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Special Topics

Agricultural Plastics

Material Description

The term "agricultural plastics" (or "ag plastics") covers a wide variety of products and plastic types. These include:

  • Low density polyethylene (LDPE) and low linear density polyethylene (LLDPE) film used to make silage and haylage bags, bunker silo covers, greenhouse covers, bale wrap, mulch film, and other flexible products.
  • High density polyethylene (HDPE), a more rigid plastic used in pesticide containers and nursery pots.
  • Polystyrene (PS), another rigid plastic used in nursery containers and flats.
  • Polypropylene (PP), used in nursery pots, row covers and woven tarps.

Plastic products are used for an increasing number of purposes in agriculture and at nurseries and greenhouses because of their durability, flexibility and low costs. Dairy industry experts estimate that approximately 15-20 pounds of all types of ag plastics a year are used per cow. A 300-head dairy farm using plastic silage bags may produce as much as 6,000 pounds a year of waste plastic.

Environmental Impacts

Burning plastic can release toxic and potentially cancer-causing chemicals into the air, where they can be inhaled by humans and animals and deposited in soil and surface water. Residue from burning contaminates the soil and groundwater and can enter the human food chain through crops and livestock. In addition, certain chemicals released by burning can accumulate in the fats of animals and then in humans as we consume meat, fish and dairy products. Because agricultural burning often occurs near food sources, it is particularly important to reduce this health hazard to food production.

Some of the most dangerous chemicals created and released during burning some types of plastic are dioxins and furans, many of which are highly toxic. Dioxins, which are byproducts formed when chlorine-containing products are burned, tend to adhere to the waxy surface of leaves and then enter the food chain. Even if certain types of plastic (such as polyethylene or polypropylene) do not contain chlorine, other materials burned with the plastic may be a chlorine source.

Other chemicals released while burning plastics include benzo(a)pyrene (BAP) and other polycyclic aromatic hydrocarbons (PAHs), which have both been shown to cause cancer. If film or containers are contaminated with pesticides or other harmful substances, those will also be released into the air. If plastics are burned with other materials, additional toxic chemicals may be created from the interaction of the different substances.

For more information on the health and environmental effects of open burning, visit the DNR's open burning pages.

Unburned portions of the plastic become litter on the ground and in lakes and rivers. As it disintegrates, animals may eat the plastic and get sick. Larger pieces of plastic can become a breeding ground for diseases, such as by trapping water that provides habitat for mosquitoes.

Too Valuable to Waste

There is a growing worldwide demand for many types of used plastic, which can be reused, recycled and turned into new products, or in some cases incinerated in controlled conditions to generate energy. While there are currently few recycling options in the upper Midwest, there are well-established recycling markets in other parts of the country and we anticipate that there will soon be infrastructure for collecting and reusing these valuable plastics in Wisconsin.

Legal Requirements

Burning plastics and most other garbage--whether in the open or in burn barrels--is illegal in Wisconsin under ss. NR 429.04 [PDF 8KB, exit DNR] and NR 502.11 [PDF 194KB, exit DNR], Wis. Adm. Code.

Preferred Handling Option: Recycle or Landfill

Take used pesticide containers or containers with leftover chemicals to an agricultural Clean Sweep in your area. Visit the Department of Agriculture, Trade and Consumer Protection's Clean Sweep page [exit DNR] to see when an event will be held in your area and learn more about what is accepted at Clean Sweeps.

In Wisconsin and other parts of the country, options for recycling silage bags, bale wrap, bunker silo covers and other plastic films are starting to emerge. The biggest challenge in recycling these materials is cleaning, collecting and transporting the film, which can then be processed and used in products such as plastic lumber and garbage bags. Recycling options are also developing for nursery pots and other more rigid plastics. Ask your suppliers about recycling options and let them know you'd like to be able to recycle your used plastics.

For now, send any plastics you cannot recycle to the landfill, rather than burning or burying them on your land.

For More Information

Last Revised: Tuesday May 13 2008