Queensland growers are adopting new farming systems that reduce the use of fertiliser, increase its effectiveness through better-targeted delivery and lessen environmentally damaging run-off.
With support from the Australian Government Reef Programme (AGRP, formerly Growcom’s Reef Rescue), they are implementing new practises, the most promising of which is 'fertigating' - using existing irrigation lines to deliver fertiliser to crops.
Reef Rescue and AGRP projects have helped hundreds of Queensland growers improve their chemical and nutrient management practices by various means: using low-volume spray applicators, targeted spray applicators, whole-of-farm nutrient balance recording systems and advanced fertigation systems.
Early feedback from participating growers indicated that implementing these new practices could lead to savings of between 10 and 50 percent in fertiliser costs, and that improving fertiliser application could reduce fertiliser inputs by 25 percent – a figure revised upwards recently to 30 percent.
Add these considerable savings to those made by reducing labour inputs, lowering diesel consumption, boosting product quality, improving soil health and fostering a sustainable future, and you have a compelling case for change, especially when ROI is typically achieved within a year, even without AGRP funding.
One practice Queensland farmers are trialling is known as ‘fertigation’: using irrigation lines to deliver fertiliser to crops. Keen to support agricultural methods that lessen environmental stress on waterways, AGRP has been funding fertigation projects around the state.
One beneficiary is Gladstone farmer Ian Pershouse, host of a recent AGRP fertigation workshop. Pershouse has been fertigating for more than a decade and recently received an upgrade to his equipment as part of an AGRP project.
Using a third less fertiliser doesn’t bring big savings, notes Pershouse, because the soluble type required for fertigation is pricier, but he thinks the new method is worth adopting as it substantially reduces run-off and enables him to make more effective use of fertiliser, cutting the amount required by 30 percent – nearly a third.
By using water-delivery infrastructure, fertigation reduces the time, labour and expense required to fertilise crops. And as irrigation systems target crops more directly than spraying does, fertigation does its job more effectively while cutting fertiliser use dramatically. In a win-win for agriculture and the environment, fertigating results in significantly less run-off into local soils and waterways.
With fertigation, explains Doyle, “It's going to the crop; it's getting used relatively quickly. [There’s] very little run-off from the farm – hence it's a good water quality outcome."
It’s not all good news, however. Fertigation requires higher levels of monitoring and testing than do traditional methods such as spraying. And as fertiliser running through irrigation lines cannot be seen, explains Growcom’s Robert Doyle, it’s difficult to ascertain where it is within the system, how diluted it is, and how evenly a particular crop or paddock is being fertigated.
"We need to know how long it takes to get to the paddock and how long it takes to get across the paddock, so we need to do a little bit of calibrating to know that we're going to be fertigating our field uniformly,” he says.
At a recent AGRP workshop on a mango farm near Gladstone, Doyle conducted a field experiment in which he ran red dye through grower Ian Pershouse’s watering system to ascertain how long it would take fertiliser to reach a crop via irrigation lines (thus demonstrating the watering time required to deliver fertiliser to the crop).
"We're able to put our fertiliser out there a little bit and often, rather than the old days of spreading it on,” Doyle told the Gladstone gathering. “And the issue there is it can get washed away or leached.”
According to Doyle, most horticulturalists in the Gladstone region use fertigation to some extent. Pershouse notes that while farmers are adopting the practice of fertigation in increasing numbers, many – particularly older farmers – still stand by traditional methods of fertiliser delivery.
Given the added expense of soluble fertiliser, farmers can’t expect to make substantial savings from the change, but they can expect more bang for their fertiliser buck in terms of effective, targeted delivery to crops and less wasteful, environmentally destructive run-off.
All things considered, fertigation seems like a win-win for farmers and the health of our waterways.