Farmers globally use large amounts of nitrogen fertiliser on their fields every year, and cut in half those inputs are unaccounted for by leaching into groundwater, volatiles into the atmosphere, or chemically stored in soils before plants absorb them.
The differences in use rate make this a major concern for the economy and environmental issues. A solution to this problem has emerged. It has been well documented scientifically over the past several decades, and it is becoming both commercially available and require by regulators.
Controlled-release fertilisers with biodegradable coatings that regulate nutrient release patterns/amounts will convert the problem of fertiliser efficiency away from chemistry to that of engineering/designing for more efficient use; they are being developed at a rapid pace.
What Are Biodegradable Coated Fertilisers and How Do They Work?
Controlled-release fertilizers (CRFs) are granules encased in a thin polymer barrier that controls the rate at which nutrients dissolve and leach from the product into the soil. In contrast to standard fertilizers, which release all of their nutrients at once, causing nutrient leaching, volatilization, and eutrophication, coated fertilizers release nutrients in coordination with the plants’ needs.
The coating of CRFs allows for nutrient diffusion from the fertilizer into the root zone of the soil. As moisture from the soil permeates through the coating, dissolved nutrients will diffuse from the coating into the root zone over time. The rate at which nutrients release is governed by three primary factors:
- Coating thickness: Thickness of the coating could slow the rate of nutrient release
- Hydrophilicity of the polymer: A polymer with a higher degree of hydrophilicity could increase the duration of nutrient release
- Temperature sensitivity: Some polymers may release nutrients at a faster rate at higher temperatures; this would occur during optimal plant growth conditions.
The current primary type of commercial coatings are petroleum-based polyurethane or polyolefin coatings. Although these coatings function well, they do not biodegrade, and according to ScienceDirect (2024), these synthetic polymers can take 500 years to decompose in soil. This creates an accumulation of microplastic residue in crop soils globally.
The creation of biodegradable coatings is meant to resolve this issue.
The EU Mandate
The regulatory pressure for the move to biodegradable coatings is now a certainty. According to the ACS Journal of Agricultural and Food Chemistry (2025), the European Union has declared that all components of fertilisers with a coating must be biodegradable by July 2024 and that coating materials must have a minimum of 90% carbon degradation/organic decomposition within 48 months after nutrient release. As such, the modification to the EU Fertiliser Regulation created an environment whereby non-degradable polymer coated fertilisers can no longer be viable products as of 2026 (Nousbo 2025).
These changes will also reshape the global controlled-release fertiliser industry as it currently relates to the estimated annual CRF market of approximately 1.7 million metric tonnes.
Biodegradable Coating Materials
Cellulose and Lignin:
Within the publication by PMC, ACS Journal of Agriculture and Food Chemistry in the year 2025, cellulose as well its derivatives such as cellulose acetate, ethylcellulose, and cellulose acetate butyrate are among the most anticipated biodegradable coating products for the commercial production of controlled-release fertilizers (CRFs).
The cellulose market is expected to reach $144 Billion USD (2024) and $226 Billion USD (2035), based on consumer needs from both agriculture and regulatory agencies. Additionally, Lignin (a by-product of the paper manufacturing process, approximately 50 million tons produced annually world-wide) exhibits natural slow-release properties because the molecular structure of Lignin is hydrophobic which will reduce the amount of water penetrating through when it is placed into the topsoil.
Starch and Biochar-Based Coatings:
Coatings made from a combination of maize starch as an adhesive and biochar produced from maize cob and sewage sludge ash act as dense, hydrophobic barrier coatings that delay the release of nutrients from urea and DAP. The coatings produced with 3 grams of biochar/ash exhibited the greatest length of time for dissolution; these coatings are all made from crop waste and municipal waste.
Bio-Polyurethane Coatings:
Polymers derived from bio-based plant oils (castor oil, palm kernel oil and soybean epoxide) have produced the most advanced biodegradable controlled release fertilizer coating products available to date. These bio-based polyurethane coated products have replaced the use of polyurethanes derived from petroleum for controlled release of nutrients from fertilizers.
Bio-based polyurethane made from palm kernel oil has been used as a renewable coating material for the first time, and the results indicate that this bio-based coating material can provide controlled release of nutrients comparable to that of synthetic coating alternatives. A fully bio-based polyurethane coating was developed and tested in 2025 exhibiting a 27% loss of mass after 12 months of soil burial; this is a significant indicator of the biodegradability of the material and cannot be supported by the same evidence as petroleum-derived coatings.
PBAT/PBS Biodegradable Blend:
One of the most commercially significant results comes from Nousbo in Korea, which has developed a PBAT/PBS based synthetic biodegradable coating that reduces N-P-K fertilizer application on rice crops by 50% when compared to traditional application methods. Furthermore, the performance of the rice crop is equal to that of traditionally grown rice crops. This has not only been tested in a research facility but is also a production ready system being launched into the marketplace in early 2025 and targeting Europe’s estimated 500,000 tonne annual CRF market.
Let’s do the performance comparison,
Biodegradable vs Conventional Coatings:
|
Coating Type |
Is it Biodegradable |
N Release Control |
Soil Residue |
Key Source |
|
Polyurethane (petroleum) |
No |
Excellent (100+ days) |
Microplastics persist 500 yrs |
ScienceDirect, 2024 |
|
Sulfur coating |
Partial |
Moderate |
Acidifies soil |
Standard industry |
|
Cellulose/lignin |
Yes |
Good (30–90 days) |
90% degradation <48 months |
ACS JAFC, 2025 |
|
Starch + biochar |
Yes |
Moderate-good |
Fully biodegradable |
Springer Nature, 2025 |
|
Bio-PU (plant oil) |
Yes |
Excellent (comparable to synthetic) |
27% mass loss in 12 months |
Arabian J. Chem., 2025 |
|
PBAT/PBS blend |
Yes |
Excellent; 50% less fertiliser needed |
Fully biodegradable |
Nousbo, 2025 |
Frequently Asked Questions
Q: How do biodegradable coatings improve fertilizer efficiency?
With the help of biodegradable coatings, which create a diffusion-based membrane for the fertilizers, nutrients are released according to the needs of plants, thus avoiding nutrient loss due to the problems such as leaching, volatilization, and fixation. Such coatings can enhance crop production while minimizing nutrient pollution.
Q: Are biodegradable fertiliser coatings now required by law?
Indeed, in the European Union, biodegradability of coating materials is compulsory starting July 2024. All components used in fertilizers have to degrade at least 90% in organic carbon form within 48 months of release. In addition, non-degradable coatings will be banned in the EU as of 2026.
Q: What are the best biodegradable coating materials for fertilisers?
As of today, some of the most successful biodegradable fertilizer coating materials are cellulose derivatives (cellulose acetate, ethylcellulose), lignin, starch composite materials, plant oil (castor, palm kernel, soybean) bio-polyurethanes, and PBAT/PBS blends.
Q: Can biodegradable coated fertilisers replace conventional coated fertilisers commercially?
Yes, several methods already show comparable performance and even advantages over existing technologies. For instance, PBAT/PBS-coated fertilizers provided a 50% reduction in the NPK content while yielding equal rice harvests. Biodegradable coatings have been shown to provide similar release curves as the synthetic alternative.
Concluding
Coatings for fertiliser that are biodegradable exist in the area of agronomic efficiency, environmental need, and regulatory compliance. All three of these driving forces are moving together in the same direction at the same time.
From starch-biochar composites built from crop waste, to bio-polyurethanes derived from plant oils, to PBAT/PBS blends that cut fertiliser use in half. The materials science is mature, the regulatory mandate is active, and the commercial transition has begun.
The question isn’t whether or not conventionally manufactured coatings will be replaced by biopolymer coatings, the question is in fact about the rate at which this transition will occur.
