Axel Barrett Biodegradation & Composting Definitions

Impact of Compostable Plastics on Compost and Soil

Are compostable plastics good for the quality of the compost and soil?

What is Compost and Composting

Compost is organic matter that has been decomposed in a process called composting. Compost is full of nutrients and could be referred to as a kind of soil conditioner.

The word “compost” finds its etymological root in the french word “compote” meaning stewed fruit.

The oldest trace of the practice of composting dates back to the Roman Empire and was mentioned in a work called De Agri Cultura in 160 BCE.

Nature doesn’t produce compost by itself and, initially, doesn’t need compost. Compost is not a natural product and composting is not a natural process, they’re human inventions.

Composting started as a domestic activity before becoming an industrial activity. Home composting is done in your garden and industrial composting is done by commercial composting facilities.

Initially, compost had a dual purpose: waste management and soil conditioner. There were no waste management facilities during the Roman Empire or Middle Ages, so composting was a creative and productive way to deal with food waste. Compost was also used to bring nutrients to and improve soil quality.

Industrial and intensive farming have led to the reduction of soil quality. We can speak of a physical, biological and chemical degradation of the soil. The consequence is that the soil is less fertile and plants and crops grow weaker.

To fight this trend, two products are used in industrial quantities: compost and fertilizers. Compost feeds the soil and fertilizers feed the plants.

Compost has other purposes including

  • regulating soil pH;
  • improving soil texture;
  • regulating moisture;
  • helping microbes transfer nutrients to plant roots.

Compost Nutrients

nutrient is a substance used by an organism to survive, grow, and reproduce. Good compost is rich in following nutrients:

  • Nitrogen
  • Phosphorus
  • Potassium

Compost contains following micronutrients and minerals:

  • Sulfur
  • Carbon
  • Magnesium
  • Calcium
  • Boron
  • Copper
  • Iron
  • Iodine
  • Zinc
  • Manganese

Compostable Plastics

Compostable plastics is an industrial end-of-life option for plastics; it’s a kind of alternative to recycling. There are two types of compostable plastics: home compostable and industrial compostable plastics.

Compostable plastics are polymers (plastics) that degrade through bacterial digestion; the residual waste is a kind of biomass. The biomass are the dead bodies of the bacteria and microorganisms who have degraded the polymer.

Some people refer to this biomass as compost. Technically speaking, it’s not compost as

  • it doesn’t contain useful nutrients for the soil. In the contrary, the biomass resulting from the bacterial digestion of compostable plastics is said to increase the acidity of the soil; and
  • it’s not coming from the degradation of food or garden waste.

It’s referred to as compost because the degradation process takes place at a composting facility.

Contamination of the Compost

It could become a big problem if suddenly all plastic packaging were compostable because the industrial composting facilities would be flooded with plastic waste and wouldn’t be able to deal with the quantities.

It would create a huge mono stream of plastic waste entering the industrial composting facilities. More than being neutral, it would kill the compost … and the soil afterwards.

Conflict of interest

Someone told me that compostable plastics are good for the compost?

Well, ask yourself these questions:

  • Does that person has a financial stake in this business?
  • Is that person working for or is related to BASF? BASF invented compostable plastics and they have the biggest stake in this industry.

Common Sense

What about common sense? What does your intuition tells you? Do you sincerely believe we should dump plastic waste on our farm lands because some multinationals told us that was sustainable? They even call it circular.

Are we going to be remembered as the generation that dumped plastic waste on our farm lands?

I don’t know what to say … I’m speechless.



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