The applicability of water-permeable plastic film and biodegradable film as alternatives to polyethylene film in crops on the Loess Plateau

Polyethylene film (PEF) cannot retain “ineffective precipitation” (< 10 mm) in drylands, and PEF residues in farmland have detrimental impacts on soil health. Thus, water-permeable plastic film (WPF) that can retain ineffective precipitation and biodegradable film (BF) that can be degraded were developed. However, the yield performance using WPF and BF varied a lot in different crops and experimental sites as compared with PEF. Here, we evaluated the applicability of WPF and BF as alternatives to PEF on millet, sorghum and corn with different growth periods on the northern Loess Plateau of China. Our results showed that, compared with PEF, ineffective precipitation was successfully preserved and soil water storage was 13–19 mm higher under WPF. Furthermore, the activities of urease, alkaline phosphatase, catalase, and contents of soil NO₃––N, available phosphorus were also higher under WPF, due to the improved soil water conditions and mitigated soil temperature. Consequently, the yields of the three crops were 5–18% higher under WPF. The yield under BF did not decrease in millet, while it was 8–15% lower in sorghum and corn than that under PEF. When a large area of BF cracks appeared, sorghum and corn were in the middle growth period with a low leaf area index (LAI), and the rainy season did not come yet; but for millet, it coincided with the rainy season in its late growth period with a high LAI. Therefore, compared with PEF, soil water storage was 9–30 mm lower under BF in sorghum and corn during the middle growth stage, which resulted in lower soil enzyme activities and nutrient contents. In conclusion, as an alternative to PEF, WPF application is favorable in areas with high ineffective precipitation, and BF application is not suitable for crops with long growth period and low LAI.