Plastic mulching significantly improves soil enzyme and microbial activities without mitigating gaseous N emissions in winter wheat-summer maize rotations

Plastic mulching is an important agricultural practice to increase crop yield by increasing soil temperature and moisture. Plastic mulching can also affect soil greenhouse gas emissions [e.g., N2O emissions and NH3 volatilization] and soil characteristics such as soil enzyme and microbial activities, but the simultaneous effects of plastic mulching on these parameters and the potential links between them are rarely evaluated. Here, we conducted a field study to investigate the concurrent responses of N2O emissions, NH3 volatilization, soil enzyme and microbial activities, soil dissolved organic C (DOC) and N (DON), and crop yield to plastic mulching (mulching) and no mulching (ambient) under consecutive winter wheat–summer maize rotation cycles in China’s Loess Plateau. The mulching treatment significantly increased soil water-filled pore spaces (WFPS) and soil temperature during growing cycle 1 (2018–2019 winter wheat and 2019 summer maize) and cycle 2 (2019–2020 winter wheat and 2020 summer maize). Averaged across both growing cycles, the mulching treatment significantly increased winter wheat yield by 31.8 %, summer maize yield by 36.4 %, soil NO3–-N content by 18.2 %, NH4+-N content by 27.4 %, cumulative N2O emissions by 34.0 % and NH3 volatilization by 50.6 %, relative to the ambient treatment. Moreover, the mulching treatment significantly enhanced soil alkaline phosphatase, invertase, catalase, and urease activities and soil microbial biomass C and N contents in the 0–10 cm soil layer across both growing cycles. This study revealed a tradeoff, with plastic mulching significantly improving crop yields and soil enzyme and microbial activities but not mitigating N2O emissions or NH3 volatilization. Our results highlight that simultaneously documenting gaseous N emissions and changes in soil properties under plastic mulching can advance the understanding of sustainable agriculture in semi-arid areas.