Sorption Behavior of Polylactic Acid/Poly(butylene adipate-co-terephtalate) Mulching Film Toward Active Substances

Plastic mulching films are often used in agriculture for contributing to reduce water evaporation from the soil, to decrease weed growth and the consequent use of chemicals, and to increase soil temperature at the root level. Petrol-derived polymers, such as low-density polyethylene, can be replaced by biodegradable (bio)polymers in mulching activities, which, after crop harvest, do not need to be removed, but they are very often buried in the soil, thus allowing the farmers to economize on their disposal. A kind of biodegradable mulching film is constituted of a polylactic acid/poly(butylene adipate-co-terephtalate) blend, which is known to be subjected to both enzymatic and photooxidative degradation under aerobic conditions. However, during degradation processes, the mulching films can give rise to microplastic debris, which, in turn, could act as micro-vectors of organic and inorganic pollutants. Understanding the adsorption capability of agricultural mulching films toward active substances commonly used in agricultural activities to enhance crop harvesting could help farmers in choosing the appropriate plastic while trying to reduce environmental pollution. In this study, the adsorption behavior of a commercial polylactic acid/poly(butylene adipate-co-terephtalate) film is investigated, considering azoxystrobin, a widely used organic fungicide, as the active substance.