Minimising Waste And Making Good, Paddock To Mill

By Joseph Borg, Chairman, CANEGROWERS Mackay

The Queensland Sugar industry is celebrated by its peers throughout the world as one of the most environmentally and economically sustainable industries in the world, bringing together farming best practice and near zero waste across paddock to mill.

The Canegrowers Smartcane BMP (Best Management Practice) program is a world-leading independently audited sustainability accreditation program which is widely acknowledged by both our international customers and competitors.
These sustainability credentials give us access to premium markets such as the UK and major buyers like Coca Cola. The BMP program integrates documenting on-farm procedures and inputs including but not limited to nutrient, chemical, tillage, irrigation and all sorts of other factors involved farm operations.
Whilst this BMP program is making headway into proving our industry’s environmental credentials, it is also interesting to take a step back and admire the sugar cane industry’s history around waste and by product integration.

Coming from a farming family, something which we take for granted, as growers, in regard to by-products and waste of the sugarcane harvesting and milling process is actually quite a remarkable but little-told story.
In the early 1990s, green cane harvesting and trash blanket retention was introduced into the central region and revolutionized the industry. It reduced need for the burning of cane almost every night, and gave growers more flexibility in their harvest roster. The trash blanket also has tremendous benefits for moisture retention and weed suppression, acting as a mulch layer on the paddocks.

It also brings a benefit to gardeners and landscapers: cane trash can be used as mulch in the garden and selling that on can be helpful in management of farms if the trash blanket needs to be reduced rather than destroyed.

On the milling side of production, the core business of a sugar mill is to produce high quality raw sugar. There are of course numerous by-products of this process: all are processed, recycled or repurposed and utilised in some way.

A great example of this is mill mud, which is dirt and other impurities from the milling process as well as ash from the boilers. It’s a nutrient-rich by-product and is reapplied to the cane fields to improve soil health and nutrition.

Bagasse, another by-product, is used to power the factory’s boilers to produce steam, which is the energetic heart of a sugar mill. Bagasse is the fibre pulp left when cane is crushed and juice extracted. In some instances, such as Mackay Sugar’s Racecourse Mill, bagasse is used to produce steam from the boilers to power a co-generation plant, supplying clean green renewable energy to the wider Mackay community. A third of the city’s energy needs.

Finally, water is a large by-product of the milling process. As it leaves the factory, water is pumped into the mill ponds where a natural process takes place and the water is purified to strict environmental standards. It is then released back to farmers to irrigate onto their paddocks and produce the next year’s crops.

In a time where we are increasingly looking to circular waste streams, it is positive that sugar has been there historically. The full integration of the sugarcane growing and milling process has been in place for many generations and has successfully operated under a zero-waste management system which should be celebrated by all in the community.

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Paddock to mill, the sugar industry recycles and reuses its waste streams into useful byproducts in a near-zero-waste system. Note the large bagasse stockpiles at Racecourse Mill in the foreground, used not just to power the mill, but also to co-generate energy for Mackay city. Photo credit: Mackay Sugar Ltd

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