Forty-one growers from Mareeba to Ingham have trialled changes to their cane-growing practices across 10,000 hectares of land to find the ‘sweet spot’ for productivity and sustainable agriculture.

Changes have ranged from using enhanced efficiency nitrogen fertiliser and applying fertiliser at variable rates to improving soil health through compost production, mill mud application and planting legumes fallow crops. They have also included upgrading soil and yield mapping to better understand each cane block.

The Wet Tropics Reef Trust IV Repeated Tender program is funded by the Australian Government and delivered by Terrain NRM in partnership with Cairns Canegrowers, Herbert Cane Productivity Services and Tully Canegrowers.

Hear from Abergowrie grower Andrew Vella:

Andrew Vella – Abergowrie

Abergowrie cane grower Andrew Vella’s change to enhanced efficiency liquid nitrogen fertiliser has enabled him to average 140kg per hectare on the family’s farms, which collectively have 300 hectares under cane.

Application is down to between 80 and 100kg per hectare on plant blocks – depending on whether he can get a legume crop in or not – so that rates can remain higher on ratoons.

“With the rising cost of fertiliser, you don’t want to waste it. But when you’re cutting back on nitrogen you want to still be able to maximise your production. You want the plant to use the whole lot. It’s a challenge because our growing season varies every year. Sometimes we get a lot of late growth.”

Enhanced efficiency fertilisers

He believes new products, like enhanced efficiency fertiliser, are the key to dropping nitrogen fertiliser rates because “you’re not losing as much nitrogen to volatility or leaching”. But they are currently a more expensive option – and that’s where the Wet Tropics Reef Trust IV Repeated Tender program has helped.

Thirty-eight growers from Mareeba to Ingham have trialled changes to their cane-growing practices across 10,000 hectares of land to find the ‘sweet spot’ for productivity and sustainable agriculture.

Changes have ranged from using enhanced efficiency nitrogen fertiliser and applying fertiliser at variable rates to improving soil health through compost production, mill mud application and planting legumes fallow crops. They have also included upgrading soil and yield mapping to better understand each cane block.

The Wet Tropics Reef Trust IV Repeated Tender program is funded by the Australian Government and delivered by Terrain NRM in partnership with Cairns Canegrowers, Herbert Cane Productivity Services and Tully Canegrowers.

Hear from Ingham grower Paul Marbelli:

Paul Marbelli – Ingham

Third-generation cane farmer Paul Marbelli describes the last three years as a ‘learning curve’. But he says they’ve led to cost-savings and a much better understanding of what his soil needs across 200 hectares of diverse cane blocks.

The Ingham grower reduced his inorganic nitrogen use to an average of 135 kilos per hectare over plant and ratoon cane with the “peace of mind” that the Wet Tropics Reef Trust IV Repeated Tenders program was a financial buffer if he’d dropped too far for his land and the seasons.

“I probably reduced it a little too much,’’ he said. “Now I know how low I can go before starting to lose production when conditions are not as favourable, I’m back around the 140 mark and following soil tests and the Six Easy Steps nutrient management program to the letter.”

The project also helped him to move into variable rate fertiliser application. “Getting a rate control system fitted means we know more accurately how much fertiliser we are placing, so we can be more confident in reducing nitrogen.”

In addition, the Marbellis have focused more on their mill mud application.

“Our farms are close to the mill so we’ve used a lot of mill by-products over the years. But previously we haven’t reduced our fertiliser rates where we’re using mill mud. Now we’ve got more confidence to do that. With fertiliser prices doubling, there is plenty of incentive. There are huge cost savings in finding the balance between minimising impacts on the environment and maintaining a productive farming business.”

The Marbelli family’s farms have creeks crossing through them that flow to the Herbert River. There are wetlands and sediment ponds on most of their properties.

Thirty-eight growers from Mareeba to Ingham have trialled changes to their cane-growing practices across 10,000 hectares of land to find the ‘sweet spot’ for productivity and sustainable agriculture.

Changes have ranged from using enhanced efficiency nitrogen fertiliser and applying fertiliser at variable rates to improving soil health through compost production, mill mud application and planting legumes fallow crops. They have also included upgrading soil and yield mapping to better understand each cane block.

The Wet Tropics Reef Trust IV Repeated Tender program is funded by the Australian Government and delivered by Terrain NRM in partnership with Cairns Canegrowers, Herbert Cane Productivity Services and Tully Canegrowers.

Hear from Tully grower Mario Quagliata:

Mario Quagliata – Tully

The old days of “six bags to the acre” are gone on Mario’s cane farm in the Tully region. Ask him how he’s successfully dropped his rates from 187 to 140kg of inorganic nitrogen per hectare and he’ll tell you he’s been using “witches brews”.

Mario has trialled bio-stimulants among a range of other changes, and he credits that with the reversal of an initial drop in yield when the Wet Tropics Reef Trust IV Repeated Tender program began on his land.

“In the first two years it felt like we were going backwards. But last year we saw yield increase that looks to be a combination of very favourable growing conditions and, we’re thinking, a liquid product that supposedly unlocks phosphate in the ground. I’m applying it at the same time as fertiliser and it looks to be giving the cane something to balance out the lower nitrogen input.”

Mario has also tried seaweed and worm juice as supplements in recent years, with varying results.

Extending bio-stimulant trial

He’s now looking at extending the current bio-stimulant trial to other parts of the farm. He has 400 hectares under cane with owned and leased land. He’s also adopted semi zonal tillage and legume systems.

The home farm has a bioreactor which was constructed as part of the Wet Tropics Major Integrated Project – a 10-metre trench between sugarcane paddocks and a nearby drain that is trapping paddock run-off. Water is slowly filtered through woodchips, where bacteria strips it of nitrates.

“We keep trying. The funding and assistance helps. We need a few more years to see the results given all the variables, and to see if other products come on board.”

Riverside revegetation projects in the Wet Tropics are proving to be a win-win – they can solve rat problems for cane farmers while also stabilising river banks and improving the quality of water flowing to the Great Barrier Reef.

Growers and researchers have reported a 70 to 100 per cent reduction in rat numbers after tree planting initiatives on land between cane crops and waterways. And growers who are involved say crop damage from rats becomes largely a thing of the past.

Here are three examples:

Frank Gatti, Woopen Creek near Innisfail

A dramatic decrease in rats was a major benefit of cane farmers Frank and Stephen Gatti’s revegetation project. The Gattis revegetated 3.5 kilometres – a 30-40m strip between cane and creek – as part of a trial in partnership with the Bureau of Sugar Experimental Station and Queensland Parks and Wildlife 25 years ago.

The intention was to reduce rat numbers – and it worked.  After 12 months an 80 per cent reduction in the rat population was recorded.

“There was no grass for the rats anymore,’’ Frank said.  “We left some sections with grass initially for the trial.  As part of the trial, rats were captured in the grass areas but there was virtually nil capture of rats where we had revegetated. We have virtually eliminated them.”

Before the revegetation project, rats would usually decimate more than 20 metres of cane either side of a creek in the lead-up to harvesting season.

“We started with a bare creek bank and grass,’’ Frank said. “Now we’ve got full cover. The rats have been replaced by scrub hens and owls and the creek bank is more stable.”

The Gattis planted native trees and say the local varieties have proved themselves over time, with a strong showing from quondongs, Leichardt trees and river cherries. Redgums and mahoganies were destroyed by Cyclone Larry in 2006 whereas the endemic varieties shed limbs but survived.  The Gattis began with nursery supplies but later moved to propagating their own seedlings.

“We planted 1 to 2 metres apart with sacrificial trees in between like bleeding hearts – fast-growing pioneer plants that shade out the weeds, get their roots in the ground fast and make it easier for the other trees to grow.”

The rat numbers began declining once the grass was eliminated. Frank said it was important not to leave grass in between the plantings. He said the project was labour-intensive for the first few years but the benefits were well worth the effort. These days he makes sure there are no overhanging branches that would cause problems for harvesters and the rest of the revegetation site doesn’t need to be maintained.

“There were challenges along the way and there was a cost in creating the revegetation site, but the benefits have well outweighed that outlay. Some people worry that trees will shade the cane but you’ve got to weigh up is whether you’re prepared to put up with the rats or some shade. Once the rats chop into the cane it doesn’t grow anymore and you lose CCS.”

“I would recommend revegetation to other growers as a way to reduce rat problems.”

Lawrence Di Bella, Ingham

Ingham cane farmer Lawrence DiBella says 70 per cent of his rat problems ended after he revegetated land bordering the Herbert River.

“We used to lose 20 to 50 metres of cane every year on our riverbank country,’’ he said. “Over the years we have taken the guinea grass out by revegetating the riverbank area.  It keeps the grass species down and we don’t have the problem we had.”

The Lawrence family began their revegetation project in 1994 after visiting a trial revegetation site on Woopen Creek grower Frank Gatti’s land and hearing about his results.

They now have about 1.5 kilometres of riverbank land under trees, varying from 10 to 40m in thickness depending on the area.

Lawrence said he learnt by trial and error that endemic species were the best because they could withstand cyclones and flooding better than natives from outside the local area. His plantings feature Queensland maples, black bean trees and bleeding hearts. In the wetter areas, he has melaleucas and the Leichhardt tree.