https://digitalcommons.calpoly.edu/nres_rpt/19
Date of Award
8-2021
Degree Name
MS in Environmental Sciences and Management
Department
Natural Resources Management
College
College of Agriculture, Food, and Environmental Sciences
Advisor
Seeta Sistla
Advisor Department
Natural Resources Management
Advisor College
College of Agriculture, Food, and Environmental Sciences
Abstract
Agricultural plastic mulch reduces weeds, yields higher crop quality and quantity, and increases soil temperature, but it can also become a soil pollutant. The impact of agricultural plastic contamination on soil microbial activity remains poorly documented. To better understand how plastic pollution influences soil microbial decomposers, we sampled three farms in Watsonville, CA. Each site is characterized by large amounts of plastic contamination in the form of polyethylene mulch and polyvinyl chloride dripline. The fields contain marked amounts of macro- (and presumably micro-) plastic fragments primarily derived from PVC dripline and polyethylene mulch. We haphazardly collected 6" deep soil samples from the fields (i.e., “bulk PC soil”) to compare with soil which had come directly in contact with the remaining surface mulch and dripline (i.e., “macroplastic fragment associated soil”). If plastic incorporation alters edaphic factors while leaching novel compounds, this may alter microbial decomposer community structure and function. We hypothesized that the soil directly associated with plastic fragments would have reduced microbial biomass and decomposer activities relative to the bulk soil, due to a greater likelihood of toxicity and altered microhabitat. We evaluated a suite of abiotic and biotic characteristics to assess the influence of agricultural plastic contamination on soil decomposers. Our study suggests that prolonged contact with agricultural plastic waste may create a novel habitat in low carbon agricultural soils.