Biodegradability of photodegradable coating materials used for coated fertilizers in agricultural soils

Photodegradable polyethylenes, which produce alkane-like substances following sustained exposure to sunlight, are used as coating materials for some agricultural fertilizers. In this study, the biodegradability of these substances was examined in two different agricultural soil types using the biochemical oxygen demand (BOD) method. After a 21-d test period, high molecular weight photodegradation products showed a negligible biodegradation. However, the low molecular weight fractions extracted from the photodegradation products using hexane showed biodegradabilities of 8 to 18% within the same 21-d period. Furthermore, the two soil types were found to display different biodegradation patterns, presumably due to the differences in the microbial communities present. These results suggest that the tested agricultural soils contain microorganisms that can degrade and utilize the low molecular weight photodegradation products of photodegradable polyethylenes.