Soil Properties as Key Determinants for the Biodegradation Kinetics of Polymer Blends in Indian Agroecosystems

The growing worldwide plastic pollution challenge needs the development of biodegradable polymers as potential alternatives. The present research the soil biodegradation behaviour of four polymer blends viz. PVA/starch, PAM/starch, PEG/HPMC and PVP/HPMC in three different Indian soil types: nutrient-rich alluvial soil (Gomti river, Lucknow), clay-rich black cotton soil (Bhopal) and nutrient-deficient mountainous soil (Kasar Devi, Almora). The PVA/starch blend exhibited the highest degradation over 28 days, with a 72% weight loss in Gomti soil, likely due to hydrophilicity of PVA and the high microbial accessibility of starch. PVP/HPMC, on the other hand, showed only minor degradation (18-35%) due to the chemical inertness of PVP. Degradation rates were found to be significantly influenced by porosity, nutrient content (Fe, Mg and K) and microbial activity, according to soil characterization using FE-SEM and EDX. The acidic pH (6.3) and compact structure of Kasar Devi soil hindered degradation, whereas the alkaline pH (7.8) and high porosity of Gomti soil facilitated favourable conditions for microbial colonization. In a range of agroclimatic zones, the present findings highlight the significance of customizing biodegradable polymers to local soil conditions, providing useful information for green packaging and agricultural films.