Soil Phosphorus

AUS-TDG-FOR-SOP General Low confidence

Benchmark Value

15 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 14 benchmarks together — the OptimalRange form drives the primary score, while 13 guard(s) constrain the result.

Contributing Benchmarks

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

Evidence & Context

Available P levels consistently exceeding 10-15 mg/kg (Colwell P/Olsen P), particularly due to P inputs, are considered detrimental to overall ecosystem health.

Metric Definition:

Available soil phosphorus level above which detrimental effects on ecosystem health occur.

Benchmark Definition:

This benchmark defines the upper detrimental soil phosphorus threshold above which ecological harm occurs in Australian temperate dry woodlands and native grasslands under production forestry.

Justification:

Levels above this threshold cause negative impacts on P-sensitive native species, loss of understorey biodiversity, and shifts towards weedy species.

Sources (3)

Preview of Phosphorus fertiliser management for pastures based on native grasses in south-eastern Australia - CSIRO Publishing, accessed August 5, 2025,

Phosphorus fertiliser management for pastures based on native grasses in south-eastern Australia - CSIRO Publishing, accessed August 5, 2025, GreyLiterature

Phosphorus nutrition of phosphorus-sensitive Australian native ...

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

(PDF) Sensitivity of seedling growth to phosphorus supply in six tree ...

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Preview of Sensitivity of seedling growth to phosphorus supply in six tree species of the Australian Great Western Woodlands - ResearchGate, accessed August 11, 2025

Sensitivity of seedling growth to phosphorus supply in six tree species of the Australian Great Western Woodlands - ResearchGate, accessed August 11, 2025 Journal

Understanding soil tests for pastures | Soil | Farm management ...

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Context

Region Australia
Biome Temperate Dry Woodlands & Native Grasslands
Land Use Production Forestry
Assessment Not Stated
Evidence Type DegradationThreshold

Lifecycle

Status Active
Version 2
Effective From 10 Jun 2026

Notes

Production forestry practices must avoid P inputs that elevate soil available P into this detrimental zone to maintain biodiversity and ecological function. AssessmentContext defaulted to 'Not Stated' because the source document did not state one.

Related Benchmarks

Other benchmarks in the AUS-TDG-FOR-SOP family.