Legumes make cane more able
GroundCover™ Issue: 115 | Author: Melissa Marino
Ground Cover continues its matchmaker series highlighting collaborations between growers and researchers. Here, we look at game-changing research that has turned around the fortunes of cane growers through grains diversification
Professor Mike Bell and Neil Halpin
"We have gone from full sugar to introducing legumes, to a stage where some cane growers are now producing record peanut and soybean yields in their own right." – Mike Bell
In southern Queensland the nature of sugarcane farming has changed dramatically in the 21st century. From what was once a stagnant monoculture, cane fields – particularly around Bundaberg and Childers – are now home to dynamic cropping systems incorporating legumes, minimum till and controlled traffic.
On the ground, a fundamental system change has seen profits rise by as much as 50 per cent through increased yields, reduced fertiliser costs, and a longer cane life span, plus the bonus cash crop the legumes provide. And in the ground, growers are seeing healthier soils from planting a break crop and using reduced tillage.
“It’s come full circle,” says University of Queensland agronomist Professor Mike Bell, who has played no small part in the change. “We have gone from full sugar, to introducing legumes, to a stage where some cane growers are now producing record peanut and soybean yields in their own right.”
The shift began in the late 1990s through a 12-year Sugar Research and Development Corporation project dubbed the ‘Sugar Yield Decline Joint Venture’, which comprised biologists, physicists, chemists, engineers, growers and agronomists led by Dr Alan Garside and including Mike, who describes the collaboration as a highlight of his career.
This work is being continued by Queensland Department of Agriculture, Fisheries and Forestry agronomist Neil Halpin, who is helping sugarcane and legume growers refine their systems for reduced input costs and maximised productivity through the Coastal Grower Solutions Group.
Funded by the GRDC since 2012, the group tailors elements of national programs to regional priorities, and also determines its own local research agenda by teaming researchers with growers, including Peter Russo.
Mike says the original initiative was borne from necessity, after three decades of zero growth in an industry defined by monoculture, heavy tilling and declining soil health. “What should have been a healthy soil had been turned into one that was like concrete and full of pathogens,” he says.
The joint venture established the parameters for a new sugar farming system. Its first task was to pull apart the established sugarcane cropping system to identify the problems.
“We needed to know how much of the trouble was being caused by pathogens, how much was compaction, and how were the different components contributing to the stalled productivity,” Mike says.
“There was a whole suite of pathogens, and compaction was everywhere, so the problem was not something that could be solved through better breeding. The system had to change,” Mike says.
As the solution lay in changing farm practice, Mike says the venture really took off when growers such as Peter Russo came on board. It meant new practices and parameters could be put in place on-farm and tested for effectiveness and practicality.
Mike says the introduction of legumes and reduced tillage were the key. This is because the soil pathogens responsible for knocking out sugarcane root systems are quelled by break crops. However, those benefits are diluted, or lost, through heavy tillage.
“If we were going to integrate legumes into the system we had to marry-up with reduced tillage and controlled traffic, so we did a fair amount of work on-farm to determine ‘when, where and why’,” Mike says.
Over several years of trials, many of which were held on Peter’s properties, the researchers finetuned the changes, assessing the effects of specific break crops and the practicalities of introducing them on-farm, including various options for reduced tillage in a system that leaves 12 to 15 tonnes of sugarcane trash after harvest.
Managing trash by raking it onto sugarcane beds, as well as careful zonal, or strip, tillage, have been the best solutions to that issue. Other obstacles included reducing cadmium accumulation in the soil (a heavy metal that does not affect sugar but is a problem for peanuts), and the ongoing issue of dealing with soil compaction.
Controlled traffic can help reduce compaction and build soil resilience by keeping the heavy weight of machinery on particular tracks, but it means rearranging sugarcane rows to fit wheel spacings.
This remains a challenge as the wheel spacings of sugarcane and peanut machinery are not consistent and peanut harvesters can run over the top of sugarcane beds established in the controlled-traffic system.
Grower group action
"We are working with growers at a local level to be reactive and listen to their concerns to find solutions for their problems." – Neil Halpin
With manufacturers reluctant to adapt, it is an issue being tackled directly by Peter and Neil, who is today heading up research through the Coastal Grower Solutions Group with growers in the Childers–Bundaberg region.
Neil and Peter travelled to the US to investigate the issue, but believe they may have found the answer closer to home. “We hope to modify Peter’s peanut thresher so we can match our wheel spacings to our row spacings,” Neil says.
While there are real opportunities to reduce tillage further in a sugarcane/legume farming system, Neil says the machinery needs to be consistent to fully realise its potential. “And while we have trial evidence saying this is the right direction, commercially there is a little bit of a void.”
Neil says growers in the region are aiming to produce 8t/hectare of peanuts and 5t/ha of soybeans – ambitious but achievable yields – so the program works to deliver these through its research. This includes work on nutrition, herbicide application, row configuration and, given the high cost of water, strategic irrigation.
“We are working with growers at a local level to be reactive and listen to their concerns to find solutions for their problems,” he says. “We are backing their ideas with robust trials and good stats to produce defendable data and expand the legume industry.”
And expand it has. Without Bundaberg supplying peanuts there would be no Peanut Company of Australia, Neil says. “That’s how important this district has become; from 1995 and not really having an industry to where we are today.”
However, Neil says, no matter how successful the peanuts are in their own right, it is their benefit to the sugarcane crop that has earned legumes their place in the system, giving growers a 20 per cent average better sugar yield, a longer sugarcane crop cycle, free nitrogen and a healthier environment.
“Even with the costs of sowing an extra crop it’s a lot more profitable than empty fallow and then you’ve got increased sugarcane yield after that and reduced fertiliser costs – so it’s one of those rare win-wins.”
More information:Professor Michael Bell,
07 5460 1140,
0407 171 335,
When Peter Russo introduced peanuts and the concept of controlled traffic to the family sugarcane farm in Childers, Queensland, about a decade ago, he was bucking a three-generation-long trend of sugarcane monoculture.
"You can read all the books you like but when you can touch it and feel it, it's a big difference."
However, he says, with sugar prices low, costs on the rise and productivity flat, a new system was needed.
Introducing a peanut break crop and GPS-controlled machinery required a change of thinking, as well as new equipment and practices, but the biggest challenge for Peter was convincing his brothers – and business partners at the time – to make the change with him.
“It got to the point where one of my brothers said ‘You are going to plant that block near your house so every day for the rest of your life you wake up in the morning and see what sort of mess you made’,” he says.
Peter dutifully obliged his brother and is still admiring that first block today. “It’s perfect,” he says. “We don’t argue about row spacing or growing peanuts anymore, that’s for sure.”
Having seen GPS-controlled equipment in action at an exhibition, Peter was inspired by the reduction in soil disturbance that controlled traffic could achieve. Then, as a member of Professor Mike Bell’s Sugar Yield Decline Joint Venture, he was introduced to the benefits of a break crop and the rationale for minimum till and wider row spacing.
“When I brought these ideas home you could imagine trying to convince three brothers … it was a bit hard to tell them that if we reduced our rows we would grow more sugarcane,” he says.
Higher yield is one of the many benefits that have since come from adopting these changes.
In a district that averaged 72 tonnes per hectare in 2014, Peter is disappointed with anything under 100t/ha. In fact, he expects up to 110t/ha across his 225ha cropping operation in the Isis region around Bundaberg and Childers, 350 kilometres north of Brisbane.
This, he says, is largely due to the peanut break crop. As well as providing an extra income stream, peanuts have led to a marked and sustained increase in sugarcane yields because of the benefits the legumes have brought to the soil. These include supressing sugarcane root disease, encouraging beneficial biota and adding nitrogen.
However, it is not the peanuts alone that have heralded the improvements, he says, with wider row spacings and reduced compaction also leaving the soil in much better shape.
He describes compaction as “the silent killer” and is the reason he is modifying his peanut thresher to keep wheels off the beds.
With no compaction and the ground soft and pliable, Peter says he can sow sugarcane immediately following the peanut harvest. And an earlier sowing time leads to even bigger yields.
Paddocks on overtime
Today, Peter plants his peanut crop after harvesting sugarcane in November or December. While monoculture growers’ paddocks lie empty over summer, Peter’s and other legume growers’ are filled until the autumn legume harvest after which sugarcane is sown again.
“The land is never vacant and he capitalises on all that legume nitrogen,” Mike says.
And almost more significant than increased yields is the extra year or two Peter is getting from his sugarcane crop. Usually sugarcane will yield well for three seasons, with each new shooting of the perennial plant known as a ratoon. This year, Peter’s cane is on its fifth ratoon and is still yielding 100t/ha and so he faces a conundrum: given sugarcane is his most expensive crop to sow, should he try for a sixth ratoon and sacrifice his next scheduled peanut break crop, which would bring further benefit to the soil?
“I’ll leave a small block in to trial it,”he says.
For Peter, changing his system has given him a greater understanding of the land and the soil he works. He was, he says, on a steep learning curve when first recruited to Mike’s joint venture, but now, through continued work with Neil Halpin’s Coastal Grower Solutions Group, he is actually helping to chart the direction of future research.
He says he has come this far because he was willing to put ideas into practice as a research partner and as a grower. “You can read all the books you like but when you can touch it and feel it, it’s a big difference,” he says.
Today, Peter is confident enough to experiment on-farm himself and will be putting what he has learnt into practice with a new 150ha degraded sugarcane farm he has bought. With the Russo brothers recently amicably splitting their business partnership, Peter has given himself and his own sons five years to turn the new property around and improve the 14t/ha the farm is currently returning.
Legumes are now an established part of sugarcane growing in the region and Peter, who is also chair of the Isis Central Sugar Mill, hopes more legumes in rotations will see averages in the district increase from 70t/ha to at least 90t/ha.
Despite being one of the region’s best legume producers, he still sees himself essentially as a sugarcane grower: “But I cannot go forward without having peanuts as part of my business,” he says.
More information:Peter Russo,
GRDC Project Code DAQ00184, UQ00053
Region National, Overseas, North