Sandy soil case studies unearth keys to increasing yields

Effective ways to overcome the constraints Eyre Peninsula farmers face when cropping on sandy soils have been unearthed in a series of case studies, with hopes the findings will lead to increased yields.

As part of the project, led by AIR EP, six local EP farmers joined a total of 16 demonstration sites across SA and Victoria where farming practices enhancing the productive capacity of sandy soils were trialled during the 2022 and 2023 growing seasons.

The findings from the sites have now been published in a series of case studies that are available to farmers keen to build the drought resilience and overall productivity of their own properties.

AIR EP Executive Officer Naomi Scholz said the project unearthed techniques and approaches that proved effective in combating common sandy soil constraints such as compaction, acid soils, low fertility and water repellence.

“This project has shown there are solutions to the challenges our farmers face here on the EP in treating and enhancing the productivity of sandy soils,” Ms Scholz said.

“Being able to test different machines, techniques and approaches on properties in our own backyard is invaluable because farmers can see firsthand at the demonstration sites, and via the case study data, what works on soils unique to our area.

“It’s also helpful for our growers to see how a combination of factors, such as different soil types, rainfall levels, available biomass, nutrition levels, or the depth of issues such as soil compaction, can impact the outcomes of using different techniques.”

EP farmers involved in the trial include Mark Dolling at Kielpa, Brett O’Brien (Kyancutta), Wes Daniell (Poochera), Nigel Oswald (Mt Damper), Dion Williams (Streaky Bay) and Ben Ranford (Arno Bay).

Over at Arno Bay, Ben Ranford trialled deep tillage combined with carbon-based nutrition in 2022 to improve sandy soils struggling with water repellence, compaction and low fertility. Areas with ripped treatments delivered higher yields – with one small trial site combining ripping and companion planting with peas showing promising results with the highest yield overall.

For Ben, the estimated $100/ha cost of ripping was more than covered in the overall yield boost.

“With wheat at $400/t, the gross returns were $600/ha on the unripped country and $1600/ha on ripped country,” he said.

“After the cost of ripping, there’s still nearly $1000/ha extra income in year one. Yes we need to use higher fertiliser rates to account for the new yield potential, but ripping is a no brainer.”

The trials also highlighted the importance of supporting techniques such as soil amelioration with adequate nutrition, and understanding the unique challenges and limitations of each individual site before deciding on a management approach.

On Mark Dolling’s property at Kielpa, five machines were compared in a trial to reduce compaction and bring up clay to treat water repellence and soil acidity. While there was no clear ‘winner’, it did show that all machines helped alleviate soil compaction and improve biomass. Another key tip from this case study is to measure pH before tillage as, if subsoil acidity is an issue, tillage is the ideal time to incorporate lime into the acid layer.

“Finding the right solution for improving land management and productive capacity is going to be different from site to site – and it was clear from this project that not all options deliver the same benefits across all properties. However, these case studies have shown that interventions such as ripping, early pH testing and acid treatment, and matching nutrition to soil needs can be extremely beneficial,” Ms Scholz said.

“There may be some trial and error involved, and soil recovery and improvement may happen slowly over successive seasons, but we do believe the case studies will provide EP farmers with a valuable tool to assist in planning their future sandy soil management approaches.”

Of the 16 project sites, a further six were located in the South Australian and Victorian Mallee, two on the Yorke Peninsula and two in the South East.

The project was funded through the Australian Government’s Future Drought Fund and the Grains Research and Development Corporation. It was also supported by the South Australian Drought Resilience Adoption and Innovation Hub.

Project delivery partners included Mallee Sustainable Farming, Northern Sustainable Soils, MacKillop Farm Management Group and the University of South Australia Agricultural Machinery Research and Design Centre, with technical support provided by Primary Industries and Regions South Australia, CSIRO, Soil Function Consulting, Frontier Farming Systems and Trengove Consulting. Case studies were compiled by Alluvio Pty Ltd.

To read the case studies, visit https://airep.com.au/research/building-drought-resilience-by-scaling-out-farming-practices-that-will-enhance-the-productive-capacity-of-sandy-soil-landscapes/

For more information about AIR EP or to become a member, visit the website at AIR EP.