Modeling the impacts of groundwater depth and biochar addition on tomato production under climate change using RZWQM2

Abstract

The south of China is prone to waterlogging and non-point source pollution due to its heavy rainfall. Draining excess water to lower the groundwater level and application of biochar to improve soil properties can mitigate the waterlogging to some extent. Hence, the RZWQM2 model calibrated and validated using measured data was used to identify suitable field management scenarios (defined as a combination of different groundwater depths and biochar additions) under different future climate conditions (RCP 4.5 and RCP 8.5 under the BCC–CSM1–1 regional climate model). Dry yield and water use efficiency (WUE) simulations showed that compared to no biochar addition, dry yield increased by 0.17 – 2.94% and -0.3 – 2.77% under RCP 4.5 and RCP 8.5, respectively, and WUE increased by -0.72 – 2.91% and -1.59 – 2.79% under RCP 4.5 and RCP 8.5, respectively, for biochar additions of 1 – 2%. The simulation results of the N loss showed that compared to the groundwater depth of 60 cm, the N loss from surface drainage and subsurface drainage was reduced by 36.68 – 81.79% and 30.53 – 80.67% under RCP 4.5 and RCP 8.5, respectively, when the groundwater depth was 80 – 100 cm. It is appropriate to control the groundwater depth in the range of 80 – 100 cm and biochar addition ratio around 2% under RCP 4.5, and under RCP 8.5, the groundwater depth in the range of 80 – 100 cm and biochar addition ratio around 1%. The results of the study suggest that it is necessary to adopt reasonable strategies to cope with future climate change in order to ensure the safety of agricultural production. The RZWQM2 model may be a reliable approach to optimize field management strategies.