Climate change and environmental impacts on and adaptation strategies for production in wheat-rice rotations in southern China

Process-based agricultural simulation models are effective tools which can be applied to assess the potential impact of climate change and agronomic practices on yield and nutrient cycling. This study investigates the effects of climate change and fertilization on yield, nitrogen (N) contribution efficiency (the percentage of remobilized N from the vegetative material in grains out of total N content in grains at harvest, (ANCE)), N loss to water and nitrous oxide (N2O) emissions in the wheat (Triticum aestivum L.) - rice (Oryza sativa L.) cropping system in southern China, using the SPACSYS (v6.0) model. The model was first evaluated using crop production and N accumulation data from three-year field experiments, and then applied to simulate production and N processes under three representative concentration pathway (RCP) scenarios for the wheat-rice cropping region, with projections for the years 2020 to 2100. Results indicated that N management as well as shifting sowing or transplantation dates could greatly mitigate the yield losses and N contribution efficiency (ANCE) reduction in the winter wheat-rice rotation system. Delaying sowing dates of wheat and transplanting rice earlier could reduce N leaching losses. Unexpectedly, climate change indirectly increased N2O emissions, showing significant variation depending on the interaction with high N fertilization for rice pre-anthesis, indicating that emissions can be limited by restricting fertilizer application. Changing growing season start dates, along with implementing appropriate N management practice is a potential way to increase resilience to climate change in the wheat-rice cropping system of China