Soil Phosphorus

AUS-TGP-CON-SOP General Moderate confidence

Benchmark Value

No specific value — see range
Range: 2 to 6 mg/kg
Optimal Range: 2 to 6
Direction: Lower 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 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

Benchmark Value: The benchmark representing the highest ecological condition, capable of supporting P-sensitive keystone species like Themeda triandra, is a range of 2–6 mg/kg for available phosphorus (measured as Colwell-P or Olsen-P).

Metric Definition:

Available phosphorus (Olsen-P or Colwell-P) concentration in soil

Benchmark Definition:

This benchmark defines the optimal range of available soil phosphorus (2 to 6 mg/kg) in temperate grassy woodlands and plains under conservation management, supporting phosphorus-sensitive native species such as Themeda triandra.

Justification:

Derived from measurements in unfertilised native forests and defined botanical stability thresholds for high-quality native grasslands.

Sources (1)

Preview of Phosphorus responses of perennial native pasture species endemic to south-eastern Australia to P application: a review. Crop & Pasture Science, 71(9), 797-815. (Lodge, G. M., Murphy, S. R., & Harden, S., 2020)
Phosphorus responses of perennial native pasture species endemic to south-eastern Australia to P application: a review. Crop & Pasture Science, 71(9), 797-815. (Lodge, G. M., Murphy, S. R., & Harden, S., 2020) Journal

Phosphorus fertiliser management for pastures based on native grasses in south-eastern Australia

View Source

Supporting Sources (20)

Additional references from the underlying research that informed this benchmark.

Preview of (PDF) Phosphorus accumulation and other changes in soil ..., accessed August 11, 2025
(PDF) Phosphorus accumulation and other changes in soil ..., accessed August 11, 2025
Contextual Support Journal

Phosphorus accumulation and other changes in soil properties as a consequence of vegetable production, Sydney region, Australia - 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 GreyLiterature

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

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

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

View Source
Preview of Australian Journal of Botany - CSIRO PUBLISHING, accessed August 11, 2025
Australian Journal of Botany - CSIRO PUBLISHING, accessed August 11, 2025
Contextual Support Journal

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

View Source
Preview of Busted: The I-hate-phosphorus myth - AusBonsai, accessed August 11, 2025
Busted: The I-hate-phosphorus myth - AusBonsai, accessed August 11, 2025
Contextual Support GreyLiterature

Busted: The I-hate-phosphorus myth - AusBonsai, accessed August 11, 2025,

View Source
Preview of Identifying ecological barriers to restoration in temperate grassy woodlands: soil changes associated with different degradation states - ResearchGate, accessed August 5, 2025,
Identifying ecological barriers to restoration in temperate grassy woodlands: soil changes associated with different degradation states - ResearchGate, accessed August 5, 2025,
Contextual Support Direct Evidence GreyLiterature

(PDF) Identifying ecological barriers to restoration in temperate grassy woodlands: soil changes associated with different degradation states - ResearchGate, accessed August 4, 2025,

View Source
Preview of Old field restoration improves biodiversity and soils and large parts of Australia have huge potential to be remediated, accessed August 11, 2025
Old field restoration improves biodiversity and soils and large parts of Australia have huge potential to be remediated, accessed August 11, 2025
Contextual Support GreyLiterature

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

View Source
Preview of Phosphorus - WA | Fact Sheets | soilquality.org.au, accessed August 4, 2025
Phosphorus - WA | Fact Sheets | soilquality.org.au, accessed August 4, 2025
Contextual Support GreyLiterature

Phosphorus - Tas | Fact Sheets | soilquality.org.au, accessed August 11, 2025,

View Source
Preview of Phosphorus fertiliser management for pastures ... - CSIRO Publishing, accessed August 11, 2025
Phosphorus fertiliser management for pastures ... - CSIRO Publishing, accessed August 11, 2025
Contextual Support Methodology Source Journal

Phosphorus fertiliser management for pastures ... - CSIRO Publishing

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
Contextual Support Journal

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

View Source
Preview of Phosphorus: a finite resource essential for life, critical for agriculture and food security - CSIRO, accessed August 11, 2025
Phosphorus: a finite resource essential for life, critical for agriculture and food security - CSIRO, accessed August 11, 2025
Contextual Support Government

Nitrogen and Phosphorus Retranslocation of Leaves and Stemwood in a Mature Eucalyptus Forest Exposed to 5 Years of Elevated CO2 - Frontiers

View Source
Preview of Restoring ecological function in temperate grassy woodlands: Manipulating soil nutrients, exotic annuals and native perennial grasses through carbon supplements and spring burns - the UWA Profiles and Research Repository, accessed August 11, 2025
Restoring ecological function in temperate grassy woodlands: Manipulating soil nutrients, exotic annuals and native perennial grasses through carbon supplements and spring burns - the UWA Profiles and Research Repository, accessed August 11, 2025
Contextual Support Direct Evidence Journal

Restoring ecological function in temperate grassy woodlands: Manipulating soil nutrients, exotic annuals and native perennial grasses through carbon supplements and spring burns - the UWA Profiles and Research Repository, accessed August 11, 2025,

View Source
Preview of Sensitivity of seedling growth to phosphorus supply in six tree species of the Australian Great Western Woodlands - ResearchGate, accessed August 11, 2025
Sensitivity of seedling growth to phosphorus supply in six tree species of the Australian Great Western Woodlands - ResearchGate, accessed August 11, 2025
Contextual Support Journal

Understanding soil tests for pastures | Soil | Farm management ...

View Source
Preview of Soil nutrient critical limits | MBFP | More Beef from Pastures - MLA, accessed May 13, 2025,
Soil nutrient critical limits | MBFP | More Beef from Pastures - MLA, accessed May 13, 2025,
Direct Evidence Government

Understanding soil tests for pastures | Soil | Farm management ..., accessed July 17, 2025

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
Direct Evidence

(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 Soil phosphorus and tree cover modify the effects of livestock grazing on plant species richness in Australian grassy woodland - ResearchGate, accessed July 10, 2025,
Soil phosphorus and tree cover modify the effects of livestock grazing on plant species richness in Australian grassy woodland - ResearchGate, accessed July 10, 2025,
Direct Evidence

Regenerative agriculture in Australia: the changing face of farming - Frontiers

View Source
Preview of The changing the availability of nutrients in global grasslands | TERN Australia, accessed August 11, 2025
The changing the availability of nutrients in global grasslands | TERN Australia, accessed August 11, 2025
Contextual Support Government

The changing the availability of nutrients in global grasslands | TERN Australia, accessed August 11, 2025,

View Source
Preview of The development and application of functions describing pasture yield responses to phosphorus, potassium and sulfur in Australia using meta-data analysis and derived soil-test calibration relationships - CSIRO Publishing, accessed August 11, 2025
The development and application of functions describing pasture yield responses to phosphorus, potassium and sulfur in Australia using meta-data analysis and derived soil-test calibration relationships - CSIRO Publishing, accessed August 11, 2025
Contextual Support Methodology Source Journal

The role of regenerative agriculture in sustainable land use - ClimateWorks Australia

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
Preview of Why phosphorus is important - NSW Department of Primary Industries, accessed August 4, 2025
Why phosphorus is important - NSW Department of Primary Industries, accessed August 4, 2025
Contextual Support Government

Why phosphorus is important - NSW Department of Primary Industries

View Source

Context

  • Region Australia
  • Biome Temperate Grassy Woodlands & Plains
  • Land Use Conservation / Protected Natural Areas
  • Assessment Conservation Target
  • Evidence Type ReferenceCondition

Lifecycle

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

Notes

The benchmark represents available phosphorus in high-integrity temperate grassy woodlands. Low phosphorus levels (2-6 mg/kg) are desirable to maintain native biodiversity. A lower critical threshold is not relevant. Other literature notes an optimal range <5 to 15 mg/kg and a critical upper threshold near 20 mg/kg where exotic species dominate.