Are biodegradable plastics compatible with organic practices?

With the proliferation of plastic in the environment and in our lives generally, it’s no wonder that interest is growing in biodegradable forms of plastic. However, there is an ongoing debate concerning how completely these items biodegrade and how compatible they are with organic principles. One example occurs with biodegradable dishware and cutlery. Although many such products are “biodegradable” and “compostable,” the Organic Materials Review Institute (OMRI) is not aware of any products that meet the organic standards for compost feedstock. These products generally contain prohibited ingredients as binders, or otherwise as part of the manufacturing process. As such, biodegradable dishware is not allowed as a feedstock in compost for organic growers. This means that composters are required to remove such items from any compost intended for the organic market – a time-consuming and challenging step for waste handlers. In order for a compost to be OMRI Listed, the compost manufacturer must first demonstrate this type of “removal step.”

master composter rick carr
Master Composter at Rodale Institute, Rick Carr demonstrates using a compost pile


An even more complex debate surrounds the use of biodegradable “bioplastic” mulches on organic farms. The USDA organic regulations currently permit “mulching with fully biodegradable materials” as well as “Plastic or other synthetic mulch, provided that they are removed from the field at the end of the growing or harvest season.” Some organic producers have misunderstood the allowance for biodegradable mulches to mean that any mulch that is fully biodegradable would be allowed under this section. However, the allowance currently only applies to nonsynthetic materials such as straw and specific synthetic substances like paper mulches.

There are several advantages to plastic mulches, including warmer soil for early season planting, water conservation, and weed suppression, all with minimal impact on the surrounding soil and water resources. They even protect the underlying soil from compaction by air and water, reducing the need for tilling and protecting soil health. However, most plastic mulches are removed and discarded at the end of the growing season, and disposal is a concern. Recycling is possible, but transportation is an issue, and it can be hard to find plastic recyclers in all areas. In addition, the application and removal of plastic mulches requires significant additional labor. All in all, it adds up to a lot of plastic waste and a search for better solutions.

checking the soil

Earlier this year, an effort to allow leave-in-place, biodegradable mulches for organic use generated a lot of enthusiasm and support from all types of stakeholders, resulting in a change to the organic regulations. The 2014 addition of biodegradable biobased mulch films to the National List permits their use in organic production as long as they are not derived from genetically modified organisms and meet the following criteria:

  • Meets the compostability specifications of one of the following standards: ASTM D6400, ASTM D6868, EN 13432, EN 14995, or ISO 17088;
  • Demonstrates at least 90% biodegradation absolute or relative to microcrystalline cellulose in less than two years, in soil, according to one of the following test methods: ISO 17556 or ASTM D5988;
  • Must be biobased with content determined using ASTM D6866

In January 2015, National Organic Program (NOP) Memo 15-1 further clarified that these mulches cannot contain any prohibited ingredients. OMRI researched the availability of such mulches and found no product on the market that meets the standard as written.

Bioplastic mulches are generally made up of several polymers, some derived from renewable vegetable biomass and others from biodegradable fossil fuel materials (petroleum products). For example, some currently available biodegradable mulches are made primarily with polylactic acid, an ingredient derived from corn starch, tapioca root, or sugarcane, but they also contain feedstocks derived from petroleum chemicals. More details about the makeup and manufacturing process are available in OMRI’s Report on Biodegradable Biobased Mulch Films, authored for the USDA.

While manufacturers continue to work on developing a technology that will meet the standards, the debate on whether the benefits are worth the costs continues. If and when there is an OMRI Listed biodegradable, bioplastic mulch, that will be big news indeed!

About OMRI

Founded in 1997, the Organic Materials Review Institute (OMRI) provides organic certifiers, growers, manufacturers, and suppliers an independent review of products intended for use in certified organic production, handling, and processing under U.S. and Canadian organic standards. OMRI is a 501(c)(3) nonprofit organization. When companies apply, OMRI reviews their products against the organic standards. Acceptable products are OMRI Listed® and appear on the OMRI Products List© or OMRI Canada Products List©. OMRI also provides technical support and training for organic professionals.

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