Soil pH — Benchmark Detail

Benchmark Value

No specific value — see range

Range: 6.5 to 9 pH

Optimal Range: 6.5 to 9

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. The scoring engine uses 15 benchmarks together — the OptimalRange form drives the primary score, while 14 guard(s) constrain the result.

Contributing Benchmarks

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

Evidence & Context

The Reference Value for Soil pH is the range 6.5 – 9.0 (measured in water).

Metric Definition:

Soil pH measured in water as a proxy for soil ecosystem pH in arid inland floodplains.

Benchmark Definition:

This benchmark represents the natural pH range for soils in healthy, protected arid floodplain ecosystems, measured in water.

Justification:

Derived from direct measurements from a high-quality conservation area (Diamantina-Georgina catchment) and corroborated by continental-scale soil surveys and pedogenesis principles.

Sources (3)

Preview of (PDF) The pH of Australian soils: field results from a national survey - ResearchGate, accessed July 25, 2025,

(PDF) The pH of Australian soils: field results from a national survey - ResearchGate, accessed July 25, 2025, Journal

Caritat, P. de, & Cooper, M. (2011). The pH of Australian soils: Field results from a national survey. Soil Research, 49, 172-182.

View Source

Preview of Australian Soil Classification edition 3 - CALCAROSOLS

Australian Soil Classification edition 3 - CALCAROSOLS Government

Monitoring changes in soil salinity and sodicity to depth, at a ...

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Water and sediment quality in the Diamantina-Georgina River ..., accessed July 21, 2025, Journal

Water and sediment quality in the Diamantina-Georgina River ..., accessed July 21, 2025,

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Supporting Sources (9)

Additional references from the underlying research that informed this benchmark.

ASC - VERTOSOLS - Soil Science Australia

Contextual Support

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

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AusEarthed. (n.d.). Soil Reading.

Contextual Support Journal

Victorian Resources Online | Resources | Support and resources ..., accessed July 21, 2025,

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Ecological impacts of flood mitigation and drainage in coastal lowlands - AustLII

Contextual Support

Ecological impacts of flood mitigation and drainage in coastal lowlands - AustLII, accessed July 21, 2025,

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Government of South Australia, Department for Environment and Water. (n.d.). Soil Health and Condition.

Contextual Support Government

Soil acidity - Department for Environment and Water

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National Guidance on Acid Sulfate Soils - Water Quality Australia

Contextual Support Journal

Managing soils - Department of Primary Industries and Regional Development, accessed July 17, 2025

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Soil Constraints in an Arid Environment - Encyclopedia.pub

Contextual Support GreyLiterature

Soil Constraints in an Arid Environment - Encyclopedia.pub, accessed July 27, 2025

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Soil pH - SA | Fact Sheets | soilquality.org.au

Contextual Support Government

Soil Acidity - NSW | Fact Sheets | soilquality.org.au

View Source

Victorian Resources Online | Resources | Support and resources ...

Contextual Support Government

Structural controls on the orientation of erosion gullies in mid-western New South Wales, Australia, accessed July 22, 2025

View Source

Water and sediment quality in the Diamantina-Georgina River catchment, Lake Eyre Basin

Direct Evidence Journal

Water quality in the Georgina-Diamantina River catchment

View Source

Context

Region Australia
Biome Arid Inland Floodplains & Ephemeral River Systems
Land Use Conservation / Protected Natural Areas
Assessment Pristine Reference
Evidence Type ReferenceCondition

Lifecycle

Status Active
Version 1
Effective From 3 Jun 2026

Notes

This range reflects the naturally alkaline conditions of arid Australia and is based on water quality data in equilibrium with floodplain soils.

Related Benchmarks

Other benchmarks in the AUS-AIF-CON-SPH family.