Soil pH

AUS-TDG-FOR-SPH General Moderate confidence

Benchmark Value

No specific value — see range
Range: 5 to 6.5 pH
Optimal Range: 5 to 6.5
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. The scoring engine uses 16 benchmarks together — the OptimalRange form drives the primary score, while 15 guard(s) constrain the result.

Evidence & Context

Based on the available evidence, a reference range of pH (CaCl₂) 5.0 - 6.5 is proposed for topsoil in Temperate Dry Woodlands & Native Grasslands under best-practice production forestry.

Metric Definition:

Soil pH measured in a 1:5 soil:0.01M CaCl₂ solution, representing soil acidity or alkalinity affecting nutrient availability and ecosystem health.

Benchmark Definition:

This benchmark represents the optimal soil pH range measured in CaCl₂ solution for topsoil in Temperate Dry Woodlands & Native Grasslands under best-practice production forestry, indicating soil acidity or alkalinity that supports nutrient availability and ecosystem health.

Justification:

The range is based on conditions observed in high-quality, little-disturbed temperate grassy Eucalypt woodlands in SE Australia, considered representative of high ecological health and supporting native plant communities and essential soil functions adapted to naturally moderately acidic conditions.

Sources (1)

Preview of Prober, S.M., Thiele, K.R., & Lunt, I.D. (2002). Determining reference conditions for management and restoration of temperate grassy woodlands: relationships among trees, topsoils and understorey flora in little-grazed remnants. Australian Journal of Botany, 50(6), 687-697.
Prober, S.M., Thiele, K.R., & Lunt, I.D. (2002). Determining reference conditions for management and restoration of temperate grassy woodlands: relationships among trees, topsoils and understorey flora in little-grazed remnants. Australian Journal of Botany, 50(6), 687-697. Journal

Prober, S.M., Thiele, K.R., & Lunt, I.D. (2002). Determining reference conditions for management and restoration of temperate grassy woodlands: relationships among trees, topsoils and understorey flora in little-grazed remnants. Australian Journal of Botany, 50(6), 687-697.

View Source

Supporting Sources (2)

Additional references from the underlying research that informed this benchmark.

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

Soil acidity | Soil | Farm management - Agriculture Victoria, accessed August 28, 2025

View Source
Preview of Temperate Grasslands - Greening Australia, accessed August 4, 2025
Temperate Grasslands - Greening Australia, accessed August 4, 2025
Contextual Support Journal

Managing natural areas | City of Gold Coast, accessed May 19, 2025

View Source

Context

  • Region Australia
  • Biome Temperate Dry Woodlands & Native Grasslands
  • Land Use Production Forestry
  • Assessment Pristine Reference
  • Evidence Type ReferenceCondition

Lifecycle

  • Status Active
  • Version 1
  • Effective From 25 Mar 2026

Notes

Lower Critical Threshold: Soil pH (CaCl₂) below 4.8 is critically low, causing Al/Mn toxicity, reduced nutrient availability, and impaired microbial activity. Optimal Range: 5.0-6.5 supports native biodiversity, nutrient cycling, and sustainable tree growth. Upper Detrimental Threshold: Sustained pH above 6.5-7.0 may be detrimental, causing nutrient imbalances and shifts in native plant community composition.