Biodegradable Poly(butylene adipate-co-terephthalate)/Poly(lactic) Acid Mulch Film with Soy Waste Filler for Improved Biodegradation and Plant Growth

The accumulation of plastic waste in agriculture (e.g., nonbiodegradable polyethylene mulch films) necessitates sustainable alternatives. This study investigates biodegradable mulch films composed of poly(butylene adipate-co-terephthalate) (PBAT), poly(lactic acid) (PLA), and 10% soy waste (predetermined from literature). The PBAT/PLA/Soy films are subjected to accelerated aging, respirometry, and field trials to evaluate their biodegradation, mulch performance, and impact on plant growth. Accelerated aging tests reveal that soy incorporation enhanced hydrolysis and mineralization rates, with PBAT/PLA/Soy films exhibiting earlier weight loss compared to PBAT/PLA films. Field studies demonstrate that plants grown with soy-containing films showed 49% higher plant heights, potentially because soy may act as a biostimulant. Based on ASTM D5338, PBAT/PLA/Soy films show a percent mineralization of 49.6 ± 1.1%, while PBAT/PLA/Soy was lower (44.7 ± 0.8%), indicating that the soy enhances the biodegradation. This research emphasizes the potential of repurposing soy waste as a sustainable additive to enhance the biodegradability of polymer films, addressing environmental concerns and promoting sustainable agriculture. This effort begins to explore the interactions between biodegradable mulch films and plant responses under diverse environmental conditions that can lead to optimization of mulch designs and applications. These findings present a step toward reducing plastic pollution and advancing the use of bioplastics in agriculture.