Soil pH — Benchmark Detail

Benchmark Value

7 pH

Thresholds: Lower: —, Upper: 7.5

Direction: Higher is desirable ↑

Form: MaximumOnly

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 13 benchmarks together — the OptimalRange form drives the primary score, while 12 guard(s) constrain the result.

Contributing Benchmarks

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

Evidence & Context

Thus, for soils that are not naturally alkaline, pushing the pH above pH_CaCl2 7.0 - 7.5 (approximately pH_w 7.8 - 8.3) through management interventions is likely to be detrimental from an ecological balance perspective.

Metric Definition:

Upper detrimental threshold of soil pH measured in 0.01M calcium chloride above which ecological harm may occur.

Benchmark Definition:

Upper soil pH threshold beyond which nutrient imbalances and ecological harm may occur on non-alkaline soils.

Justification:

Evidence indicates high pH can reduce micronutrient availability and disrupt native flora adapted to acidic soils.

Supporting Sources (7)

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

Caritat, P. de, & Cooper, M. (2011). The pH of Australian soils: Field results from a national survey. Soil Research, 49, 172-182.

View Source

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

Direct Evidence

Kaur et al. (2005) Impact of tree clearing on soil pH.

View Source

Horiba (2018) Soil pH and Nutrient Availability

Methodology Source GreyLiterature

Soil Acidity - Land degradation in Australia, accessed July 20, 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

Soil Research - CSIRO PUBLISHING

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

The Soils of Cape York Peninsula. Cooktown and Weipa Sections. Land Resource Survey and Evaluation.

View Source

Context

Region Australia
Biome Tropical Monsoonal Savannas
Land Use Production Forestry
Assessment Not Stated
Evidence Type DegradationThreshold

Lifecycle

Status Active
Version 1
Effective From 1 Jun 2026

Notes

Exceeding pH 7.0-7.5 on non-alkaline soils can lead to micronutrient deficiencies and ecological imbalance. AssessmentContext defaulted to 'Not Stated' because the source document did not state one.

Related Benchmarks

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