Plastic Mulch Leaves Contamination in Agricultural Fields, Study Finds

Researchers at California Polytechnic State University published a study in PNAS Nexus in which they sampled 12 farm fields on California’s Central Coast after plastic mulch had been removed for the season according to best practices. According to a press release, all the fields surveyed had plastic contamination and the authors found up to 25 kg of macroplastic debris per hectare, covering up to 3.4% of field surface area. Microplastics were also found in all fields, and microplastic concentrations positively correlated with macroplastic concentrations. Key soil heath traits were negatively correlated with macroplastic accumulation, even at relatively low contamination levels. The authors suggest exploring a non-plastic, biodegradable alternative mulch to limit the threat to soil function and agricultural productivity caused by unabated plastic accumulation, given that around the world, over 25 million acres of farmland is seasonally covered with opaque plastic films.