Soil Potassium

AUS-TSR-CON-SOK General Low confidence

Benchmark Value

50 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

A general lower critical threshold of <50 mg/kg is appropriate for sandy soils, while a threshold of <120 mg/kg should be applied to clay-rich soils.

Metric Definition:

Colwell K value representing plant-available potassium in soil

Benchmark Definition:

This benchmark represents the lower critical threshold below which sandy soils show impaired ecosystem functions in tropical and subtropical rainforest conservation areas.

Justification:

Data from agricultural systems serve as a conservative proxy for the point at which fundamental physiological stress begins, impairing ecosystem health.

Sources (2)

Preview of Australian Journal of Soil Research - CSIRO Publishing, accessed August 5, 2025
Australian Journal of Soil Research - CSIRO Publishing, accessed August 5, 2025

Australian Journal of Soil Research - CSIRO Publishing, accessed July 22, 2025

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

A Revegetation Guide for Sub-Tropical Forest - Greening Australia, accessed July 20, 2025,

View Source

Supporting Sources (3)

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

Sediments and nutrients in north Queensland tropical streams ...

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

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

View Source

Context

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

Lifecycle

  • Status Active
  • Version 4
  • Effective From 9 Jun 2026

Notes

Below this threshold, ecosystem functions such as biomass accumulation, disease resistance, and nutrient cycling are likely compromised.

Related Benchmarks

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

300 mg/kg High
Conservation / Protected Natural Areas · Conservation Target · Forest
MinimumOnly Active v2
250 mg/kg Low
Conservation / Protected Natural Areas · Conservation Target · Forest
MinimumOnly Active v2
— mg/kg Moderate
Conservation / Protected Natural Areas · Conservation Target · Forest
OptimalRange Active v2
100 mg/kg Low
Conservation / Protected Natural Areas · Conservation Target · Forest
MinimumOnly Superseded v3
50 mg/kg Low
Conservation / Protected Natural Areas · Conservation Target · Forest
MinimumOnly Superseded v2
120 mg/kg Low
Conservation / Protected Natural Areas · Conservation Target · Forest
MinimumOnly Rejected v2
— mg/kg Moderate
Conservation / Protected Natural Areas · Conservation Target · Forest
OptimalRange Superseded v1
300 mg/kg High
Conservation / Protected Natural Areas · Conservation Target · Forest
MinimumOnly Superseded v1
250 mg/kg Low
Conservation / Protected Natural Areas · Conservation Target · Forest
MinimumOnly Superseded v1
100 mg/kg Low
Conservation / Protected Natural Areas · Conservation Target · Forest
MinimumOnly Superseded v1