Soil Potassium

AUS-AIF-CON-SOK General Moderate confidence

Benchmark Value

No specific value — see range

Range: 150 to 300 mg/kg

Thresholds: Lower: 100, Upper: —

Optimal Range: 150 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.

Evidence & Context

A benchmark representing the best available condition for clay-rich soils (Vertosols and similar alluvial clays) in arid floodplain conservation areas can be established as a range of 150 - 300 mg/kg (Colwell K).

Metric Definition:

Available soil potassium concentration measured as Colwell K

Benchmark Definition:

This benchmark represents the available soil potassium concentration for clay-rich soils (Vertosols) in arid inland floodplains under conservation management, indicating a healthy, potassium-replete natural ecosystem based on synthesis and proxy data.

Justification:

Derived by synthesis due to lack of direct data from conservation sites, based on natural sufficiency and non-responsive agricultural trials on similar soils.

Sources (1)

Soil potassium—crop response calibration relationships and criteria for field crops grown in Australia

Soil potassium—crop response calibration relationships and criteria for field crops grown in Australia

View Source

Context

Region Australia
Biome Arid Inland Floodplains & Ephemeral River Systems
Land Use Conservation / Protected Natural Areas
Assessment Conservation Target
Evidence Type ReferenceCondition

Lifecycle

Status Active
Version 1
Effective From 24 Mar 2026

Notes

Lower Critical Threshold: 100 mg/kg. No upper detrimental threshold — higher values are always better up to natural saturation. The upper boundary is one of natural saturation; levels far exceeding the benchmark range may indicate external contamination rather than a high-health state.

Related Benchmarks

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