The widespread use and disposal of plastics are associated with significant environmental impacts, such as accumulation in landfills and the natural environment, and threats to wildlife via entanglement and ingestion (Thompson et al., 2009a, 2009b). Of the 6.3 billion tonnes of plastic waste generated since the 1950s, an estimated 79% has accumulated in landfills and the natural environment (Geyer et al., 2017). Plastic pollution in marine environments has been well documented (Law, 2017; Worm et al., 2017). More recent research has focused on the contamination of terrestrial ecosystems, including agroecosystems, by microplastic particles (<5 mm) and nanoparticles (<0.1 µm) (Machado et al., 2018a, 2018b; Ng et al., 2018; Rillig et al., 2017; Rodríguez-Seijo and Pereira, 2019). Of particular concern are the environmental impacts associated with the use and disposal of low-density polyethylene plastic mulch films for crop production (He et al., 2015; Kasirajan and Ngouajio, 2012; Liu et al., 2014; Steinmetz et al., 2016).
PE mulch offers many benefits to farmers, such as improved weed management, moderated soil temperature, increased soil moisture, higher yields, improved crop quality, and higher profits (Freeman and Gnayem, 2005; Garwood, 1998; Lamont, 1993, 2005). Because PE mulch does not biodegrade, disposal options include recycling, incineration, on-farm burning, and landfilling (Hempill, 1993; Moore and Wszelaki, 2016). The number of recycling facilities that accept PE mulch is limited because of contamination with soil and/or vegetation (up to 50% by weight) (Kasirajan and Ngouajio, 2012). Moreover, the labor and transport costs associated with recycling, burning, and landfilling force some farmers to stockpile, bury, or illegally dump their spent PE mulch. Plastic fragments and additives can accumulate in soil, thus altering soil physical properties, nutrient availability, and microbial activity (Bandopadhyay et al., 2018; Steinmetz et al., 2016).
Introduced in the 1990s, biodegradable plastic mulch is a potential alternative to PE mulch (Kasirajan and Ngouajio, 2012; Miles et al., 2017; Sintim and Flury, 2017). Made from starch and other biodegradable polymers, biodegradable plastic mulch is designed to perform comparably to PE mulch while also biodegrading in soil or composting environments at the end of its useful lifetime (Miles et al., 2017). The long-term environmental impacts of biodegradable plastic mulch require further investigation (Bandopadhyay et al., 2018; Brodhagen et al., 2017; Li et al., 2014; Razza and Cerutti, 2017; Sintim et al., 2019). Nevertheless, biodegradable plastics are one possible way to mitigate global agricultural plastic pollution (Cassou, 2018).
Although polymer scientists, soil scientists, toxicologists, and related scientists conduct research on the environmental impacts of plastic mulching practices, it is instructive also to study the human dimensions of plastic use and disposal in agriculture. For example: What are farmers’ perceptions of the advantages and disadvantages of PE mulch? How do farmers typically dispose of PE mulch? Is biodegradable plastic mulch perceived to be a viable alternative to PE mulch? What is the likelihood that farmers would consider using biodegradable plastic mulch? To answer these and related questions, we surveyed strawberry growers in California, the Pacific Northwest (Oregon and Washington), and the Mid-Atlantic (New York and Pennsylvania) in 2016 to explore regional differences in strawberry growers’ experiences and opinions related to the use of PE and biodegradable plastic mulches. Strawberry growers were chosen as the study population because of their widespread use of plastic mulch, high crop value, and potential interest in biodegradable plastic mulch products. Two hundred and nineteen strawberry growers completed the survey, for a response rate of 21%. Our study not only contributes to the nascent literature on farmers’ adoption of biodegradable plastic mulch (Cowan et al., 2015; Goldberger et al., 2015; Scaringelli et al., 2016) but also meets the call for more research on stakeholders’ perceptions of the environmental impacts of agricultural landscapes under plastic mulch (Steinmetz et al., 2016).
In 2017, the United States produced 3.6 billion pounds of strawberries, valued at $3.5 billion [U.S. Department of Agriculture (USDA), 2018]. Fresh market strawberries accounted for 83% of total strawberry production, and processing strawberries (i.e., frozen, freeze-dried, or included in strawberry-based food products) accounted for the remaining 17% (USDA, 2018). According to the 2012 U.S. Census of Agriculture, 10,388 farms grew strawberries on a total of 67,467 acres in 2012 (Table 1). California produced 91% of the strawberry crop in 2017 (USDA, 2018). The other top 10 strawberry-producing states are located in the South Atlantic (Florida, North Carolina), Mid-Atlantic (New York, Pennsylvania), Pacific Northwest (Oregon, Washington), and Midwest (Ohio, Michigan, Wisconsin). Globally, the largest producer of strawberries is China, followed by the United States, Mexico, Egypt, Turkey, and Spain (Food and Agriculture Organization of the United Nations, 2017).
Strawberry production in the United States and selected states. Data from the 2012 Census of Agriculture (USDA, 2014).
U.S. strawberry production and marketing practices vary by region (Samtani et al., 2019). For example, most California strawberries are annual plantings for fresh market (Fennimore, 2017); the Pacific Northwest is known for the production of high-quality processing fruit in a perennial matted row system (Finn, 2017); and the Northeast and Mid-Atlantic states exhibit a combination of perennial matted rows and raised-bed plasticulture for fresh-market strawberries (Pritts, 2017). Plastic mulch is increasingly popular across all U.S. strawberry production regions because of its ability to suppress weeds, moderate soil temperature, conserve water, and protect plants (DeVetter et al., 2017; Fernandez et al., 2001; Freeman and Gnayem, 2005). Biodegradable plastic mulch has been shown to perform comparably to PE mulch for strawberry production in terms of weed suppression (Andrade et al., 2014), soil moisture retention (Costa et al., 2014), fruit quality (Bilck et al., 2010), crop yield (DeVetter et al., 2017), and material functionality from planting to harvesting (Kapanen et al., 2008). Biodegradable plastic mulch costs two to three times more than PE mulch (Velandia et al., 2018; Zhang et al., 2018); however, because it does not need to be removed and discarded at the end of its useful lifetime, farmers do not incur the removal and disposal costs associated with PE mulch. Economic research has shown that U.S. consumers are willing to pay more for strawberries grown with biodegradable plastic mulch, which may in part offset the higher upfront cost of the mulch (Chen et al., 2018).
Our human dimensions study, which focuses on farmers’ experiences and opinions related to PE and biodegradable plastic mulch, is part of a larger project, “Performance and Adoptability of Biodegradable Plastic Mulch for Sustainable Specialty Crop Production,” funded by the USDA National Institute of Food and Agriculture’s Specialty Crop Research Initiative program (award no. 2014–51181–22382). The survey was conducted by the project’s Technology Adoption Working Group with guidance from a transdisciplinary team of scientists, Extension personnel, farmers, mulch manufacturers, and other stakeholders.
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