Abstract
Plastic mulch accounts for approximately 16% of agricultural plastics, with approximately 2.5 million metric tons of plastic mulch films used globally each year. Polyethylene (PE) is the most widely used polymer in mulch manufacturing because of its low cost, excellent mechanical strength, and barrier properties that prevent weed growth, optimize soil temperature, and conserve soil moisture for crop growth. However, PE mulch is a growing source of plastic pollution because it is nonbiodegradable, and there is a lack of sustainable end-of-life disposal options, resulting in nearly all PE mulch being burned, buried, stockpiled, or landfilled. Soil-biodegradable plastic mulch (BDM) is an eco-friendly alternative that is designed to be tilled into soil at the end of the growing season, and soil microorganisms degrade it into carbon dioxide, methane, water, and microbial biomass. Generally, BDM has an agronomic performance similar to that of PE mulch (dependent on thickness and color), is applied with the same equipment, and its in situ disposal saves labor as well as removal and disposal costs. Yet, BDM adoption in the United States has been limited because of questions regarding its ingredients, costs, biodegradability, and impacts on soil ecosystems and overall soil health. This article answers these most frequently asked questions regarding BDM. For example, BDM that meets the EN 17033 standard is biodegradable in soil and has not been found to have negative impacts on soil ecology or health. The BDM purchase cost can be twice the cost of PE mulch, but the overall cost tends to be similar because there is no cost to remove or dispose of BDM. Two to 10 years are required for BDM to biodegrade in soil, depending on environmental conditions, such as climate, soil temperature, and soil moisture. Much of the misinformation regarding BDM comes from a lack of adherence by marketers and the scientific community to the definition of biodegradable plastic, leading to the usage of plastics that are not biodegradable, thus resulting in plastic pollution.