Soil Phosphorus

AUS-AMR-AGR-SOP General Moderate confidence

Benchmark Value

No specific value — see range

Range: 20 to 25 mg/kg

Optimal Range: 20 to 25

Direction: Higher 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.

Evidence & Context

The benchmark range provides sufficient P for healthy crop growth while supporting soil biology. Above this threshold, the risk of suppressing mycorrhizal fungi and losing native species diversity increases significantly.

Metric Definition:

Available soil phosphorus measured as Colwell-P concentration in mg/kg.

Benchmark Definition:

Functional range of available phosphorus for Tenosols in sustainable cropping systems in the Arid Mountain Ranges & Uplands biome.

Justification:

Derived from agronomic critical thresholds and ecological limits identified in literature, balancing crop productivity and ecological health.

Sources (2)

Regenerative Phosphorus Management - Agresol - Regenerative ..., accessed August 4, 2025 GreyLiterature

Regenerative Phosphorus Management - Agresol - Regenerative ...

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Preview of Soil phosphorus–crop response calibration ... - CSIRO Publishing, accessed May 11, 2025,

Soil phosphorus–crop response calibration ... - CSIRO Publishing, accessed May 11, 2025, Journal

Soil phosphorus–crop response calibration relationships and criteria for winter cereal crops grown in Australia - CSIRO Publishing

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Supporting Sources (5)

Additional references from the underlying research that informed this benchmark.

A simple phosphorus buffering index for Australian soils - ResearchGate

Contextual Support GreyLiterature

(PDF) A simple phosphorus buffering index for Australian soils - ResearchGate

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Crop NutritioN FACT SHEET - Grains Research and Development Corporation (GRDC)

Contextual Support Journal

What are the optimum nutrient targets for pastures? - Soil Health Knowledgebase

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Phosphorus - WA | Fact Sheets | soilquality.org.au, accessed July 21, 2025,

Contextual Support GreyLiterature

Phosphorus - Qld | Fact Sheets | soilquality.org.au, accessed July 18, 2025

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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

View Source

Preview of Soil phosphorus tests II: A comparison of soil test–crop response relationships for different soil tests and wheat - CSIRO PUBLISHING | Crop and Pasture Science

Soil phosphorus tests II: A comparison of soil test–crop response relationships for different soil tests and wheat - CSIRO PUBLISHING | Crop and Pasture Science

Contextual Support Journal

Soil phosphorus tests II: A comparison of soil test–crop response relationships for different soil tests and wheat - CSIRO PUBLISHING | Crop and Pasture Science

View Source

Context

Region Australia
Biome Arid Mountain Ranges & Uplands
Land Use Agricultural Crop Production
Assessment Not Stated
Evidence Type HealthyOperationalRange

Lifecycle

Status Active
Version 1
Effective From 10 Jun 2026

Notes

Below 15-20 mg/kg, yield is severely limited by P deficiency. Above 25 mg/kg, risk of suppressing mycorrhizal fungi and losing native species diversity increases. Low PBI soils require less fertiliser but have higher leaching risk. AssessmentContext defaulted to 'Not Stated' because the source document did not state one.

Related Benchmarks

Other benchmarks in the AUS-AMR-AGR-SOP family.