Soil Potassium

AUS-TMS-CON-SOK General Moderate confidence

Benchmark Value

45.7 mg/kg
Range: 35.2 to 450 mg/kg
Thresholds: Lower: 35.2, Upper: —
Optimal Range: 35.2 to 450
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.

Evidence & Context

Based on available peer-reviewed data from an undisturbed native forest site on Melville Island (Red Kandosol soil), a mean exchangeable potassium value of 45.7 mg/kg (with an observed range of 35.2 – 450.0 mg/kg) is proposed as a reference point.

Metric Definition:

Available soil potassium, typically measured by methods such as Colwell K or exchangeable K, expressed in mg/kg.

Benchmark Definition:

This benchmark represents the available exchangeable soil potassium in a pristine native forest soil in the Tropical Monsoonal Savannas biome, indicating natural soil nutrient status relevant to ecosystem health.

Justification:

The benchmark is based on a single primary study site representing a best available natural condition, with moderate confidence due to the wide observed range and potential spatial heterogeneity.

Sources (2)

Preview of industry.nt.gov.au
industry.nt.gov.au Journal

industry.nt.gov.au

View Source
Preview of Plantation tree growth responses to P, N, K and minor and trace elements on low fertility savanna soils (data from undisturbed native forest comparison site on Red Kandosol)
Plantation tree growth responses to P, N, K and minor and trace elements on low fertility savanna soils (data from undisturbed native forest comparison site on Red Kandosol) Journal

Plantation tree growth responses to P, N, K and minor and trace elements on low fertility savanna soils (data from undisturbed native forest comparison site on Red Kandosol)

View Source

Supporting Sources (1)

Additional references from the underlying research that informed this benchmark.

Preview of Soil Research - CSIRO PUBLISHING, accessed May 16, 2025,
Soil Research - CSIRO PUBLISHING, accessed May 16, 2025,
Contextual Support Journal

Litchfield Savanna BASE Contextual, Soil Physico-Chemical Data ...

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Context

  • Region Australia
  • Biome Tropical Monsoonal Savannas
  • Land Use Conservation / Protected Natural Areas
  • Assessment Pristine Reference
  • Evidence Type ReferenceCondition

Lifecycle

  • Status Active
  • Version 1
  • Effective From 25 Mar 2026

Notes

Lower Critical Threshold: 35.2 mg/kg. No upper detrimental threshold — higher values are always better up to natural saturation. Wide observed range reflects natural spatial variability.