Decreased greenhouse gas intensity of winter wheat production under plastic film mulching in semi-arid areas

Greenhouse gas intensity (GHGI), the evaluation of GHG emissions per unit yield rather than per unit land area, has recently received much attention. Plastic film mulching (PFM) is one of the major agricultural practices in semi-arid areas, but few studies have synthetically studied the effects of PFM on GHGI, grain yield, soil characteristics, and their potential relationships at different winter wheat (Triticum aestivum L.) growing stages. Here in the semi-arid Chinese Loess Plateau, we simultaneously investigated two cropping systems from 2018 to 2020: PFM with 100 % cover and no film mulching (control). Averaged across two growing seasons, the PFM treatment significantly increased soil temperature, water-filled pore spaces and soil water storage, while sustaining high aboveground biomass (31.9 %) and grain yield (45.5 %). The PFM treatment significantly increased cumulative N2O emissions by 56.2 %, CO2 emissions by 39.7 %, and CH4 uptake by 151.4 % compared to the control treatment. GHGI are on average 14.2 % lower in the PFM treatment than in the control treatment. Moreover, the PFM treatment significantly improved soil enzyme activities (alkaline phosphatase, catalase, invertase, and urease) and microbial biomass carbon and nitrogen from grain filling to maturity stage. Altogether, the reductions in GHGI suggest that PFM-induced increases in grain yield could outweigh the adverse impacts on GHG emissions, underscoring the potential to apply PFM for sustainable intensification of crop production in semi-arid areas.