Soil Phosphorus

AUS-TSR-FOR-SOP General High confidence

Benchmark Value

No specific value — see range
Range: 2 to 5 mg/kg
Thresholds: Lower: 2, Upper: 6
Optimal Range: 2 to 5
Direction: Higher 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 3 benchmarks together — the OptimalRange form drives the primary score, while 2 guard(s) constrain the result.

Contributing Benchmarks

OptimalRange Primary OptimalRange Guard MinimumOnly Guard

Evidence & Context

the proposed reference benchmark for available soil phosphorus (Colwell-P) is 2–5 mg/kg.

Metric Definition:

Available Phosphorus refers to a suite of chemical extraction methods designed to estimate the portion of soil P that is readily available for plant uptake during a growing season.

Benchmark Definition:

This benchmark defines the optimal range of available soil phosphorus in tropical rainforest production forestry soils, representing the best available condition for sustainable productivity and ecosystem health.

Justification:

This range represents the 'best available condition' as it is consistent with healthy native forests, provides sufficient P for sustainable productivity, and maintains a safety margin below the identified detrimental threshold of >6 mg/kg.

Sources (2)

Preview of Soil phosphorus transformations along a 500,000-year coastal dune chronosequence under subtropical rainforest in Australia
Soil phosphorus transformations along a 500,000-year coastal dune chronosequence under subtropical rainforest in Australia Journal

Soil Development and Nutrient Availability Along a 2 Million-Year Coastal Dune Chronosequence Under Species-Rich Mediterranean - Smithsonian Institution, accessed July 19, 2025

View Source
Preview of Too much of a good thing: phosphorus over-fertilisation in rehabilitated landscapes of high biodiversity value
Too much of a good thing: phosphorus over-fertilisation in rehabilitated landscapes of high biodiversity value Journal

Too much of a good thing: phosphorus over-fertilisation in rehabilitated landscapes of high biodiversity value, accessed May 7, 2026

View Source

Supporting Sources (18)

Additional references from the underlying research that informed this benchmark.

Preview of (PDF) A review of the effects of forest fire on soil properties - ResearchGate, accessed July 19, 2025
(PDF) A review of the effects of forest fire on soil properties - ResearchGate, accessed July 19, 2025
Contextual Support GreyLiterature

(PDF) A review of the effects of forest fire on soil properties - ResearchGate, accessed July 19, 2025

View Source
Preview of (PDF) Soil phosphorus transformations along two long-term chronosequences with contrasting climate in south-western Australia - ResearchGate, accessed July 19, 2025
(PDF) Soil phosphorus transformations along two long-term chronosequences with contrasting climate in south-western Australia - ResearchGate, accessed July 19, 2025
Contextual Support GreyLiterature

Organic phosphorus speciation in Australian Red Chromosols: stoichiometric control, accessed July 19, 2025

View Source
Preview of A Critical Review on Soil Chemical Processes that Control How Soil pH Affects Phosphorus Availability to Plants - MDPI, accessed July 19, 2025
A Critical Review on Soil Chemical Processes that Control How Soil pH Affects Phosphorus Availability to Plants - MDPI, accessed July 19, 2025
Contextual Support Journal

A Critical Review on Soil Chemical Processes that Control How Soil pH Affects Phosphorus Availability to Plants - MDPI, accessed July 19, 2025

View Source
Preview of A new detailed map of total phosphorus stocks in Australian soil - ResearchGate, accessed August 11, 2025
A new detailed map of total phosphorus stocks in Australian soil - ResearchGate, accessed August 11, 2025
Contextual Support GreyLiterature

(PDF) Strategies to acquire and use phosphorus in phosphorus-impoverished and fire-prone environments - ResearchGate, accessed July 22, 2025

View Source
Preview of Browsing Smithsonian Tropical Research Institute by Title, accessed July 19, 2025
Browsing Smithsonian Tropical Research Institute by Title, accessed July 19, 2025
Contextual Support Journal

Soil phosphorus responses to chronic nutrient fertilisation and seasonal drought in a humid lowland forest, Panama - CSIRO Publishing, accessed July 19, 2025

View Source
Preview of Critical phosphorus values from the Better Fertiliser Decisions for Pastures project: early insights from validation trials - BioOne Complete, accessed July 28, 2025,
Critical phosphorus values from the Better Fertiliser Decisions for Pastures project: early insights from validation trials - BioOne Complete, accessed July 28, 2025,
Contextual Support Journal

Soil nutrient critical limits | MBFP | More Beef from Pastures - MLA

View Source
Preview of Different profiles of soil phosphorous compounds depending on tree species and availability of soil phosphorus in a tropical rainforest in French Guiana - PubMed Central, accessed July 19, 2025
Different profiles of soil phosphorous compounds depending on tree species and availability of soil phosphorus in a tropical rainforest in French Guiana - PubMed Central, accessed July 19, 2025
Contextual Support Journal

Soil phosphorus fractions and their relation to leaf litterfall in a central Amazonian terra firme rainforest - SciELO, accessed July 19, 2025

View Source
Preview of Impacts of Logging-Associated Compaction on Forest Soils: A Meta-Analysis - Frontiers, accessed July 11, 2025,
Impacts of Logging-Associated Compaction on Forest Soils: A Meta-Analysis - Frontiers, accessed July 11, 2025,
Contextual Support Journal

Impacts of Logging-Associated Compaction on Forest Soils: A Meta-Analysis - Frontiers, accessed July 19, 2025

View Source
Preview of Maycock, Colin Rulzion (1998) Plant-soil nutrient relationships in ...
Maycock, Colin Rulzion (1998) Plant-soil nutrient relationships in ...
Contextual Support Journal

Australian Journal of Botany - CSIRO PUBLISHING, accessed July 19, 2025

View Source
Preview of Phosphorus buffering determines how soil properties and rainfall influence wheat (Triticum aestivum) yield response to - CSIRO Publishing, accessed July 19, 2025
Phosphorus buffering determines how soil properties and rainfall influence wheat (Triticum aestivum) yield response to - CSIRO Publishing, accessed July 19, 2025
Contextual Support Journal

Phosphorus buffering determines how soil properties and rainfall influence wheat (Triticum aestivum) yield response to - CSIRO Publishing, accessed July 19, 2025

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
Direct Evidence Journal

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

View Source
Preview of Phosphorus nutrition of phosphorus-sensitive Australian native plants: threats to plant communities in a global biodiversity hotspot | Conservation Physiology | Oxford Academic, accessed August 4, 2025
Phosphorus nutrition of phosphorus-sensitive Australian native plants: threats to plant communities in a global biodiversity hotspot | Conservation Physiology | Oxford Academic, accessed August 4, 2025
Contextual Support Journal

Phosphorus nutrition of phosphorus-sensitive Australian native plants: threats to plant communities in a global biodiversity hotspot | Conservation Physiology | Oxford Academic, accessed July 7, 2025,

View Source
Preview of Phosphorus Nutrition of Proteaceae in Severely Phosphorus-Impoverished Soils: Are There Lessons To Be Learned for Future Crops? - PubMed Central, accessed August 4, 2025
Phosphorus Nutrition of Proteaceae in Severely Phosphorus-Impoverished Soils: Are There Lessons To Be Learned for Future Crops? - PubMed Central, accessed August 4, 2025
Direct Evidence Journal

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

View Source
Preview of Phosphorus Transformation in Soils Following Co-Application of Charcoal and Wood Ash, accessed July 19, 2025
Phosphorus Transformation in Soils Following Co-Application of Charcoal and Wood Ash, accessed July 19, 2025
Contextual Support Journal

Phosphorus Transformation in Soils Following Co-Application of Charcoal and Wood Ash, accessed July 19, 2025

View Source
Preview of Soil condition | NSW State of the Environment, accessed August 10, 2025,
Soil condition | NSW State of the Environment, accessed August 10, 2025,
Contextual Support Government

Analysing water sensitive urban design options - Australian Water Association

View Source
Preview of Soil condition | NSW State of the Environment, accessed July 16, 2025
Soil condition | NSW State of the Environment, accessed July 16, 2025
Contextual Support GreyLiterature

Soil condition | NSW State of the Environment, accessed July 16, 2025,

View Source
Preview of Soil organic phosphorus dynamics following perturbation of litter cycling in a tropical moist forest, accessed July 19, 2025
Soil organic phosphorus dynamics following perturbation of litter cycling in a tropical moist forest, accessed July 19, 2025
Methodology Source Journal

Chronosequences, succession and soil development - Research Commons - University of Waikato, accessed July 19, 2025

View Source
Preview of Wildfire effects on soils and soil processes - CSIRO Publishing, accessed July 24, 2025,
Wildfire effects on soils and soil processes - CSIRO Publishing, accessed July 24, 2025,
Contextual Support GreyLiterature

The dynamics of microbial biomass C [MBC (a, b)] and N [MBN (c, d)]...

View Source

Context

  • Region Australia
  • Biome Tropical & Subtropical Rainforests
  • Land Use Production Forestry
  • Assessment Pristine Reference
  • Vegetation Forest
  • Evidence Type ReferenceCondition

Lifecycle

  • Status Active
  • Version 1
  • Effective From 26 May 2026

Notes

The benchmark is most critical for low P-buffering soils (e.g., sandy Tenosols). Lower Critical Threshold: 2 mg/kg. Upper Detrimental Threshold: 6 mg/kg.

Related Benchmarks

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

2 mg/kg Moderate
Production Forestry · Not Stated · Forest
MinimumOnly Active v1
6 mg/kg Moderate
Production Forestry · Not Stated · Forest
MaximumOnly Active v1