Effects of PLA/PBAT-based biodegradable film mulch on water and nitrogen dynamics in soil-potato system

Replacement of polyethylene (PE) film mulch (PM) to biodegradable film mulch (BM) can significantly reduce plastic pollution and carbon footprint in agricultural production. However, the effects of BM on nitrogen dynamics in soil-plant system remain elusive. A field experiment with two cropping seasons was conducted to investigate the effects of biodegradable film on soil nitrogen mineralization, nitrate accumulation and leaching, and plant nitrogen uptake. Although the distribution of soil water and nitrate under treatment BM was similar to that under treatment PM at early growth stage of potato plants, the decomposition of biodegradable film during later growth stage of potato plants caused a reduction in soil water content and nitrogen mineralization, leading to a decrease in soil nitrate accumulation under treatment BM. In addition, the degradation of biodegradable film enhanced the translocation of nitrate from upper to deeper soil layers. However, there was no difference in tuber yield or plant nitrogen uptake between treatments BM and PM, suggesting the decomposition of biodegradable film at later growth stage has limited effect on potato nitrogen uptake and tuber yield. Therefore, the PLA/PBAT-based biodegradable mulch film is a promising substitution to PE film for winter potato production.