Soil Potassium

AUS-TSR-CON-SOK General High confidence

Benchmark Value

300 mg/kg
Direction: Higher is desirable ↑
Form: MinimumOnly

Scoring Curve

This curve shows how a field measurement for this indicator would score across all available benchmark forms in this context.

Evidence & Context

For high-fertility clay soils such as Ferrosols and basaltic Dermosols, a benchmark representing high ecological health and function is a Colwell K value greater than 300 mg/kg.

Metric Definition:

Colwell K value representing plant-available potassium in soil

Benchmark Definition:

This benchmark represents the minimum Colwell K value indicating high ecological health and function in high-fertility clay soils within tropical and subtropical rainforest conservation areas.

Justification:

Represents nutrient-replete systems on fertile volcanic soils. Supported by data from high-production agricultural systems on similar soils and direct measurements from high-fertility rainforest sites.

Sources (2)

Preview of Rainforest – Processes (Department of the Environment, Tourism ..., accessed July 20, 2025,
Rainforest – Processes (Department of the Environment, Tourism ..., accessed July 20, 2025, Government

Nutrient distribution and cycling in a subtropical rainforest in New South Wales

View Source
Preview of TROPICAL SOILS | Terrain NRM, accessed July 16, 2025,
TROPICAL SOILS | Terrain NRM, accessed July 16, 2025, Journal

Water Retention - Oz Soils 4 - UNE, accessed May 11, 2025,

View Source

Supporting Sources (2)

Additional references from the underlying research that informed this benchmark.

Preview of Potassium | Fact Sheets | soilquality.org.au
Potassium | Fact Sheets | soilquality.org.au
Direct Evidence Government

Potassium | Fact Sheets | soilquality.org.au

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
Direct Evidence Government

Understanding soil tests for pastures

View Source

Context

  • Region Australia
  • Biome Tropical & Subtropical Rainforests
  • Land Use Conservation / Protected Natural Areas
  • Assessment Conservation Target
  • Evidence Type ReferenceCondition

Lifecycle

  • Status Active
  • Version 1
  • Effective From 24 Mar 2026

Notes

No upper detrimental threshold — higher values are always better up to natural saturation. This value serves as a valid anchor for the upper end of natural abundance in a best-case scenario.

Related Benchmarks

Other benchmarks in the AUS-TSR-CON-SOK family.

250 mg/kg Moderate
Conservation / Protected Natural Areas · Conservation Target
MinimumOnly Active v1
100 mg/kg Moderate
Conservation / Protected Natural Areas · Conservation Target
MinimumOnly Active v1
50 mg/kg Moderate
Conservation / Protected Natural Areas · Pristine Reference
MaximumOnly Active v1
120 mg/kg Moderate
Conservation / Protected Natural Areas · Pristine Reference
MaximumOnly Active v1
— mg/kg Moderate
Conservation / Protected Natural Areas · Conservation Target
OptimalRange Active v1