Soil Potassium

AUS-TSW-FOR-SOK General Moderate confidence

Benchmark Value

390 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 5 benchmarks together — the OptimalRange form drives the primary score, while 4 guard(s) constrain the result.

Contributing Benchmarks

OptimalRange Primary Point Guard Point Guard MinimumOnly Guard Point 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 concentration in soil, measured as meq/100g and converted to mg/kg.

Benchmark Definition:

This benchmark represents the best available condition for soil potassium in production forestry within Australian temperate semi-arid woodlands, indicating healthy ecosystem function.

Justification:

The benchmark is based on high-quality, scientifically rigorous data from a mature, intact woodland ecosystem relevant to the target biome and land use.

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.

Preview of Agronomic studies in Australia for grain crops and general soil fertility guides for NSW and WA
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 Conservation Target
  • Vegetation Woodland
  • Evidence Type ReferenceCondition

Lifecycle

  • Status Active
  • Version 1
  • Effective From 10 Jun 2026

Notes

Lower Critical Threshold: 50 mg/kg. No upper detrimental threshold — higher values are always better up to natural saturation. Optimal range is 120–390 mg/kg. Lower critical threshold is 50 mg/kg below which ecosystem function is compromised. No direct upper toxicity threshold; upper limit defined by cation imbalance (Mg:K ratio < 1.5:1 or K > 10% CEC).