Soil Phosphorus

AUS-AIF-FOR-SOP General Moderate confidence

Benchmark Value

15 mg/kg

Range: 10 to 20 mg/kg

Thresholds: Lower: 10, Upper: 20

Optimal Range: 10 to 20

Direction: Higher is desirable ↑

Form: Point

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 16 benchmarks together — the OptimalRange form drives the primary score, while 15 guard(s) constrain the result.

Contributing Benchmarks

OptimalRange Primary Point Guard LowerThreshold Guard UpperThreshold Guard LowerThreshold Guard MinimumOnly Guard OptimalRange Guard LowerThreshold Guard OptimalRange Guard UpperThreshold Guard Point Guard OptimalRange Guard MinimumOnly Guard Point Guard LowerThreshold Guard OptimalRange Guard

Evidence & Context

The reference value of 15 mg/kg is selected as the scientifically supported optimum within this range, as it corresponds to the soil P level where the growth of a representative native production species (Eucalyptus marginata) is maximized before declining due to P toxicity.

Metric Definition:

Soil phosphorus concentration in mg/kg representing the optimal balance for ecological health and sustainable productivity in a P-limited native ecosystem.

Benchmark Definition:

A derived benchmark value representing the optimal soil phosphorus concentration balancing ecological health and sustainable productivity in a phosphorus-limited native ecosystem.

Justification:

The benchmark is synthesized from multiple lines of evidence including productivity proxies in analogous systems, ecological impacts observed at higher phosphorus levels, and growth response of a key native species, Eucalyptus marginata.

Sources (2)

Preview of Phosphorus sensitivity in seedlings of Eucalyptus marginata (Jarrah) in relation to mycorrhizal colonisation

Phosphorus sensitivity in seedlings of Eucalyptus marginata (Jarrah) in relation to mycorrhizal colonisation

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, GreyLiterature

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

Supporting Sources (19)

Additional references from the underlying research that informed this benchmark.

Preview of 3. C THE LOCATION - Lockhart Shire Council - NSW Government, accessed July 19, 2025,

3. C THE LOCATION - Lockhart Shire Council - NSW Government, accessed July 19, 2025,

Contextual Support Journal

3. C THE LOCATION - Lockhart Shire Council - NSW Government, accessed July 19, 2025,

Preview of Al-Beidh, S., & Al-Tawaha, A. R. M. (2023). Basic Properties and Mineralogy of Soils and Their Impact on the Growth of Jarrah Forest in Southwestern Australia. Land, 12(6), 1236.

Al-Beidh, S., & Al-Tawaha, A. R. M. (2023). Basic Properties and Mineralogy of Soils and Their Impact on the Growth of Jarrah Forest in Southwestern Australia. Land, 12(6), 1236.

Contextual Support Journal

Soil Characteristics and Fertility of the Unique Jarrah Forest of Southwestern Australia, with Particular Consideration of Plant Nutrition and Land Rehabilitation - MDPI, accessed July 19, 2025,

Preview of Are Murray-Darling Basin rivers getting the water they need to stay healthy?, accessed July 19, 2025,

Are Murray-Darling Basin rivers getting the water they need to stay healthy?, accessed July 19, 2025,

Contextual Support Journal

Are Murray-Darling Basin rivers getting the water they need to stay healthy?, accessed July 19, 2025,

Preview of Arid Swamps | WetlandInfo, accessed August 1, 2025,

Arid Swamps | WetlandInfo, accessed August 1, 2025,

Contextual Support Journal

Arid Swamps | WetlandInfo, accessed July 19, 2025,

Preview of Changes in soil carbon in response to flooding of the floodplain of a semi-arid lowland river - Charles Sturt University Research Output, accessed July 19, 2025,

Changes in soil carbon in response to flooding of the floodplain of a semi-arid lowland river - Charles Sturt University Research Output, accessed July 19, 2025,

Contextual Support Journal

Floodplain inundation in the Murray–Darling Basin under current and future climate conditions - ResearchGate, accessed July 19, 2025,

Preview of Coolibah-Black Box Woodlands - IUCN Ecosystems, accessed July 19, 2025,

Coolibah-Black Box Woodlands - IUCN Ecosystems, accessed July 19, 2025,

Contextual Support Journal

Coolibah-Black Box Woodlands - IUCN Ecosystems, accessed July 19, 2025,

Preview of Determining baselines, drivers and trends of soil health and stability ..., accessed July 12, 2025,

Determining baselines, drivers and trends of soil health and stability ..., accessed July 12, 2025,

Contextual Support Journal

Phosphorus: a finite resource essential for life, critical for agriculture and food security, accessed July 19, 2025,

Preview of Hydrological assessment and analysis of the Cooper Creek Catchment, South Australia - Department for Environment and Water, accessed July 21, 2025,

Hydrological assessment and analysis of the Cooper Creek Catchment, South Australia - Department for Environment and Water, accessed July 21, 2025,

Contextual Support Journal

Riparian vegetation of a permanent waterhole on Cooper Creek, southwest Queensland, accessed July 17, 2025,

Preview of Managing soils - Department of Primary Industries and Regional Development, accessed July 21, 2025,

Managing soils - Department of Primary Industries and Regional Development, accessed July 21, 2025,

Contextual Support Journal

Gilgai wetlands - WetlandInfo, accessed July 19, 2025,

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

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

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

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, accessed July 19, 2025,

Preview of Rangeland Soil Quality: Infiltration - Natural Resources ...

Rangeland Soil Quality: Infiltration - Natural Resources ...

Contextual Support Journal

RIvER RED guMs AND wooDLAND FoREsts - Natural Resources Commission, accessed July 19, 2025,

Preview of The-importance-of-inundation-to-floodplain-soil-fertility-in-an-large-semi-arid-river.pdf - ResearchGate, accessed July 19, 2025,

The-importance-of-inundation-to-floodplain-soil-fertility-in-an-large-semi-arid-river.pdf - ResearchGate, accessed July 19, 2025,

Contextual Support

The-importance-of-inundation-to-floodplain-soil-fertility-in-an-large-semi-arid-river.pdf - ResearchGate, accessed July 19, 2025,

Preview of to ensure you are making money from phosphorus fertiliser - MLA, accessed August 4, 2025

to ensure you are making money from phosphorus fertiliser - MLA, accessed August 4, 2025

Contextual Support Journal

Towards restoration of grassy White and Yellow Box woodlands - understanding soil changes associated with degradation - Virtual Herbarium, accessed July 19, 2025,

Preview of to ensure you are making money from phosphorus fertiliser - MLA, accessed July 19, 2025,

to ensure you are making money from phosphorus fertiliser - MLA, accessed July 19, 2025,

Contextual Support

to ensure you are making money from phosphorus fertiliser - MLA, accessed July 19, 2025,

Preview of Towards restoration of grassy White and Yellow Box woodlands ..., accessed August 11, 2025,

Towards restoration of grassy White and Yellow Box woodlands ..., accessed August 11, 2025,

Contextual Support GreyLiterature

(PDF) Soil and vegetation response to thinning White Cypress Pine ..., accessed July 19, 2025,

Preview of Tropical Grasslands (2000) Volume 34, 139–146 - Soil fertility and ..., accessed July 19, 2025,

Tropical Grasslands (2000) Volume 34, 139–146 - Soil fertility and ..., accessed July 19, 2025,

Contextual Support Journal

Tropical Grasslands (2000) Volume 34, 139–146 - Soil fertility and ..., accessed July 19, 2025,

Preview of Wetlands | Environment, land and water | Queensland Government, accessed July 19, 2025,

Wetlands | Environment, land and water | Queensland Government, accessed July 19, 2025,

Contextual Support Journal

Wetlands | Environment, land and water | Queensland Government, accessed July 19, 2025,

Context

Region Australia
Biome Arid Inland Floodplains & Ephemeral River Systems
Land Use Production Forestry
Assessment Pristine Reference
Evidence Type ReferenceCondition

Lifecycle

Status Active
Version 1
Effective From 25 Mar 2026

Notes

The benchmark is not based on a single direct measurement but is inferred from analogous systems. The lower critical threshold is 10 mg/kg, below which productivity is compromised. The upper detrimental threshold is approximately 20 mg/kg, above which negative ecological impacts occur. The optimal range is 10–20 mg/kg.