Soil Potassium

AUS-TGP-LVG-SOK General Moderate confidence

Benchmark Value

50 mg/kg
Thresholds: Lower: 50, Upper: —
Direction: Higher is desirable ↑
Form: LowerThreshold

Scoring Curve

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

Evidence & Context

Agriculture Victoria and a related soil health guide for southwest Victoria define "Low" Colwell K levels as <50 mg/kg for sands, <80 mg/kg for sandy loams, <110 mg/kg for clay loams, and <120 mg/kg for clays.

Metric Definition:

Colwell K test (bicarbonate-extractable potassium) in soil at 0-10 cm depth, representing plant-available potassium.

Benchmark Definition:

Lower critical thresholds for soil potassium indicating ecological impairment.

Justification:

These thresholds represent a state where nutrient availability is clearly limiting ecosystem function and productivity.

Sources (1)

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

Understanding soil tests for pastures

View Source

Supporting Sources (24)

Additional references from the underlying research that informed this benchmark.

Preview of (PDF) Soil potassium—crop response calibration relationships and criteria for field crops grown in Australia - ResearchGate, accessed July 18, 2025,
(PDF) Soil potassium—crop response calibration relationships and criteria for field crops grown in Australia - ResearchGate, accessed July 18, 2025,
Contextual Support Journal

The Western Australian Rangeland Monitoring System (WARMS) – operating a regional scale monitoring system - ResearchGate, accessed July 24, 2025

View Source
Preview of ASC - VERTOSOLS - Soil Science Australia
ASC - VERTOSOLS - Soil Science Australia
Contextual Support

What are the optimum nutrient targets for pastures? - Soil Health Knowledgebase

View Source
Preview of Australian dryland soils are acidic and nutrient-depleted, and have unique microbial communities compared with other drylands - PMC
Australian dryland soils are acidic and nutrient-depleted, and have unique microbial communities compared with other drylands - PMC
Contextual Support Journal

Australian dryland soils are acidic and nutrient-depleted, and have unique microbial communities compared with other drylands - PMC

View Source
Preview of Gippsland Plains Grassy Woodland - Wikipedia, accessed August 11, 2025,
Gippsland Plains Grassy Woodland - Wikipedia, accessed August 11, 2025,
Contextual Support GreyLiterature

Gippsland Plains Grassy Woodland - Wikipedia

View Source
Preview of How Biodiversity-Friendly Is Regenerative Grazing? - Frontiers, accessed August 5, 2025,
How Biodiversity-Friendly Is Regenerative Grazing? - Frontiers, accessed August 5, 2025,
Contextual Support Journal

Managing Grazing to Restore Soil Health, Ecosystem ... - Frontiers

View Source
Preview of How to increase improved pasture yield | Yara Australia
How to increase improved pasture yield | Yara Australia
Contextual Support GreyLiterature

How to increase improved pasture yield | Yara Australia

View Source
Preview of How to reduce Fertiliser Costs - Eco-logical Solutions - Learning from Nature
How to reduce Fertiliser Costs - Eco-logical Solutions - Learning from Nature
Contextual Support GreyLiterature

Restoration of degraded grazing country in the semi-arid areas of NSW

View Source
Preview of Long-term rundown of plant-available potassium in Western Australia requires a re-evaluation of potassium management for grain production: a review - BioOne Complete, accessed July 10, 2025
Long-term rundown of plant-available potassium in Western Australia requires a re-evaluation of potassium management for grain production: a review - BioOne Complete, accessed July 10, 2025
Contextual Support Journal

Long-term rundown of plant-available potassium in Western Australia requires a re-evaluation of potassium management for grain production: a review - CSIRO PUBLISHING | Crop and Pasture Science, accessed July 24, 2025

View Source
Preview of Long-term rundown of plant-available potassium in Western Australia requires a re-evaluation of potassium management for grain production: a review - CSIRO PUBLISHING | Crop and Pasture Science, accessed July 10, 2025
Long-term rundown of plant-available potassium in Western Australia requires a re-evaluation of potassium management for grain production: a review - CSIRO PUBLISHING | Crop and Pasture Science, accessed July 10, 2025
Contextual Support Journal

Potassium Control of Plant Functions: Ecological and Agricultural Implications - PMC

View Source
Preview of Pastures and acid soils - NSW Government
Pastures and acid soils - NSW Government
Contextual Support Journal

What do you see and when? What could this indicate? What test can I do to confirm? - MLA

View Source
Preview of Potassium | Fact Sheets | soilquality.org.au, accessed July 10, 2025
Potassium | Fact Sheets | soilquality.org.au, accessed July 10, 2025
Contextual Support Government

Potassium - Tas | Fact Sheets | soilquality.org.au, accessed May 11, 2025,

View Source
Preview of Potassium and sulphur - emerging deficiencies in the southern region - GRDC, accessed July 13, 2025
Potassium and sulphur - emerging deficiencies in the southern region - GRDC, accessed July 13, 2025
Contextual Support Government

Potassium and sulphur - emerging deficiencies in the southern region - GRDC

View Source
Preview of Potassium Control of Plant Functions: Ecological and Agricultural Implications - PMC, accessed July 30, 2025,
Potassium Control of Plant Functions: Ecological and Agricultural Implications - PMC, accessed July 30, 2025,
Contextual Support Journal

Regenerative Agriculture - Nuffield Farming Scholarships

View Source
Preview of Potassium for high-performing pastures | Nutrient Advantage, accessed July 18, 2025,
Potassium for high-performing pastures | Nutrient Advantage, accessed July 18, 2025,
Contextual Support Journal

Potassium for high rainfall pastures - DPIRD's Digital library

View Source
Preview of Potassium in the soil - Potash Development Association (PDA)
Potassium in the soil - Potash Development Association (PDA)
Contextual Support GreyLiterature

Potassium in the soil - Potash Development Association (PDA)

View Source
Preview of Semi-arid woodlands (grassy sub-formation) | NSW Environment, Energy and Science
Semi-arid woodlands (grassy sub-formation) | NSW Environment, Energy and Science
Contextual Support GreyLiterature

Semi-arid woodlands (grassy sub-formation) | NSW Environment, Energy and Science

View Source
Preview of Semi-arid woodlands (grassy sub-formation) | NSW Environment, Energy and Science, accessed July 12, 2025, )
Semi-arid woodlands (grassy sub-formation) | NSW Environment, Energy and Science, accessed July 12, 2025, )
Contextual Support Government

Temperate Grasslands - Greening Australia

View Source
Preview of Soil nutrient critical limits | MBFP | More Beef from Pastures - MLA, accessed May 13, 2025,
Soil nutrient critical limits | MBFP | More Beef from Pastures - MLA, accessed May 13, 2025,
Contextual Support GreyLiterature

Understanding soil tests for pastures | Soil | Farm management ..., accessed July 17, 2025,

View Source
Preview of Soil Potassium Availability and Role of Microorganisms in Influencing Potassium Availability to Plants - ResearchGate
Soil Potassium Availability and Role of Microorganisms in Influencing Potassium Availability to Plants - ResearchGate
Contextual Support GreyLiterature

Soil Potassium Availability and Role of Microorganisms in Influencing Potassium Availability to Plants - ResearchGate

View Source
Preview of Southeast Australia temperate savanna - Wikipedia, accessed August 4, 2025
Southeast Australia temperate savanna - Wikipedia, accessed August 4, 2025
Contextual Support

Southeast Australia temperate savanna - Wikipedia

View Source
Preview of Temperate Grasslands - Greening Australia, accessed August 4, 2025
Temperate Grasslands - Greening Australia, accessed August 4, 2025
Contextual Support Journal

Managing natural areas | City of Gold Coast, accessed May 19, 2025

View Source
Preview of The development and application of functions describing pasture yield responses to phosphorus, potassium and sulfur in Australia using meta-data analysis and derived soil-test calibration relationships - CSIRO Publishing, accessed August 11, 2025
The development and application of functions describing pasture yield responses to phosphorus, potassium and sulfur in Australia using meta-data analysis and derived soil-test calibration relationships - CSIRO Publishing, accessed August 11, 2025
Contextual Support Journal

The role of regenerative agriculture in sustainable land use - ClimateWorks Australia

View Source
Preview of Willydah - Soils For Life
Willydah - Soils For Life
Contextual Support

Willydah - Soils For Life

View Source
Preview of www.climateworkscentre.org, accessed May 11, 2025
www.climateworkscentre.org, accessed May 11, 2025
Contextual Support Journal

How Biodiversity-Friendly Is Regenerative Grazing? - Frontiers

View Source

Context

  • Region Australia
  • Biome Temperate Grassy Woodlands & Plains
  • Land Use Livestock Grazing & Pasture
  • Assessment Degradation Threshold
  • Evidence Type DegradationThreshold

Lifecycle

  • Status Active
  • Version 2
  • Effective From 24 Mar 2026

Notes

Below these thresholds, ecosystem function and resilience are compromised.

Related Benchmarks

Other benchmarks in the AUS-TGP-LVG-SOK family.

— mg/kg High
Livestock Grazing & Pasture · Pristine Reference
OptimalRange Active v1
80 mg/kg Moderate
Livestock Grazing & Pasture · Degradation Threshold
LowerThreshold Superseded v1