1400 Independence Avenue, SW.

Room 2642-South, STOP 0268

Washington, DC 20250-0268

October 16, 2019 

MEMORANDUM TO THE NATIONAL ORGANIC STANDARDS BOARD

FROM: Jennifer Tucker, Ph.D. 

 Deputy Administrator

 National Organic Program

SUBJECT: Biodegradable Biobased Mulch Film

In response to a recommendation of the National Organic Standards Board (NOSB), 

biodegradable biobased mulch film was added to the National List, effective October 30, 2014 

(79 FR 58655). 

Subsequently, the National Organic Program (NOP) published Policy Memorandum 15-1 

“Biodegradable Biobased Mulch Film” to clarify how certifying agents and material evaluation 

programs should review the biobased requirement for these products. 

Today, the NOP is transmitting a study completed by Michigan State University (MSU), 

“Biodegradable Biobased Mulch Films in Organic Crop Production” (September 2019). This 

study was funded by the NOP to compare the criteria in the final rule to the criteria in the policy 

memorandum and to supplement the technical information on mulch films. The study is attached 

and also available on the NOP’s Petitioned Substances website. 

Following our analysis of all information, we determined that Policy Memorandum 15-1 

(January 22, 2015) did not present new information or impose additional requirements compared 

to the 2014 final rule. The NOP is therefore withdrawing Policy Memorandum 15-1 to 

simplify analysis of options and next steps. A copy of the withdrawn policy memorandum is 

attached for your reference. 

The NOSB Crops Subcommittee should review the MSU study and consider next steps to

advance or conclude work on this topic. 

Attachments: 

Policy Memorandum 15-1 (Withdrawn October 10, 2019) 

MSU Study, “Biodegradable Biobased Mulch Films in Organic Crop Production” 
United States Department of Agriculture 1400 Independence Avenue S.W. Policy Memo 15-1

Agricultural Marketing Service Room 2648-South Building Page 1 of 2

National Organic Program Washington, DC 20250

Policy Memorandum

To: Stakeholders and Interested Parties

From: Miles V. McEvoy, Deputy Administrator 

National Organic Program 

Subject: Biodegradable Biobased Mulch Film

Date: Approved on January 22, 2015 

This policy is directed at certifying agents and material evaluation programs that are reviewing 

biodegradable biobased mulch film products for compliance with the USDA organic regulations 

(7 CFR part 205). 

On October 30, 2014, the USDA organic regulations were amended to allow the use of 

biodegradable biobased mulch film in organic crop production (79 FR 58655). The term 

“biodegradable biobased mulch film” was added to sections 205.2 and 205.601 of the USDA 

organic regulations. The National Organic Program (NOP) has received questions from certifiers 

and material evaluation programs regarding interpretation of the term “biobased” in evaluating 

products for compliance. This policy memorandum clarifies how certifying agents and material 

evaluation programs should review the biobased requirement for these products. 

As explained in the final rule, and consistent with the National Organic Standards Board’s 

(NOSB) recommendation for this material, certifiers and material review organizations should 

review these products to verify that all of the polymer feedstocks are biobased. Pigments and 

processing aids are not considered feedstocks. ASTM International defines biobased as organic 

material in which carbon is derived from a renewable resource via biological processes. 

Biobased materials include all plant and animal mass derived from carbon dioxide recently fixed 

via photosynthesis, per definition of a renewable resource. Biobased feedstocks are composed of 

biological products or renewable agricultural or forestry materials. 

Biodegradable mulch film that contains non-biobased synthetic polymer feedstocks, such as 

petrochemical resins, does not comply with the USDA organic regulations.

References 

Organic Foods Productions Act of 1990, as amended 

7 U.S.C. § 6517 National List 

USDA Organic Regulations (7 CFR Part 205)

7 CFR § 205.2 Terms Defined 

NOP 15-1 Biobased Mulch Policy Memo Authorized Distribution: Public

WITHDRAWN
United States Department of Agriculture 1400 Independence Avenue S.W. Policy Memo 15-1

Agricultural Marketing Service Room 2648-South Building Page 2 of 2

National Organic Program Washington, DC 20250

Biodegradable biobased mulch film. A synthetic mulch film that meets the following criteria:

(1) Meets the compostability specifications of one of the following standards: ASTM D6400, 

ASTM D6868, EN 13432, EN 14995, or ISO 17088 (all incorporated by reference; see 

§205.3); 

(2) 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 (both incorporated by reference; see §205.3); and 

(3) Must be biobased with content determined using ASTM D6866 (incorporated by 

reference; see §205.3). 

7 CFR § 205.601 Synthetic substances allowed for use in organic crop production. 

(2) Mulches. 

(iii) Biodegradable biobased mulch film as defined in §205.2. Must be produced 

without organisms or feedstock derived from excluded methods 

NOSB Recommendations 

NOSB Recommendation for Biodegradable Biobased Mulch Film. 

Approved on January 22, 2015 

If you have any questions regarding this memorandum, please contact Lisa M. Brines at (202) 

720-3252 or lisa.brines@ams.usda.gov. 

NOP 15-1 Biobased Mulch Policy Memo Authorized Distribution: Public

WITHDRAWN
This work was supported by the U.S. Department of Agriculture’s Agricultural Marketing 

Service under Agreement No. 19-NOPXX-MI-0002. Any opinions, findings, conclusions or 

recommendations expressed in this presentation are those of the author(s) and do not necessarily 

reflect the view of the U.S. Department of Agriculture.

Biodegradable Biobased Mulch Films in Organic Crop Production

September 2019

Ramani Narayan

Department of Chemical Engineering & Materials Science

Michigan State University

East Lansing, MI 48824
EXECUTIVE SUMMARY

Plastic mulch film provides significant benefits to farming by increasing crop yields, crop quality, 

enhanced weed control, reduced evaporative water loss, and control of soil temperature. Today’s mulch 

films are carbon-carbon backbone polymers like polyethlene (PE), which is not biodegradable. USDA 

organic regulations permit the use of this “synthetic” PE mulch film if it is removed at the end of each 

growing or harvest season. However, PE mulch becomes brittle due to weathering and fragments. The 

fragments can accumulate in soil and decrease soil productivity by blocking water infiltration, impede soil 

gas exchange, constrains root growth, and alters soil microbial community structures. Removal of these 

heavily soiled mulch films at the end of harvest season for trucking to landfill or recycling centers is 

difficult, laborious, and costly. A solution to the problems created at the end-of-life of the PE mulch film 

is to use completely soil-biodegradable mulch films that retain the performance characteristics of PE films 

but at the end-of-life can be plowed into the soil or recovered for on-farm composting (Sections 1 & 2.0)

This report reviews and analyzes the use of biodegradable, biobased mulch films in organic cropping 

systems. It provides the science of biodegradability, the conditions and end-point requirements for a 

completely soil biodegradable mulch film (Section 2.0, 2.1). The report explains “biobased”, its value 

proposition, and shows with examples that biobased (carbon) content, while valuable, does not impact or 

control biodegradability (Section 2.2 & 2.3). Examples of polymers that are biodegradable and biobased 

are discussed in section 2.4. Fully biodegradable polyester polymers are synthesized from fossil and/or 

biobased monomers and provide viable mulch films that contain biobased content. This is discussed in 

Section 2.5. Discussions around the specific class of polymers used in biodegradable mulch films is 

presented in Section 2.6. Experimental studies, including using isotopic lables, validate complete 

biodegradability in soil. Section 2.7 summarizes field studies of commercial fully biodegradable mulch 

films and concludes that there is no significant effect on soil health (over a two year period) and no 

impact on crop yield or quality.

The report provides discussion and analysis on specific questions asked by USDA Agricultural Marketing 

Services and summarized below:

1. Based on the regulatory language in the current USDA organic regulations (7 CFR Part 

205), what criteria should be used to assess compliance of formulated (brand name) products 

that are available on the market today or to be developed. In addition, what is the threshold 

for minimum biobased content in such formulated products? 

The USDA organic regulations provide the criteria to be met by mulch film polymer products. The 

regulatory language requires biobased content without specifying minimum biobased content. The 

minimum biobased content for these products can be set at 25% or higher similar to the USDA 

BioPreferred program requirements (see Section 4.1). The EU mulch film standard does not specify any 

biobased content requirement. Biobased content has no impact on the biodegradability – the ability of soil 

microorganisms to utilize the carbon mulch film as food/fuel for its life process. A 100% biobased mulch 

film could be totally not biodegradable. Refer to sections 2.0, 2.1 through 2.5 and schemes 6 through 10 

for specific discussions. 

2. Do the evaluation criteria for formulated products differ between the introductory 

(“preamble”) text published in the final rule and the regulatory language of the final rule?

The regulatory language does not specify minimum biobased content, but in the preamble, the use of 

synthetic polymer components is excluded, i.e requiring 100% biobased content. Sections 4.0, 4.1, and 

4.2 discuss and analyze this issue and suggests alternate.
3. Do the evaluation criteria in the AMS policy memorandum dated January 22, 2015, differ 

from the criteria in the regulatory language or the preamble to the final rule? 

Consistent with the preamble and regulatory language. Section 5.0 and section 4.2 discuss and analyze 

this issue.

4. Evaluate currently available formulated products against the criteria delineated in the final 

rule regulatory text, the final rule preamble, and the policy memorandum. Does evaluation 

using these three sets of criteria lead to different outcomes in terms of the number and/or 

types of products that meet the criteria? If no currently available formulated products meet 

any of the three sets of criteria, what specific criteria are not met by currently available 

products? 

As discussed and analyzed in the report, currently available biodegradable, biobased mulch film can meet 

the requirements except for “no synthetic components”/100% biobased content. Section 4.2 explains that 

synthetic substances allowed for use in organic production are (§205.601).:

(i) Plastic mulch and covers (petroleum-based other than polyvinyl chloride (PVC), 

(ii) Biodegradable, biobased mulch film as defined in §205.2. Must be produced without organisms or 

feedstock derived from excluded methods. 

Provided, that the use of such substances do not contribute to contamination of crops, soil, or water.

Polymers described in sections 2.4 to 2.6; schemes 8 through 10 are completely biodegraded (utilized by 

the soil microorganisms) as per standards specified in the organic regulations. The biodegradation process 

is a “naturally occurring biological process” and the end-products of this process are carbon dioxide and 

microbial biomass. Therefore, they will not contribute to contamination of crops, soil or water and 

comply with §205.601 for allowed synthetic substances. 

5. In consideration of the three sets of criteria (i.e., regulatory text, preamble text, and policy 

memo) together, if no formulated products meet the current criteria, outline at least three 

different scenarios for modifying the criteria that would allow for use of some currently 

available mulch films. Describe the impact each scenario might have on the number and 

types of products available, and the tradeoffs between the various scenarios.

As discussed above, the only criteria that needs to be modified and aligned is “biobased (carbon) 

content/no synthetic polymer components requirements. Synthetic substances are allowed as per §205.601 

provided it does not contribute to contamination of crops, soil, or water. The biodegradability 

requirements set by the regulatory text, preamble text, and policy memo will ensure that these 

biodegradable mulch film polymers will not contribute to contamination of crops, soil, or water. 

An alternate scenario would be to permit use of biodegradable “synthetic” mulch film if they are removed 

from the field similar to current PE mulch films followed by composting. This would be more economical 

and environmentally responsible approach to using PE mulch film. The report documents the issues with 

non-biodegradable PE mulch film fragments accumulating in soil with negative impacts on soil health and 

productivity (section 2.0 and references cited there). The use of biodegradable mulch film 

(biodegradability requirements identified in the USDA organic regulations, section 4.0) will ensure no 

build up or accumulation in soil of mulch film fragments. Section 2.7 and the references cited there 

document the benefits and the data indicates that biodegradable mulch films show no adverse impacts on 

soil health and productivity. 

6. Provide a brief review of recent (i.e., post 2015) studies addressing: (1) the persistence of 

biodegradable mulch films (either biobased or non-biobased) following field application; (2) 

the effects of these materials (biobased or non-biobased) on the soil and agroecosystem; and 
(3) the broader environmental and/or economic impacts of using biodegradable films, as 

compared to nonbiodegradable films, in agricultural production. 

Section 2.0, 2.6 and 2.7 and the references cited discuss this point. 

7. Are there USDA Biopreferred® products, produced without excluded methods as defined by 

§ 205.2 of the USDA organic regulations,1 that would meet the criteria for use of 

biodegradable biobased mulch in the USDA organic regulations

There are polymer intermediates and formulations produced without excluded methods in the USDA 

BioPreferred program that could meet the criteria for use in biodegradable, biobased mulch films. 

However, these polymer candidates have synthetic polymer components and are not 100% biobased.

 
Biodegradable Biobased Mulch Films in Organic Cropping Systems

September 1, 2019 Page 2

Contents

1. Introduction................................................................................................................................. 4

2.0 The plastic mulch film problem................................................................................................ 4

2.1. Understanding biodegradability .......................................................................................... 5

2.2. Understanding Biobased ...................................................................................................... 7

2.3. Examples of polymers that are biobased but not biodegradable in soil or compost............ 9

2.4. Examples of polymers that are both biobased and biodegradable in soil/compost. .......... 10

2.5. Examples of fossil based polyesters and copolyesters containing biobased content that are 

fully biodegradable in compost and soil................................................................................... 10

2.6. Biodegradable, biobased polymers used in agricultural mulch films................................ 11

2.7. Field Studies of Biodegradable Mulch Films (BDMs)...................................................... 14

2.8. Additive (oxo or organic) based PE biodegradables.......................................................... 15

3.0. European Union activities on biodegradable mulch films..................................................... 15

4.0. Analysis & Comments on USDA Organic Regulations for use of biodegradable, biobased 

mulch film..................................................................................................................................... 16

4.1. USDA BioPreferred Program ............................................................................................ 17

4.2 The “Synthetics” Issue........................................................................................................ 18

5.0. Analysis and Comments on USDA Policy Memorandum on Biodegradable Biobased Mulch 

Film............................................................................................................................................... 18

6.0. Analysis & Comments on the Preamble to the final rule ...................................................... 19

7.0. References.............................................................................................................................. 20
Biodegradable Biobased Mulch Films in Organic Cropping Systems

September 1, 2019 Page 3

Table of figures 

Scheme 1: Conditions and end-point for completely biodegradable mulch film in soil. ............... 5

Scheme 2: Biodegradation process schematic ................................................................................ 6

Scheme 3: Basic equations describing the microbial utilization of carbon substrates. .................. 6

Scheme 4: Measuring rate and extent of biodegradability using biodegradable polymer as the 

sole carbon source in compost (ASTM D5338, ISO 14855) or soil (ASTM D5988, ISO 17556). 7

Scheme 5: Overview of biobased vs fossil-based product origins, and use of radiocarbon analysis 

to quantify biobased carbon content (ASTM D6866; ISO 16620)................................................. 8

Scheme 6: Scheme showing route to biobased and fossil based PE and PET molecules –

biobased but not biodegradable in soil or compost......................................................................... 9

Scheme 7: Structures of 100% biobased polymers with complete biodegradability in compost 

and soil.......................................................................................................................................... 10

Scheme 8: Overall process for producing biodegradable polyesters and copolyesters using both 

fossil and 100% biobased monomers............................................................................................ 11

Scheme 9: General synthesis of biodegradable copolyesters. ...................................................... 11

Scheme 10: General structure of biodegradable PBAT copolyesters........................................... 12

Scheme 11: Soil biodegradability of PBAT with biobased content – www.ows.be .................... 12

Scheme 12: Radiocarbon composting studies showing complete biodegradation of aromatic 

component of PBAT. .................................................................................................................... 13

Scheme 13: Carbon-13 isotopic labelling experiments showing soil biodegradation of all 

components of PBAT.................................................................................................................... 14
Biodegradable Biobased Mulch Films in Organic Cropping Systems

September 1, 2019 Page 4

1. Introduction

In September 2014, the U.S. Department of Agriculture (USDA) Agricultural Marketing Service 

(AMS) National Organic Program (NOP) revised the USDA organic regulations (7 CFR Part 

205) to allow synthetic biodegradable biobased mulch film in organic crop production (79 FR 

58655; September 30, 2014). Subsequently, NOP published a policy memorandum clarifying 

how certifying agents and material review organizations should review the biobased 

requirements for these products (Policy Memo 15-1; January 22, 2015). 

NOP has received numerous questions about the criteria for biodegradable biobased mulch films

under the USDA organic regulations. Questions have come from USDA-accredited certifying 

agents, material review organizations, manufacturers, organic crop producers, and others.

This report provides a review and analysis of biodegradable biobased mulch films. It discusses 

issues and information gaps in the USDA organic regulations related to the biodegradable 

biobased mulch films. This report suggests scenarios with scientific rationale for modifying the 

regulatory criteria to permit use of currently available biodegradable biobased mulch films in 

organic cropping systems. 

2.0 The plastic mulch film problem

U.S. farmers and farmers worldwide use plastic mulch film for growing vegetables and specialty

crops because they provide significant benefits – increased crop yields, improved crop quality, 

enhanced weed control, reduced evaporative water loss, and control of soil temperature. The 

global agricultural film market is predicted to reach an annual volume of 7.5 million tons by 

2021 with mulch films having a major share (1-2). Currently, China uses the most polyethylene 

(PE) mulch film, with an estimated 1.25−1.4 million tons of film applied annually (3, 4) covering 

approximately 20 million hectares or 12% of China’s farmland (5, 6). 

Today’s mulch films are carbon-carbon backbone polymers like PE, which is not biodegradable. 

Removal of these mulch films at the end of harvest season for trucking to landfill or recycling 

centers is difficult, laborious, and costly. The mulch films are heavily soiled and are not easily 

recycled. PE mulch films, especially thin films, undergo embrittlement and fragmentation due to 

weathering (4, 6, 7). The fragments accumulate in agricultural soils. The Xinjiang region in 

northwest China practices intense mulch film application, and the PE concentrations in soils 

range from 120−350 kg residual film per ha and as high as 500 kg residual film per ha (7, 8). 

This accumulation of recalcitrant PE mulch film fragments in agricultural soils around the world

is cause for alarm because it decreases soil productivity by blocking water infiltration, impedes

soil gas exchange, constrains root growth, and alters soil microbial community structures (3, 9). 

Plastic pollution of soils is also a threat to soil ecosystem health and function (10-12). PE micro 

fragments dispersed in soil and water readily absorb and concentrate toxins present in the 

environment (much like a sponge). Microorganisms colonize these fragments, and the birds and 

fishes eat them because they think it is food. This results in toxins and PE micro fragments being 

transported up the food chain (13). 

A solution to the problems created at the end-of-life of the PE mulch film is to use completely 

soil-biodegradable mulch films that retain the performance characteristics of PE films but at the 

end-of-life can be plowed into the soil or recovered for on-farm composting. Complete soilbiodegradability requires demonstrating 90% + utilization (mineralization) of the mulch film’s 

carbon by the soil microorganisms in the prescribed time (2 years or less for soil 
Biodegradable Biobased Mulch Films in Organic Cropping Systems

September 1, 2019 Page 5

biodegradability). Scheme 1 explains this process and defines the conditions and endpoint for 

completely biodegradable mulch film in soil. 

Scheme 1: Conditions and end-point for completely biodegradable mulch film in soil.

2.1. Understanding biodegradability

Biodegradability is an end-of-life process that harnesses soil microorganisms to assimilate/utilize 

the plastic film’s carbon as food/fuel for its life processes in a safe and timely manner. Terms 

like “oxo”, “hydro”, “chemo”, or “photo” degradable represent abiotic (non-biological process) 

mechanisms of degradation, and do not constitute “biodegradability”. Biodegradability 

represents the biological process by which microorganisms present in the disposal environment 

assimilate/utilize carbon substrates as food for their life processes. Scheme 2 shows this process. 

Polymer chains with susceptible linkages designed into the polymer backbone degrade by 

hydrolytic, oxidative (abiotic), or enzymatic (biotic) reactions to smaller molecules or fragments. 

Microorganisms present in the disposal system (soil, compost) must completely utilize the 

fragments in a defined time as measured by the evolved carbon dioxide to make a soil 

biodegradable or compostable claim (14, 15). 

Measuring the rate and extent of carbon dioxide evolved due to microbial metabolism forms the 

basis of ASTM, European, (EN) and International Organization for Standardization (ISO) 

standards. 

SOIL

Moisture content

Temperature (~ 25 0C)

Soil characteristics

2 years or less

90% +

Molecular structure

(polymer backbone linkage)

Crystallinity

ASTM D5988 test method

EN 17033 Specification mulch film

Lab scale Standard for complete

soil biodegradability
Biodegradable Biobased Mulch Films in Organic Cropping Systems

September 1, 2019 Page 6

Scheme 2: Biodegradation process schematic

Under aerobic conditions, microorganisms biologically oxidize the polymer carbon to CO2

releasing energy as shown in the equation below. Microorganisms harness this energy for its life 

processes in a highly specialized cellular phenomenon that requires the participation of three 

metabolically interrelated processes: tricarboxylic acid cycle (TCA cycle); electron transport; 

and oxidative phosphorylation. All of the processes take place inside the cell. Under anaerobic 

conditions, CO2+CH4 (biogas) are produced (see scheme 3 below). 

Thus, a measure of the rate and amount of CO2 or (CO2+CH4) evolved, as a function of total 

carbon input to the process is a direct measure of the amount of carbon substrate utilized by the 

microorganism (i.e., the percent biodegradation). 

Scheme 3: Basic equations describing the microbial utilization of carbon substrates.

Thus, one can measure the rate and extent of biodegradation or microbial utilization

(mineralization) of the test plastic material by using it as the sole carbon source in a test system 

containing soil or compost in the presence of air and under suitable temperature conditions (25

0

C for soil and 58 0C for compost). Scheme 4 shows a typical graphical output of the percent 

carbon converted to CO2 as a function of time in days. First is a lag phase during which the 

microbial population adapts to the available test C-substrate. Next is the biodegradation phase 

during which the adapted microbial population begins to utilize the carbon substrate for its 

cellular life processes as measured by the evolved CO2. When all the substrate carbon is utilized, 

the CO2 output reaches a plateau. Linear or any other form of data extrapolation is strictly 

prohibited because credible scientific substantiation for the extrapolation model does not exist 

Oligomers & polymer fragments

Hydrolytic

Polymer chains with 

susceptible linkages

Enzymatic

Oxidative

Environment – soil, compost, 

waste water plant, marine

STEP 1

Biodegradation(Step 2): Only if all fragmented 

residues consumed by microorganisms as a food 

& energy source as measured by evolved CO2 in 

defined time and disposal environment

CO2 + H2O + Cell biomass

Complete

microbial 

assimilaton

defined time 

frame, no residues STEP 2

Glucose/C-bioplastic + 6O2 6CO2 + 6H2O; ∆G0’= -686 kcal/mol

Aerobic process

Glucose/C-bioplastic 2 lactate 3CO2 + 3CH4 ∆G0’= -47 kcal/mol

Anaerobic process
Biodegradable Biobased Mulch Films in Organic Cropping Systems

September 1, 2019 Page 7

for such complex biological systems. 

Scheme 4: Measuring rate and extent of biodegradability using biodegradable polymer as the sole 

carbon source in compost (ASTM D5338, ISO 14855) or soil (ASTM D5988, ISO 17556).

Claims of degradable, partially biodegradable, or eventually biodegradable are not acceptable,

because the degraded fragments can have negative environmental and health impacts as 

previously discussed in section 2.0 (10-13). Biodegradable mulch films must demonstrate 

complete biodegradability in two years or less using ASTM D5988 or ISO 17556 test methods

(14, 15). 

2.2. Understanding Biobased (16, 17)

The term “biobased” refers to the origin of the carbon in the polymer molecule and indicates

whether the carbon is derived from plant-biomass or fossil resources. Biobased plastics are 

“plastics in which the (organic) carbon (of the polymer molecule) in part or whole comes from 

plant-biomass like agricultural crops and residues, marine and forestry materials, algae, and 

fungi living in a natural environment in equilibrium with the atmosphere.”

Biobased offers the value proposition of carbon footprint reduction and supports rural agrarian 

economy. Biobased carbon content of a product is the amount of biobased carbon as a percent of 

the total organic carbon in the product. The biobased content is experimentally measured using 

radiocarbon analysis as codified in ASTM (D6866) & ISO (IS1660 pt2) standards. If inorganic 

carbon (talc, calcium carbonate) is part of the plastic, then one can report biogenic carbon 

content which is the amount of biobased carbon (organic + inorganic) as a percent of the total 

carbon (organic + inorganic) in the product. Scheme 5 provides an information capsule about 

biobased products and radiocarbon analysis for quantifying biobased (carbon) content.

0

10

20

30

40

50

60

70

80

90

100

0 20 40 60 80 100 120 140 160 180 200

Time (days)

% C conversion to CO2 (% biodegradation)

lag

phase

biodegradation phase

plateau phase

biodegradation degree 
Biodegradable Biobased Mulch Films in Organic Cropping Systems

September 1, 2019 Page 8

Scheme 5: Overview of biobased vs fossil-based product origins, and use of radiocarbon analysis to 

quantify biobased carbon content (ASTM D6866; ISO 16620)

Plant-biomass (biobased) resources are photoautotrophs. They convert (remove) CO2 in the 

environment to carbohydrates, lipids, and proteins found in plant biomass using water and 

sunlight energy (photosynthesis). Petro/fossil resources (e.g., oil, coal, natural gas) are formed

from plant biomass over millions of years. Therefore, plastics made from plant biomass 

resources can be credited with removal of CO2 from the environment and incorporating the 

carbon into the polymer molecule in a short time (1-10 years). Plastics made from fossil 

resources cannot be credited with any CO2 removal from the environment even if one considers a 

100-year time scale (the time used in measuring global warming potential, GWP100) because the 

fossil carbon has formed over millions of years (16, 17). 

The term “BioPlastics” is used many times in literature and print/e-media to describe “Biobased”

and “Biodegradable-Compostable” plastics without clearly differentiating between them. This 

has resulted in much confusion in the marketplace and amongst stakeholders and the public. 

Biobased refers only to the origins of the carbon in the molecule – the “beginning of life”, 

whether the carbon originated from plant biomass or fossil resources. Biodegradable or 

compostable refers to the end-of-life – whether soil or compost microorganisms completely 

utilize (metabolize) the carbons as their food/energy source. Biobased plastics are not 

necessarily biodegradable or compostable and biodegradable-compostable plastics are not 

necessarily biobased. Sections 2.3 – 2.6 provide details with polymer examples. Biobased 

carbon content in a polymer molecule has no connection with its end-of-life behavior. The 

molecular structure of the polymer, particularly its backbone linkage and physical characteristics

biobased –containing organic carbon of renewable origin from agricultural, plant, animal, 

fungi, microorganisms, marine or forestry materials living in a natural environment in 

equilibrium with the atmosphere. 

CO2 + H2O (CH2O)X + O2

photosynthesis

sunlight energy

Plant-Biomass, Ag & Forestry 

crops & residues

NEW CARBON

Petro-Fossil Resources (Oil, Coal, Natural gas) -- OLD CARBON

> 106 YEARS

1-10 years

PRODUCTS 12C (98.89%); 13C (1.1%); 14C (1x10-10 )

14C/12C = ~ 10-12 in the atmosphere in equilibrium with 

plant-biomass living systems

14C t0.5 = 5730 years; so fossil carbons 

have no 14C carbons remaining -- zero 

radioactivity 

Biobased carbons will have the same 

14C radioactivity as in plant biomass 

and in the atmosphere – providing a 

tracer for carbon in the environment 

to product molecule 

The amount of 14C is measured relative to a more abundant isotope (i.e., 13C or 12C) in the ion beam of an AMS 

(accelerator mass spectrometry) or by decay counting. Absolute quantification comes from comparing the sample's 

measured isotope ratio to that of pre 1950 biobased oxalic acid radiocarbon Standard Reference Material (NIST SRM) 

4990c, (referred to as HOxII) after correcting for isotopic fractionation. Values must also be corrected for the C-14 pulse 

injected into the atmosphere (1950-63) from atmospheric testing of nuclear weapons

 
Biodegradable Biobased Mulch Films in Organic Cropping Systems

September 1, 2019 Page 9

(like crystallinity and morphology), dictate the extent and rate of microbial assimilation 

(biodegradation) in disposal environments – see Scheme 1. 

2.3. Examples of polymers that are biobased but not biodegradable in soil or compost.

Scheme 6 shows polyethylene (PE) manufacture from plant biomass via ethanol fermentation 

and from Naptha/natural gas (fossil feedstock). There is a 220-kton plant manufacturing 100% 

biobased PE from sugarcane in Brazil. As can be seen from scheme 6, the chemical-molecular 

structure of PE and its starting monomer ethylene is the same (identical) irrespective of whether 

the carbon originated from plant-biomass or petro-fossil feedstocks. The biobased or fossil-based

PE molecule has a strong carbon-carbon backbone linkage (bond circled in red) and is 

crystalline. It is the linkage and the crystallinity that renders the PE molecule recalcitrant to 

biodegradation in soil or compost. The biodegradability is not dependent on the origins/source of 

the carbons. The end-of-life option for PE is recycling and not biodegradability or 

compostability. 

Scheme 6: Scheme showing route to biobased and fossil based PE and PET molecules – biobased but 

not biodegradable in soil or compost.

Biobased PET containing 20% biobased carbon content is manufactured by condensing biobased 

ethylene glycol with fossil-based terephthalic acid as shown in scheme 6. Coca-Cola, Danone, 

and several brand owners use biobased PET resin for their packaging. R&D efforts to 

manufacture terephthalic acid monomer from plant-biomass is being actively pursued but is not 

yet a commercial reality. The chemical-molecular structure, physical and chemical 

characteristics of 20% biobased PET or 100% biobased PET or 100% fossil PET is identical. The 

PET molecule has an ester backbone linkage (circled in red in scheme 6), but the hydrophobic 

aromatic ring (50 mol percent), crystallinity, and morphology renders this molecule not 

biodegradable in soil or compost. 

The above two polymer molecules are classic examples of biobased but not biodegradable 
Biodegradable Biobased Mulch Films in Organic Cropping Systems

September 1, 2019 Page 10

products – the biodegradability being evaluated as per ASTM/ISO standards discussed earlier in 

section 2.1, Scheme 3 & 4. 

2.4. Examples of polymers that are both biobased and biodegradable in soil/compost. 

PLA (polylactide) is 100% biobased and fully biodegradable polymer in compost. It is an 

aliphatic polyester with ester group in the polymer backbone similar to PET. Soil

biodegradability depends on the percent crystallinity and morphology of the polymer molecule. 

Microbial polyesters, the PHAs (polyhydroxy alkanoates) is another class of 100% biobased and 

completely biodegradable in soil, and compost environments. Scheme 7 shows the chemical 

structures and the origins of the carbon in this class of polymers. PLA and PHA polymers by 

itself are not readily usable in manufacture of agricultural mulch films because of processability, 

performance and cost issues. However, blends of these polymers with biodegradable synthetic 

polyesters are usable for manufacture of mulch films (see sections 5 & 6 for more discussions). 

Scheme 7: Structures of 100% biobased polymers with complete biodegradability in compost and soil.

2.5. Examples of fossil based polyesters and copolyesters containing biobased content that 

are fully biodegradable in compost and soil

Condensation polymerization of diacids with diols gives polyesters whose properties including 

“biodegradability” is dictated by the molecular structure, crystallinity, morphology and other 

physio-chemical characteristics. As shown in Scheme 8 the diacids and diols can be obtained 

from both fossil and plant-biomass feedstocks. Polybutylene succinate (PBS) is obtained from 
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September 1, 2019 Page 11

the condensation of succinic acid and 1,4-butane diol monomers. It can be 100% fossil-based (so 

called “synthetic”) or 100% biobased or partial biobased depending on the amount of biobased 

monomers used in place of the fossil based monomers. PBS is fully biodegradable in compost

and soil as per the ASTM/ISO standards discussed earlier. 

Scheme 8: Overall process for producing biodegradable polyesters and copolyesters using both fossil 

and 100% biobased monomers.

Scheme 8 & 9 show the general process for producing completely biodegradable polyesters and 

copolyesters with biobased (carbon) content.

Scheme 9: General synthesis of biodegradable copolyesters.

In the above synthesis (Scheme 9), when x and y is 4, the commercial polymer Polybutylene 

adipate-co-terephthalate (PBAT) structure is formed (scheme 10, section 2.7). It is comprised of 

adipic acid, terephthalic acid and 1,4-butanediol monomer units. Replacing these fossil based 

monomers with biobased monomers in part or full will result in a biobased and fully 

biodegradable PBAT. 

2.6. Biodegradable, biobased polymers used in agricultural mulch films

Aliphatic and aliphatic-aromatic copolyesters of the general structure shown in schemes 8 & 9

find application as biodegradable agricultural mulch film. There are several manufacturers of this 

class of polymer resins. 
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Scheme 10: General structure of biodegradable PBAT copolyesters.

As discussed earlier, using monomers derived from plant-biomass feedstocks like succinic or 

adipic acids or butanediol or other diols in the synthesis of these copolyesters (schemes 8 &9)

creates biobased content in the co-polyester molecule. Blending with other biobased polyesters 

like PLA or PHAs (Scheme 7) is another approach to incorporating biobased content. Blends of 

PBAT-PLA are commercially available and used in agricultural mulch film applications.

PBAT and PBAT-PLA blend formulations used in agricultural mulch films show complete 

biodegradability using ASTM/ISO standards referenced in the USDA organic regulations and 

discussed earlier (section 2.1). OWS, an approved, internationally recognized biodegradability 

and compostability testing laboratory reported on the soil biodegradability of an EU certified 

PBAT based mulch film (18). Soil biodegradability study was conducted under ISO 

17556/ASTM D5988, which are specified in USDA organic regulations. Attached graph 

(Scheme 11) shows the results. The PBAT molecule 

Scheme 11: Soil biodegradability of PBAT with biobased content – www.ows.be

shows 94.4% ± 1.7% absolute biodegradation in 180 days. On average, cellulose shows 90.5% ± 

9.6% soil biodegradability based on 79 experiments that ran for 95 to 1,811 days. The minimum 

biodegradability obtained was 73.0% as a minimum and 112.8% as a maximum (18). In longer

Copolyester

C C

O O

O CH2 O C

O

CH2 C

O

m n

x y z

Terephthalic acid Diol Aliphatic diacid

 

 

 

 

ost eca c t a 
Biodegradable Biobased Mulch Films in Organic Cropping Systems

September 1, 2019 Page 13

running experiments, the biodegradation percentage sometimes reaches over100% due to the 

“priming effect” – microorganisms cannibalize dead microorganisms in a carbon-starved 

environment. 

Carbon isotopic labelling studies provide unequivocal experimental evidence that soil 

microorganisms mineralize even the most recalcitrant aromatic carbon of the polymer molecule. 

PBAT has been synthesized with a C-14 radiolabel on the most recalcitrant aromatic carbon 

(circled in red in scheme 10). Biodegradability using ASTM D5338 was studied and the results 

are shown in scheme 12. The data shows that 90% of the radiolabel carbon appears as CO2, a few 

percent in biomass, and some in solution – providing a total (closed) carbon balance and 

validating the complete microbial utilization (biodegradation) of the aromatic component of 

PBAT.

Scheme 12: Radiocarbon composting studies showing complete biodegradation of aromatic component 

of PBAT.

More recently, Zumestein et al, (19) labelled the carbon of each monomer unit in the PBAT 

molecule as shown below:
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September 1, 2019 Page 14

They found that soil microorganisms, including filamentous fungi, used carbon from each 

monomer unit of PBAT. to gain energy and to form biomass. Biomass refers to cellular biomass, 

and the PBAT carbons incorporated into lipid molecules. Mineralization (biodegradation from 

each of the monomer units constituting PBAT) was also observed as shown in scheme 13 below. 

Scheme 13: Carbon-13 isotopic labelling experiments showing soil biodegradation of all components 

of PBAT

Both these experiments unequivocally establish that soil microorganisms completely assimilate 

PBAT in acceptable periods of 2 years or less – a requirement of the USDA regulations. 

2.7. Field Studies of Biodegradable Mulch Films (BDMs).

In the field, the biodegradable mulch films like PBAT, PBAT-PLA, and PHA-PLA blends are 

just as effective as PE mulch in improving the production of specialized crops compared to bare 

soil for several different cropping systems and different environmental conditions. 

Environmental studies have not shown any adverse impacts associated with the incorporation of 

biodegradable mulch films (BDMs) into the soil to date. More research is needed to monitor any 
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September 1, 2019 Page 15

potential formation of terrestrial micro and nanoplastics from biodegradable mulch films and 

ensure that there is no residual soil ecotoxicity. There is need for tuning the physicochemical 

properties of the biodegradable mulch films with the needs of specific cropping systems and 

climates. The biodegradable mulch films could provide additional environmental benefits by 

formulating them to deliver macro and micronutrients to the crop as they biodegrade in soil, or 

deliver pesticides directly into the soil (20).

Sintim et al. (21) showed that there was no significant effect on soil health over two years of 

monitoring and that the soil microbial communities did not differ much either. They found 

significant enrichment in bacterial and fungal gene copies under BDM treatments over 2 years, 

but no significant change under PE and no mulch. Another important observation was that 

repeated tillage of BDMs into the soil across 4 years did not impact crop yield significantly and 

had no major effect on crop quality. 

2.8. Additive (oxo or organic) based PE biodegradables.

Oxo, organic, or enzyme additives added to conventional plastics like PE, do not make these 

plastics biodegradable in soil or compost in any meaningful time. They can break down into very 

small particles, potentially contributing to environmental contamination by microplastics. The 

potential impact of microplastics on the (aquatic) environment and human health have generated 

serious concerns worldwide. The U.S. Federal Trade Commission, the European Union, and 

major NGOs have reviewed the data and the biodegradable claims have not been substantiated

(20, 21). 

3.0. European Union activities on biodegradable mulch films

Biodegradable mulch films have been available on the EU market for many years, meeting a 

high level of acceptance among European farmers. The use of mulch films increase yield, 

improve the quality of crops, enhance weed control, and reduce use of irrigation and pesticides. 

Biodegradable mulch films offers all of the performance characteristics of the standard 

conventional mulch films, but provides the added advantage of being plowed into soil at the end 

of the growing season. Soil microorganism completely utilize these biodegradable mulch films 

as their carbon food and remove it from the soil in 2 years or less.

EN 17033:2018 (24) is the new European product standard developed by the European 

Committee for Standardization (or “CEN”) Technical Committee 249 on Plastics, titled 

“Biodegradable mulch films for use in agriculture and horticulture – Requirements and test 

methods” (available via https://standards.cen.eu/). It specifies the necessary requirements for 

complete biodegradability and appropriate test methods for measurement. The standard is 

expected to be the reference document for farmers, distributors, and stakeholders, and form the 

basis for certification and according labels for biodegradable mulch films. EN 17033 is likely to 

replace other pre-existing national standards in Europe.

EN 13655, the applicable standard for conventional mulch films, was split into two standards to 

include end-of-life options: a) for mulch films that have to be recovered after use (revised EN 

13655), and b) for mulch films that can be incorporated into the soil due to their property of 

biodegradation (new EN 17033).

Specifically:

1. The European Parliament in October 2017 voted to include biodegradable mulch film in 

the EU Fertilizer Regulation. After deliberations by the three EU institutions (European 
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September 1, 2019 Page 16

Parliament, European Council and European Commission) the final text language states 

that the EU will assess the inclusion of biodegradable mulch film in the EU fertilizer 

regulation. 

2. Article 50 on biodegradability review states that by July 16, 2024, the EU Commission 

will carry out a review in order to assess the possibility of determining the 

biodegradability criteria for mulch films. This will include a consideration of 

incorporating them into component material as part of the regulation annex II in 2024.

3. The voluntary consensus European standard EN 17033 assesses and specifies the 

biodegradability and the ecotoxicology parameters together with mechanical and optical 

characteristics of mulch film. 

4. Biobased content is not a requirement of the EN 17033. 

5. The EU Fertilizer Regulation does not include any provision for organic vs conventional 

farming.

6. Countries such as France, Italy, Spain, and Portugal can use biodegradable mulch films. 

The Italian association for organic farming has signed a protocol with the Italian 

association for bioplastics on the use of biodegradable mulch film that meet EN 17033

requirements. 

7. In general, European agricultural stakeholders have reacted positively to EN 17033 and 

they see this document as an important step in defining truly biodegradable mulch films. 

4.0. Analysis & Comments on USDA Organic Regulations for use of biodegradable, 

biobased mulch film

The USDA organic regulations define “biodegradable biobased mulch film” at 7 CFR 205.2 as

synthetic mulch film that meets the following criteria:

(1) Meets the compostability specifications of one of the following standards: ASTM 

D6400, ASTM D6868, EN 13432, EN 14995, or ISO 17088 (all incorporated by 

reference; see §205.3);

Composting represents the most aggressive biological environment, and if the biodegradable

mulch film cannot meet the specification requirements set for compostable products as 

prescribed in the ASTM/EN/ISO standards, then it will not completely biodegrade in soil at 

room temperature conditions. Furthermore, this mandatory requirement ensures that the 

biodegradable mulch film after breakdown in soil will satisfy safety requirements of ecological 

toxicity. It also ensures that minor constituents present at 1 to 10% levels are completely 

biodegradable – see requirement (2) below. 

(2) 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 (both incorporated by reference; see §205.3); and

ASTM D5988 and ISO 17556 are test methods that provide specific guidance on conducting a 

test to measure biodegradability of mulch films under soil conditions. Section 2.1; and schemes 

1 through 4 describe and illustrate the scientific fundamentals and basis for measuring 

biodegradability. Test method standards do not provide pass/fail criteria. Therefore, the USDA 

organic regulations set the pass/fail criteria (specifications) for biodegradable mulch film at 
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September 1, 2019 Page 17

90%+ biodegradability using D5988 or ISO 17556 test methods. 

Note: 90% + biodegradability represents the experimental threshold that must be met to claim 

complete biodegradability or full microbial utilization – the 90% experimental threshold 

accounts for experimental error, few percent carbon remaining tied up in microbial biomass, and 

the statistical requirements of setting an absolute threshold value. The 90%+ biodegradability 

requirement does not imply that 10% of non-biodegradable material can be used in the 

formulations. This is a major misperception. Indeed, compostability specification standards 

ASTM D6499 & D6868 strictly mandate that any other material/s present at levels between 1-

10% must be tested separately for complete biodegradability. This ensures that all of the organic 

components in a mulch film formulation are completely utilized (biodegraded) by the soil 

microorganisms. 

(3) Must be biobased with content determined using ASTM D6866 (incorporated by 

reference; see §205.3).

Section 2.3 explains the concept, the science, and the basis for using biobased (carbon) content 

(ASTM D6866). As explained in that section, biobased (carbon) content is the amount of 

biobased carbon as a percent of the total (biobased + fossil based) organic carbon in the product. 

It provides for a reduced carbon footprint based on the amount of biobased carbon content, and 

experimentally measured using radiocarbon analysis as per ASTM/ISO standards. It supports a 

rural agrarian economy. The USDA BioPreferred Program envisions increasing the purchase and 

use of biobased products. Most importantly, the USDA Biopreferred Program identifies 

products/product categories containing a range of biobased (carbon) content and does not require 

100% biobased (carbon) content. 

4.1. USDA BioPreferred Program

The BioPreferred Program was created by the Farm Security and Rural Investment Act of 2002 

(the 2002 Farm Bill) and reauthorized and expanded as part of the Agricultural Act of 2014 (the 

2014 Farm Bill). The program's purpose is to spur economic development, create new jobs and 

provide new markets for farm commodities. The increased development, purchase, and use of 

biobased products reduces our nation's reliance on petroleum, increases the use of renewable 

agricultural resources, and contributes to reducing adverse environmental and health impacts.

The two major parts of the program are:

• Mandatory purchasing requirements for federal agencies and their contractors

Purchase biobased products in categories identified by the Department of Agriculture (USDA). 

To date, USDA has identified 139 categories (e.g. cleaners, carpet, lubricants, paints) of 

biobased products for which agencies and their contractors have purchasing requirements. Each 

mandatory purchasing category specifies the minimum biobased content for products within 

the category

• Voluntary labeling initiative for biobased products.

USDA wants to make it easy for consumers to identify biobased products. The USDA Certified 

Biobased Product label provides useful information to consumers about the biobased content of 

the product. This label assures consumers that the product contains a verified amount of 

renewable biological ingredients (referred to as biobased content). Consumers can trust the label 

to mean what it says because manufacturer's claims concerning the biobased content are third-
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September 1, 2019 Page 18

party certified and strictly monitored by USDA.

The USDA BioPreferred program defines Biobased Products as products derived from plants and 

other renewable agricultural, marine, and forestry materials and provide an alternative to 

conventional petroleum derived products. Biobased products include diverse categories such as 

lubricants, cleaning products, inks, fertilizers, and bioplastics. For the purposes of the 

BioPreferred Program, biobased products do not include food, animal feed, or fuel. Biobased 

(carbon) content is measured using ASTM D6866. 

4.2 The “Synthetics” Issue.

Item 3 (see section 4.0 above) of the USDA Organic Regulations requires that the mulch film 

must be “biobased” with content determined using ASTM D6866. It does not specifically state 

that 100% biobased content is required. More importantly, biobased content does not impact or 

influence soil biodegradability – see Scheme 1 and section 2.1. However, the preamble to the 

final rule (section 6) indicates that NOSB intended to define biobased so that this category would 

not allow products derived from petroleum – polymers derived from fossil based monomers like 

adipic acid, terephthalic acid, 1,4-butanediol partly or completely – see section 2.6, scheme 8 

and 9. 

Synthetic substances allowed for use in organic production are (§205.601):

(i) Plastic mulch and covers (petroleum-based other than polyvinyl chloride (PVC), 

(ii) Biodegradable, biobased mulch film as defined in §205.2. Must be produced without 

organisms or feedstock derived from excluded methods. 

Provided, that the use of such substances do not contribute to contamination of crops, soil, or 

water.

Biobased, soil biodegradable polymer formulations are available commercially with minimum 

biobased contents 25% for mulch film applications. Increasing biobased content reduces

performance and processability, while increasing cost. These polymers are described in sections 

2.4 to 2.6; schemes 7, 8, & 9. They are completely biodegraded (utilized by the soil 

microorganisms) as per standards specified in the organic regulations. It is a “naturally occurring 

biological process” and the end-products of this process are carbon dioxide and microbial 

biomass. Therefore, they will not contribute to contamination of crops, soil or water and comply 

with §205.601 for allowed synthetic substances. 

The USDA BioPreferred products in the voluntary labelling program have biobased content 25% 

or higher. In the Federal mandatory purchasing program, biobased contents range from 10% to 

90% as designated by the USDA based on commercial availability, cost, and performance.

5.0. Analysis and Comments on USDA Policy Memorandum on Biodegradable Biobased 

Mulch Film (PM 15-1, January 22, 2015; available in the NOP Program Handbook) 

The policy memorandum is generally consistent with the regulatory language, as it relates to 

biobased content and biodegradability requirements at the end-of-life of the product. While the 

following sentence is consistent with the preamble of the final rule, it poses issues in terms of 

currently available mulch films: 

“Biodegradable mulch films that contain non-biobased synthetic polymer feedstocks, such as 

petrochemical resins, do not comply with the USDA organic regulations”. 
Biodegradable Biobased Mulch Films in Organic Cropping Systems

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Polymers described in section 2.4, scheme 7 are 100% biobased and fully biodegradable in soil. 

However, these polymers are not readily processable into mulch films with the required 

performance properties. Polymers described in section 2.5 and 2.6 (schemes 8 through 10) can be 

processed into mulch films with biobased content (but not 100%). The mulch film demonstrates 

complete soil biodegradability using specified ASTM/ISO standards, which is validated by 

isotope labelling studies. 

The USDA BioPreferred program and the legislative language in the 2002 Farm Bill and the 

reauthorized and expanded 2014 Farm Bill defines biobased products as “derived in whole” or 

“in part” from renewable biomass feedstocks like plants and other renewable agricultural, 

marine, and forestry materials. The USDA BioPreferred program products in the voluntary 

labelling program have biobased content 25% or higher. In the Federal mandatory purchasing 

program, biobased contents range from 10% to 90% as designated by the USDA. There is no 

requirement for 100% biobased content. More importantly, biobased content does not influence 

or affect the soil biodegradability of the polymer molecule. 

The process to manufacture PLA and PHAs (Figure 7), polymers used in biobased, 

biodegradable mulch film formulations does not, typically, use excluded methods and contain no 

GMOs. However, it is not clear if this extends to the growing of the crops – U.S. corn in 

particular which provides the starting “sugar” feedstock for manufacturing PLA. Almost all U.S. 

corn is GMO based, and is the feedstock used by the only U.S. manufacturer of PLA. Potato or 

tapioca starch or sugarcane, which may be non-GMO sources, can also provide the “sugar” 

feedstock. Several Chinese and one European company use this sugar feedstock for manufacture 

of PLA. 

6.0. Analysis & Comments on the Preamble to the final rule (79 FR 58655, September 30, 

2014) 

The preamble is generally consistent with the regulatory language and AMS policy 

memorandum 15-1. The following paragraph/statements raises issues that may need resolution:

“We noted that the NOSB intended to define biobased so that this category would not allow 

products derived from petroleum. We understand this to mean that mulch films derived from 

aliphatic aromatic copolymers (AACs), e.g. synthesized from adipic acid, terephthalic acid, and 

1,4-butanediol, would be prohibited. Further guidance in this area may be more appropriate for 

other organizations or agencies with specialized technical expertise in this area. We note that 

this list may need to be updated over time in response to advances in technology”

Currently, fully biodegradable commercial mulch films are not 100% biobased. The new ester 

backbone polymers (schemes7 through 10) are completely biodegradable in soil within two years 

and meet prescribed regulatory requirements except for 100% biobased content. Scheme 7

describes 100% biobased and fully soil biodegradable polymers. However, these polymers are 

not readily processable into films and do not meet performance and cost requirements. Schemes 

8, 9, & 10 describe polymers that can be formulated to give biodegradable mulch films with 

biobased (carbon) content of 25% and higher. The value proposition (as pointed out in the 

beginning section) is its ability to deliver performance and at its end-of-life (end of growing 

season) plowed into the soil where soil microorganisms completely utilize (biodegrade) it as 

food for its life process. Sections 2.0 through 2.2 provides discussion on basics of 
Biodegradable Biobased Mulch Films in Organic Cropping Systems

September 1, 2019 Page 20

biodegradability and section 2.6 schemes 12 & 13 present isotopic labelling studies that validate

complete biodegradability in soil.

Specifying a minimum “biobased content” instead of 100% biobased content would be in 

harmony with the USDA BioPreferred program.

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Bioplastics for a Sustainable Modern Agriculture; Green Chemistry and Sustainable 

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2. FAO. The Future of Food and Agriculture − Trends and Challenges; Rome, 2017.

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plastic film mulch in China. Environ. Res. Lett.2014, 9 (9), 091001.

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(3), 18−19.

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status and distribution characteristics of residual mulching film in Xinjiang, China. J. 

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the soil ecosystem: A review. Environ.Pollut. 2018, 240, 387−395.

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Wagner, M.; Kohler, H.-P. E.; McNeill, K.; Sander,M. Biodegradation of synthetic 

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economy. 2017.

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the use of oxo-degradable plastic, including oxo-degradable plastic carrier bags, on the 

environment, 2018.

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horticulture–Requirements and test methods. European Standard, European Committee 

for Standardization, Brussels, Belgium, 2018.