Recycling, disposal, or biodegradable-alternative of polyethylene plastic film for agricultural mulching? A life cycle analysis of their environmental impacts

Abstract

Plastic mulching is widely used in croplands to improve yields, while its mismanagement leads to plastic pollution in rural areas. China has explored different approaches to manage post-use plastic mulching, while there is still inadequate research regarding their corresponding environmental impacts. This study establishes five plastic mulching management scenarios, i.e., plastic mulching disposed of in nature, substituting biodegradable plastic, recycling, incineration, and landfilling, and maize cultivation in rural areas of northern China was taken as the studied case. We determine the comprehensive environmental impacts through a life cycle assessment (LCA) approach and completed a field investigation to obtain local datasets. The impurity content of used polyethylene mulching (PEM), an essential parameter for the entire life-cycle environmental impact assessment, is 80.1% ± 9.5%, examined by on-site sampling and scanning electron microscope. Results show that: 1) the use of biodegradable mulching (BM) instead of traditional PEM reduces carbon emissions by 22.6%; 2) the increment of soil carbon flux caused in the application stage is more significant than that in the post-use stage; 3) incineration of post-use mulch causes relatively significant photochemical oxidant formation effect; furthermore, recycling of plastic mulching leads to negative impacts in terms of human toxicity effect, meanwhile the positive environmental impact of fossil depletion effect is 2.3 times higher than that of incineration. Reducing the rate of impurity content in wasted plastic mulching can reduce transportation costs and promote sustainable plastic pollution management in rural areas.