Soil Phosphorus

AUS-AMR-AGR-SOP General Moderate confidence

Benchmark Value

No specific value — see range

Range: 25 to 30 mg/kg

Thresholds: Lower: 20, Upper: 30

Optimal Range: 25 to 30

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 is presented as an optimal range, bounded by a lower critical threshold where system function is compromised and an upper detrimental threshold where ecological health begins to decline.

Metric Definition:

Available soil phosphorus measured as Colwell-P in sustainable cropping systems.

Benchmark Definition:

This benchmark represents the optimal range of soil phosphorus for sustainable cropping in arid mountain uplands, balancing crop yield and ecological health.

Justification:

It is derived by integrating agronomic critical thresholds with ecological limits identified in separate literature.

Sources (2)

Preview of Regenerative Phosphorus Management - Agresol - Regenerative ..., accessed August 4, 2025

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

Regenerative Phosphorus Management - Agresol - Regenerative Agriculture Consulting Australia, accessed August 28, 2025

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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

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Context

Region Australia
Biome Arid Mountain Ranges & Uplands
Land Use Agricultural Crop Production
Assessment Pristine Reference
Evidence Type TargetCondition

Lifecycle

Status Active
Version 1
Effective From 24 Mar 2026

Notes

The agronomic optimum for maximum yield may be higher (>40 mg/kg), but this benchmark deliberately prioritises long-term ecological function. The high pH of these soils affects P availability; the DGT-P test may provide a more reliable measure of P supply than Colwell-P.

Related Benchmarks

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