Soil Phosphorus

AUS-TMI-CON-SOP General Moderate confidence

Benchmark Value

No specific value — see range

Range: 0 to 15 mg/kg

Optimal Range: 0 to 15

Direction: Lower is desirable ↓

Form: OptimalRange

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

Contributing Benchmarks

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

Evidence & Context

The optimal condition is therefore defined by a low level of available phosphorus, likely in the range of <2 to 15 mg/kg (Colwell P).

Metric Definition:

Available phosphorus (Colwell P) concentration in soil, indicating plant-available phosphorus relevant for ecological health assessment.

Benchmark Definition:

The natural, low-phosphorus state that maximizes endemic biodiversity and ecosystem resilience in P-sensitive maritime island conservation areas.

Justification:

This range reflects the naturally low phosphorus availability to which native flora are adapted, supporting high biodiversity and ecosystem resilience.

Sources (1)

Preview of Common soil types | Environment, land and water | Queensland ...

Common soil types | Environment, land and water | Queensland ... Government

Phosphorus nutrition of phosphorus-sensitive Australian native ...

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Supporting Sources (5)

Additional references from the underlying research that informed this benchmark.

A simple phosphorus buffering index for Australian soils - ResearchGate

Contextual Support GreyLiterature

(PDF) A simple phosphorus buffering index for Australian soils - ResearchGate

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LORD HOWE ISLAND BOARD On-Site Wastewater Management ...

Contextual Support Journal

LORD HOWE ISLAND BOARD On-Site Wastewater Management ...

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Preview of Phosphorus nutrition of phosphorus-sensitive Australian native plants: threats to plant communities in a global biodiversity hotspot - PMC

Phosphorus nutrition of phosphorus-sensitive Australian native plants: threats to plant communities in a global biodiversity hotspot - PMC

Contextual Support Journal

(PDF) Sensitivity of seedling growth to phosphorus supply in six tree ..., accessed May 15, 2025,

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Soil and Landscape Grid National Soil Attribute Maps - Total Phosphorus (3" resolution) - Release 2 - CSIRO Data Access Portal

Direct Evidence Government

Soil and Landscape Grid National Soil Attribute Maps - Total Phosphorus (3" resolution) - Release 2

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Torres Strait Islands - Wikipedia, accessed July 27, 2025,

Contextual Support GreyLiterature

Torres Strait Islands - Wikipedia

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Context

Region Australia
Biome Tropical & Subtropical Maritime Islands
Land Use Conservation / Protected Natural Areas
Assessment Conservation Target
Evidence Type ReferenceCondition

Lifecycle

Status Active
Version 2
Effective From 24 Mar 2026

Notes

No upper detrimental threshold — higher values are always better up to natural saturation. The lower end (<2 mg/kg) represents the most P-impoverished sites, while the upper end (15 mg/kg) approaches the upper detrimental threshold.

Related Benchmarks

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