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Effect of Western Australia's South-West Agricultural Climate in Increasing Degradation of Conventional and Biodegradable Plastic Mulch Films, Above and Below Ground

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Thursday, July 24, 2025
1:42 PM - 1:54 PM

Overview

Samantha Viljoen | Murdoch University


Speaker

Agenda Item Image
Miss Samantha Viljoen
Student
Murdoch University

Effect of Western Australia's South-West Agricultural Climate in Increasing Degradation of Conventional and Biodegradable Plastic Mulch Films, Above and Below Ground

Abstract

Plastic mulch films are widely used in agriculture to overcome growth constraints in soils, but their persistence creates environmental concerns. This study employed advanced analytical techniques to characterize the degradation of nine plastic mulch films (conventional and biodegradable) in sandy soils of Southwest Western Australia. Films were subjected to above-ground exposure and below-ground burial (using 100 μm and 5000 μm mesh bags) for 12 months at DPIRDs Northam Grains Research Facilities, Western Australia. The location has a Mediterranean type of climate with coarse-textured sandy soils known for low fertility and minimal microbial diversity. Visual degradation of plastic films was quantified through photo image analysis software, while chemical transformation was monitored using Fourier Transform Infrared (FTIR) spectroscopy across four key spectral regions. Results demonstrated significant decreases (p < 0.03) in film area for most samples above and below ground, with significant differences in mass loss between film types observed only in above-ground treatments after one year. FTIR analysis revealed significant spectral changes (p < 0.005) for above-ground films after the year, with the in the carbonyl region (1500-1700 cm⁻¹) having the most noticeable difference. While below-ground samples exhibited significant changes (p < 0.03) in at least one spectral region regardless of mesh size. All films showed significant differences (p < 0.04) between above and below-ground degradation after 12 months. Above ground samples exhibited more extreme spectral changes so degradation occurred more readily above ground. This analytical approach provides valuable insights for developing biodegradable alternatives that can effectively address plant growth constraints in sandy agricultural soils while minimizing environmental impacts. The unique degradation patterns observed in Western Australia's sandy soils contribute to understanding how biodegradable mulch films can be optimized for regions with similar challenging soil properties, potentially improving sustainable agricultural practices in sandy landscapes worldwide.

Biography

Samantha Viljoen is a Ph.D. student with the Bioplastic Innovation Hub and SoilsWest at Murdoch University. Her research specializes in the degradation of agricultural plastics and their additives, with a focus on their impacts on soil health and sustainability. Through her work, she has contributed to the team’s development of sustainable agricultural bioplastics that reduce long-term environmental impacts and support healthy ecosystems.
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