Biodegradable Mulch Film for Organic Production Systems

Biodegradable mulch film is considered to be a sustainable technology with several potential advantages as compared to traditional plastic mulch, such as: reduced labor costs (biodegradable mulch does not need to be removed from the field), cost savings for disposal, and reduced landfill waste. Effective 30 Oct. 2014, the USDA-AMS National Organic Program (NOP) added biodegradable biobased mulch film to their list of allowed substances for organic crop production. Biodegradation of biobased mulch film is considered to be a form of removal at the end of a growing season. To be considered biodegradable and biobased, a mulch film must: 1) reach at least 90% degradation in the soil within two years or less in accordance with ISO 17556 or ASTM D5988; 2) be biobased in accordance with ASTM D6866; and 3) must meet compostability specifications of one of the following standards: ASTM D6400, ASTM D6868, EN 13432, EN 14995, or ISO 17088. In addition, a biodegradable biobased mulch film may not be produced with organisms or feedstock derived from excluded methods, and it may not be produced with non-biobased synthetic polymers; minor additives such as colorants and processing aids are not required to be biobased. Field research results show variability in degradation of biodegradable biobased mulch film in soil across diverse sites such that some products may not achieve 90% degradation within 2 years. Factors that affect degradation include climate, soil type, pH, microbes, irrigation, and other production practices. If more than 10% of the mulch remains in the soil after 2 years, the grower will be in non-compliance with organic certification standards. Organic certifying agencies are responsible for verifying that adequate degradation of biodegradable biobased mulch film has occurred in the soil, however there is no established, verified protocol for this measurement. If biodegradable biobased mulch film is used on the same field for consecutive years, it is not clear how the grower or inspector will differentiate between mulch that remains after 2 years and mulch that has been in the soil for less than 2 years. There is an assumption that the remaining 10% of the biodegradable biobased mulch film will degrade in the soil after 2 years but this is not specified in the rule. At this time, no biodegradable mulch films available in the U.S. are allowable for use in certified organic production systems primarily because they do not meet the standards regarding non-biobased content.