Effects of aging behavior of biodegradable mulch on soil microbial community composition: An offline simulation study

Agricultural mulch is beneficial to agricultural production, but it will cause serious environmental pollution. Poly (butylene adipate-co-terephthalate) (PBAT) mulch has the potential to replace PE mulch to reduce the micro- plastic pollution in farmland soil. To clarify the effects of the aging behavior of PBAT mulch on soil microbial community composition. Four types of PBAT mulch were selected to carry out a 60-day outdoor soil aging test. The microstructure, Fourier transform infrared spectroscopy (FTIR), thermal properties of PBAT mulch and the soil microbial community composition were tested after aging. The results indicated that the addition of starch could accelerate the aging of PBAT mulch, while the addition of poly(lactic acid) (PLA) could slow down the aging of PBAT mulch. After 60 days of aging, the elongation at break of starch-filled PBAT mulch was significantly reduced by more than 90%. According to the characterization of aged PBAT mulch, the degradation rate of PLA in the PBAT mulch was lower than that of PBAT. The results of high-throughput sequencing showed that PBAT mulch affected the community composition of soil fungi, which led to an increase in the abundance of Mortierella and a decrease of Hanseniaspora. According to all the results of the present study, there was no evidence that degradation products of PBAT mulch would harm the farmland soil. The research results would provide theoretical support for the popularization of PBAT mulch.