Reducing greenhouse gas emissions and improving net ecosystem economic benefit through long-term conservation tillage in a wheat-maize multiple cropping system in the Loess Plateau, China

Abstract

Reducing greenhouse gas emissions and loss of soil fertility, while ensuring stable yield, is crucial to achieving “Carbon Peak” and “Carbon Neutrality” in grain production but is different to achieve. In this study, we aimed to understand the effects of conservation tillage on the yield, GHG emissions, soil carbon and nitrogen sequestration, and net ecosystem economic benefit (NEEB) to promote the transformation of tillage methods in the Loess Plateau, China, based the continuous application (>11 yr) of conservation tillage. Four-year observations showed that zero tillage and chisel plough tillage obviously reduced N2O and CO2 emissions but greatly increased CH4 uptake relative to plow tillage. Furthermore, the coupling relationship between CO2 and N2O fluxes was weakly antagonistic during the winter wheat growing season, whereas there was a strong synergistic coupling between these fluxes during the summer maize growing season. An antagonistic coupling relationship appeared between CH4 and N2O fluxes, whereas CO2 and CH4 fluxes appeared to be randomly related. Importantly, when carbon (C) emission reached 17.5 Mg C ha−1yr−1, and nitrogen (N) emission reached 7.8 kg N ha−1yr−1, the soil changed from a C sink to C source; when C emission reached 17.3 Mg C ha−1yr−1, and N emission reached 6.8 kg N ha−1yr−1, the soil changed from a N sink to N source. Considering yield gains, agricultural activity costs, and global warming potential costs together, chisel plough tillage significantly increased NEEB by 19.87%. Together, the advantages of long-term chisel plough tillage can reduce greenhouse gases emissions and increase NEEB while achieving soil carbon and nitrogen sequestration. Therefore, chisel plough tillage practice has both economic and environmental benefits.