Biofilm Issue Brief


Farming is a challenging occupation - particularly when one is committed to ecological methods. So when a new tool or technology comes along that can improve efficiencies and crop yields, while reducing negative environmental impacts, it deserves careful consideration. 

One relatively new tool is known as "biodegradable plastic mulch film", or biofilm. Many believe biofilm is an asset to sustainable farmers, and have recommended it be allowed in CNG operations, with some restrictions. However, to date CNG's certification standards haven't explicitly addressed biofilm. We have polled our members on whether they support the use of biofilm on CNG operations, and on the draft standards below, in particular. While there are diverse opinions on the issue, overall we found significant support for this update to our weed management standard.

Biofilm offers an alternative to the commonly used black plastic film made of polyethylene. Unlike black plastic, which must be taken up and discarded at the end of the growing season, biofilm is designed to break down in the soil. Biofilms save hours of labor required with black plastic, and reduce solid waste going into landfills. While it's not a great fit for all farming operations, depending on their soils and climate, we have concluded that it can be a valuable asset that will enhance the sustainability of many farms. 

Before we make this policy official, we're seeking input from the public on our proposed update to CNG's weed management standard. The public comment period will remain open until August 30, 2017.

The proposed updates are indicated below in red. 


Draft CNG Weed Management Practice Standard

Weed problems may be controlled through the following methods:
  • Mulching with natural or paper-based fully biodegradable materials
  • Hand weeding and mechanical cultivation
  • Mowing
  • Livestock grazing
  • Flame, heat or electrical means
  • Woven landscape fabric, provided it's removed before degradation
  • Polyethylene mulches, provided that they are removed at the end of the growing or harvest season
  • Biodegradable plastic mulch film, or biofilms, with the following restrictions:
    1. CNG producers must register their use of biofilm and provide feedback to CNG when requested at the end of the growing season
    2. Oxo-degradable and photodegradable plastic mulch films are prohibited
    3. Repeated use of bio-based plastic mulch film in the same location for multiple years in succession is strongly discouraged
    4. CNG may prohibit continued use of biofilm on a particular property if the degradation rate appears low, according to CNG's best judgement informed by consultation with inspector


We recognize that some people have reservations about biofilm, given the newness of these products, the lack of long-term research on their impact on the microbiology of the soil, and the fact that they don't always fully biodegrade in actual farm conditions, even if they do in commercial composting facilities. Further, there are currently no biofilms on the market today that are approved for use in certified organic operations. (While biofilms have been approved "in theory" for organic farms, there are no actual products on the market that meet the particular definition of biodegradable that was set by the USDA organic program.)

However, we believe that today's biofilm products offer farmers a good alternative to polyethylene sheet plastic mulch, with a considerably smaller environmental footprint. Whereas biofilm can be turned into the soil post harvest, and can break down within a year or two, plastic mulch must be taken up at the end of the season and will remain as solid waste for decades or centuries. Rarely can it be re-used. In 2004, 143,000 tons of agricultural plastic mulch were discarded.* Most agricultural plastic waste is sent to landfills, where it doesn't biodegrade. Sometimes black plastic gets burned, putting dioxins and other toxic fumes into the atmosphere.

Farmers have found the effectiveness and cost efficiency of biofilm a great benefit to their farm's success. Many have found that their soils and climates allow for thorough degradation of the biofilm, with little to no residue whatsoever. University-based soil scientists researching biofilms have not identified any negative impacts on the microbiology of the soil. We will continue to monitor their ongoing research in case their findings indicate a refinement of our standards.

Biofilms aren't a good fit for all soil types or climates. But we believe farmers should have access to all available tools that can enhance their farm's sustainability, taken holistically to include social wellbeing, economic impact, and environmental impact. 

Kindly provide us with your feedback on this proposed update to CNG's weed management standard. The public comment period will remain open until August 30, 2017.



*Overview by eXtension on plastic mulch and biodegradable plastic mulch in organic operations

To view our infographic on this issue, visit our blog post "Seeking Comments on Draft Biofilm Standard"