Data-driven biology unlocking soil-bound nutrients
How prescription microbes released tied-up phosphorus and delivered a 17% yield response in canola. A field trial at Gerogery NSW by Great Southern Biology.
There’s a problem sitting in a lot of Australian soils right now. The nutrients are there: phosphorus, nitrogen, potassium. But the crop can’t access them. They’re chemically present but biologically locked up, bound to minerals like aluminium, calcium or iron and effectively invisible to the plant.
This is exactly what we found when we conducted a soil microbiome assessment at Daniel and Stirling Moll’s ‘Elderslie’ property, near Gerogery in Southern NSW.
Phosphorus locked by aluminium
Daniel and his brother Stirling farm and lease around 3,200 acres near Gerogery. They’re known locally for rigorous on-farm trialling, having hosted the GRDC variety trials each year, so when we identified significant phosphorus tie-up in their soil, Daniel was open to testing a biological solution.
The metagenomic soil test told a clear story. Phosphorus solubilisation and micronutrient bioavailability were both low. The phosphorus wasn’t missing. It was bound with aluminium, sitting in the soil but unavailable to the crop.
Boxed indicators highlight the two most critical findings: low phosphorus solubilization and limited micronutrient bioavailability.
A microbial intervention, not a fertiliser
Rather than applying more fertiliser, we suggested trialling Great Southern Biology’s nutrient solubiliser, a consortium of three fungi and one bacterium designed to release nutrients already present in the soil. It was applied as a granular formulation at 20 kg/ha through the fertiliser box at canola sowing, running as a strip east-west across the paddock.
Pre-harvest soil tests confirmed the biology was working. Available nutrients had improved meaningfully across the board:
| Nutrient | Control | Treated | Change |
|---|---|---|---|
| Colwell P | 42 mg/kg | 57 mg/kg | +35.7% |
| N – Ammonium | 1 mg/kg | 2 mg/kg | +100% |
| N – Nitrate | 26 mg/kg | 38 mg/kg | +46% |
| Colwell K | 184 mg/kg | 217 mg/kg | +17.9% |
The Colwell P result was the most significant. Phosphorus previously bound to aluminium had become plant-available.
The proof is in the paddock
When the crop was harvested, the yield map told the rest of the story. The treated strip running east-west across the paddock was unmistakable in the data, a consistent band of higher-yielding canola that stood out clearly against the rest of the paddock.
You could even see, in the bottom corner of the treated strip, where the granules began to run out and the yield response tapered off with them. It doesn’t get much clearer than that.
Yield map, Queltara | Waitara | Crawshaw Thistle paddock, Gerogery NSW, 27/11/2025. The treated strip running east-west is clearly visible.
A clear link between biology and yield
This is the first dataset we’ve obtained that demonstrates such a clear, visible link between microbial inoculation and yield response. It raises a straightforward question for any farmer working with soils with locked-up nutrients: what would it mean for your yields if that fertility was actually available to the crop?
“It shows a clear link between microbial inoculation and yield. At a canola price of approximately $700/t, this equates to a net benefit of roughly $330/ha after product costs.”
Grant Kelson, Managing Director, Great Southern BiologyInterested in biological solutions for your soil?
If you’d like to learn more about what GSB’s biological approach could mean for your operation, get in touch with the team.
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