Poor yields reversed on Queensland sugar cane operation
Scott is the fourth generation of the McLean family to run the 200 ha sugar cane farm in Mackay, Queensland. The farm is well-managed with a history of good yields, but Scott found himself facing increased pest and disease pressure and low yields — down from a 100T/ha peak in the 1980’s to
80T/ha or less. This was having a major financial impact on the operation.
“We were going from disease to disease, trying new treatments — spraying, inoculating. Nothing was doing much good,” Scott explained. “Yields were down, so we were putting on more fertiliser but still getting less production. The cane wasn’t even responding to irrigation.”
Despite input changes and support from local agronomists, Scott was unable to address the decline until a New Zealand pilot, employed by the family aerial spraying business, suggested he talk to Kiwi soil and plant nutritionist, Corey Martin from iFert. After some discussion, Scott persuaded Corey to come over to Queensland to take a look at the farm for himself.
Corey quickly identified reasons for the issues that the farm was facing: very low soil pH, high aluminium toxicity and deficiencies in minerals like phosphorous, sulphur, boron, zinc and silica. Many of the deficiencies were significant enough for Corey to be able to identify them in the field. All his observations were backed up by thorough soil and herbage analysis.
“Corey was very logical and could prove what he was saying scientifically through testing in the field. He explained why we were having the problems we’d been having and it all made sense. So, we decided to put his recommendations into practice.”
Corey then set about adapting his knowledge and technology to Queensland conditions where a crop can go from drowning to drought in the space of a month. Scott and Corey started a staggered trial, now in its fourth year, always leaving a conventionally treated area to act as a control. The trials were
carefully positioned on square blocks of land of a consistent soil type and with irrigation across the whole block. This ensured that the only variable was the fertiliser treatment applied. Corey used the soil and herbage analysis to put together a prescription fertiliser treatment to address the specific, yield-limiting nutrient deficiencies he had found in the soil. The conventional phosphorous applied in previous seasons had been getting tied up in the soil and wasn’t reaching the plant, so Corey recommended a form of P with very different release characteristics.
“Corey’s knowledge of mineral interactions, soil structure and biology — and the chemistry of different products and how they work — has made all the difference,” said Scott.
The first year, five hectares were treated with Corey’s prescription of fertiliser, micronutrients and bio- stimulants. The second year, 30 hectares were given the iFert treatment and the third year, 60 hectares.
This year, iFert has treated all but a 40 hectare fallow block on Scott’s farm. “It’s no longer a trial,” said Scott. “It’s a proven, successful approach with consistent results. We’re at a stage where the gains we’ve made in yield and sugar content mean that I can’t afford not to treat most of the crop.”
When it comes to results, Scott has the data to back the improvements he’s seen. “Our objective was to increase the sugar content per hectare, not necessarily the tonnage,” he explained. “Over the last four years our yield has improved by an average of 10% and the PRS by 15% — and it’s still getting better.”
“The gains have been consistent year on year. Now, we’re not wondering if there will be an increase, the question is how big will it be?”
To ground these results in science, Scott gets Corey to do a full soil analysis on a single section of the farm every year and he maps the results. “The line on the graph is still going up. While things continue to improve, we’ll keep on tweaking and putting on the right stuff at the right levels. When we find the
sweet spot, I’ll make a commercial decision to get the best yield for the right spend – we won’t necessarily go for maximum output, we’re more focused on profitability.”
In some blocks of the farm, Scott and Corey are now trialing the reduction of some inputs see if they can maintain yields. In the meantime, the results speak for themselves. The iFert-treated crops scored an average 15 PRS and 82T/ha yield compared with 14 PRS and 70T/ha from the blocks treated with
conventional fertiliser. Earning Scott roughly $400/ha more on the iFert blocks.
Soil respiration is a reliable indicator of soil health. A good average measurement for healthy soil is 3,500. The baseline figure on Scott’s farm was 700 before the first iFert treatment — it’s now 4,500 to 5,000 and continuing to improve.
“This year it’s been a really difficult season. We’ve gone from December floods to January drought and we’ve still been able to maintain our yields — which means the iFert treatment is paying for itself. By investing in the health of our soil, we’re building strong foundations for seasons to come,” said Scott. “I’m getting a 10% return from iFert and only 4% with the bank – I know where I’m putting my money.”