Soil pH — Benchmark Detail

Benchmark Value

8.2 pH

Thresholds: Lower: —, Upper: 8.2

Direction: Higher is desirable ↑

Form: UpperThreshold

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 16 benchmarks together — the OptimalRange form drives the primary score, while 15 guard(s) constrain the result.

Contributing Benchmarks

OptimalRange Primary MinimumOnly Guard OptimalRange Guard Point Guard LowerThreshold Guard LowerThreshold Guard OptimalRange Guard LowerThreshold Guard UpperThreshold Guard Point Guard LowerThreshold Guard OptimalRange Guard UpperThreshold Guard OptimalRange Guard LowerThreshold Guard UpperThreshold Guard

Evidence & Context

Thus, while many arid zone ecosystems are adapted to alkalinity, a pH(w) of 8.2 represents a reasonable upper boundary for a healthy, functioning system.

Metric Definition:

Soil pH measured in water (pHw), indicating onset of significant micronutrient deficiencies and risk of sodicity.

Benchmark Definition:

This benchmark sets the upper detrimental soil pH threshold beyond which nutrient deficiencies and soil structural degradation due to sodicity are likely in the Arid Mountain Ranges & Uplands biome under production forestry.

Justification:

This threshold is based on evidence of increasing risk of micronutrient lock-up and sodicity beyond this pH.

Sources (1)

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

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

Soil pH - SA | Fact Sheets | soilquality.org.au, accessed July 30, 2025,

View Source

Supporting Sources (4)

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

Peppermint Box (Eucalyptus odorata) Grassy Woodland of South Australia, accessed August 9, 2025,

Direct Evidence Journal

Northern Mount Lofty Ranges and Southern Flinders Ranges soil descriptions.

View Source

Peppermint Box (Eucalyptus odorata) Grassy Woodland of South Australia, accessed July 30, 2025,

Contextual Support GreyLiterature

Peppermint Box (Eucalyptus odorata) Grassy Woodland of South Australia, accessed July 30, 2025,

View Source

Soil acidity is starting to emerge in the Southern Mallee on certain soils types. - GRDC, accessed July 30, 2025,

Direct Evidence

Soil acidity is starting to emerge in the Southern Mallee on certain soils types. - GRDC, accessed July 30, 2025,

View Source

Context

Region Australia
Biome Arid Mountain Ranges & Uplands
Land Use Production Forestry
Assessment Pristine Reference
Evidence Type DegradationThreshold

Lifecycle

Status Active
Version 1
Effective From 25 Mar 2026

Notes

Above this pH, soil physical structure degrades, water infiltration is impeded, and root growth is restricted.

Related Benchmarks

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