Specialty Crop Growers' Perceptions of Soil Health Impacts from Polyethylene and Biodegradable Plastic Mulches.

Specialty crop production often involves the use of plastic mulch to impede weed growth and regulate soil temperature and water. Plastic mulches are either polyethylene (PE) products, which are removed from the field at the end of the growing season, or starch- and/or copolyester-based products intended to biodegrade in the soil. Soil scientists are investigating whether biodegradable plastic mulch completely biodegrades in the soil, producing only carbon dioxide, water, and biomass as intended. They note a paucity of information about the effects on agricultural ecosystems of all plastic types, including PE mulch which remains in agricultural soils when sections of the film are torn by agricultural weathering or inadvertently during mulch’s retrieval after crop harvest. No robust quantification of the amount of product left in the soil is available. As social scientists, we are studying growers’ perceptions of soil health as it relates to PE and biodegradable plastic mulches through focus groups and a survey of specialty crop growers. Focus group findings suggest that PE mulch users perceive the product to deplete soil organic matter and thus compensate for this impact by increasing crop rotation and fertilizer use. PE mulch fragments in the soil are perceived as benign or inconsequential relative to production benefits. Some growers refer to a potential environmental benefit because both mulches reduce herbicide applications. None of the focus group participants expressed concern about adverse soil health impacts associated with biodegradable plastic mulch. In contrast, the survey results indicate that similar percentages of growers believe that PE and biodegradable plastic mulches harm the soil (9% and 6%, respectively). Three-quarters of the survey respondents said they would consider using biodegradable plastic mulch if research shows that the products do not harm the soil, suggesting that uncertainty about soil impacts is a significant barrier to adoption.