Modeling impacts of mulching and climate change on crop production and N2O emission in the Loess Plateau of China

Abstract

Covering soils using mulch can increase crop productivity in dryland agriculture. However, there remains large uncertainty regarding impacts of mulching on nitrous oxide (N2O) emissions, especially under climate change (increases in air temperature and atmospheric CO2 concentration and changes in precipitation). In this study, we applied a biogeochemical model, DeNitrification-DeComposition (DNDC), to predict impacts of different mulching practices on wheat (Triticum aestivum L.) and maize (Zea mays L.) yields and N2O emissions under future climate scenarios in the South Loess Plateau of China. When tested against the observed crop yields and N2O emissions under no-mulching (NM), straw mulching (SM), and plastic film mulching (PM), DNDC successfully simulated crop yields and annual N2O emissions under all treatments. Simulations and observations both suggested that applying SM or PM increased crop yields and N2O emissions in comparison with NM. Sensitivity analyses of crop yields and N2O emissions indicated that the crop yields were primarily influenced by precipitation and N2O emissions were sensitive to changes in air temperature, precipitation, soil organic carbon, and nitrogen application rate. Application of SM or PM reduced the sensitivity of the crop yield and N2O emissions to precipitation change. Compared with historical climate conditions, future climate from 2017 to 2100 significantly increased crop yields except during the 2090s for NM or SM and during the 2070s to 2090s for PM under the high emission scenario (RCP8.5), while N2O emissions were increased under all treatments. The positive impacts of PM on crop yields could be reduced under the RCP8.5 scenario. The DNDC predictions suggest that straw mulching might be an optimum mulching method to improve crop productivity and mitigate increasing N2O under future climate conditions in semi-arid to sub-humid areas such as the South Loess Plateau of China.