Glass sand for turf

SESL Australia

Glass sand, looking a lot like beach sandSports turf needs sand for regular maintenance. The continued removal of sand from “the wild” is depleting resources and contributing to environmental degradation. So why not use crushed glass as a substitute? After all, glass started life as sand, and we throw away more glass than we recycle.

Indeed, SESL’s biggest client, Benedict Industries, has invested substantially in the development of a glass sand product for the construction industry. But what about in agriculture or turf?

World first in New Zealand

Nelson city claims that its Trafalgar Park is the first in the world to use crushed glass as the basis for growing turf. The park was covered with 2800 tonnes of recycled glass sand in readiness for the 2011 Rugby World Cup.

New Zealand can claim another world first with the use of crushed glass sand as a reflective mulch under grape vines. In 2006, Lincoln University’s Food and Wine Group began a trial at Sandihurst vineyard, near Christchurch, laying the mulch under about 200 m of vines. The results showed that the crushed glass has improved soil moisture retention, grape cluster weight, ripening and weed suppression. It will be another couple of years before the quality of the wines can be assessed.

Golf bunkers too

A market study of potential uses of recycled glass in NZ states (Thomas 2005):

“A typical golf course will use 2,000–3,000 tonnes of sand per year for bunkers, divot repairs, and dressing of fairways, greens and tees. UK and USA trials have shown that a significant proportion of this could be replaced by glass sand. In particular glass sand is suitable for root zone construction and conforms to USGA specifications although it requires careful management of pH levels.”

All that glisters …

Research so far shows that recycled glass sand has potential as a substitute for sand, but a study in the UK found that its physical properties need to be improved before it can be used in playing fields (Geary 2007). The problem is that the particles are very angular, as you would imagine crushed glass to be. The study concluded that there is a serious risk of abrasion to players’ skin, and that the particles will need to be rounded off like sand before the material can be considered suitable. In addition, the glass sand has a very high infiltration rate – up to 87 m/day, in comparison with 20 m/day for sand – and will need substantial irrigation.

So for now there is potential for agriculture and turf, but more development still needs to be done.

Further reading

Geary P. 2007. The use of glass derived sand in winter sports pitches. MSc dissertation. Cranfield University, UK.

Thomas C. 2005. Market Study for Recycled Glass in the South Island. Zero Waste New Zealand Trust, Auckland.