Multi-Criteria Economic and Environmental Assessment of Biodegradable and Plastic Mulch Films in Peanut Production Systems

Biodegradable mulch films are recognized as promising eco-friendly alternatives, yet their high costs and uncertain field performance constrain adoption. Systematic cost–benefit comparisons with traditional polyethylene films across thickness gradients remain limited. This study compared white and black low-density polyethylene (LDPE) films (0.006–0.015 mm; the 0.015 mm film in 2023 only), biodegradable Polylactic Acid/Polybutylene Adipate Terephthalate (PLA/PBAT) films (0.008 mm in all years and 0.010 mm in 2024) and a bare-soil control in a three-year (2022–2024) randomized complete block trial with three replicates on peanut in Shandong, China. Field experiments were conducted. Peanut yield and quality, economic inputs and returns, and visible mulch residue and recovery were comprehensively evaluated using the Technique for Order Preference by Similarity to Ideal Solution (TOPSIS) and Data envelopment analysis (DEA). Microplastics were not directly quantified; therefore, environmental assessment was based on visible residual film mass and recovery rate. All mulched treatments out-yielded the control (p < 0.05). Net returns ranged from 12,609 to 27,272 CNY ha−1. After the current 1800 CNY ha−1 subsidy, biodegradable films still cost 280–330 CNY ha−1 (1.7–2.0%) more than the matching conventional films. The black 0.010 mm LDPE film left the lowest residue (5 kg ha−1 in 2023; 29 kg ha−1 in 2022) with recovery up to 97.2%; microplastics were not directly quantified. TOPSIS rankings identified white biodegradable film as the highest-ranked treatment under the evaluated economic and agronomic criteria, while DEA revealed white 0.008 mm polyethylene film and white biodegradable film as consistently strong and efficient. Optimal mulch selection depends on farmers’ risk preferences and environmental priorities. This study provides systematic thickness-gradient cost–benefit comparisons and measured visible residue and recovery assessments for biodegradable versus traditional films. Targeted incentive policies combining subsidies with risk-mitigation instruments are recommended.