Researchers in New Zealand say they have found that nine months is all that it takes for merino wool garments to biodegrade when buried in soil. The New Zealand Merino Company (NZM) carried out research where two sets of trials compared the biodegradation behaviour of knitted merino and polyester fabrics when buried in soil. 

Consumer demand is said to have prompted NZM to commission trials comparing the biodegradation behaviour of merino and synthetic fabrics. Complete garments and fabric samples, including an Icebreaker merino base layer, were buried in soil and excavated at various intervals to assess the rate of biodegradation.

The results are said to have come out strongly in favour of merino fabrics, which lost around 36% of their mass after only two months burial in soil and up to 99% after nine months.

The first trials, which included a complete garment burial, were carried out over a six-month period at the end of which it was found that the merino wool garment had lost approximately 60% of its mass.  The researchers say that by comparison the polyester garment did not show any signs of biodegradation.

A second biodegradation trial was also conducted, which compared three weights of merino wool knitted fabric ( 150, 260 and 340g/m2) to a 133g/m2 polyester knitted fabric.  Sampling was carried out at 1, 2, 3, 6 and 9 months and the merino samples lost around 36% of their mass after two months burial and approximately 76-99% at nine months.  Again, by comparison polyester knitted fabric did not degrade at all during the course of the nine-month burial period, the researchers say.

Video of the biodegradation trial and results

Maree Hamilton, a textile specialist from The New Zealand Merino Company, said: “There is a growing global trend toward eco-friendly apparel and textile products. In today’s ‘throw-away’ society the ability of a product to be composted, and to meet the ‘cradle-to-cradle’ philosophy, provides retailers with an important point of difference and is seen as a definite advantage in the market.”

“The active outdoors market is a key segment for us and these consumers make considered choices regarding the impact of their lifestyle on the environment,” Hamilton explained.

“These are people who live, work and play in the outdoors and already appreciate the comfort and performance benefits of merino garments. These new findings further validate their choice and demonstrate a huge advantage of merino over synthetics, which will not biodegrade at all.”

While the researchers did not include other materials apart from wool and polyester in their trials, work has been done on the biodegradation behaviour of cellulosic material, and cellulosic material in comparison to wool fabric, two examples of which are:

Warnock, M., Davis, K., Wolf, D., and Gbur, E., University of Arkansas. ‘Soil burial effects on biodegradation and properties of three celluslosic fabrics’, AATCC Review, January/February 2011, www.aatcc.org

Arshad. K., and Mujahid., M., 2011, ‘Biodegradation of textile materials’, Degree of master in Textile Technology, the Swedish School of Textiles.

The research was carried out by The New Zealand Merino Company with financial assistance from the Wool Research Organisation of New Zealand (Inc).

The New Zealand Merino Company Limited (NZM) is an integrated sales, marketing, and innovation company focused on transforming New Zealand’s merino sheep industry. NZM selectively partners with the world’s best brands, operating as a business extension by providing greater depth through specific expertise, and creating loyal brand advocates.

The New Zealand Merino Company’s Zque Merino brand aims to guarantee the best merino fibre available through an accreditation promgramme that ensures environmental, social and economic sustainability, animal welfare and traceability.

The mission of the Wool Research Organisation of New Zealand (Inc) is to promote, encourage and fund scientific and industrial research, development, technology and information transfer that benefits New Zealand’s post harvest wool industry.