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

Abstract

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., N 2 O emissions and NH 3 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 N 2 O emissions, NH 3 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 NO 3 – -N content by 18.2 %, NH 4 + -N content by 27.4 %, cumulative N 2 O emissions by 34.0 % and NH 3 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 N 2 O emissions or NH 3 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. • Soil water-filled pore spaces and soil temperatures differed highly in plastic mulching and no mulching. • Plastic mulching had higher grain yield and soil mineral N content than no mulching. • Plastic mulching significantly improved soil enzyme and microbial activities. • Plastic mulching increased NH 3 volatilization and N 2 O emissions.