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.”

Carbon farming, composting and cover cropping… Here are three soil health events which are being delivered or supported by Terrain NRM in March and April:

Sunflowers are good for the soil and good for the soul. That’s the consensus at the O’Kane farm near Tully where a blaze of yellow is wowing family and friends.

Cane farmer Mick O’Kane has planted out 80 acres with sunflowers and legumes as a mixed-species fallow crop to improve the health of his soil. The result has stunned him.

“They’ve taken really well. They’re awesome, just beautiful,’’ he said. “We normally just plant soy beans and you always get a nice crop of cane after a good crop of beans.

“This year, we’ve planted four different species together after doing a soil health course with Terrain NRM. The cowpeas are climbing up the sunflowers.”

Terrain’s Michael Waring said mixed species fallow crops were relatively new to the Far North.

“Diversity is important when it comes to soil health,’’ he said. “Different species bring different benefits and sometimes they balance out less favourable traits too.’’

Local farmers are setting paddocks aside for farm demo sites to show the water quality benefits possible when soil health is improved through different farming practices.

Farmers are seeing evidence that healthy soil stores nutrients more efficiently, saving them money and improving the quality of water flowing to the Great Barrier Reef.

The demonstration sites are being closely monitored as part of the Wet Tropics Major Integrated Project (MIP). A recent field day reported initial findings back to farmers.

Fiona George is responsible for managing the project’s on-ground activities and says that nitrogen use in the Wet Tropics is critical for crop growth, but comes with some issues.

“We live in a high-rainfall area and our agriculture is close to the coast, so when nitrogen and sediment is lost from our farming systems it doesn’t have far to travel before it impacts the marine ecosystem,” Ms George said.

“Agricultural industries around the world are working to manage nitrogen better”.

Tully Sugar Limited is hosting a side-by-side demonstration site comparing how much nitrogen and sediment reduction can be achieved by improving soil carbon with a range of strategies.

An ‘industry standard’ or control paddock sits next to a comparison paddock with a multi-species cover crop fallow, added organic matter (compost), 1.9m dual row planting and controlled traffic.

These practices are addressing soil constraints by improving soil organic matter and soil biological activity, through reducing tillage and paddock disturbance.

Water coming from both paddocks is monitored. Sophisticated equipment samples surface runoff, as well as water from below the crop’s root zone, to give a more comprehensive picture of how nitrogen is moving through the landscape.

Ms George said they hope to work out how much of a reduction in nitrogen input can be achieved, without affecting productivity.

“We’re all trying to get plants to function in the most efficient way possible, in this case by starting with the soil. Every farm is different, but we can show farmers the results and then support them to make decisions about what will work best for them in their circumstances,” Ms George said.

At the recent field day to the demonstration site, visiting growers saw constraint mapping results done via drone and electro-magnetic induction, the condition of soil at plant after cover cropping, and innovative machinery for minimum tillage and planting with minimal disturbance.

Tully Sugar Limited CEO, Shunjie Guo, said the company’s involvement in the MIP is an opportunity to contribute to a growing understanding of nitrogen losses.

“It’s important to us that we’re not just talking about doing the right thing, but actually doing it.”

“Sugar cane is an important rural industry for the Wet Tropics, and Australia. We see it as our responsibility to show leadership and take steps that ensure its viability into the future.”

“Both corporate and family farms depend on the land. We’re very happy to be part of a project that’s getting relevant data back to farmers.”

“Nobody wants to be losing nitrogen. It’s not just a loss to waterways, it’s a financial loss. Farmers are very interested in maximising efficiencies and we hope demonstration days like this will show which practices could have application to the broader Tully cane industry.”

The Wet Tropics Major Integrated Project is funded by the Queensland Government through the Queensland Reef Water Quality Program.