Soil Phosphorus

AUS-TSW-CON-SOP General High confidence

Benchmark Value

10 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 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

The benchmark of <10 mg/kg (Colwell-P) represents the upper limit for available phosphorus in high-integrity, unfertilised remnant temperate semi-arid woodlands in Australia, which are associated with the highest native plant species richness.

Metric Definition:

Available soil phosphorus measured by the Colwell-P method.

Benchmark Definition:

This benchmark represents the upper limit of available soil phosphorus in high-integrity, unfertilised temperate semi-arid woodlands in Australia, associated with the highest native plant species richness.

Justification:

This value is derived from Dorrough et al. (2011), who identified it as the characteristic condition of the best-on-offer reference sites.

Sources (1)

Preview of Individual plant species responses to phosphorus and livestock grazing
Individual plant species responses to phosphorus and livestock grazing Journal

Individual plant species responses to phosphorus and livestock grazing

View Source

Supporting Sources (16)

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

(PDF) Mineral Nutrition of Plants in Australia's Arid Zone - ResearchGate

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 Journal

A new detailed map of total phosphorus stocks in Australian soil

View Source
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

Root Structure and Functioning for Efficient Acquisition of Phosphorus: Matching Morphological and Physiological Traits

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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 (Pollution) - Scotch College Library

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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, accessed August 1, 2025

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, accessed July 12, 2025,

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

Putting the P in Ptilotus: a phosphorus-accumulating herb native to Australia | Annals of Botany | Oxford Academic

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, accessed August 1, 2025

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

The Big Phosphorus Issue - Australian Native Plants — The Gardeners Lodge, accessed August 1, 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

View Source

Context

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

Lifecycle

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

Notes

No upper detrimental threshold — higher values are always better up to natural saturation. In these naturally P-limited ecosystems, P enrichment is a primary driver of degradation.

Related Benchmarks

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

75 mg/kg Moderate
Conservation / Protected Natural Areas · Pristine Reference
MinimumOnly Active v2
— mg/kg High
Conservation / Protected Natural Areas · Pristine Reference
OptimalRange Active v1
5 mg/kg Moderate
Conservation / Protected Natural Areas · Pristine Reference
MinimumOnly Superseded v1