Future climate change impacts on grain yield and groundwater use under different cropping systems in the North China Plain

Crop production in the North China Plain (NCP) is heavily influenced by the unfolding climate change and water shortage. Groundwater overdraft for irrigation in this region has caused serious ecological and environmental problems. Cropping systems adjustment offers an effective approach for the sustainable use of groundwater. However, the assessment of the impacts of future climate change on crop production and water consumption under different cropping systems with/without straw mulching has not been reported in the NCP. In this study, we applied the well validated APSIM model to explore the implementation of five cropping systems (i.e., two maturities per year, 1Y2MS0; three maturities per two year without (with) straw mulching during the fallow period, 2Y3MS0 (2Y3MS1); and one maturity per year without (with) straw mulching during the fallow period, 1Y1MS0 (1Y1MS1)). Statistical downscaled daily climate data based on 33 global climate models (GCMs) were used to drive APSIM to simulate crop phenology, yield and water use under future climate change. We found that cropping system adjustment significantly reduced the amount of water required for irrigation, thereby decreasing groundwater overdraft to a certain extent. Straw mulching could have mitigating effect on groundwater overdraft. Multi-GCMs ensemble means show an increase in temperature, precipitation and solar radiation in the future. Under future climate change scenarios, the phenological date (e.g. flower and maturity dates) of maize and wheat were advanced due to climate warming. Our simulated results indicated that future climate change would have negative impact on maize yield across all cropping systems but have positive impact on wheat yield under most climate change scenarios. Both irrigation and groundwater overdraft reduced in the future due to decreased evapotranspiration and increased precipitation. We concluded that 2Y3MS1 would be the optimum cropping system to balance crop yield and groundwater overdraft. This knowledge can inform the development of improved regional impact assessments of the sustainability of multi-crop rotation systems.