Soil Phosphorus

AUS-TDG-FOR-SOP General Low confidence

Benchmark Value

3 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 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 below approximately 2-3 mg/kg (Colwell P/Olsen P) are considered critically low. Below this, significant impairment of essential ecological functions (e.g., nutrient cycling, primary productivity), tree health, regeneration, and long-term site productivity for forestry is likely, even for adapted native systems.

Metric Definition:

Available soil phosphorus level below which significant impairment of ecological functions and forestry productivity occurs.

Benchmark Definition:

This benchmark defines the critical minimum soil phosphorus level necessary to maintain forest health and essential ecological functions in Australian temperate dry woodlands and native grasslands under production forestry.

Justification:

Below this level, significant impairment of essential ecological functions, tree health, nutrient cycling, and long-term site productivity is likely, even for adapted native systems.

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 ...

View Source
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 Journal

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

View Source
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 ...

View Source

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

Represents the lower boundary of soil phosphorus availability necessary to sustain production forestry and ecological health in P-impoverished Australian temperate dry woodlands and native grasslands. AssessmentContext defaulted to 'Not Stated' because the source document did not state one.

Related Benchmarks

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

— mg/kg Low
Production Forestry · Not Stated
OptimalRange Active v2
15 mg/kg Low
Production Forestry · Not Stated
MaximumOnly Active v2
— mg/kg Moderate
Production Forestry · Not Stated
OptimalRange Superseded v2
15 mg/kg Low
Production Forestry · Not Stated
MaximumOnly Superseded v1
— mg/kg Moderate
Production Forestry · Not Stated
OptimalRange Superseded v1
3 mg/kg Low
Production Forestry · Not Stated
MinimumOnly Superseded v1