Integrated water and nitrogen management sustains rice yield and efficiency under changing climate scenarios

Abstract

CONTEXT

Evidence on how alternate wetting and drying (AWD) irrigation and nitrogen management together influence rice yield and resource efficiency under climate variability is still limited, yet such knowledge is critical for climate-smart agricultural planning. Climate change and inefficient agronomic practices increasingly threaten the sustainability of rice production systems by intensifying water scarcity and lowering nitrogen use efficiency (NUE).

OBJECTIVE

The objective of this study was to assess the combined effects of irrigation regimes, continuous flooding (CF) and AWD, and nitrogen application strategies on rice yield, nitrogen uptake, and resource use efficiency under projected climate change scenarios using the ORYZA (v3) model.

METHODS

The ORYZA (v₃) crop growth model was used to simulate rice growth, water consumption (ET), irrigation water requirements (IR), water use efficiency (WUE) and nitrogen use efficiencies (NUE) under historical and future climate scenarios (RCP2.6 to RCP8.5). Two irrigation strategies: CF and AWD, and multiple nitrogen application schedules were tested.

RESULTS AND CONCLUSIONS

Future climate scenarios projected substantial yield reductions, reaching up to 36 % under CF and 43 % under AWD in the 2080s under RCP 8.5. The difference between regimes was small under moderate scenarios but became more pronounced with extreme heat and water stress. Water productivity also declined sharply, with WUE dropping by up to 58 % and irrigation water use efficiency (IWUE) by 72 %. Nitrogen use efficiencies consistently decreased at higher application rates, though moderate N input (150–190 kg ha⁻¹) with split applications sustained relatively better performance. AWD reduced irrigation water demand by 7–70 % compared with CF, but its yield advantage diminished under severe climate stress. Elevated CO₂ modestly improved efficiencies but could not counteract overall declines. Overall, these findings highlight that combining AWD with moderate nitrogen rates offers a practical pathway for sustaining rice production while conserving resources under changing climate conditions.

SIGNIFICANCE

These findings provide evidence that combining AWD with moderate nitrogen inputs can guide policies and farm practices aimed at sustaining rice yields, conserving water, and improving input efficiency under a changing climate.