Soil pH

AUS-TMI-LVG-SPH General Moderate confidence

Benchmark Value

No specific value — see range
Range: 6.1 to 6.9 pH
Optimal Range: 6.1 to 6.9
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

Recommended Benchmark Value: A range of 6.1–6.9, interpreted as pH(water).

Metric Definition:

Soil pH measured in water (pH(water)) representing the optimal soil pH range for best available condition under livestock grazing in the Tropical and Subtropical Maritime Islands biome.

Benchmark Definition:

The optimal soil pH range measured in water (pH(water)) for sustainable livestock grazing on volcanic Ferrosol soils in the Tropical and Subtropical Maritime Islands biome.

Justification:

This range is based on the Norfolk Island Agricultural Audit, representing the only geographically relevant data within the biome, and is supported by mainland pasture targets. It is a proxy for high-health pasture soils, reflecting minimal chemical constraints and optimal nutrient availability.

Sources (1)

Preview of AGRICULTURAL AUDIT & LAND USE CAPABILITY ASSESSMENT ..., accessed July 30, 2025,
AGRICULTURAL AUDIT & LAND USE CAPABILITY ASSESSMENT ..., accessed July 30, 2025, Journal

Norfolk Island Agricultural Audit and Land Capability Assessment Report

View Source

Context

  • Region Australia
  • Biome Tropical & Subtropical Maritime Islands
  • Land Use Livestock Grazing & Pasture
  • Assessment Pristine Reference
  • Evidence Type ReferenceCondition

Lifecycle

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

Notes

The range is interpreted as pH(water) and aligns with mainland Australian pasture targets. The confidence is moderate due to the use of a land-use proxy and inferred measurement method. The functional range includes a lower critical threshold at pH(CaCl₂) < 4.8 and an upper detrimental threshold above pH(CaCl₂) ~7.0.