Effects of different tillage systems and cropping sequences on soil physicochemical properties and greenhouse gas emissions

The greenhouse gas emissions (GHGE) are major contributor to climate change and farmlands are prominent source of GHGE that are affected by soil chemical and physical properties. Field management practices e.g. no-till (NT) and cropping sequences (CSs) can regulate GHGE by changing soil physicochemical properties. To understand the role of soil physicochemical properties on GHGE under different tillage and CSs, a field experiment was conducted during 2019 and 2020 consisting of two tillage systems (NT and rotary tillage (RT)) and CSs (maize-wheat-soybean-wheat (MWS), soybean-wheat-maize-wheat (SWM), wheat-soybean (SW) and wheat-maize (WM)). The results showed that N2O emissions were higher in 2019, mainly under SWM and SW as compared to other CSs. Higher cumulative N2O emissions (28.89% (2019) and 37.94% (2020)) under RT were observed than NT. RT had higher CH4 sink in 2019 (20.93%) and 2020 (19.6%) in comparison to NT. Moreover, CH4 uptake was increased almost 91.49% in 2020 as compared to 2019. These inter-annual changes between GHGE were mainly due to water filled pore spaces (WFPS) induced by inter-annual precipitation anomalies, where higher precipitation (79.91%) in 2019 increased about 50.71% WFPS as compared to 2020. The global warming potential (GWP) was negatively correlated to TN, PON, SOC, POC and SOC stock, but positively correlated to WFPS. These results suggested that RT could negatively impact WFPS, SOC, TN and their associated fractions in different CSs and enhance GWP. In conclusion, NT with diversified CSs could offer a solution for decreasing GWP and improving maize equivalent yield.