Soil Potassium

AUS-TDG-FOR-SOK General Moderate confidence

Benchmark Value

74.1 mg/kg
Direction: Higher is desirable ↑
Form: Point

Scoring Curve

This curve shows how a field measurement for this indicator would score across all available benchmark forms in this context. The scoring engine uses 5 benchmarks together — the OptimalRange form drives the primary score, while 4 guard(s) constrain the result.

Contributing Benchmarks

OptimalRange Primary Point Guard Point Guard MinimumOnly Guard Point Guard

Evidence & Context

The Sapsford et al. (2021) study provides compelling data from Corymbia calophylla (marri) forests in southwest Western Australia, a key species within the temperate eucalypt woodlands. In this study, "intact forest" areas, characterized by higher ectomycorrhizal (ECM) fungal diversity and lower incidence of canker disease, exhibited significantly lower soil potassium concentrations (mean: 74.1±5.4 mg/kg) compared to "disturbed edge" habitats (mean: 103.8±8.1 mg/kg), which showed lower ECM diversity and higher disease incidence.

Metric Definition:

Available soil potassium concentration measured by Colwell-K or equivalent extractable K method.

Benchmark Definition:

Soil potassium concentration representing the best available ecological condition in production forestry within Australian temperate dry woodlands and native grasslands.

Justification:

Derived from peer-reviewed study linking soil potassium levels to ecological health indicators in a relevant Australian temperate eucalypt woodland, supported by agricultural guidelines and ecological principles.

Sources (4)

Preview of Agriculture Victoria. (2024). Understanding soil tests for pastures.
Agriculture Victoria. (2024). Understanding soil tests for pastures. Government

Agriculture Victoria. (2024). Understanding soil tests for pastures.

View Source
Preview of Daws, M. I., Standish, R. J., Grigg, A. H., Morald, T. K., & Tibbett, M. (2021). Seeing the forest for the trees: fertiliser increases tree growth but decreases understorey diversity in the Northern Jarrah Forest, southwest Australia. Journal of the Royal Society of Western Australia, 104, 5-9.
Daws, M. I., Standish, R. J., Grigg, A. H., Morald, T. K., & Tibbett, M. (2021). Seeing the forest for the trees: fertiliser increases tree growth but decreases understorey diversity in the Northern Jarrah Forest, southwest Australia. Journal of the Royal Society of Western Australia, 104, 5-9. Journal

Daws, M. I., Standish, R. J., Grigg, A. H., Morald, T. K., & Tibbett, M. (2021). Seeing the forest for the trees: fertiliser increases tree growth but decreases understorey diversity in the Northern Jarrah Forest, southwest Australia.

View Source
Preview of Sapsford, S. J., Paap, T., Hardy, G. E. St. J., & Burgess, T. I. (2021). Anthropogenic Disturbance Impacts Mycorrhizal Communities and Abiotic Soil Properties: Implications for an Endemic Forest Disease. Frontiers in Forests and Global Change, 3, 593243.
Sapsford, S. J., Paap, T., Hardy, G. E. St. J., & Burgess, T. I. (2021). Anthropogenic Disturbance Impacts Mycorrhizal Communities and Abiotic Soil Properties: Implications for an Endemic Forest Disease. Frontiers in Forests and Global Change, 3, 593243. Journal

Sapsford, S. J., Paap, T., Hardy, G. E. St. J., & Burgess, T. I. (2021). Anthropogenic Disturbance Impacts Mycorrhizal Communities and Abiotic Soil Properties: Implications for an Endemic Forest Disease.

View Source
Preview of Understanding soil tests for pastures | Soil | Farm management ..., accessed May 12, 2025
Understanding soil tests for pastures | Soil | Farm management ..., accessed May 12, 2025 Government

Agriculture Victoria. (2025). Understanding soil tests for pastures. Farm Management.

View Source

Supporting Sources (1)

Additional references from the underlying research that informed this benchmark.

Preview of Restoring Australia's temperate grasslands and grassy woodlands | Request PDF - ResearchGate, accessed August 6, 2025,
Restoring Australia's temperate grasslands and grassy woodlands | Request PDF - ResearchGate, accessed August 6, 2025,
Contextual Support Journal

Restoring Australia's temperate grasslands and grassy woodlands | Request PDF - ResearchGate, accessed August 6, 2025

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Context

  • Region Australia
  • Biome Temperate Dry Woodlands & Native Grasslands
  • Land Use Production Forestry
  • Assessment Conservation Target
  • Vegetation Forest
  • Evidence Type ReferenceCondition

Lifecycle

  • Status Active
  • Version 1
  • Effective From 9 Jun 2026

Notes

Lower Critical Threshold likely below 50-80 mg/kg depending on soil texture; Optimal Range approximately 70-120 mg/kg for sandy to loamy soils; Upper Detrimental Threshold above 100-120 mg/kg may indicate disturbance or nutrient imbalance unfavorable to native biodiversity.