Soil Phosphorus

AUS-TSW-CON-SOP General Moderate confidence

Benchmark Value

75 mg/kg
Direction: Lower 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 11 benchmarks together — the OptimalRange form drives the primary score, while 10 guard(s) constrain the result.

Contributing Benchmarks

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

Evidence & Context

An upper detrimental threshold is identified at ~75 mg/kg (Colwell-P), representing a state of severe ecological degradation.

Metric Definition:

Available soil phosphorus measured by the Colwell-P method, representing plant-available phosphorus in soil.

Benchmark Definition:

Upper detrimental threshold above which severe ecosystem degradation occurs in temperate semi-arid woodlands.

Justification:

Based on modeling showing catastrophic loss of native species at this P concentration.

Sources (1)

Preview of Australian Journal of Botany - CSIRO PUBLISHING, accessed August 11, 2025
Australian Journal of Botany - CSIRO PUBLISHING, accessed August 11, 2025 Journal

Individual plant species responses to phosphorus and livestock grazing - CSIRO PUBLISHING | Australian Journal of Botany

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Supporting Sources (17)

Additional references from the underlying research that informed this benchmark.

Preview of (PDF) Mineral Nutrition of Plants in Australia's Arid Zone - ResearchGate, accessed July 13, 2025
(PDF) Mineral Nutrition of Plants in Australia's Arid Zone - ResearchGate, accessed July 13, 2025
Contextual Support

Putting the P in Ptilotus: a phosphorus-accumulating herb native to Australia - PMC

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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

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Preview of Australian dryland soils are acidic and nutrient-depleted, and have unique microbial communities compared with other drylands - PMC, accessed August 5, 2025,
Australian dryland soils are acidic and nutrient-depleted, and have unique microbial communities compared with other drylands - PMC, accessed August 5, 2025,
Contextual Support Journal

How should we manage our soils to increase soil carbon?, accessed May 10, 2026

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Preview of Australian dryland soils are acidic and nutrient‐depleted, and have
Australian dryland soils are acidic and nutrient‐depleted, and have
Contextual Support Journal

Australian dryland soils are acidic and nutrient‐depleted, and have

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Preview of Eutrophication (nutrient enrichment) - Government of Western Australia
Eutrophication (nutrient enrichment) - Government of Western Australia
Contextual Support GreyLiterature

Eutrophication (nutrient enrichment) - Government of Western Australia

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Preview of Identifying limitations for invasion: the effect of phosphorus availability on the growth of the non-native tree, Tipuana tipu - CSIRO Publishing
Identifying limitations for invasion: the effect of phosphorus availability on the growth of the non-native tree, Tipuana tipu - CSIRO Publishing
Contextual Support Journal

Identifying limitations for invasion: the effect of phosphorus availability on the growth of the non-native tree, Tipuana tipu - CSIRO Publishing

View Source
Preview of Indicative Soil Phosphorus Report | LongPaddock | Queensland Government
Indicative Soil Phosphorus Report | LongPaddock | Queensland Government
Contextual Support Government

Indicative Soil Phosphorus Report | LongPaddock | Queensland Government

View Source
Preview of Individual plant species responses to phosphorus and livestock grazing
Individual plant species responses to phosphorus and livestock grazing
Contextual Support Journal

Individual plant species responses to phosphorus and livestock grazing

View Source
Preview of management of inland arid and semi-arid woodland ... - DBCA Library, accessed July 12, 2025,
management of inland arid and semi-arid woodland ... - DBCA Library, accessed July 12, 2025,
Contextual Support Journal

management of inland arid and semi-arid woodland ... - DBCA Library

View Source
Preview of Multiple adaptive responses of Australian native perennial legumes with pasture potential to grow in phosphorus- and moisture-limited environments
Multiple adaptive responses of Australian native perennial legumes with pasture potential to grow in phosphorus- and moisture-limited environments
Contextual Support Journal

Multiple adaptive responses of Australian native perennial legumes with pasture potential to grow in phosphorus- and moisture-limited environments

View Source
Preview of Phosphorus - Qld | Fact Sheets | soilquality.org.au, accessed August 28, 2025
Phosphorus - Qld | Fact Sheets | soilquality.org.au, accessed August 28, 2025
Contextual Support Government

Phosphorus - WA | Fact Sheets | soilquality.org.au

View Source
Preview of Phosphorus requirements of Australian native plants - ResearchGate, accessed August 4, 2025
Phosphorus requirements of Australian native plants - ResearchGate, accessed August 4, 2025
Contextual Support Journal

Australian dryland soils are acidic and nutrient-depleted, and have unique microbial communities compared with other drylands - PMC, accessed July 22, 2025

View Source
Preview of Phosphorus sorption in relation to soil properties for the major soil types of South-Western Australia | Request PDF - ResearchGate
Phosphorus sorption in relation to soil properties for the major soil types of South-Western Australia | Request PDF - ResearchGate
Contextual Support Journal

(PDF) Mobility of phosphorus through intact soil cores collected from the Adelaide Hills, South Australia - ResearchGate

View Source
Preview of Plant and soil carbon, nitrogen and phosphorus on the Australian continent - CiteSeerX, accessed July 16, 2025,
Plant and soil carbon, nitrogen and phosphorus on the Australian continent - CiteSeerX, accessed July 16, 2025,
Contextual Support GreyLiterature

Soil phosphorus testing: Colwell P and DGT-P - WA Soil Knowledge Base

View Source
Preview of Soil factors influencing eutrophication. In Soilguide. A handbook for understanding and managing agricultural soils. (ed. Geoff - DPIRD's Digital library
Soil factors influencing eutrophication. In Soilguide. A handbook for understanding and managing agricultural soils. (ed. Geoff - DPIRD's Digital library
Contextual Support

Soil factors influencing eutrophication. In Soilguide. A handbook for understanding and managing agricultural soils. (ed. Geoff - DPIRD's Digital library

View Source
Preview of Soil phosphorus and tree cover modify the effects of livestock grazing on plant species richness in Australian grassy woodland - ResearchGate, accessed August 11, 2025
Soil phosphorus and tree cover modify the effects of livestock grazing on plant species richness in Australian grassy woodland - ResearchGate, accessed August 11, 2025
Contextual Support

(PDF) Soil phosphorus and tree cover modify the effects of livestock grazing on plant species richness in Australian grassy woodland - ResearchGate

View Source
Preview of Too much of a good thing: phosphorus over-fertilisation in rehabilitated landscapes of high biodiversity value - Australian Centre for Geomechanics, accessed August 11, 2025
Too much of a good thing: phosphorus over-fertilisation in rehabilitated landscapes of high biodiversity value - Australian Centre for Geomechanics, accessed August 11, 2025
Contextual Support Journal

Too much of a good thing: phosphorus over-fertilisation in rehabilitated landscapes of high biodiversity value - Australian Centre for Geomechanics

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Context

  • Region Australia
  • Biome Temperate Semi-Arid Shrublands & Open Woodlands
  • Land Use Conservation / Protected Natural Areas
  • Assessment Conservation Target
  • Evidence Type DegradationThreshold

Lifecycle

  • Status Active
  • Version 1
  • Effective From 10 Jun 2026

Notes

Represents near-total collapse of native understorey community.

Related Benchmarks

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

— mg/kg Moderate
Conservation / Protected Natural Areas · Conservation Target
OptimalRange Active v1
5 mg/kg High
Conservation / Protected Natural Areas · Conservation Target
MinimumOnly Active v1