Soil pH

Benchmark Value

4 pH

Direction: Higher is desirable ↑

Form: MinimumOnly

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 4 benchmarks together — the OptimalRange form drives the primary score, while 3 guard(s) constrain the result.

Contributing Benchmarks

OptimalRange Primary MinimumOnly Guard LowerThreshold Guard MinimumOnly Guard

Evidence & Context

pH 4.0 — extremely acid — Irreversible soil structural breakdown can occur.

Metric Definition:

Soil pH measured in 0.01 M calcium chloride (CaCl2)

Benchmark Definition:

Boundary where physical soil integrity is compromised beyond standard remediation.

Justification:

Represents severe land degradation.

Sources (1)

Preview of Agriculture Victoria. (2024). Soil acidity.

Agriculture Victoria. (2024). Soil acidity. Government

Agriculture Victoria. (2025). Soil acidity. Farm Management.

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Supporting Sources (9)

Additional references from the underlying research that informed this benchmark.

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

Contextual Support Journal

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

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Agriculture Victoria. (2020). Improving high-country native pastures. Sheep Notes, Spring 2020.

Contextual Support Government

Agriculture Victoria. (2020). Improving high-country native pastures. Sheep Notes, Spring 2020.

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Alpine soils in Australia with reference to conditions in Europe and New Zealand, accessed August 28, 2025,

Contextual Support GreyLiterature

NSW Department of Primary Industries. (2021). Soil acidity and liming. Soils Guides.

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estuaries.dwer.wa.gov.au, accessed May 12, 2025

Contextual Support Journal

Turner, B. L., et al. (2014). Soil organic phosphorus speciation in Australian alpine and sub-alpine soils. Journal of Soils and Sediments.

View Source

Making More From Sheep. (2021). Tool 6.7: Soil health benchmarks and guidelines for managing problem soils. Manual Module 6: Healthy Soils.

Contextual Support GreyLiterature

Making More From Sheep. (2021). Tool 6.7: Soil health benchmarks and guidelines for managing problem soils. Manual Module 6: Healthy Soils.

View Source

NSW Environment Protection Authority. (2021). State of the Environment - Soil Condition 2021.

Contextual Support Government

Schiedung, M., et al. (2004). Impacts of Road Disturbance on Soil Properties and on Exotic Plant Occurrence in Subalpine Areas of the Australian Alps. Arctic, Antarctic, and Alpine Research, 36(2), 201-207.

View Source

Soil Quality Knowledge Base. (2024). Soil Acidity.

Contextual Support

Soil Quality Knowledge Base. (2024). Soil Acidity.

View Source

Preview of Soil surface pH DSM data of the Southern Gulf catchments (NT and Qld) generated by the Southern Gulf Water Resource Assessment - CSIRO Data Access Portal, accessed May 13, 2025,

Soil surface pH DSM data of the Southern Gulf catchments (NT and Qld) generated by the Southern Gulf Water Resource Assessment - CSIRO Data Access Portal, accessed May 13, 2025,

Contextual Support Government

Gibbons, P., & Sharp, A. (2015). Impacts of warming and fire on soil moisture and available nutrients in a sub-alpine heathland. Climate Research, 64, 159-170.

View Source