Biodegradation of sugarcane bagasse and rice husk plates in tropical soils in Pucallpa, Peruvian Amazon

Biodegradable food-service items are increasingly sought to reduce the environmental impact of single-use plastics. This study evaluated the biodegradation performance of plates made from sugarcane bagasse (SB) and rice husk (RH) under tropical field conditions and different soil types. Plates were produced via thermoforming using six starch and glycerol formulations and their physico-mechanical properties were characterized prior to selecting the best formulation. Biodegradation trials were conducted over 90 days in three soil environments: open soil (OS), eucalyptus-reforested soil (ER), and compost-amended soil (OC). Weight loss was measured periodically, alongside monitoring of environmental parameters and soil physicochemical and microbiological changes. Both SB and RH plates exceeded 96% biodegradation within 90 days, meeting ISO 14855-2:2018 and ASTM D5338-15 criteria. SB generally degraded faster than RH in OS and ER, while no significant differences were observed in OC. The highest degradation occurred within the first 15 days, followed by a slower phase. Biodegradation contributed to increased soil moisture, total nitrogen, and apparent density, and altered microbial populations. These findings demonstrate that agricultural-residue-based plates can serve as viable alternatives to plastics, effectively reintegrating organic matter into soils. However, limitations include low physico-mechanical performance, the restricted range of environmental conditions tested, and the absence of performance assessment under actual food-service use. Future work should address durability improvements and evaluate degradation in diverse real-world settings.