Microplastics and Agriculture

left image microplastics under magnifying lens, right image photo of cattle with heavy duty vehicle dumping biosolids

by Art Hirsch, AHirsch@Terralogicss.com

Plastic and microplastic contamination is prevalent in large and small agricultural operations, posing a threat to current and future food production systems, human health, and the environment. Microplastics are small plastic materials, less than five mm in diameter, and are known to cause environmental risks to terrestrial and aquatic ecosystems and public health. The University of New Castle-Australia and the University of Vienna estimated that globally, each person ingests 0.1- 5 grams of microplastics per week from air, water and food ingestion. 

There are two types of microplastics. Primary microplastics are less than 5 mm and manufactured at a specific size for a given application or function such as cosmetics, industrial cleaning operations, and residential cleaning materials. Secondary microplastics are also less than 5 mm in diameter and are generated from the degradation of plastic materials into the environment from single use plastics (plastic bags, water bottles), synthetic textiles, and construction materials.

Microplastics enter the environment through numerous sources and pathways. Synthetic microfibers can be generated from the degradation of clothing textiles by washing and drying. Microfibers can be released from automobile tires that contain 20% plastic material. Cosmetics and cleaning materials contain microbeads that enter surface water from waste treatment systems. Landfills contain plastic materials such as synthetic textiles from fast fashion disposal. Single use plastics are the #1 source of microplastics that enter the Great Lakes.

Agricultural operations use plastic extensively for numerous applications that promote the use or generation of microplastics, contaminating terrestrial and aquatic environments. Plastic mulch improves agricultural efficiency in water usage and moisture loss. This increase in agricultural productivity by plastic comes with a high environmental cost by generating microplastics. Plastics are highly integrated into agricultural operations such as greenhouse films, plastic mulches, sheeting for hoop houses, product, and plastic irrigation tubes which generate microplastics and soil impacts. Microplastics are used to encapsulate pesticides, herbicides and seeds. Major agricultural sources and pathways for microplastics include biosolids, stormwater, encapsulation, and plastic sheeting mulch.

Pathways for Microplastics

Needed Agricultural Actions

Stopping the accumulation of microplastic pollution in the environment is critical for protecting human health, biodiversity, and even the climate. The quality and integrity of our food and agricultural environment is at stake. The Center for International Law believes that agriculture is one of the most controllable sources of microplastics by using best practices and material substitution. The following are needed agricultural actions that can be done in Michigan to control microplastic generation and transport:

  • Develop legislation that will prohibit the use of microplastic encapsulation for agricultural operations for pesticide, herbicides and seeding applications. 
  • Precautionary microplastic management by the Michigan agriculture agencies and industrial agricultural operations is needed to create proactive best management practices designed to eliminate significant microplastic sources.
  • Increase research on the source, fate and transport of agricultural microplastics.
  • Reduce the dependency of industrial agriculture on chemical fertilizers and pesticides.
  • Increase the public awareness about microplastics in the agricultural environment and food ingestion.
  • Initiate and maintain agricultural awareness and education regarding the implementation of best management practices for plastic management and soil erosion/transport.
  • Use organic mulching materials instead of plastic mulches such as crop residues, tree leaves, rice straws, husks, wood dust and other natural materials.
  • Eliminate the use of microplastic contaminated wastewater for agricultural irrigation.
  • Use regenerative agricultural practices using natural mulches, cover crops and no till practices.
  • Use agricultural manure that is low in microplastics to replace the biosolids.