The mulch films are thin sheet of plastic that is used directly on the surface of the ground as a kind of a cover for crops. This is because the mulch film helps in trapping soil moisture, preventing sunlight from reaching the soil thus suffocating weed plants that grow and do not require any chemicals and also regulating temperature of roots based on the climatic conditions.
Selection of the material and its thickness depends greatly on the type of crop that is grown and the ground conditions. Lightweight black-black films are great for weed control, while silver-black or white-black films can be used to reflect sunlight to manage temperature and repel pests. Thinner materials, 18-21 microns in thickness are suitable for short season crops, while standard 25-micron thickness is perfect for regular vegetables such as tomatoes, peppers, and cucumbers. In the case of longer growth periods or more rocky soil conditions, farmers move on to films of 30+ microns for extra strength.
Agricultural Plastic Film
Global use of agricultural plastic film is heading for 9 – 14 million tonnes a year by 2030, and it already generates 3 – 5 million tonnes of waste that nobody manages (Zeng et al., 2026). The same review puts yield gains from film mulching at 7% to 48% and soil water retention improvements at 9% to 25%.
What stays behind is the microplastics.
Agricultural films account for 10% to 30% of the microplastics found in farm soils, and concentrations in some fields reach roughly 13,000 particles per kilogram (Zeng et al., 2026).
The Bihar Study
A 2025 survey published in Environmental Pollution sampled 22 sites across six districts of Bihar and separated fields by two variables at once. First, whether they were mulched and second, how close they sat to a road (Karwadiya et al., 2025).
The pattern was unusually clear. Mulched fields beside roads carried 803 ± 371 microplastic particles per kg of soil. Mulched fields further from roads carried 657 ± 143. Unmulched fields near roads still carried 494 ± 327 plastic that too without any farmer putting it there. Unmulched road-distant fields came in lowest at 335 ± 76. Across all sites, counts ranged from 150 to 1,460 particles per kg, with microplastic averaging 7.5 ± 3.6 pieces.
Polyethylene and polypropylene accounted for more than 95% of the recovered plastics. When tested, microplastic films pulled directly from the fields showed noticeably lower contact angles than fresh material—a clear sign that their surfaces had oxidized, making them water-attracting and setting off the initial stages of fragmentation. Crucially, these weathered particles had adsorbed toxic heavy metals like lead, copper, chromium, cadmium, cobalt, arsenic, and zinc, effectively transforming aging mulch from mere plastic litter into active carriers for harmful pollutants. As a result, every field type examined in the study, whether actively mulched or not, was classified as high risk. To address the problem, the researchers offered a direct solution: implement stricter disposal practices and accelerate the switch to biodegradable alternatives.
What “Biodegradable” is Supposed to Mean
However, the label “biodegradable” is always loaded down with many unnecessary tasks on product packaging. So, Europe pinned it down. The European standard, EN 17033, released in February 2018, specifies the exact requirements and tests that need to be conducted on mulch films that are intended to be buried in the soil. Accordingly, a complying film should contain at least 90% degradation of its organic carbon to CO2 after undergoing the soil biodegradation test for a period of 24 months. Also, there is a need to conduct complete ecotoxicity testing so that no harm is done to plants, earthworms, or nitrifying bacteria.
It is the last part that growers tend to miss. The fact that a film might decompose and yet fail the standard is possible due to the reason that fragmentation does not equal degradation. According to Zeng et al. (2026), there have been instances where roughly about 30% of the biodegradable film was transformed into microplastics in two years while complete mineralization stayed limited. Certification is what separates a film that disappears from one that simply becomes harder to see.
Moisture Decides More Than Polymer
The explanation behind these vastly different outcomes lies in one simple laboratory test. Films of PHB and PHBV, both polyhydroxyalkanoates, made inside bacterial cells, were buried in soil at two moisture levels.
In fully saturated soil, both lost most of their mechanical strength within three days and had degraded completely after two weeks. In soil held at 40% relative humidity, the same films looked untouched after six weeks (Kim et al., 2023).
For a grower, the same film behaves differently on a drip-irrigated plot in a dry district than on a flooded field. Match thickness and grade to your own moisture regime, not to a brochure figure.
The Nutrient Factor
A 2026 review in Frontiers in Microbiology found that at field-relevant amounts, PHA degradation has generally caused limited or neutral effects on crops and soil. When PHA is applied heavily or concentrated in one spot, soil microbes consuming that carbon pull hard on nitrogen, phosphorous and sulphur, locking those nutrients temporarily into microbial biomass and leaving less for the crop (Govil et al., 2026). The authors call this a soil-mediated effect, not polymer toxicity. Practically, it argues foe even film distribution and watching nitrogen in the season after incorporation.
How TerraPHA Fits
TerraPHA Biotech, World’s first commercial non-GMO biopolymer company, produces polyhydroxyalkanoate (PHA) from naturally occurring, non-GMO microorganisms. PHA for mulch is one of the few materials that soil bacteria genuinely metabolise, the same microbes that refuse to utilise polyethylene recognise PHA as food and mineralise it in the ground.
A PHA-based mulch is designed to be tilled in and consumed rather than pulled up and hauled away, which removes the two failure points at once i.e. the fragments left behind by removal, and the persistent microplastics left behind by films that only half-degrade. It turns end-of-season plastic from a liability you manage into a step you can skip.
Frequently Asked Questions
Can I plough biodegradable mulch straight into the soil?
Only if the film is certified to a soil-biodegradation standard such as EN 17033, which requires 90% conversion to CO2 within 24 months plus ecotoxicity clearance. Films labelled “oxo-degradable” or only “compostable” do not meet that bar.
Will the film breakdown before the crop is completely ready to harvest?
Mulch film degradation rate depends greatly on the environmental conditions that include the soil moisture content and temperature levels. For example, even though soil saturated with water is able to completely degrade the PHB and PHBV film within just two weeks, dry soil maintained at 40% relative humidity is able to maintain their integrity for more than six weeks (Kim et al., 2023). Since the film performance depends on local field conditions, it is important to disclose your watering program and crops life cycle to the film supplier.
References
European Bioplastics. (2018, February 28). New EU standard for biodegradable mulch films in agriculture published. https://www.european-bioplastics.org/new-eu-standard-for-biodegradable-mulch-films-in-agriculture-published/
Govil, T., Saxena, P., Thakur, K., Sharma, Y., Allen, M., Kaur, J., Samanta, D., Sani, R. K., Salem, D. R., & Sharda, A. (2026). Polyhydroxyalkanoate degradation in soils: Mechanisms, controls, biological responses, and knowledge gaps. Frontiers in Microbiology, 17, 1832091. https://doi.org/10.3389/fmicb.2026.1832091
Karwadiya, J., Kerketta, A. R., Pathak, S. K., Srivastava, S., & Darbha, G. K. (2025). Agronomic practices and road proximity drive plastic pollution in agricultural soils: Insights from Bihar, India on weathering, elemental association, and ecological risk. Environmental Pollution, 384, 126975. https://doi.org/10.1016/j.envpol.2025.126975
Kim, J., Gupta, N. S., Bezek, L. B., Linn, J., Bejagam, K. K., Banerjee, S., Dumont, J. H., Nam, S. Y., Kang, H. W., Park, C. H., Pilania, G., Iverson, C. N., Marrone, B. L., & Lee, K.-S. (2023). Biodegradation studies of polyhydroxybutyrate and polyhydroxybutyrate-co-polyhydroxyvalerate films in soil. International Journal of Molecular Sciences, 24(8), 7638. https://doi.org/10.3390/ijms24087638
Zeng, J., Wang, X., Wang, J., Dong, H., Zhou, Y., MacLeod, M., Cousins, I. T., Li, Y., Xia, X., Graf, M., Jones, D. L., & Liu, X. (2026). The use, fate and environmental impacts of plastic films in agriculture. Nature Reviews Earth & Environment, 7(8), 528-545. https://doi.org/10.1038/s43017-026-00808-9
