Soil Potassium

AUS-AKW-AGR-SOK General Moderate confidence

Benchmark Value

300 mg/kg
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 15 benchmarks together — the OptimalRange form drives the primary score, while 14 guard(s) constrain the result.

Contributing Benchmarks

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

Evidence & Context

A value of 300 mg/kg serves as a practical and conservative benchmark, situated within the optimal range and representative of the non-responsive trial sites.

Metric Definition:

Colwell K concentration in soil, a measure of plant-available potassium

Benchmark Definition:

A benchmark value representing a non-depleted, high-functioning, K-replete state of Calcarosol soils in arid karstic agroecosystems.

Justification:

Based on multi-site field trials showing Colwell K >280 mg/kg with no yield response to K fertiliser, indicating a naturally sufficient potassium supply.

Sources (1)

Preview of (PDF) Soil potassium—crop response calibration relationships and criteria for field crops grown in Australia - ResearchGate, accessed July 18, 2025,
(PDF) Soil potassium—crop response calibration relationships and criteria for field crops grown in Australia - ResearchGate, accessed July 18, 2025, Journal

The Western Australian Rangeland Monitoring System (WARMS) – operating a regional scale monitoring system - ResearchGate, accessed July 24, 2025

View Source

Supporting Sources (3)

Additional references from the underlying research that informed this benchmark.

Preview of Calcareous Soils Initiative - GRDC, accessed July 22, 2025,
Calcareous Soils Initiative - GRDC, accessed July 22, 2025,
Contextual Support Government

Calcareous Soils Initiative - GRDC, accessed July 24, 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 Potassium Control of Plant Functions: Ecological and Agricultural Implications - PMC
Potassium Control of Plant Functions: Ecological and Agricultural Implications - PMC
Contextual Support Journal

Potassium Control of Plant Functions: Ecological and Agricultural Implications - PMC

View Source

Context

  • Region Australia
  • Biome Arid Karstic Woodlands & Shrublands
  • Land Use Agricultural Crop Production
  • Assessment Pristine Reference
  • Evidence Type ReferenceCondition

Lifecycle

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

Notes

This benchmark reflects a state of high natural capital. The lower critical threshold is ~50-80 mg/kg, below which ecological resilience is compromised. The optimal range is 80-300 mg/kg, representing a healthy system conserving its native K. Levels >300 mg/kg, especially from fertiliser, risk cation imbalances.

Related Benchmarks

Other benchmarks in the AUS-AKW-AGR-SOK family.

— mg/kg Moderate
Agricultural Crop Production · Pristine Reference
OptimalRange Active v2
300 mg/kg Moderate
Agricultural Crop Production · Pristine Reference
MinimumOnly Active v1
— mg/kg Moderate
Agricultural Crop Production · Pristine Reference
OptimalRange Superseded v1