Soil Phosphorus

AUS-AKW-LVG-SOP General Moderate confidence

Benchmark Value

20 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 10 benchmarks together — the OptimalRange form drives the primary score, while 9 guard(s) constrain the result.

Contributing Benchmarks

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

Evidence & Context

Synthesis for the Upper Threshold: A soil available phosphorus level of > 20 mg/kg (Colwell P) represents the upper detrimental threshold. Concentrations exceeding this value are a clear indicator that the system is no longer in a state of high ecological health. It signifies a transition to a degraded condition characterized by the loss of resilient native perennial species and the likely dominance of less desirable exotic annuals.

Metric Definition:

Soil available phosphorus level measured by Colwell P method

Benchmark Definition:

This benchmark represents the upper detrimental threshold of soil available phosphorus beyond which ecological integrity is lost in the Arid Karstic Woodlands & Shrublands under livestock grazing.

Justification:

Based on evidence that phosphorus levels above 20 mg/kg lead to native species displacement

Sources (1)

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, Government

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

Supporting Sources (20)

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 23, 2025,

(PDF) Mineral Nutrition of Plants in Australia's Arid Zone - ResearchGate, accessed July 23, 2025,

Contextual Support Journal

Ecology of Australia: The effects of nutrient-poor soils and intense fires - ResearchGate

Preview of A review of the economics of regenerative agriculture in Western Australia - DPIRD's Digital library, accessed August 4, 2025

A review of the economics of regenerative agriculture in Western Australia - DPIRD's Digital library, accessed August 4, 2025

Contextual Support Journal

A review of the economics of regenerative agriculture in Western Australia - DPIRD's Digital library

Preview of A simple phosphorus buffering index for Australian soils - University of Tasmania Open Access Repository Cover sheet

A simple phosphorus buffering index for Australian soils - University of Tasmania Open Access Repository Cover sheet

Contextual Support GreyLiterature

Phosphorus - NSW | Fact Sheets | soilquality.org.au, accessed July 22, 2025

Preview of Australian dryland soils are acidic and nutrient-depleted, and have unique microbial communities compared with other drylands - PMC, accessed July 23, 2025,

Australian dryland soils are acidic and nutrient-depleted, and have unique microbial communities compared with other drylands - PMC, accessed July 23, 2025,

Contextual Support Journal

Australian dryland soils are acidic and nutrient-depleted, and have unique microbial communities compared with other drylands - PMC, accessed July 23, 2025

Preview of Do regenerative grazing management practices improve vegetation and soil health in grazed rangelands? Preliminary insights from a space for time study in the Great Barrier Reef catchments - CSIRO Research Publications Repository, accessed July 18, 2025,

Do regenerative grazing management practices improve vegetation and soil health in grazed rangelands? Preliminary insights from a space for time study in the Great Barrier Reef catchments - CSIRO Research Publications Repository, accessed July 18, 2025,

Direct Evidence Journal

Case Study - Regenerative Rangelands - Landcare Australia, accessed July 23, 2025

Preview of Do regenerative grazing management practices improve vegetation and soil health in grazed rangelands? Preliminary insights from a space for time study in the Great Barrier Reef catchments - CSIRO Research Publications Repository, accessed July 23, 2025,

Do regenerative grazing management practices improve vegetation and soil health in grazed rangelands? Preliminary insights from a space for time study in the Great Barrier Reef catchments - CSIRO Research Publications Repository, accessed July 23, 2025,

Contextual Support Journal

Grazing Systems to Retain and Redistribute Soil Phosphorus and to Reduce Phosphorus Losses in Runoff - MDPI, accessed July 23, 2025,

Preview of Do regenerative grazing management practices improve vegetation and soil health in grazed rangelands? Preliminary insights from a space-for-time study in the Great Barrier Reef catchments, Australia - CSIRO Publishing, accessed July 23, 2025,

Do regenerative grazing management practices improve vegetation and soil health in grazed rangelands? Preliminary insights from a space-for-time study in the Great Barrier Reef catchments, Australia - CSIRO Publishing, accessed July 23, 2025,

Contextual Support Journal

Soil Microbial Composition and phoD Gene Abundance Are Sensitive to Phosphorus Level in a Long-Term Wheat-Maize Crop System - Frontiers, accessed May 7, 2026

Preview of Geology of the Nullarbor Plain (Webb and James 2006; courtesy JA Webb). - ResearchGate, accessed July 26, 2025,

Geology of the Nullarbor Plain (Webb and James 2006; courtesy JA Webb). - ResearchGate, accessed July 26, 2025,

Direct Evidence

Geology of the Nullarbor Plain (Webb and James 2006; courtesy JA Webb). - ResearchGate, accessed July 23, 2025

Preview of Improving native pastures - FutureBeef, accessed August 5, 2025,

Improving native pastures - FutureBeef, accessed August 5, 2025,

Contextual Support Journal

Improving native pastures - FutureBeef

Preview of Limited evidence for the use of livestock for the conservation management of exotic plant cover - CSIRO PUBLISHING | Australian Journal of Botany, accessed July 23, 2025,

Limited evidence for the use of livestock for the conservation management of exotic plant cover - CSIRO PUBLISHING | Australian Journal of Botany, accessed July 23, 2025,

Contextual Support Journal

Limited evidence for the use of livestock for the conservation management of exotic plant cover - CSIRO PUBLISHING | Australian Journal of Botany, accessed July 23, 2025,

Preview of Managing Grazing to Restore Soil Health, Ecosystem Function, and Ecosystem Services - Frontiers, accessed July 30, 2025,

Managing Grazing to Restore Soil Health, Ecosystem Function, and Ecosystem Services - Frontiers, accessed July 30, 2025,

Contextual Support Journal

Do regenerative grazing management practices improve vegetation and soil health in grazed rangelands? Preliminary insights from a space-for-time study in the Great Barrier Reef catchments, Australia - CSIRO Publishing, accessed July 10, 2025,

Preview of Nullarbor Plains Xeric Shrublands | One Earth, accessed July 26, 2025,

Nullarbor Plains Xeric Shrublands | One Earth, accessed July 26, 2025,

Contextual Support

Ecological literature on nutrient adaptation in arid ecosystems

Preview of Phosphorus for high rainfall pastures - DPIRD's Digital library, accessed July 23, 2025,

Phosphorus for high rainfall pastures - DPIRD's Digital library, accessed July 23, 2025,

Contextual Support

Phosphorus Nutrition of Proteaceae in Severely Phosphorus-Impoverished Soils: Are There Lessons To Be Learned for Future Crops? - PubMed Central, accessed July 18, 2025

Preview of Phosphorus Plays Key Roles in Regulating Plants' Physiological Responses to Abiotic Stresses - MDPI, accessed July 23, 2025,

Phosphorus Plays Key Roles in Regulating Plants' Physiological Responses to Abiotic Stresses - MDPI, accessed July 23, 2025,

Contextual Support Journal

Phosphorus Plays Key Roles in Regulating Plants' Physiological Responses to Abiotic Stresses - MDPI

Preview of Regenerative agriculture in Australia: the changing face of farming - Frontiers, accessed August 4, 2025

Regenerative agriculture in Australia: the changing face of farming - Frontiers, accessed August 4, 2025

Contextual Support Journal

Regenerative agriculture is key to dry season preparation - Soils For Life, accessed July 23, 2025

Preview of SA Arid Lands | From the Ground Up - Landscape South Australia, accessed July 25, 2025

SA Arid Lands | From the Ground Up - Landscape South Australia, accessed July 25, 2025

Contextual Support Government

Rangelands Living Skin - NSW Department of Primary Industries, accessed July 30, 2025,

Preview of Scale�related effects of grazing on native plant communities in an arid rangeland region of South Australia | Request PDF - ResearchGate, accessed July 29, 2025,

Scale�related effects of grazing on native plant communities in an arid rangeland region of South Australia | Request PDF - ResearchGate, accessed July 29, 2025,

Direct Evidence

The effects of drought and climate variability on Australian farms - DAFF

Preview of Soil organic matter in cropping systems - NSW Department of Primary Industries, accessed July 22, 2025,

Soil organic matter in cropping systems - NSW Department of Primary Industries, accessed July 22, 2025,

Contextual Support Journal

SOIL pH—SOUTH AUSTRALIA

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

Preview of Understanding soil tests for pastures | Soil | Farm management ..., accessed May 12, 2025

Understanding soil tests for pastures | Soil | Farm management ..., accessed May 12, 2025

Contextual Support Government

Agriculture Victoria. (2025). Understanding soil tests for pastures. Farm Management.

Context

Region Australia
Biome Arid Karstic Woodlands & Shrublands
Land Use Livestock Grazing & Pasture
Assessment Not Stated
Evidence Type DegradationThreshold

Lifecycle

Status Active
Version 1
Effective From 4 Jun 2026

Notes

Critical tipping point indicating transition to degraded ecosystem state AssessmentContext defaulted to 'Not Stated' because the source document did not state one.

Related Benchmarks

Other benchmarks in the AUS-AKW-LVG-SOP family.