Soil pH — Benchmark Detail

Benchmark Value

No specific value — see range

Range: 5.5 to 7.5 pH

Optimal Range: 5.5 to 7.5

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 proposed Optimal Range is pH (CaCl2) 5.5 - 7.5.

Metric Definition:

Optimal functional range for soil pH measured in calcium chloride (CaCl2) solution

Benchmark Definition:

This benchmark represents the optimal soil pH range measured in calcium chloride solution for healthy ecosystem function in temperate semi-arid shrublands and open woodlands under production forestry in Australia, specifically for general sandy/loamy soils.

Justification:

The range is set based on evidence that acidity-related problems begin below 5.5 and the natural slightly alkaline condition of the GWW reference site at 7.2.

Sources (1)

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

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

OzFlux-TERN GWW SuperSite presentation: Soil Chemical Properties

View Source

Supporting Sources (1)

Additional references from the underlying research that informed this benchmark.

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

Direct Evidence Government

Soil acidity - Department for Environment and Water, accessed July 30, 2025,

View Source

Context

Region Australia
Biome Temperate Semi-Arid Shrublands & Open Woodlands
Land Use Production Forestry
Assessment Pristine Reference
Evidence Type HealthyOperationalRange

Lifecycle

Status Active
Version 1
Effective From 24 Mar 2026

Notes

Maintaining pH above 5.5 ensures fundamental chemical and biological processes are not constrained by acidity. The upper bound stops short of highly alkaline conditions associated with calcareous or sodic soils.

Related Benchmarks

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