Optimizing fertilization strategies for a climate-resilient rice – wheat double cropping system

Properly managing nitrogen (N) in different climate scenarios is crucial for enhancing plant growth while minimizing N losses to the environment. This study used a modelling approach to elucidate the effects of climate change and N management practices on grain yields and N losses in the winter (Triticum aestivum L.) – rice (Oryza sativa L.) cropping system in China. The aim of the study was to optimize fertilizer management practices through diverse manure types, N application rates and timings and to increase the resilience of the system to climate change. The SPACSYS (v6.0) model was used, calibrated and validated based on a ten–year field experiment, to simulate crop grain yields and soil N balances under three Shared Socioeconomic Pathways (SSP) scenarios for the period 2020 to 2100, so as to identify the optimal basal and topdressing fertilization regimes and timings for both winter wheat and rice. Our results revealed that the practice of splitting N fertilizer applications, as opposed to applying N fertilizers all at once, mitigated yield losses in wheat and rice under climate projections. Moreover, a higher proportion of topdressing, specifically 60% of the total N application amount for wheat and 50% for rice, showed potential in minimizing N loads to the environment. However, compared with local fertilization practices, additional N through manure under future climate scenarios (2061–2100) significantly increased N losses to water by 0.1–1.2 kg N ha−1 and 1.0–1.8 kg N ha−1 during the wheat and rice growing periods, respectively. Thus, the judicious adoption of various manure types alongside sound N management practices holds promise for increasing the resilience of agricultural systems to climate change.