Soil Potassium

AUS-AIF-FOR-SOK General Moderate confidence

Benchmark Value

No specific value — see range

Range: 150 to 210 mg/kg

Thresholds: Lower: 120, Upper: 210

Optimal Range: 150 to 210

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.

Evidence & Context

The optimal range for loamy soils is therefore proposed as 150 – 210 mg/kg.

Metric Definition:

Available potassium concentration in loam soils measured as exchangeable K or equivalent method.

Benchmark Definition:

Optimal available potassium range for loam soils to achieve high ecosystem health and productivity.

Justification:

Derived from Goulburn Broken CMA target range of 0.38-0.54 cmol(+)/kg for loam soils.

Sources (1)

Preview of Potassium | Fact Sheets | soilquality.org.au, accessed August 11, 2025,

Potassium | Fact Sheets | soilquality.org.au, accessed August 11, 2025, Government

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

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Supporting Sources (4)

Additional references from the underlying research that informed this benchmark.

Crop and Pasture Science - CSIRO PUBLISHING, 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, accessed July 17, 2025,

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NSW Department of Primary Industries

Contextual Support GreyLiterature

NSW Department of Primary Industries

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Potassium for crop production | UMN Extension

Contextual Support Government

Potassium for crop production | UMN Extension, accessed July 28, 2025,

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Preview of Potassium limitation of forest productivity – Part 1: A mechanistic model simulating the effects of potassium availability on canopy carbon and water fluxes in tropical eucalypt stands - BG

Potassium limitation of forest productivity – Part 1: A mechanistic model simulating the effects of potassium availability on canopy carbon and water fluxes in tropical eucalypt stands - BG

Contextual Support GreyLiterature

Potassium limitation of forest productivity – Part 1: A mechanistic model simulating the effects of potassium availability on canopy carbon and water fluxes in tropical eucalypt stands - BG

View Source

Context

Region Australia
Biome Arid Inland Floodplains & Ephemeral River Systems
Land Use Production Forestry
Assessment Conservation Target
Evidence Type TargetCondition

Lifecycle

Status Active
Version 1
Effective From 24 Mar 2026

Notes

Lower Critical Threshold: 120 mg/kg. Upper Detrimental Threshold: 210 mg/kg. Levels above 210 mg/kg offer diminishing returns and may risk nutrient imbalance.

Related Benchmarks

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