RW, corresponding shares of positive trends were 10%, 18%, and 44% for Control, NPK, and NPK+FYM, respectively, with declines dropping from 30% to 11% and 9%. Meta-analysis of crop yields showed consistent patterns: under NPK+FYM, pooled correlations were positive for RR (kharif rice: r = 0.41, P = 0.001; rabi rice= 0.28, P = 0.004), and RW (rice: 0.27, P = 0.011; wheat r = 0.18; P = 0.002), whereas NPK effects were weaker – positive for RW-wheat (0.15, p = 0.048) and RR-rice (rabi; r = 0.29, P = 0.007) but near zero for RR-rice (kharif) and RW-rice. Residual coefficient of variation (residual CV) fell from about 20-30% (Control) to 15-18% (fertilized). Agronomic efficiency of fertilizer-N (AEN) and the sustainability yield index (SYI) were higher under NPK and NPK+FYM than under control, and NPK+FYM kept AEN similar to NPK while reducing the number of sites with low AEN and low SYI. Practical priorities include combining organic resources with balanced NPK; retaining crop residues where possible, reducing puddling where it harms wheat, and routinely tracking AEN, SYI, and trend/stability indicators alongside mean yield.

Source: Crop and Environment

DOI: 10.1016/j.crope.2026.100132