Wool is a natural and renewable resource. As long as there is grass to eat, sheep will continue to produce wool. When wool is disposed of, it will naturally decompose in soil in a matter of months or years, slowly releasing valuable nutrients back into the earth. Synthetic fibres, on the other hand, can be extremely slow to degrade and significantly contribute to the world’s overflowing landfills.
How does wool biodegrade?
All materials of animal and vegetable origin have some degree of biodegradability, meaning that they are capable of being decomposed by the action of living organisms, such as fungi and bacteria.
Wool is composed of the natural protein keratin, which is similar to the protein that makes up human hair. When keratin is broken down naturally by microorganisms, the products do not pose any environmental hazard.
Wool readily biodegrades in warm, moist conditions
On disposal, if wool is kept warm and moist or buried in soil, fungal and bacterial growths develop which produce enzymes that digest wool.
On the other hand, thanks to the unique chemical structure of keratin and wool’s tough, water-repellent outer membrane, clean and dry wool fibres do not readily degrade. This allows wool products to be resilient and long-lasting in normal conditions.
HOW WOOL BIODEGRADES
How long does wool take to biodegrade?
Wool biodegrades readily in as little as three to four months but the rate varies with soil, climate and wool characteristics. This releases essential elements such as nitrogen, sulphur and magnesium back to the soil, able to be taken up by growing plants. Some studies found more rapid degradation after only four weeks’ burial in soils.
What does wool return to the soil?
On burial in soil, wool becomes a slow-release fertiliser providing nutrients for uptake and growth by other organisms. Some have even used wool fertiliser to foster herb and vegetable growth. Other beneficial effects of adding wool to soils include enhanced water holding capacity, improved water infiltration, soil aeration and reduced erosion.
Wool does not add to landfill volumes or microfibre pollution
Natural fibres biodegrade naturally in a relatively short period in soils and aquatic systems and therefore do not accumulate in landfill and oceans. In contrast, synthetic textiles persist for many decades and can disintegrate to small fragments. A single polyester fleece garment can produce more than 1900 fibres per wash. Ingestion has a negative impact on organisms, sometimes causing death through starvation as plastic replaces food in the stomach.