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

Contributing Benchmarks

OptimalRange Primary MaximumOnly Guard MinimumOnly Guard OptimalRange Guard OptimalRange 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 measured as Colwell-P, the fraction of soil phosphorus readily accessible for uptake by plants and microbes.

Benchmark Definition:

This benchmark represents the upper limit of available phosphorus in natural, undisturbed virgin soils within the Arid Karstic Woodlands & Shrublands biome, indicating a phosphorus-limited ecosystem.

Justification:

Selected as the best-on-offer reference due to direct measurement in minimally disturbed remnant vegetation in a comparable P-impoverished region.

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 Active
  • Version 1
  • Effective From 10 Jun 2026

Notes

This value represents the upper limit for available phosphorus in a natural, undisturbed, P-limited ecosystem and serves as a proxy benchmark for the Arid Karstic Woodlands & Shrublands biome due to lack of direct data.

Related Benchmarks

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

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