The Silent Threat of Microplastics in Australian Agricultural Ecosystems: Sources, Risks, and the Role of Policy in Addressing the Issue.
We recently attended a webinar hosted by the Australian Land and Groundwater Association (ALGA), titled “Microplastics: The Silent Threat of Microplastics in Australian Agricultural Ecosystems – Sources, Risks, and the Role of Policy in Addressing the Issue.”
One of the key speakers was Dr. Shima Ziajahromi from Griffith University’s Australian Rivers Institute. Dr. Ziajahromi is a leading researcher on microplastics in the environment, with a focus on their impacts in both water and soil. Her work has helped improve how we detect and understand microplastics and has shaped policy efforts to reduce their risks - particularly in agricultural settings.
The session gave us a deeper understanding of how microplastics are entering Australian farms, the risks they pose to soil and crops, and what steps are needed to tackle the issue.
What Are Microplastics?
Microplastics are tiny plastic particles less than 5 millimetres in size. They originate from the breakdown of larger plastic waste (secondary microplastics) or are manufactured at that size for specific uses (primary microplastics), such as in cosmetics or industrial processes. While much attention has been given to their presence in oceans and waterways, growing evidence shows that microplastics are also infiltrating our soils, particularly in agricultural settings.
Sources of Microplastics in Agriculture
One of the key takeaways from the webinar was the variety of pathways through which microplastics enter agricultural ecosystems. These include:
-
Plastic Mulch Films: Widely used to suppress weeds and conserve moisture, these films degrade over time and leave plastic fragments behind.
-
Biosolids: Wastewater treatment byproducts often used as fertilisers can contain microplastic particles.
-
Compost and Organic Amendments: Contaminated compost materials can introduce plastics directly into the soil.
-
Irrigation and Runoff: Water used for irrigation or flooding can carry microplastics from upstream sources.
-
Atmospheric Deposition: Microplastics can even settle on farmland from the air, carried by wind from urban or industrial areas.
Risks to Soil Health and Crops
Dr. Shima Ziajahromi from Griffith University’s Australian Rivers Institute was a featured speaker at the webinar. Her research has been instrumental in highlighting the environmental risks posed by microplastics, particularly in soil ecosystems.
Some of the key risks discussed include:
-
Soil Structure Disruption: Microplastics can affect how soil particles bind together, impacting aeration and water retention.
-
Microbial Community Imbalance: The presence of plastics can alter soil microbiota, which are critical for nutrient cycling and plant health.
-
Reduced Crop Productivity: Changes in soil chemistry and biology can lead to decreased plant growth and crop yields.
-
Chemical Contaminants: Microplastics can attract and carry harmful pollutants like pesticides and heavy metals, introducing additional risks to food safety.
Moving Forward: What Can Be Done?
To address the growing issue of microplastics in agriculture, a combination of scientific innovation, sustainable land management practices, and informed policy is essential. Awareness and education are also key - farmers, suppliers, and policymakers must work together to reduce reliance on plastic inputs and mitigate their environmental impact.