Soil pH

AUS-TSR-FOR-SPH General Moderate confidence

Benchmark Value

6 pH
Direction: Higher is desirable ↑
Form: Point

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

A mature, ~50-year-old first-rotation plantation, representing a stable and productive system, exhibited a topsoil (0-10 cm) pH of 6.0.

Metric Definition:

Soil pH measured in water at a 1:5 soil to water ratio in the top 0-10 cm of soil.

Benchmark Definition:

Soil pH is the measure of acidity or alkalinity of the soil, here measured in water at a 1:5 soil to water ratio, representing a stable and productive mature plantation in tropical and subtropical rainforest production forestry.

Justification:

The 1R plantation is a long-established, commercially productive forest that has reached a state of relative maturity and ecological stability over a 50-year period. It is the most appropriate representation of a sustainable, 'best-on-offer' condition within a production context.

Sources (1)

Preview of Soil carbon and nutrient pools, microbial properties and gross nitrogen transformations in adjacent natural forest and hoop pine plantations of subtropical Australia
Soil carbon and nutrient pools, microbial properties and gross nitrogen transformations in adjacent natural forest and hoop pine plantations of subtropical Australia
View Source

Supporting Sources (4)

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 Carbon and Nitrogen Mineralization in Relation to Soil Particle-Size Fractions after 32 Years of Chemical and Manure Application in a Continuous Maize Cropping System, accessed July 19, 2025
Carbon and Nitrogen Mineralization in Relation to Soil Particle-Size Fractions after 32 Years of Chemical and Manure Application in a Continuous Maize Cropping System, accessed July 19, 2025
Direct Evidence Journal

Soil carbon and nutrient pools, microbial properties and gross nitrogen transformations in adjacent natural forest and hoop pine plantations of subtropical Australia - ResearchGate, 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 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 Soil pH | Environment, land and water - Queensland Government, accessed July 30, 2025,
Soil pH | Environment, land and water - Queensland Government, accessed July 30, 2025,
Contextual Support Government

Improving Soil Structure and pH Levels (DPIFM_NT) - Department of ..., accessed July 20, 2025

View Source

Context

  • Region Australia
  • Biome Tropical & Subtropical Rainforests
  • Land Use Production Forestry
  • Assessment Pristine Reference
  • Evidence Type ReferenceCondition

Lifecycle

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

Notes

This value is situated within the optimal range for nutrient availability and is higher than both the adjacent natural forest (pH 5.0) and a recently harvested second-rotation site (pH 5.4), indicating that long-term, sustainable management has not resulted in degradational acidification.