Soil Phosphorus

AUS-AKW-CON-SOP General Moderate confidence

Benchmark Value

2 mg/kg

Direction: Higher is desirable ↑

Form: MinimumOnly

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

The benchmark of <2 mg/kg Colwell-P is considered the lower critical threshold, below which the system would likely be under severe stress

Metric Definition:

Lower critical threshold for available phosphorus (Colwell-P) below which ecosystem function is compromised.

Benchmark Definition:

This benchmark marks the phosphorus level below which native flora in the Arid Karstic Woodlands & Shrublands biome experience severe nutrient stress.

Justification:

Based on the typical values for virgin soils and Queensland Government classification of 0-4 mg/kg as acutely deficient.

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 DegradationThreshold

Lifecycle

Status Active
Version 1
Effective From 10 Jun 2026

Notes

Represents the floor of a functioning native system in this P-impoverished biome.

Related Benchmarks

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