Abstract

The incomplete degradation of biodegradable mulch films (BMFs) in agricultural soils poses environmental challenges, with persistent plastic residues impacting soil health. This dissertation investigates the use of bioaugmentation with P. guariconensis to enhance BMF degradation under laboratory, raised bed, and field conditions. The research focuses on optimizing microbial delivery methods, evaluating the efficacy of drip and spray bioaugmentation techniques, and assessing mass loss as a primary metric for degradation. Laboratory experiments established proof-of-concept by demonstrating enhanced carbon mineralization, weight loss, and fragmentation of BMFs under bioaugmented conditions. These findings were translated to field-scale trials, where bioaugmentation treatments consistently outperformed untreated controls in terms of mass loss. Among all treatments, the highest bioaugmentation treatment, which combined inoculation 15 days before tillage and 7 days before tillage using both drip and spray methods, achieved the most significant degradation, with near-complete breakdown of the BMF observed in some instances. Raised bed trials provided a controlled environment to validate field results, showing consistent trends in accelerated degradation for both Multi Layered Agricultural Mulch Film (MLAMF) and EcoVio-2 (EV2) films. Despite these outcomes, a one-way ANOVA revealed no statistically significant differences between treated and untreated sample masses after one year, likely due to variability introduced by field conditions such as soil heterogeneity, environmental fluctuations, and microbial competition. Mass loss was the primary metric for evaluating biodegradation, offering practical insights into film breakdown. However, the study highlights the limitations of this approach and emphasizes the need for complementary techniques, such as enzymatic assays and carbon mineralization analyses, to directly measure microbial activity and quantify biodegradation. For example, monitoring plastic-degrading enzymes like depolymerases could validate the mechanistic role of bioaugmentation, while carbon mineralization assays could better link microbial processes to observed mass loss. This work demonstrates the promise of bioaugmentation as a scalable and sustainable strategy for managing BMF residues in agricultural soils. While challenges remain in achieving consistent results under real-world conditions, this research lays the groundwork for integrating bioaugmentation into agricultural practices to mitigate the environmental impact of biodegradable plastics.

Publication Date

11-26-2025

Document Type

Dissertation

Student Type

Graduate

Degree Name

Sustainability (Ph.D.)

Department, Program, or Center

Sustainability, Department of

Advisor

Thomas A Trabold

Advisor/Committee Member

Jeffrey S Lodge

Advisor/Committee Member

Carlos A Diaz

Campus

RIT – Main Campus

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