Field day showcases methods of ‘growing’ more topsoil

After almost eighteen months of actively exploring ways to develop a more robust topsoil for climate variability, Gippsland Agricultural Group (GAgG) is beginning to see tangible results.

Growing More Topsoil is an active project underway at Gippsland Research Farm and involves a trio of recommended soil treatments alongside a control strip for comparison purposes.

Through the use of soil coring techniques, changes in subsoil characteristics have been continually measured since the project’s commencement in June last year.

According to GAgG chief executive officer Trevor Caithness, benefits of the applied treatments are being revealed by deep soil cores drawn at regular intervals.

“Soil cores extracted throughout the project’s lifespan are showing obvious subsoil improvements, particularly when measured against the control strip,” Trevor said.

“Among the observable differences are the ability for plants to put their root systems down deeper and the capacity for soils to hold more moisture. The samples are offering a visual sense of what’s happening beneath the surface where the trial activity has taken place,” he said.

“Effectively, the soil is becoming more robust.”

Farmer and Gippsland Agricultural Group CEO, Trevor Caithness

‘Growing More Topsoil’ was recently showcased at GAgG’s spring field day in October, providing an opportunity for farmers and interested stakeholders to learn more about the study’s methodology.

Attendees heard from three presenters, each discussing the different applications and soil improvement methods at the trial site. Prepared pits demonstrated the comparison between individual treatments for the purpose of quantifying what the soil samples have consistently revealed.

One of the prepared pits showing subsoil characteristics

Soil amendments within each strip of the study adopt three distinct approaches. One strip follows recommendations from Federation University; another is led by a small steering group of farmers from Central and East Gippsland; and a third strip uses treatment methods as advised by private consultants Full Circle Nutrition.

Federation University’s approach incorporates compost as the primary focus, with the intention of balancing soil chemistry, enhancing soil structure, and improving subsoil constraints which affect the plant’s ability to access water and nutrients.

Bill Grant, Federation University

FedUni research fellow Bill Grant, one of the presenters, reflected on the long-term outlook for subsoil improvement above clay at the trial site, located just outside Bairnsdale.

“The differences we are seeing down the soil profile - deeper roots, more friable soil at depth - suggest we can make deeper topsoils on this ‘challenging’ duplex soil, but the proof will be [seen] when we measure yields and soil-water characteristics in next year's crop,” Bill said.

Peter Norwood (R), Full Circle Nutrition

Ruminant nutritionist and agronomic adviser Peter Norwood from Full Circle Nutrition was another presenter.

Trevor Caithness described Peter’s approach as one that is very much about having a balanced soil, not focusing on one element but instead looking at what the element deficiencies are and then balancing them up through different soil treatments.

“Peter has done a lot of work in this area, not only throughout the Gippsland region, but around the world,” Trevor said.

“With this particular project, he’s looking at trying to achieve the appropriate amount of calcium, magnesium, and key elements - potash, phosphorous and sulphur - along with trace elements such as copper, zinc and manganese.”

Field day participants at the ‘Growing More Topsoil’ session

Observers at the trial site also heard from Trevor about the dry work undertaken within the strip managed by the steering group of Gippsland farmers.

The project recently received a boost with further funding extending its lifespan until mid-2025.

Trevor acknowledged the project extension is a huge bonus for measuring the study’s long-term outcomes.

“Working with soils is a slow process due to its structural characteristics, nutrient retention capacity and water holding qualities,” said Trevor.

“Monitoring the ability to uptake moisture and how quickly soils can take in rainfall events is something that happens quite slowly, even though we’ve put some substantial amendments on these sites.”

Trevor noted that GAgG has a strong passion to keep the trial going beyond the funded period.

“It’s something we can keep coming back to and seeing just what sort of a response we’ve had, particularly when you consider the soil within the control strip is in its native state,” Trevor said.

“I guess that’s why it was so important to have the control strip there in this project, so that we can always go back and look at what the control strip looks like for comparison purposes in the future.”

Visible differences in the soil profile are being observed

With land becoming more valuable and the availability of productive soils finite, Trevor believes the project supports the theory we should be preserving and improving the soils that we have available. Over time, he says, the cost benefits will be realised through the treatment methods employed.

“I think eventually we’ll be able to put a financial dollar figure on what the productivity improvement has been, as a result of the project’s activities.”

“It’s a study that is so relevant to every industry that uses soil.”

The ‘Growing More Topsoil’ project has received funding from the Australian Government’s Future Drought Fund and is being delivered by Gippsland Agricultural Group with support by Food & Fibre Gippsland.

Victoria Drought Resilience Adoption & Innovation Hub (Vic Hub) links regional communities with the latest science and research to help strengthen drought preparedness.  Food & Fibre Gippsland is the Gippsland Node of the Vic Hub and is one of eight Hubs established nationally through the Australian Government’s Future Drought Fund.

More information can be found about the Growing More Topsoil project on the Vic Hub website, via Gippsland Agricultural Group, or by contacting Rick Blackshaw, drought adoption officer: 0400 100 035.