Disintegration and mineralization of mulch films and leaf litter in soil

Abstract

Biodegradable mulch films are used in agriculture for controlling weeds. The intrinsic biodegradability and safety of the films is proven by using standard test methods in the laboratory. On the other hand, the degradation that occurs in fields after use can be followed by observing the fragmentation and disappearance over time. The disintegration that occurs after use is a relevant process, because persistent shreds can interfere with the subsequent crop and disrupt the agricultural cycle in the long term. Disintegration is not proof of biodegradation. If fragmentation is not followed by ultimate biodegradation, it is just a shift of the pollution from a visible to an invisible state, which is ultimately the source of microplastics. In this article we followed both the “disappearance” of pieces of a conventional mulch film, a biodegradable one, filter paper, and dried maple leaves and their parallel conversion into CO2. The results showed that there was a clear correlation between the visual disappearance of the tested material and the mineralization level. The final mineralization of the biodegradable mulch film was similar to the level reached by filter paper and dried leaves, while the conventional mulch film showed neither fragmentation nor mass loss nor mineralization.