The Effect of Pesticides on the Degradation of Oxobiodegradable Agricultural Mulch Films

Abstract

Oxobiodegradable agriculture mulch films made from polyethylene (PE) are known to have many benefits for agriculture practice, including increased yields and resource efficiency, without the drawback of removing the film after the growing season. However, anecdotal evidence suggested when pesticides are applied to these films, their rate of degradation may be affected. The goal of this investigation was to characterize the delay in degradation that occurs when pesticides are applied to oxobiodegradable agriculture mulch films. Two pesticides, Pyrinex 480 and Round Up, were tested in the field and laboratory environment to determine the effects on degradation with normal and accelerated exposure conditions for the films. Exposure tests indicated the pesticides were having stabilizing effects on the PE films, delaying degradation. Therefore, tests were designed to explore the chemical mechanisms underlying each pesticide’s stabilizing influence. These included experimental and computational measurements of redox potential to define chain breaking donor and chain breaking acceptor capacities of the pesticides. UV (ultraviolet) screener capacity of the pesticides was also investigated. We concluded that Pyrinex 480 likely has the ability to absorb UV energy that would normally break bonds in PE, along with some other capacity to stabilize degradation, such as the ability to accept electrons. In contrast, Round Up likely donates electrons or atoms to prevent degradation reactions and stabilize PE films.