What does Biodegradability actually mean?
Biodegradability is nature’s way of recycling. This is what happens when leaves fall in autumn, and then become part of the soil feeding new growth in the spring.
So, what is biodegradability really? And how does it work?
In nature, organic things like leaves, fruit, and carcasses are a source of food for bacteria and fungi. They “eat” the leaves, and in the process produce carbon dioxide and water, and also break the leaves into smaller parts. These small pieces themselves become biomass, which is vital to soil health. The biomass itself contains nutrients that are useful to plants growing in the soil.
One of the basic features of biodegradability is that all of the products and leftovers from the process are completely natural – it’s water, carbon dioxide, and biomass. And it happens using living organisms.
What about composting?
In our lab, we view biodegradation as part of the process of composting, but not all of the process. Composting needs both biodegradation and disintegration to make it work.
When you create a compost heap at home, to help it “work” better you might break the sticks into smaller pieces. This is the starting point of disintegration, and a combination of wind, heat, rain, and specialised fungi will all work to break the materials down into smaller and smaller pieces. But breaking it down into smaller pieces isn’t the whole process. In theory you could do this with plastics, but you still wouldn’t get compost.
The magic of compost is biodegradation, where the bacteria and fungi eat the smaller pieces in order to make soil nutrients, as well as water and carbon dioxide.