Soil pH — Benchmark Detail

Benchmark Value

No specific value — see range

Range: 5.5 to 6.5 pH

Optimal Range: 5.5 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 19 benchmarks together — the OptimalRange form drives the primary score, while 18 guard(s) constrain the result.

Contributing Benchmarks

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

Evidence & Context

The reference benchmark of pH(CaCl₂) 5.5 - 6.5 is proposed.

Metric Definition:

Soil pH measured in calcium chloride (pH(CaCl₂))

Benchmark Definition:

This benchmark represents the optimal soil pH range in calcium chloride for Tropical Monsoonal Savannas under livestock grazing, supporting key nitrogen-fixing legumes and productive grasses that enhance soil health and nutrient cycling.

Justification:

This range supports key ecological functions, including the growth of nitrogen-fixing legumes vital for soil fertility and pasture quality, and aligns with pH values observed in less disturbed or well-managed savanna grazing lands on common soil types like Kandosols.

Sources (1)

Preview of Tropical Pasture - Barenbrug Australia, accessed July 18, 2025,

Tropical Pasture - Barenbrug Australia, accessed July 18, 2025, Journal

Soils of the Koolpinyah Surface (Chen et al., 2005)

View Source

Supporting Sources (37)

Additional references from the underlying research that informed this benchmark.

S11

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S11, S8

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S46, S25

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S46, S25

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Preview of Soil health: looking for suitable indicators. What should be considered to assess the effects of use and management on soil heal - alice Embrapa, accessed July 28, 2025,

Soil health: looking for suitable indicators. What should be considered to assess the effects of use and management on soil heal - alice Embrapa, accessed July 28, 2025,

Contextual Support Journal

www.barenbrug.com.au, accessed May 13, 2025,

View Source

Soil nutrient critical limits | MBFP | More Beef from Pastures - MLA, accessed May 13, 2025,

Direct Evidence GreyLiterature

Understanding soil tests for pastures | Soil | Farm management ..., accessed July 17, 2025,

View Source

Preview of Soil organic carbon content at a range of north Australian tropical savannas with contrasting site histories - OPUS at UTS, accessed May 16, 2025,

Soil organic carbon content at a range of north Australian tropical savannas with contrasting site histories - OPUS at UTS, accessed May 16, 2025,

Contextual Support Journal

opus.lib.uts.edu.au, accessed May 13, 2025,

View Source

Soil Quality and Its Management in Humid Subtropical and Tropical Environments - UKnowledge, accessed May 15, 2025,

Contextual Support

a comparisonof the soils of tropical latin america ano tropical australia, accessed May 13, 2025,

View Source

Preview of Soil surface pH DSM data of the Southern Gulf catchments (NT and Qld) generated by the Southern Gulf Water Resource Assessment - CSIRO Data Access Portal, accessed May 13, 2025,

Soil surface pH DSM data of the Southern Gulf catchments (NT and Qld) generated by the Southern Gulf Water Resource Assessment - CSIRO Data Access Portal, accessed May 13, 2025,

Contextual Support Government

Categories - Soil pH - CSIRO Data Access Portal, accessed May 13, 2025,

View Source

Context

Region Australia
Biome Tropical Monsoonal Savannas
Land Use Livestock Grazing & Pasture
Assessment Pristine Reference
Evidence Type TargetCondition

Lifecycle

Status Superseded
Version 1
Effective From 25 Mar 2026
Effective To 25 Mar 2026

Notes

It sits well within the optimal functional range (pH(CaCl₂) 5.0 - 6.5) and above the lower critical threshold (pH(CaCl₂) < 4.5), avoiding conditions of excessive acidity that impair pasture health and ecological function.

Related Benchmarks

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