Soil Potassium

AUS-TGP-FOR-SOK General Moderate confidence

Benchmark Value

No specific value — see range
Range: 101 to 300 mg/kg
Optimal Range: 101 to 300
Direction: Higher is desirable ↑
Form: OptimalRange

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 10 benchmarks together — the OptimalRange form drives the primary score, while 9 guard(s) constrain the result.

Contributing Benchmarks

OptimalRange Primary OptimalRange Guard Point Guard MaximumOnly Guard UpperThreshold Guard OptimalRange Guard LowerThreshold Guard Point Guard MinimumOnly Guard OptimalRange Guard

Evidence & Context

The following table presents the derived benchmark (as the "Optimal Range") and the associated functional ranges for plant-available potassium, stratified by major soil texture classes.

Metric Definition:

Plant-available potassium concentration in soil measured by Colwell-K test, stratified by soil texture.

Benchmark Definition:

This benchmark represents the optimal range of plant-available potassium in soils of production forests in the Temperate Grassy Woodlands & Plains biome of Australia, stratified by soil texture, indicating levels that support vigorous, healthy plant growth and resilient ecosystem function.

Justification:

This benchmark is derived by synthesizing ecological principles from remnant woodlands with a quantitative framework from agricultural soil science. It represents the "Ideal" range (Colwell-K test) for non-limiting plant growth, which is a prerequisite for high ecological health.

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 (21)

Additional references from the underlying research that informed this benchmark.

Preview of 6. POTASSIUM - Nutrient Management, accessed August 9, 2025
6. POTASSIUM - Nutrient Management, accessed August 9, 2025
Contextual Support Journal

Nutrient Disorders in - Plantation Eucalypts - Murdoch Research Portal, accessed August 9, 2025

View Source
Preview of Appendix A - DAFF, accessed August 9, 2025
Appendix A - DAFF, accessed August 9, 2025
Contextual Support Journal

NSW State forest estate - Forestry Corporation, accessed August 9, 2025

View Source
Preview of Australian dryland soils are acidic and nutrient-depleted, and have unique microbial communities compared with other drylands - PMC, accessed August 5, 2025,
Australian dryland soils are acidic and nutrient-depleted, and have unique microbial communities compared with other drylands - PMC, accessed August 5, 2025,
Contextual Support Journal

Root Structure and Functioning for Efficient Acquisition of Phosphorus: Matching Morphological and Physiological Traits

View Source
Preview of Determining reference conditions for management and restoration of temperate grassy woodlands: Relationships among trees, topsoils and understorey flora in little-grazed remnants - the UWA Profiles and Research Repository, accessed August 5, 2025,
Determining reference conditions for management and restoration of temperate grassy woodlands: Relationships among trees, topsoils and understorey flora in little-grazed remnants - the UWA Profiles and Research Repository, accessed August 5, 2025,
Contextual Support Journal

Determining reference conditions for management and restoration of temperate grassy woodlands: Relationships among trees, topsoils and understorey flora in little-grazed remnants - the UWA Profiles and Research Repository, accessed August 9, 2025

View Source
Preview of Environmental factors affecting plant growth | OSU Extension Service, accessed August 9, 2025
Environmental factors affecting plant growth | OSU Extension Service, accessed August 9, 2025
Contextual Support Government

Environmental factors affecting plant growth | OSU Extension Service, accessed August 9, 2025

View Source
Preview of Forest Health - Sustainable Timber Tasmania, accessed August 9, 2025
Forest Health - Sustainable Timber Tasmania, accessed August 9, 2025
Contextual Support

Forest Health - Sustainable Timber Tasmania, accessed August 9, 2025

View Source
Preview of Graham, R. C., & Wilson, B. R. (2007). The influence of scattered trees on soil properties in temperate pastures. Soil Research, 45(2), 121-131.
Graham, R. C., & Wilson, B. R. (2007). The influence of scattered trees on soil properties in temperate pastures. Soil Research, 45(2), 121-131.
Contextual Support Journal

Towards restoration of grassy White and Yellow Box woodlands ..., accessed August 9, 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 - 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 Plans + Policies - Sustainable Timber Tasmania, accessed August 9, 2025
Plans + Policies - Sustainable Timber Tasmania, accessed August 9, 2025
Contextual Support Journal

Plans + Policies - Sustainable Timber Tasmania, accessed August 9, 2025

View Source
Preview of Potassium | Fact Sheets | soilquality.org.au, accessed August 11, 2025,
Potassium | Fact Sheets | soilquality.org.au, accessed August 11, 2025,
Contextual Support Government

Soil fertility in grazing systems: Manage potassium to manage nitrogen - Crops and Soils, accessed July 28, 2025,

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 Its Role in Sustainable Agriculture - ResearchGate, accessed August 9, 2025
Potassium and Its Role in Sustainable Agriculture - ResearchGate, accessed August 9, 2025
Contextual Support GreyLiterature

Soil condition | NSW State of the Environment, accessed July 28, 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 10, 2025
Potassium for high-performing pastures | Nutrient Advantage, accessed July 10, 2025
Contextual Support GreyLiterature

A review of plantations as a water intercepting land use in South Australia, accessed August 9, 2025

View Source
Preview of Potassium limitation of forest productivity – Part 2: CASTANEA-MAESPA-K shows a reduction in photosynthesis rather - Agritrop, accessed August 9, 2025
Potassium limitation of forest productivity – Part 2: CASTANEA-MAESPA-K shows a reduction in photosynthesis rather - Agritrop, accessed August 9, 2025
Contextual Support Journal

Australian dryland soils are acidic and nutrient-depleted, and have unique microbial communities compared with other drylands - PMC, accessed August 9, 2025

View Source
Preview of Potassium management in crops - Soil fertility - Government of Alberta, accessed August 9, 2025
Potassium management in crops - Soil fertility - Government of Alberta, accessed August 9, 2025
Contextual Support Government

Potassium management in crops - Soil fertility - Government of Alberta, accessed August 9, 2025

View Source
Preview of Queensland Acid Sulfate Soil Technical Manual, accessed August 9, 2025
Queensland Acid Sulfate Soil Technical Manual, accessed August 9, 2025
Contextual Support Journal

Queensland Acid Sulfate Soil Technical Manual, accessed August 9, 2025

View Source
Preview of The importance of travelling stock reserves for maintaining high-quality threatened temperate woodlands - CSIRO PUBLISHING | Australian Journal of Botany, accessed August 12, 2025,
The importance of travelling stock reserves for maintaining high-quality threatened temperate woodlands - CSIRO PUBLISHING | Australian Journal of Botany, accessed August 12, 2025,
Contextual Support

Approved Conservation Advice for the White Box - Yellow Box - Blakely's Red Gum Grassy Woodland and Derived Native Grassland - DCCEEW, accessed August 6, 2025

View Source
Preview of Understanding soil tests for pastures | Soil | Farm management - Agriculture Victoria, accessed August 9, 2025
Understanding soil tests for pastures | Soil | Farm management - Agriculture Victoria, accessed August 9, 2025
Contextual Support Government

Understanding soil tests for pastures | Soil | Farm management - Agriculture Victoria, accessed August 9, 2025

View Source
Preview of www.ari.vic.gov.au, accessed May 13, 2025,
www.ari.vic.gov.au, accessed May 13, 2025,
Contextual Support Journal

Mean concentrations of soluble and exchangeable cations in ..., accessed August 9, 2025

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Context

  • Region Australia
  • Biome Temperate Grassy Woodlands & Plains
  • Land Use Production Forestry
  • Assessment Pristine Reference
  • Evidence Type TargetCondition

Lifecycle

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

Notes

The value is highly dependent on soil texture: Sands (101-150 mg/kg), Sandy Loams (121-200 mg/kg), Clay Loams (161-250 mg/kg), Clays (181-300 mg/kg). Lower Critical Threshold: A level below which health is compromised, ranging from <50 mg/kg (Sands) to <120 mg/kg (Clays). Upper Detrimental Threshold: Evidence does not support direct toxicity. Instead, an upper limit exists where high K induces magnesium deficiency. This occurs when exchangeable K exceeds 10% of the soil's Cation Exchange Capacity (CEC).

Related Benchmarks

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

50 mg/kg Moderate
Production Forestry · Pristine Reference
LowerThreshold Active v1
80 mg/kg Moderate
Production Forestry · Pristine Reference
LowerThreshold Active v1
110 mg/kg Moderate
Production Forestry · Pristine Reference
LowerThreshold Active v1
120 mg/kg Moderate
Production Forestry · Pristine Reference
LowerThreshold Active v1