Soil Phosphorus

AUS-TSR-CON-SOP General Moderate confidence

Benchmark Value

20 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 2 benchmarks together — the Point form drives the primary score, while 1 guard(s) constrain the result.

Contributing Benchmarks

Point Primary MaximumOnly Guard

Evidence & Context

The >20 mg/kg (Colwell P) value serves as a compelling, evidence-based upper detrimental threshold for oligotrophic and mesotrophic rainforest systems, where this represents a significant departure from the natural state.

Metric Definition:

Available Phosphorus: This measures the fraction of phosphorus that is readily available for plant uptake.

Benchmark Definition:

This benchmark represents the upper detrimental threshold of available phosphorus for oligotrophic and mesotrophic rainforest systems in Australia.

Justification:

This value represents a significant departure from the natural state and indicates ecological degradation.

Sources (1)

Preview of Nutrient relationships of tree species in a New South Wales Subtropical rainforest (Turner & Lambert 1990)
Nutrient relationships of tree species in a New South Wales Subtropical rainforest (Turner & Lambert 1990) GreyLiterature

Tool 2.8: Soil nutrient critical limits (Meat & Livestock Australia 2020)

View Source

Supporting Sources (1)

Additional references from the underlying research that informed this benchmark.

Preview of Plant-soil nutrient relationships in the wet tropical rainforests of north Queensland, Australia (Maycock 1998)
Plant-soil nutrient relationships in the wet tropical rainforests of north Queensland, Australia (Maycock 1998)
Contextual Support Journal

Plant-soil nutrient relationships in the wet tropical rainforests of north Queensland, Australia (Maycock 1998)

View Source

Context

  • Region Australia
  • Biome Tropical & Subtropical Rainforests
  • Land Use Conservation / Protected Natural Areas
  • Assessment Pristine Reference
  • Evidence Type DegradationThreshold

Lifecycle

  • Status Active
  • Version 1
  • Effective From 25 Mar 2026

Notes

Above this threshold, native grasses are outcompeted by introduced species, leading to loss of native floristic character.

Related Benchmarks

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

100 mg/kg Moderate
Conservation / Protected Natural Areas · Pristine Reference
Point Active v2
10 mg/kg Moderate
Conservation / Protected Natural Areas · Pristine Reference
MinimumOnly Active v1
60 mg/kg Moderate
Conservation / Protected Natural Areas · Pristine Reference
MaximumOnly Active v1
— mg/kg Moderate
Conservation / Protected Natural Areas · Pristine Reference
OptimalRange Active v1
3030 mg/kg Moderate
Conservation / Protected Natural Areas · Pristine Reference
Point Active v1
— mg/kg Moderate
Conservation / Protected Natural Areas · Pristine Reference
OptimalRange Active v1
1300 mg/kg Moderate
Conservation / Protected Natural Areas · Pristine Reference
Point Superseded v1