Soil pH — Benchmark Detail

Benchmark Value

No specific value — see range

Range: 5 to 6.5 pH

Thresholds: Lower: 4.8, Upper: 7

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.

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

Therefore, an optimal soil pH range of pH_CaCl2 5.0 to 6.5 (equivalent to approximately pH_w 5.8 to 7.3) is proposed for sustainable production forestry in this biome.

Metric Definition:

Topsoil pH measured in 0.01M calcium chloride (pH_CaCl2), indicative of chemical balance crucial for sustainable vegetation growth and soil health.

Benchmark Definition:

Optimal soil pH range for sustainable production forestry in Australian Tropical Monsoonal Savannas.

Justification:

Based on inherent soil properties, plant physiological requirements, ecological health, and sustainable production principles.

Sources (1)

Helyar Porter (1989) Soil acidification, its measurement and the processes involved (in S8)

Helyar & Porter (1989) Soil acidification, its measurement and the processes involved (in S8)

View Source

Supporting Sources (5)

Additional references from the underlying research that informed this benchmark.

(PDF) Soil acidification and natural resource management ..., accessed May 16, 2025,

Contextual Support GreyLiterature

(PDF) Soil acidification and natural resource management ..., accessed May 16, 2025

View Source

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

Contextual Support Journal

Soil pH | Environment, land and water - Queensland Government, accessed August 28, 2025,

View Source

Preview of Multiple soil element and pH interactions constrain plant performance on tropical soils with a long history of fire - CSIRO PUBLISHING | Soil Research, accessed May 16, 2025,

Multiple soil element and pH interactions constrain plant performance on tropical soils with a long history of fire - CSIRO PUBLISHING | Soil Research, accessed May 16, 2025,

Contextual Support Direct Evidence Journal

Multiple soil element and pH interactions constrain plant performance on tropical soils with a long history of fire - CSIRO PUBLISHING | Soil Research, accessed July 20, 2025

View Source

Preview of Using digital photography to monitor changes in biocrusts and ground cover in a savanna rangeland - CSIRO Publishing, accessed May 16, 2025,

Using digital photography to monitor changes in biocrusts and ground cover in a savanna rangeland - CSIRO Publishing, accessed May 16, 2025,

Contextual Support Methodology Source Journal

Hunt, L. P., Petty, S., Cowley, R., Fisher, A., Ash, A., & MacDonald, N. (2014). Principles and guidelines for managing cattle grazing in the grazing lands of northern Australia: stocking rates, pasture resting, prescribed fire, paddock size and water points – a review. Rangeland Journal, 36(2), 109-130.

View Source

www.publications.qld.gov.au, accessed May 16, 2025,

Contextual Support Journal

Soils of Cape York Peninsula - Queensland Government publications, accessed May 11, 2025,

View Source

Context

Region Australia
Biome Tropical Monsoonal Savannas
Land Use Production Forestry
Assessment Pristine Reference
Evidence Type ReferenceCondition

Lifecycle

Status Retired
Version 1
Effective From 15 Mar 2026
Effective To 24 Mar 2026

Notes

Lower Critical Threshold: 4.8 pH. Upper Detrimental Threshold: 7 pH. Lower critical threshold is pH_CaCl2 4.8; upper detrimental threshold for non-alkaline soils is pH_CaCl2 7.0-7.5. pH_CaCl2 values are generally 0.5-0.9 units lower than pH measured in water. Retired via Evidence Integrity Review on 2026-03-24 09:41 UTC — all DirectEvidence sources confirmed dead or inaccessible.

Related Benchmarks

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