Earthtwine™ is a versatile biodegradable twine that looks and behaves like the plastic twines currently being used in horti- and agricultural applications. It is made from a polymer derived from plant-based starches which gives it the same look and feel as twines made from polymers derived from petro-chemical sources (i.e. conventional plastic). Biodegradable polymers are increasingly being used in short life or single use applications. Since twines used by growers are generally used for a single season, it made sense to look at biopolymers which can be composted as a means of disposal. This provides a real opportunity to divert some plastic waste from landfill.
Extrutec is a Northland based manufacturer specialising in extrusion and product design. We were approached by a large commercial grower looking for a viable alternative to the plastic twines they had to dispose of annually at the end of the season. We worked closely with them to redesign, test and now manufacture Earthtwine™ to specifications that are the same as those of the conventional twine. The added benefit is that this twine can be fully composted at the end of the season without having to be separated from any remaining plant material.
The conventional twines being used in hothouses are generally made from recyclable plastic (PP). So technically the green waste can be recycled in compost and the twine can be recycled in a system that caters for the plastic. The problem has always been separating and cleaning the twine. The twine has to be completely free of plant residues to be accepted for recycling and plant material contaminated with plastic cannot be composted to provide clean compost. As a result, the whole lot usually ends up in landfill. It is simply too labour intensive, time consuming and uneconomical to meet the requirements for recycling and composting under these circumstances.
Earthtwine™ solves the problem. It is not necessary to separate the used twine and plant material at the end of the season. Because the twine breaks down completely into hummus, the whole lot can simply go into a commercial composting system where it will breakdown into compost with no harmful residues. Depending on the temperature and humidity of the individual composting unit, this happens in as little as three months and usually does not take longer than six months. We are currently working with a NZ CRI to complete the required testing for compostability certification.
Earthtwine™ is very versatile. Although it was originally designed to replace the twine used in commercial hothouses, we can adjust its properties to meet the requirements of other growers and users of agricultural twine. It can also be used in vineyards, kiwifruit orchards and to support hops. We have also found that it works very well as baling twine – providing the required strength to hold square bales intact, but gradually breaking down once the bales are out in the environment.
We are very excited about the opportunities this product presents. If you would like to give it a go but not sure if it will work for your particular setup, please get in touch. We are always on the look-out for new ways to use Earthtwine™ and for scenarios to test it in.