Soil pH — Benchmark Detail

Benchmark Value

5.5 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 19 benchmarks together — the OptimalRange form drives the primary score, while 18 guard(s) constrain the result.

Contributing Benchmarks

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

Evidence & Context

A preventative management target of maintaining topsoil pHCaCl2 at or above 5.5 is widely recommended.

Metric Definition:

Topsoil pH measured in 0.01M CaCl2 solution, indicating the acidity level below which ecosystem health is compromised.

Benchmark Definition:

This benchmark sets a minimum soil pH threshold to prevent acidification and aluminium toxicity in topsoil under livestock grazing in the Temperate Semi-Arid Shrublands & Open Woodlands biome.

Justification:

Maintaining pH above 5.5 prevents soils from reaching degraded states with aluminium toxicity and productivity decline.

Sources (2)

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

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

SoilQuality.org.au. (n.d.). Soil Acidity Factsheet.

Soil Acidity | Fact Sheets | soilquality.org.au, accessed July 20, 2025,

View Source

Supporting Sources (6)

Additional references from the underlying research that informed this benchmark.

Preview of Effects of soil pH on the growth, soil nutrient composition, and rhizosphere microbiome of Ageratina adenophora - PMC - PubMed Central, accessed July 30, 2025,

Effects of soil pH on the growth, soil nutrient composition, and rhizosphere microbiome of Ageratina adenophora - PMC - PubMed Central, accessed July 30, 2025,

Direct Evidence Journal

Do regenerative grazing management practices improve vegetation ...

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Heavy grazing reduces soil bacterial diversity by increasing soil pH in a semi-arid steppe, accessed July 10, 2025,

Contextual Support Journal

Heavy grazing reduces soil bacterial diversity by increasing soil pH in a semi-arid steppe

View Source

Soil | Australia state of the environment 2021, accessed August 12, 2025,

Direct Evidence Journal

OzFlux-TERN GWW SuperSite presentation: Soil Chemical Properties

View Source

Soil Acidity - Ag Excellence Alliance, accessed July 10, 2025,

Contextual Support GreyLiterature

Soil Health - Dairy Australia

View Source

Soil pH | Environment, land and water - Queensland Government, accessed July 30, 2025,

Direct Evidence Government

Australian dryland soils are acidic and nutrient‐depleted, and have unique microbial communities compared with other drylands - Arid Ecology Lab

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The Effects of High Soil pH in Lawns - Lawnpride Australia

Contextual Support GreyLiterature

The Effects of High Soil pH in Lawns - Lawnpride Australia

View Source

Context

Region Australia
Biome Temperate Semi-Arid Shrublands & Open Woodlands
Land Use Livestock Grazing & Pasture
Assessment Not Stated
Evidence Type DegradationThreshold

Lifecycle

Status Active
Version 1
Effective From 8 Jun 2026

Notes

Below pH 5.0, aluminium toxicity becomes a significant risk; 5.5 is the recommended buffer threshold. AssessmentContext defaulted to 'Not Stated' because the source document did not state one.

Related Benchmarks

Other benchmarks in the AUS-TSW-LVG-SPH family.