Meet Denis Pozzebon, a sugarcane grower in the Burdekin

Denis Pozzebon at the family farm
© Queensland Government

If no one was willing to test an on-farm bioreactor, then no one would know if it worked.

That's one of the straightforward philosophies of north Queensland sugar producer Denis Pozzebon, who has seen good results since adopting sustainable farming practices.

Based at Mount Kelly in the Burdekin, Mr Pozzebon's farm covers about 128 hectares, producing some 14,000 tonnes of cane most of which gets sent to the Kalamia Sugar Mill.

After seeing a television program about the successful results of installing a ‘bioreactor’ to help manage farm run-off on a pineapple property, Mr Pozzebon put up his hand to host a similar trial. Led by the Department of Agriculture and Fisheries (DAF) in collaboration with the Queensland University of Technology (QUT), the trial on his property involved constructing and monitoring an in-line woodchip bioreactor bed below the floor of a pre-existing drain, downslope of a 2.1ha sugarcane paddock.

The bioreactor bed is a 22m long, 0.6m deep and 1.1m wide trench filled with woodchip with associated rock inlet structure, sediment basin and outlet pipe.  Heavy-duty builders' plastic liner was laid in the trench to create a waterproof seal around the woodchip, to prevent water entering via the soil profile or from the surface. The basic idea of a woodchip bioreactor is to create an environment rich in carbon and low in oxygen to enhance the natural process of denitrification, to remove nitrate (a form of nitrogen) from water.

Mr Pozzebon said it was very pleasing to see there was minimal nitrate running off his sugarcane block in the first instance and satisfying to see the water coming out of the bioreactor was highly filtered.

"I could physically see the difference between the water that goes into the bioreactor and looks a bit murky, compared to the water coming out of it – that’s  crystal clear," he said.

"So I know for a fact that it does work. In a lot of areas it could be used to great advantage, in different industries, not just sugarcane. The potential is there."

The bioreactor trials on Mr Pozzebon’s farm and other farms in North Queensland show that woodchip bioreactors effectively reduce nitrate in farm run-off and shallow groundwater. They are particularly effective in areas with relatively high nitrate concentrations and regular water flow.

Thinking outside

MR Pozzebon has a reputation for being an innovator, something he says came from his late father Ugo, who encouraged him to embrace new ways.

"You've got to move ahead with the times or else you'll get left behind," Mr Pozzebon said.

With global interest in the health of the Great Barrier Reef, businesses and consumers alike are increasingly watching areas of potential impact, including coastal farming. The bioreactor trial will help demonstrate growers are doing the right thing to minimise impacts to the Reef.

Healthy soil healthy crop

SOIL health has been another area of focus for the Pozzebons.

"I've always believed in soil health. If you've got soil health in fallow, you've got that for your whole next ratoon for the next four or five years," Mr Pozzebon said.

Apart from adopting minimal till working practices, paddocks are in a five-year rotation between cane and a mixed legume crop. A blend of seeds including sun hemp, soybeans, cowpea and even sunflowers are planted via a bean planter to help break the monoculture.

"We get an array of different species coming up," Mr Pozzebon said.

The natural reinvigoration of the soil has resulted in a lift in cane crop output.

"The benefits are the increase in yields in the first year and the second year. That's what I'm finding in my cane," he said.

While fertiliser use may have decreased slightly, there was a balancing act to be done.

"You've got to be very careful, even though you are planting a mixed crop... you've still got to apply the right amount of fertiliser," Mr Pozzebon said.

Water from afar

THE installation of a remote, furrow flood irrigation system has brought other environmental benefits for the Pozzebon farm.

The computer-controlled system allows the farm to be irrigated in "sets" at various times, for specific durations, all of which can be started and stopped from the main office at the house. It eliminates the need for Mr Pozzebon to physically go out and switch off valves or pumps. Inter-row sensors send alerts when the water has reached a designated point so that the irrigation can be turned off, saving water, however Mr Pozzebon said he has come to know how long each paddock requires.

"It's about knowing how much water you've got to put on per set," he said. "I can control it from anywhere in the world if I have to."

That was put to the test early on after installation in 2019 when Mr Pozzebon and wife Lisa travelled to Italy just two weeks after it was operational. The system proved its worth with Mr Pozzebon monitoring and adjusting the irrigation while away.

He admits he loves to travel and the technology has opened that up.

"It's given me a better lifestyle. I can travel as much as I want, plus the savings on energy and water, and it's good for the environment as well," he said.

Irrigation water is captured in three large recycle pits and then reticulated back onto crops. Since the automated irrigation was installed, the farm has become even more water efficient. Trapping and reusing water also mean any nutrients and pesticides are prevented from leaving the farm, improving water quality in waterways and the Great Barrier Reef.

"I don't use as much water anymore, which is a good thing," Mr Pozzebon said.

“In fact, we just got some figures from NQ Dry Tropics which show that the automated irrigation reduced the volume of water applied by 13% and lowered our water costs by $47/ha. It also reduced pump energy usage by 23% and lowered energy costs by $223/ha.”

"You've still got to pay for energy, but we aren't wasting any water, put it that way."

Partnership vital

AS with many farming operations, it's a team effort with Lisa Pozzebon taking a substantial role in running the farm as well. As well as helping on the farm, and with farm management, Mrs Pozzebon contributes to the wider sugar industry through involvement with the Women in Sugar organisation, which held its annual conference in the Burdekin in May this year. About 100 women from the various cane growing regions attended the event which included a conference, bus tour and dinner.

Mr Pozzebon said it was valuable for the women within the industry to be involved and across the issues on the farm and the sector as a whole.

“Partners play an important role in farming, and we shouldn’t underestimate their contribution," he said.

Read more to find out about constructed wetland treatment systems.

To find out more about the implications of moving to innovative farm practices, call the Department of Agriculture and Fisheries on 13 25 23 or visit Farming in the Great Barrier Reef catchments.