Soil Phosphorus

AUS-AKW-CON-SOP General Moderate confidence

Benchmark Value

2 mg/kg
Direction: Higher is desirable ↑
Form: MaximumOnly

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 7 benchmarks together — the OptimalRange form drives the primary score, while 6 guard(s) constrain the result.

Contributing Benchmarks

OptimalRange Primary MaximumOnly Guard OptimalRange Guard MinimumOnly Guard MaximumOnly Guard OptimalRange Guard MinimumOnly Guard

Evidence & Context

typical Colwell P values for virgin soils (0–10 cm) in South-West Western Australia are less than 2 mg kg⁻¹

Metric Definition:

Available phosphorus estimated by Colwell-P test, representing the fraction of soil phosphorus readily accessible for uptake by plants and microbes.

Benchmark Definition:

This benchmark represents the maximum available phosphorus in undisturbed virgin soils in a P-limited ecosystem, serving as a reference for the Arid Karstic Woodlands & Shrublands biome.

Justification:

This value represents the upper limit for available phosphorus in a natural, undisturbed, P-limited ecosystem in the broader region, used as a proxy for the Arid Karstic Woodlands & Shrublands biome.

Sources (1)

Preview of An inventory and condition survey of the Western Australian part of the Nullarbor region, accessed July 25, 2025
An inventory and condition survey of the Western Australian part of the Nullarbor region, accessed July 25, 2025 Journal

(PDF) Phosphorus status and saturation in soils that drain into the ...

View Source

Context

  • Region Australia
  • Biome Arid Karstic Woodlands & Shrublands
  • Land Use Conservation / Protected Natural Areas
  • Assessment Pristine Reference
  • Evidence Type ReferenceCondition

Lifecycle

  • Status Superseded
  • Version 1
  • Effective From 25 Mar 2026
  • Effective To 25 Mar 2026

Notes

Direct data from protected areas in the Nullarbor is unavailable; this proxy is from minimally disturbed 'virgin soils' in a comparable P-impoverished region of Western Australia.

Related Benchmarks

Other benchmarks in the AUS-AKW-CON-SOP family.

2 mg/kg Moderate
Conservation / Protected Natural Areas · Pristine Reference
MaximumOnly Active v2
— mg/kg Moderate
Conservation / Protected Natural Areas · Conservation Target
OptimalRange Active v1
20 mg/kg Moderate
Conservation / Protected Natural Areas · Conservation Target
MinimumOnly Active v1