Integrated effects of polyethylene/biodegradable residual film on soil hydrothermal conditions and spring maize growth in rain-fed dryland

Mulch technology has significantly enhanced agricultural production in arid and semi-arid regions worldwide. However, the long-term use of traditional plastic mulch has caused environmental concerns due to persistent residues. Biodegradable mulch offers a potential solution to these issues. But little is known about the effects of different residual films on soil hydrothermal properties, and how this ultimately drives maize growth and yield formation. To address this gap, we conducted a two-year field experiment involving low-density polyethylene film (LDPE) and polylactic acid film (PLA), at three residual levels (75 kg ha⁻¹,150 kg ha⁻¹, and 300 kg ha⁻¹), with a control having no residual film. Our findings showed that increased amounts of residual film increased soil bulk density and decreased soil porosity, leading to decreased soil water storage and increased soil temperature. The structure equation model indicated that these deteriorated soil hydrothermal conditions hindered maize root growth, resulting in lower yield and hydrothermal use efficiency. In the second year of this experiment, the film mass density of PLA treatments declined significantly compared to LDPE, leading to fewer adverse effects on soil physical structure, moisture, and temperature. Betters soil hydrothermal environment favor maize biomass accumulation and yield formation. Compared to LDPE treatments, the grain yield, water use efficiency, and soil accumulated temperature use efficiency of PLA treatments increased by an average of 3.98 %, 3.86 %, and 4.42 %. Therefore, we recommend eco-safe PLA mulch as a sustainable alternative to LDPE mulch for maize production in arid and semi-arid areas.