For the majority of packaging products, their journey ends at the farm gate. After planting seeds, mulching, and harvesting, the mulch film ends up being someone else’s problem after the farmer has finished their job. The issue of plastic pollution does not go away with time.
Conventional polyethylene mulch film does not biodegrade. Polyethylene mulch films continue to be on this planet for decades with virtually no meaningful changes. While they do shred into microplastics and break apart over time, the tiny particles of microplastics are small enough to enter the plant foot and soil pores as well. Researchers at Nanjing Agricultural University found that just 1% microplastic contamination of the soil can result in wheat yields being suppressed by 11%. The degradation process of conventional polyethylene mulch films (PPMF) is slow and not visible, but very cumulative.
The agriculture industry has wanted an answer to this question for quite some time that can a packaging material perform its function and then, when it has fulfilled its purpose, it give something back to the soil as well?
This question is answered by PHA.
Polyhydroxyalkanoate (PHA)
PHA, also known as polyhydroxyalkanoate, represents a natural biopolymer produced by bacteria as a means of storing energy. Specifically, these living organisms create PHA from excess of carbon while experiencing limited nutrient availability.
When PHA-containing products come into contact with soil, PHA-degrading bacteria and fungi (which naturally possess enzymes that degrade PHA) begin to colonise the surface of the PHA product (i.e., “plastic”). The enzymes cleave the polymer into monomers of hydroxyalkanoic acids that are then used by these organisms as energy sources, resulting in atmospheric carbon dioxide and water, and the production of new organisms (biomass). PHA degradation yields no toxic or persistent materials such as heavy metals or microplastics.
A 2023 study published in the Journal of Cleaner Production tracked this process in the field conditions and not in a lab bioreactor or an industrial composting facility at 60°C but in open agricultural soil, ambient temperature and natural microbial community. PHA film reached full degradation within 12 months. The soil microbiome was measurably healthier at month 12 than at the month zero, because the degrading polymer acted as a slow-release carbon substrate which is food for the microorganisms that broke it down.
This is the mechanism that separates PHA from every “biodegradable” plastic currently carrying that label without earning it.
Why “Biodegradable” Is Not Enough?
PLA (polylactic acid) is the bioplastic material used most often nowadays. It really is made out of biological material. It is also degradable but it will persist for years in an agricultural field.
The issue lies in the fine print of the certificates. The majority of biodegradable plastics are certified to an industrial composting standard which is ISO 14855 / EN 13432. Accordingly, they must decompose in a controlled composting facility within 180 days at temperatures between 55 and 70 degrees. If these conditions do not exist, the chemistry will change significantly. For example, PLA (Polylactic acid) will take three to five years or longer to break down significantly in ambient temperature soils with no defined temperature or chemical controls, and it will leave behind residual oligomers that can persist indefinitely.
PHA (Polyhydroxyalkanoates), on the other hand, do not have these same conditions and their rate of degradation is run by enzymes and bacteria, not temperature. The dominant organisms found in agricultural topsoil are mesophilic soil bacteria which harbor the enzymatic capacity to degrade PHA. The enzyme degrading process is actively taking place in ambient temperature soils that are in suitable pH ranges for growth of bacteria typically associated with arable land and in both aerobic and partially anaerobic soil environments. In addition, the results published to date from the field trial in support of this are not the first to support this claim, multiple independent pieces of research going back as far as UMass and Wageningen University substantiate that the rates at which PHA will biodegrade in soil will correspond with the results of the published field trials.
One of the unexpected results of the 2024 Italian field trial evaluating PHA (polyhydroxyalkanoate) mulch films was that the fungal communities in PHA-treated plots were significantly different after decomposition than in the conventional plastic and bare soil controls. For example, beneficial mycorrhizal fungi (organisms that create symbiotic relationships with the roots of crops and enhance phosphate uptake) were 23% more diverse in population numbers in comparison to polyethylene-mulched plots.
This is the PHA mulch films providing a nutrient source to the soil at the end of their functional life. Therefore, a PHA mulch film that is applied in spring and completely decomposes by autumn has added nutrients to the soil over the course of its normal growing season. The complete lifecycle of PHA mulch is consistent and coherent, but not terminated at the point of disposal.
Why TerraPHA Fits In This?
TerraPHA Biotech, India’s first commercial non-GMO PHA biopolymer company, is manufacturing PHA with this entire lifecycle in mind. Their production process uses naturally occurring microbial systems, no genetic modification and a flexible range of renewable carbon feedstocks, making the supply chain traceable and circular.
What distinguishes TerraPHA’s approach is the integration beyond packaging. Their TerraBIO-BS70 bio-stimulant rebuilds soil microbial architecture across cropping systems, the same microbial diversity that PHA degradation supports when it works as designed. Their TerraCIDE-Herbo acts as both a weed suppressant and a slow-release soil carbon source, with zero crop residue which is critical for organic-certified and export-grade operations.
The philosophy is very simple that every input should leave the soil better than it found it. PHA packaging is the delivery mechanism for that philosophy in the packaging space.
Frequently Asked Questions
Q: Does PHA degrade during storage or on the shelf before it reaches the farm?
Not at all. The decomposition of PHA needs enzymatic activity performed by soil microbes. While stored in dry conditions without any interaction with the microbes, PHA will maintain its physical properties. The countdown does not begin until the package goes into contact with the soil. Shelf-stable versions may be produced, with a shelf life of up to 18-24 months under normal warehouse conditions.
Q: Is the CO₂ released during PHA degradation a climate concern?
The CO₂ emitted by microorganisms during their metabolic processes is considered biogenic since it has been extracted from the atmosphere when growing the raw materials that nourished the bacteria, producing PHA. It goes back to the very same atmospheric reservoir where it came from. The net effect on the carbon cycle is significantly less than what petro-plastics bring. TerraPHA production facilities use renewable resources for their processes.
Q: How does PHA degradation differ in waterlogged or flooded field conditions?
PHA biodegradability takes place both aerobically and anaerobically. In the flooded field conditions that prevail during paddy rice cultivation, PHA degradation is accomplished anaerobically. The rate may be slightly slower, but it happens nevertheless and can normally be expected to occur within 18-24 months. The regular plastic, on the other hand, would seal off the anoxic zones, preventing anaerobic processes in fields which play a role in the nitrogen cycle.
