The science
How Biodegradable Mulch Film Works: From Field to Biomass
A good biodegradable mulch film has two jobs: perform like premium mulch all season, then break down completely once the crop is off. Here is what happens at each stage — in the field and in the soil.
Stage 1 — During the season: a better seedbed
While the crop is growing, būmigro mulch film does the same work as any high-performance mulch — it shapes the environment around the roots so the plant can focus its energy on growth.
A better environment for roots
By covering the soil, the film prevents extreme temperature swings, keeping the root zone warmer in cool weather and cooler in intense heat. That stability promotes healthier, more vigorous root growth, which is essential for a plant to absorb water and nutrients efficiently. The film also locks in soil moisture, giving plants a consistent water supply even during dry periods.
Eliminating competition
Weeds compete directly with crops for water, sunlight, and nutrients. The film provides effective weed suppression by blocking sunlight from reaching the soil, which prevents weed seeds from germinating — eliminating the need for herbicides and reducing the labor of manual weeding. The detail on this is in weed control without herbicides.
Stage 2 — After harvest: from film to biomass
The defining feature of a soil-biodegradable film is what happens once the season ends. Such films are designed to be tilled into the soil, where microorganisms convert them into carbon dioxide, water, and microbial biomass[1],[2] — the same natural end products as any organic matter decomposing in the field.
What controls the speed
- Soil temperature. Warmer soils host more active microbial communities, which speeds breakdown.
- Moisture. Microbial activity needs moisture; breakdown slows in very dry conditions.
- Microbial activity & incorporation. Healthy, biologically active soil — and working film residue into the soil — accelerate the process.
Because these factors vary by region and season, the exact timeline varies too. The mechanism, however, is the same everywhere: soil biology does the cleanup for you.
Why this isn't “just bioplastic”
A true soil-biodegradable film mineralizes fully — it does not simply fragment into smaller and smaller pieces. That is the critical difference from PE plastic and from many PLA-based bioplastic films: if a biodegradable plastic isn’t fully degraded in soil, it can leave persistent fragments and microplastics behind.[1] The recognized soil-biodegradation standards — EN 17033 in Europe and ISO 23517 internationally — require that at least 90% of the film’s carbon converts to CO₂ within two years at ordinary soil temperatures, which is what separates a field-ready film from one made only for industrial composting.[1],[2] For the full comparison, see biodegradable mulch film vs. plastic.
Frequently asked questions
When does the film start breaking down?
What does it break down into?
How long does full breakdown take?
Do I need to remove anything?
References
- 1.Bandopadhyay, S. et al. (2023). SOIL, 9, 499–516 — soil-biodegradable mulches are converted by soil microbes to CO₂, water, and microbial biomass; EN 17033 requires 90% mineralization of mulch carbon within 2 years. Link
- 2.Singh, M. (2025). Biodegradable Plastic Mulch: Is it Right for your Farm? UC Agriculture & Natural Resources. Link
- 3.Withana, P.A. et al. (2025). Biodegradable plastics in soils: sources, degradation, and effects. Environmental Science: Processes & Impacts (RSC). Link
- 4.European Bioplastics. New EU standard for biodegradable mulch films (EN 17033): soil-biodegradation at ambient soil temperature, distinct from industrial-composting standards such as EN 13432. Link