Soil Phosphorus

AUS-TSR-CON-SOP General Moderate confidence

Benchmark Value

10 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 7 benchmarks together — the OptimalRange form drives the primary score, while 6 guard(s) constrain the result.

Contributing Benchmarks

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

Evidence & Context

Based on data from analogous native pasture systems, a Colwell P level of ~10 mg/kg appears to be a functional minimum for maintaining a healthy native plant community on low-PBI soils.

Metric Definition:

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

Benchmark Definition:

This benchmark represents the functional minimum level of available phosphorus needed to maintain a healthy native plant community on low-PBI soils in Australian tropical and subtropical rainforests.

Justification:

This level is a functional minimum for maintaining a healthy native plant community on low-PBI soils.

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

Below this level, nutrient cycling processes are likely too constrained to support high biomass and diversity characteristic of rainforests.

Related Benchmarks

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

100 mg/kg Moderate
Conservation / Protected Natural Areas · Pristine Reference
Point Active v2
20 mg/kg Moderate
Conservation / Protected Natural Areas · Pristine Reference
MaximumOnly 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