Characterizing Microplastic Contamination in Agricultural Soil

Project Description

Introduction: Plastic mulch film and drip tape are widely used in modern agriculture for their benefits in increasing crop yield. They aid in retaining pesticides, regulating soil temperatures, suppressing weed growth and conserving water. However, regularly removing and replacing these materials can be labor intensive and often results in the remaining plastic debris being tilled back into the soil. This raises concerns for soil ecosystem health as plastic debris can serve as vectors for pathogens, leach harmful chemicals, and generate micro- and nano- particles that have the potential to contaminate water and food sources. Additionally, agricultural plastic use affects soil microbial communities and can disrupt natural microbial functions that can directly impact soil metabolites and nutrient availability. Therefore, it is imperative to better understand the environmental implications of agricultural plastic use to inform decision making
for alternative practices, strategies for mitigation of existing plastic contamination and solutions for long-term sustainability of food systems.

Project Goals: This study aims to understand how different practices of agricultural plastic use contribute to the accumulation of plastic debris in soils. Student researchers will contribute to both wet-lab and field work, and will learn standard methods used for quantifying and analyzing microplastic contamination in different sample types. Students will overall gain a better understanding of the benefits and trade offs of agricultural plastic use, including how different
environmental factors and plastic properties contribute to the use, transport and ultimate fate of plastic contamination in the environment.

Research Methods: Soil samples will be collected from three agricultural fields that are part of the UC Agricultural and Natural Reserve System: two with a decade-long history of plastic mulch and drip tape use and one with only drip tape. Plastic contamination in soils will be quantified using size filtration and density separation for extraction. Recovered particles will then be characterized based on size, color and morphology using a stereo microscope and data will be analyzed to determine the most common plastic type.