Greenhouse gas emissions and carbon footprint under gravel mulching on China's Loess Plateau

Abstract

AbstractGravel mulching technology has been widely verified as an effective solution to reduce evaporation and improve crop production on China's Loess Plateau, but its impacts on greenhouse gas (GHG) emissions have not been well documented. This study examined the quantification of the overall GHG emissions via estimating global warming potential (GWP), GHG intensity (GHGI), C footprint (CF), and C intensity (CI) with varying experimental treatments. A 2‐yr consecutive wheat–maize rotation field experiment was conducted through monitoring GHG emissions using a closed‐chamber method with four treatments: CK (control with no mulching), WCK (CK plus 50 mm irrigation), GM (CK plus gravel mulching), and WGM (WCK plus GM). Compared with the CK, gravel mulching significantly decreased soil CO2 emissions and increased soil CH4 uptake over both cycles, although patterns of soil N2O emissions were controversial. Mixed effects of gravel mulching and irrigation significantly minimized the GWP over both cycles. Compared with the CK, annual GHGI in the WCK, GM, and WGM treatments dramatically decreased by 35.1, 53.7, and 55.9%, respectively, over Cycle 1 and by 16.7, 19.6, and 37.2%, respectively, over Cycle 2. The average CFs in the WCK, GM, and WGM treatments over both cycles were 4.4, 35.0, and 58.7% lower than in the CK, respectively. Gravel mulching had no significant effect on the CI during Cycle 1 but did have a significant effect during Cycle 2. Thus, gravel mulching is a recommended practice to mitigate GHG emissions and enhance the crop productivity on the Loess Plateau of China.