Soil Potassium

AUS-TSW-FOR-SOK General High confidence

Benchmark Value

390 mg/kg

Range: 120 to 390 mg/kg

Optimal Range: 120 to 390

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. 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

Based on the analysis of the TERN Great Western Woodlands SuperSite data, the proposed benchmark for soil potassium is 390 mg/kg of exchangeable K.

Metric Definition:

Exchangeable potassium in soil measured as mg/kg, representing plant-available potassium.

Benchmark Definition:

This benchmark represents the exchangeable potassium level in soil measured in mg/kg, indicating a high state of ecological health in a mature, intact salmon gum woodland within the temperate semi-arid shrublands and open woodlands biome under production forestry.

Justification:

The benchmark is supported by high-quality, scientifically rigorous data from a mature, intact ecosystem representing the best available condition in the biome.

Sources (1)

Preview of Soil | Australia state of the environment 2021, accessed August 12, 2025,

Soil | Australia state of the environment 2021, accessed August 12, 2025, Journal

OzFlux-TERN GWW SuperSite presentation: Soil Chemical Properties

View Source

Supporting Sources (2)

Additional references from the underlying research that informed this benchmark.

Agronomic studies in Australia for grain crops and general soil fertility guides for NSW and WA

Contextual Support GreyLiterature

Agronomic studies in Australia for grain crops and general soil fertility guides for NSW and WA

View Source

Preview of Does rapid utilization of elevated nutrient availability allow eucalypts to dominate in the tropical savannas of Australia? - PubMed Central, accessed May 11, 2025,

Does rapid utilization of elevated nutrient availability allow eucalypts to dominate in the tropical savannas of Australia? - PubMed Central, accessed May 11, 2025,

Contextual Support Journal

General soil fertility guides and commercial forestry studies

View Source

Context

Region Australia
Biome Temperate Semi-Arid Shrublands & Open Woodlands
Land Use Production Forestry
Assessment Pristine Reference
Evidence Type ReferenceCondition

Lifecycle

Status Active
Version 1
Effective From 25 Mar 2026

Notes

Lower Critical Threshold: Evidence from agricultural and forestry studies suggests a threshold of < 50 mg/kg, below which ecosystem function and resilience are significantly compromised. No upper detrimental threshold — higher values are always better up to natural saturation. The upper limit is defined by cation imbalance, where high K levels induce magnesium deficiency.

Related Benchmarks

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