Soil health measures to fight acidity on Buntine farm

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Buntine farmer and Liebe Group outgoing R&D chair Michael Dodd is keen to know if crop fertiliser availability and its plant use-efficiency can be boosted through improved soil health.

On the sandy soils across the district where Michael farms there is a percentage of fertiliser not being accessed by crops each year. This is contributing to subsoil acidity problems, lower grain production and higher on-farm costs.

To improve local knowledge about the interactions between fertiliser use, subsoil acidity, soil health, soil biology and crop yields, one of the Liebe Group’s first major projects back in 2003 involved setting up a long-term soil biology trial. 

This trial is examining how agronomic factors, such as grain yield and quality, are affected by soil organic matter breakdown and crop cycles.

Photo of a man with a tractor

Buntine farmer Michael Dodd is keen to discover how soil health and soil carbon levels affect his crops’ nitrogen fertiliser requirements.

PHOTO: CoxInall Communications

Michael says research at the trial site this year aims to help determine if there are levels of soil carbon where nitrogen fertiliser rates can be changed. The aim of the trial is to determine whether these levels can be maintained over several years, and the subsequent effect on nitrous oxide emissions from crop production.

This project is also led by the University of Western Australia and funded by the Australian Government’s ‘Filling the Research Gap’ project (as part of its Carbon Farming Futures program) in partnership with the GRDC, the Department of Agriculture and Food, WA (DAFWA), and the Liebe Group.

“We need to know the point at which increasing soil carbon will make a difference to fertiliser use (and subsoil acidity), and then work out whether the economics of going down this path stack up,” Michael says.

“And we want to ensure the nutrients in the soil are where crops can access them and won’t be lost as emissions or leached down the soil profile. It is all about getting the best value for the nitrogen fertiliser that we are applying.

“If we find out that we are wasting a big proportion of our applied nitrogen, we can change what we are doing.”


Owners: Michael and Narelle Dodd
Location: Buntine
Farm size: 6000 hectares
Enterprises: cropping and Merino sheep
Rainfall (average annual): 315 millimetres
Soil types: yellow sandplain and deep sands
Surface soil pH: 4.8 to 5.4
Subsoil pH: 4.2 to 4.5
Planned crop program 2013: wheat (3000ha), canola (600ha), barley (400ha)

On his own farm, Michael has a no-till system with stubble retention, and applies lime annually to help boost soil pH, soil health and grains productivity.

He uses local soil consultant Adriaan DeWaal to help unravel the complexities of soil health issues and fertiliser use.

Adriaan was a leader in identifying a need to incorporate lime to depth on WA’s sandy soils.

Although difficult and expensive, this strategy has been paying off for the Dodds.

Surface soil pH levels on their property now range from 4.8 to 5.4 and subsoil levels range from 4.2 to 4.5, which are close to DAFWA targets for the region. 

To further improve soil health, Michael trialled TM soil conditioner last year to help stimulate microbial activity.

He says it appeared to facilitate better soil moisture infiltration and plant root growth in canola.

This year, he also plans to use Optima CalSap®, a liquid soluble calcium to help protect the soil pH around the fertiliser (Flexi-N® will be used). “The theory is that it makes more nutrients available to the plant,” he says. (Note: this theory has not been scientifically proven using replicated experiments.)

Michael aims to cover about 60 per cent of his 4000-hectare cropping area with the soil conditioner and about 10 per cent with liquid soluble calcium this year as a short-term measure to help maintain soil pH and optimise yield potential.

More information:

Michael Dodd
08 9664 2078,

Nadine Hollamby, Liebe Group
08 9661 0570,

Next: Trials probe yield potential
Previous: Spotlight on soil carbon and nitrogen fertiliser

GRDC Project Code UWA00156

Region West, North, South