Assessing Environmental Impact: Plastic vs. Biodegradable Mulches in Agroecosystems
Presenter: Oluwatunmise Israel Dada, Graduate Research Assistant, Bioprocessing & Bioproducts Engineering Laboratory, Department of Biological Systems Engineering, Washington State University
Authors:
Oluwatunmise Israel Dada and Liang Yua, Department of Biological Systems Engineering, Washington State University and Ting Chib, Department of Apparel, Merchandising, Design and Textiles, Washington State University
The use of agricultural plastic mulch is on the rise, accompanied by a growing environmental concern. Despite acknowledged benefits, the widespread adoption of biodegradable mulch over traditional plastic mulch remains a topic of debate. This paper conducts a comprehensive review of the environmental tradeoffs between traditional plastic mulch and biodegradable alternatives, adopting a balanced comparative life cycle assessment perspective. It also addresses setbacks by proposing viable solutions. The review encompasses cradle-to-grave environmental impacts, covering raw material extraction, film production, use, and end-of-life strategies. Overall, biodegradable mulch exhibits superior merits in terms of energy use and greenhouse gas emissions. However, negative impacts such as eutrophication, acidification, and land occupation are notable, particularly in starch-based mulch. The higher cost compared to traditional plastic mulch is regarded as a major hindrance preventing the widespread adoption of biodegradable mulch. The review indicates that environmental burdens vary based on factors such as polymer type, polymer grade, the level of additives, film thickness, life cycle stage, end-of-life choices, and climate. Importantly, the manufacturing stage significantly contributes to greenhouse gas emissions and energy use. To mitigate post-use environmental impact, energy and material recovery emerge as major strategies for plastic mulch end-of-life considerations, with recycling being a preferable option, albeit with the need to address human toxicity. From an alternative perspective, straw mulch is suggested as a better option in terms of yield, cost, and environmental advantages. However, attention must be given to addressing N2O releases, particularly in rain-fed semi-arid areas. This paper elucidates these intricacies from economic, agronomic, and environmental viewpoints, providing an unbiased decision-making tool for farmers, agricultural plastic manufacturers, recyclers, and policymakers.