Agronomic performances of biodegradable and non-biodegradable plastic film mulching on a maize cropping system in the semi-arid Loess Plateau, China

Biodegradable plastic film mulch (PFM) is considered an alternative to non-biodegradable PFM to mitigate the negative impacts of residual film. However, the agronomic performance of biodegradable PFM in comparison to non-biodegradable PFM still needs to be tested. In this study, we evaluated the effects of biodegradable and non-biodegradable PFM on soil physicochemical properties, microbial community, and enzyme activities, as well as maize growth performance. Biodegradable and non-biodegradable PFM both increased soil temperature, water content, N content, and microbial biomass and maize yield by up to 30%, but decreased soil enzyme activities as compared to no mulching (control, CK). Most soil physicochemical properties, microbial community, and enzyme activities were similar under non-biodegradable and biodegradable PFM at the early stages of maize growth. However, at the late stages, soil temperature, water content, mineral N, NO₃^--N, ammonia monooxygenase (AMO) activity, and total phospholipid fatty acids (PLFAs) decreased under biodegradable PFM owing to film fragmentation. White PFM increased soil temperature, water content, and total PLFAs at the early stages of maize growth but decreased soil mineral N and total PLFAs at the late stages, as compared to black PFM. As soil temperature and N availability were the major factors affecting soil microbial community, microbial activity decreased after the fragmentation of biodegradable PFM, owing to the decreased soil temperature, water content, and mineral N. Notably, biodegradable PFM could decrease NO₃^--N accumulation in topsoil by decreasing N transformation due to the lower microbial and N-related enzyme (e.g., AMO) activities, compared with non-biodegradable PFM, which may avoid negative environmental impacts, such as NO₃^--N leaching or gas emission after harvest. Maize yield, height, aboveground biomass, and N uptake under biodegradable PFM were similar to those under non-biodegradable PFM during maize growth, implying that biodegradable PFM has no negative impact on crop growth and yield. In general, biodegradable PFM was equivalent to non-biodegradable PFM in terms of maize yield increase and N uptake, but was environmentally friendly. Therefore, biodegradable PFM can be used as an alternative to non-biodegradable PFM in semi-arid areas for sustainable agricultural practices.