Modelling the impact of climate change and tillage practices on soil CO2 emissions from dry farmland in the Loess Plateau of China

Abstract

Conservation tillage to agricultural fields has been widely used in the Loess Plateau of China. However, uncertainties remain regarding the long-term effects of this approach on soil carbon dioxide (CO2) emissions under future climate scenarios. We used the pre-validated DeNitrification DeComposition (DNDC) model to investigate the effects of no-tillage and straw mulch implementation on soil CO2 emissions from dry farmland in the Loess Plateau of China under different future climate scenarios and their dynamic changes. Based on the baseline period (1971–2019) and climate data (2022–2070) under RCP4.5 and RCP8.5 scenarios for two climate models, soil CO2 emissions from dry farmland were simulated under four tillage practices (CT: conventional tillage, CTS: conventional tillage with straw mulch, NT: no-tillage, NTS: no-tillage with straw mulch). The results showed that future climate change would affect soil CO2 emissions of each treatment. Compared with the baseline period, the annual mean CO2 emissions of four treatments increased under the RCP4.5 and RCP8.4 scenarios for the two climate models, with increases ranging from 5.81% to 56.73% under the RCP4.5 scenario and 24.48% to 68.75% under the RCP8.5 scenario. In addition, compared with CT and NT treatments, the CTS and NTS treatments with straw mulch had higher annual mean CO2 emissions under both climate scenarios, while the NT treatment had the lowest. Further analysis showed that the changes in soil CO2 emissions of each treatment under different future climate scenarios were related to the constant changes in annual mean temperature, annual precipitation, and atmospheric CO2 concentration. Simulation of the long-term effects on soil CO2 emissions under different tillage practices based on future climate scenarios led to the conclusion that conservation tillage practices, together with future changes in temperature, precipitation, and atmospheric CO2 concentrations, affect soil CO2 emissions, while no-tillage has potential to mitigate soil CO2 emissions from dry farmland in the Loess Plateau of China under future climate change.