Wet Tropics farmers improve local water quality

The Tully and Johnstone catchments have high rainfall and are close to the Great Barrier Reef. Intensive agriculture on the coastal plains includes over 50,000 hectares of sugarcane production and over 7,000 hectares of banana production. 

Since 2021, the Tully Johnstone Water Quality Program has supported over 160 sugarcane farmers and 30 banana farmers in the Wet Tropics of Queensland, to improve nutrient management practices which has positively impacted over 25,000 hectares of production land.  

The $11 million program was funded through the partnership between the Australian Government and the Great Barrier Reef Foundation and was delivered by the CANEGROWERS Innisfail, James Cook University (JCU), LiquaForce, and Terrain NRM. 

An on-farm wetland water monitoring project is helping scientists and landholders to learn more about how wetlands work as treatment systems for nutrient and sediment runoff. 

Terrain NRM has worked with JCU, Griffith University and the Queensland Government’s Departments of Environment and Science, and Agriculture and Fisheries to monitor two constructed wetlands in Innisfail and Tully. 

Water samples were collected regularly and during large rainfall events. Terrain NRM’s project officer Maria Ribbeck said the data offered valuable insights into the way wetlands function and their extensive capacity to filter pollutants and improve water quality. 

“It is also helping us to learn the best conditions for wetlands to optimise removal of nitrogen from the water cycle,’ she said.  

“One of the wetlands is on eight hectares of low-lying land on a farm managed by Tully Sugar Limited. The data has shown us it’s a high-performing site, with capacity to remove an over 1000 kg of nitrogen a year from the water passing through the wetland.” 

Greg Shannon, Cane Productivity and Development Manager at Tully Sugar Limited, said the project was raising awareness of wetlands and their usefulness in the farming landscape. 

“The last year’s findings were recently presented to us,’ he said. “This project has helped us understand how wetlands work and how we can optimise their ability to treat water. The longer this wetland is monitored, the more data we can get, and this will make the findings increasingly useful for our decision-making in terms of wetland maintenance and management as time goes by.  

“It probably should be noted that not everyone can have a wetland like this on their farm, but we had a piece of cattle grazing land with a natural depression in it already, so it was possible to develop it into a wetland.” 

Terrain NRM’s Maria Ribbeck said the most recent wet season, with significant rain and automated, high-resolution data gathering, gave the team much clearer insights into how the wetland is functioning. 

“Now we are working with Tully Sugar to optimise this wetland’s performance. Thanks to the data, we are focusing on how to remove oxidised nitrogen without generating as much ammonia, and it looks like that just comes down to better wetland vegetation management by making sure there is more open water to improve flow and to reduce pockets of extremely low dissolved oxygen,’’ she said. 

“This project is a model of successful collaboration between industry and research that’s paving the way for ongoing water quality improvement.’’ 

Joe Zappala farms in Innisfail’s Mena Creek on picturesque, unique red volcanic soil. While the ground is fertile, the naturally acidic soil is prone to drying out and sugarcane variety selection is vital to growing a healthy crop that efficiently uses nutrients to prevent surplus nitrogen entering the Great Barrier Reef. 

Access to newer, high-performing varieties has posed a problem for Joe, dating back to a disease incursion in the late 1990s. “After smut came into the industry, the plant breeding program had to target smut-resistant varieties,” he explained. “That had to happen, but we have sacrificed a lot in our productivity. Our yields and sugar content aren’t indicative of the potential of our soil types.” 

Joe began trialing tissue culture. “Initially, I dabbled with tissue culture, but I predominantly used to get whole stick cane from the local productivity services to use as seed,” he said. “In 2018-19, a very high performing variety called SRA26 was released in this area. I planted the stick cane in clean ground only to find it was infected with Ratoon Stunting Disease. 

“I needed to take back control.” Fortunately, Joe was well placed to plant tissue culture because he also grows papaya as a break crop. The seedling planters and irrigation system he uses for papaya are also suitable for sugarcane seedlings. 

This system is now being replicated across the Johnstone Catchment through the Cassowary Coast Reef Smart Farming project, which has established three tissue culture plots to accelerate basin-wide adoption of the newer, high-yielding varieties. 

“What we’ve been focusing on is what more can we do when it comes to improving Reef water quality and improving our productivity to reduce the nitrogen surplus,” Project leader Debra Telford explained. “So, our focus is growing more tonnes of cane per hectare and to do that, you need disease-free, high-yielding varieties.” 

Joe’s tissue culture seed plots have become a mainstay, allowing him to rapidly escalate the availability of varieties that suit his soil. “If I plant 200-metres, I can get equivalent to two whole stick cane trailers the following year,” Joe said. “That’s enough multiplication of clean seed material to keep me moving.” 

The Zecchinati family has been in the business of banana farming for over three decades. Michael and Belinda Zecchinati are helping their daughter, Kayla, to step up into the business. 

After attending a Nutrient Management workshop delivered by the Australian Banana Growers Council (ABGC), the couple were eager for Kayla to learn more about fertilizer and crop nutrition. They joined the Cassowary Coast Reef Smart Farming Nutrient Management Planning project run by CANEGROWERS Innisfail in collaboration with ABGC. 

“I’ve been teaching Kayla what I can, but I thought the project could be a great start for Kayla to learn the basics about farming and banana nutrition,” Michael said. 

To kick things off, the Zecchinati family met Molly Blake from ABGC’s Best Management Practice team to chat about the farm and what they wanted to get out of the project. This information was used to tailor their program and identify soil and leaf sampling locations. 

“I really enjoyed learning how to take the soil and leaf samples with Molly. It’s helped to demystify the process and understand the work agronomists do,” Kayla said. 

The results from these samples were analyzed by Anita Davina, from Total Growers Services, who produced a comprehensive nutrient management plan for their farm for the next year. Molly and Anita then met with Michael, Belinda and Kayla to go over the results and discuss some potential priorities. 

“It was great to learn new bits of knowledge from the agronomist about how to balance our crop nutrition. It makes you think differently,” Michael said. “Liming is going to be important for us going forward, to give the plants a good healthy soil foundation to be able to access the nutrients we apply.” 

Kayla joined a small group of growers at an interactive Nutrient Management workshop in South Johnstone that was led by an expert agronomist. 

“The highlight for me was learning from other growers in the room. I learnt how to identify nutrient deficiencies I’d never seen before, but some other growers see often,” Kayla explained. 

“We’ve been busy getting the new farm up to scratch, so we were worried we may not have enough time (to participate in the project). But it’s definitely been worth it. It doesn’t matter if you’re a new or more experienced grower, there is something for everyone to learn.” 

The 2023-24 wet season was affected by Cyclone Jasper with flash flooding, heavy rains and strong winds in December 2023, followed by Cyclone Kirrily in January 2024. Despite this, in-paddock and in-stream water quality monitoring sites provided a nitrogen story of paddock scale runoff events through the collaborative JCU TropWATER and CSIRO Tully Johnstone water quality monitoring project. 

In-field sensors included gauges recording rainfall, water height sensors showing how much water was running off the paddock, and nitrate sensors measuring how much nitrogen is in the runoff water. Data from these sensors was available within 10 minutes of being collected and the paddock team communicated results directly with the grower.  

The data showed that reduced nitrogen application treatment did lead to lower nitrogen losses. Discussion centred around how different soil types may alter these results on other farms in different areas of Tully. The farmer will continue to only apply fertiliser at planting after a legume fallow, as he understands this reduces nitrogen losses, and so far, has not affected biomass growth when compared to the standard application treatment. 

The LiquaForce LAND project connected sugarcane farmers to the new Land Hub decision support system, a secure digital storage system with farm, soil, and production data for easy long-term monitoring of performance over time. Crop history, land structure, and soil composition data was collected and used to produce optimised Six Easy Steps nutrient management plans enabling farmers to reduce excess nutrients flowing into local water ways. In the Tully Johnstone region, the project engaged achieved a reduction of 8.4 tonnes of DIN (Dissolved Inorganic Nitrogen) per year across 4,710 hectares of sugarcane farmland through practice changes implemented on farm. 

Growers in Far North Queensland are using tools for decision-making and nutrient management plans based on agronomic advice to improve their nutrient management practices on their farms which has improved soil health, productivity, profitability, and sustainability. This has resulted in improved water quality in the Tully and Johnstone catchments, enhancing the health of the Great Barrier Reef.