Science Revives Sandy Soil: From Fragile to Fertile

It's soil that slips through your fingers – loose, dry and stubbornly unproductive. Stretching across large parts of South Australia and western Victoria, sandy soils have long resisted conventional farming methods. They shed water, leach nutrients and, too often, swallow up a grower's best efforts. With around 900 million hectares of sandy farmland worldwide, this is far from a local problem.

In Southern Australia alone, these light, low-fertility soils span millions of hectares – from the Eyre Peninsula to western Victoria – and have traditionally been considered difficult, if not impossible, to farm well. But that perception is changing.

"As we face increasing climate volatility, the ability to produce food in our most vulnerable landscapes – and for our most vulnerable communities – becomes more and more important," said CSIRO research scientist Dr Therese McBeath, who leads the long-running Sandy Soils collaboration .

Similar sandy soil challenges are also found across the sandplains of Western Australia, though this project focuses on the southern cropping region.

"Here in Australia's south, we've experienced drought. Yet by managing the constraints within sandy soils, we're seeing crops achieve remarkably high-water use efficiency – even under those tough conditions."

That improvement doesn't just buffer yield – it creates a measure of income stability across a wider range of seasons. And it all began with a simple question: how can we fix sandy soils without creating new problems?

Sandy soils 101

The research is funded by Grains Research & Development Corporation (GRDC) and kicked off in 2016. It has focused on understanding the specific limitations in these soils. In some areas, it's water repellence – a build-up of waxy residues near the surface that stops rainfall from soaking in. In others, the problem lies deeper: the soil is compacted and dense, making it hard for roots to grow. Many sandy soils also struggle to hold on to nutrients, meaning plants can't access what they need to thrive.

"We wanted to understand the problem first, and then find the right tool to fix it," Therese explained.

Now in its second phase – running through to 2028 – the project is building on those early foundations. With more than 20 trial sites spread across the southern cropping region, researchers are not only refining treatments but also testing how to maintain and build on those gains over time.

Dr Melissa Fraser, Principal Consultant at Soil Function Consulting, delivers extension and education components of the project, translating the research into practical tools and advice for farmers.

"In addition to producing research results, we have a strong mandate in the project to build the capacity of farmers to understand their constraints, giving them the best chance of success after amelioration," Melissa said.

Deep tillage, big gains

At the heart of this approach is a technique called deep tillage, where specialised machinery is used to break up soil layers as deep as 60 centimetres. This helps plant roots go deeper, giving them access to moisture and nutrients stored below the surface.

"It's a way of protecting the crop from the highs and lows that happen near the surface – especially during drought, but it's also something we need to apply strategically and carefully," said Therese.

That caution is well founded. Unlike traditional ploughing, this deep tillage isn't meant to be used everywhere or too often. Done in the wrong soil type, it can increase the risk of erosion or even reduce crop access to water by bringing up heavy clay.

"We've developed ways to use data and mapping to pinpoint where in the paddock it will be effective – and just as importantly, where it won't," she said.

To support these precision approaches, researchers with the Agricultural Machinery Research and Design Centre (AMRDC) at the University of South Australia (soon to be Adelaide University ) have developed and modified machinery that can both rip and mix soil while incorporating organic matter – a technique called inclusion ripping.

Dr Chris Saunders, a Senior Research Fellow and agricultural engineer at Adelaide University explained that they've used discrete particle-based modelling to predict how different tillage tools will interact with soil types and where improvements are most likely to take root.

"Machine choice is critical, but in many cases, we have found that these are not available to Australian growers, or they are not optimised as in the case of inclusion ripping," Chris said.

"Improving machinery function with computer modelling, really speeds up the process of getting to a better solution that is validated in the project's field trials, helping push the boundaries of what is possible in these problem soils."

Sustainable farming on sandy soils

Improving the soil is only part of the story – keeping it healthy over time is just as important. Once a sandy patch has been treated, researchers study how best to support it with the right crops, seeding methods and nutrient inputs.

"If you make it easier for roots to grow, you need to make sure there's enough fertility there to support them," said Therese. "Otherwise, you've just shifted the problem."

In 2024, the trials – including sites at Wharminda, Coomandook and Copeville in South Australia – faced a brutal test: a season marked by frost, a late break (significant delay in the growing season's first significant rainfall after dry conditions) and record-low rainfall. Even under those conditions, ameliorated soils produced double the biomass of untreated plots. The most extreme cases have seen yield increases of up to 250 per cent in previously poor-performing zones.

The benefits aren't just about yield, though. Growers have reported better weed management, the ability to grow new crops like legumes and greater consistency across landscapes. As land prices rise and climate conditions become more unpredictable, investing in the land farmers already have is emerging as a more viable strategy than simply expanding.

Teamwork on the topsoil

The project spans 23 active trial sites and includes more than 30 researchers, seven contracted partners and around 20 collaborating growers. It's a model of participatory research, with farmer reference groups embedded into every region.

"They help shape the questions we ask and keep the science grounded in the realities of farming," said Therese.

The work is supported by partners including the University of Sydney , the University of Adelaide, EPAG Research , Soil Function Consulting and several regional agronomy groups. Together, they are building a practical, evidence-based guide to sustainable soil management – with the aim of breaking the boom-bust cycle that has defined past tillage practices.

Andrew Ware, a research agronomist and Director of EPAG Research said they found it extremely rewarding to be part of the team.

"This project brings together cutting-edge science and highly motivated growers to help transform even our most challenging soils into productive and resilient systems," Andrew said.

"There's no silver bullet," said Therese. "But what we're seeing now is a system that spins up and sustains itself. It's more productive, more resilient and better prepared for the seasons ahead."