Soil Potassium

AUS-AIF-FOR-SOK General Moderate confidence

Benchmark Value

500 mg/kg

Range: 350 to 950 mg/kg

Thresholds: Lower: 120, Upper: 950

Optimal Range: 350 to 950

Direction: Higher is desirable ↑

Form: Point

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 reference value of 500 mg/kg of available potassium is proposed.

Metric Definition:

Available potassium concentration in topsoil (0-10 cm) measured as exchangeable K or equivalent method.

Benchmark Definition:

The concentration of available potassium in soil that supports sustainable native production forestry in Australia's Arid Inland Floodplains.

Justification:

Derived from Goulburn Broken CMA target of 3-8% of CEC for clay soils, assuming an average CEC of 30 cmol(+)/kg. Lower threshold informed by Eucalyptus research and NSW pasture data.

Sources (3)

NSW Department of Primary Industries GreyLiterature

NSW Department of Primary Industries

View Source

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,

View Source

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 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

Supporting Sources (2)

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,

View Source

Potassium for crop production | UMN Extension

Contextual Support Government

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

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: 950 mg/kg. Benchmark represents a state of robust potassium sufficiency supporting ecosystem resilience and sustainable forestry. Upper threshold relates to nutrient imbalance risk rather than toxicity.

Related Benchmarks

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