Soil pH — Benchmark Detail - Nature Index

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 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

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 (1:5 H₂O) in the topsoil (0-10 cm) layer.

Benchmark Definition:

This benchmark represents the soil pH level measured in the top 0-10 cm of soil in a mature, ~50-year-old first-rotation subtropical hoop pine plantation, indicating a stable and productive production forestry system in tropical and subtropical rainforests of Australia.

Justification:

The benchmark value is derived from a single, though highly relevant, chronosequence study of a mature, ~50-year-old first-rotation hoop pine plantation in subtropical Queensland, representing a stable, long-term, best-on-offer managed system.

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

Supporting Sources (31)

Additional references from the underlying research that informed this benchmark.

Preview of (PDF) Growing up or growing out? How soil pH and light affect seedling growth of a relictual rainforest tree - ResearchGate, accessed July 20, 2025,

(PDF) Growing up or growing out? How soil pH and light affect seedling growth of a relictual rainforest tree - ResearchGate, accessed July 20, 2025,

Contextual Support Journal

(PDF) Growing up or growing out? How soil pH and light affect seedling growth of a relictual rainforest tree - ResearchGate, accessed July 20, 2025,

Preview of (PDF) Hoop pine - Araucaria cunninghamii. - ResearchGate, accessed July 20, 2025,

(PDF) Hoop pine - Araucaria cunninghamii. - ResearchGate, accessed July 20, 2025,

Contextual Support Journal

(PDF) Hoop pine - Araucaria cunninghamii. - ResearchGate, accessed July 20, 2025,

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

(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.

Preview of Agriculture Victoria. (2024). Soil acidity.

Agriculture Victoria. (2024). Soil acidity.

Contextual Support Government

Agriculture Victoria. (2025). Soil acidity. Farm Management.

Preview of Australia's State of the Forests Report, accessed August 12, 2025

Australia's State of the Forests Report, accessed August 12, 2025

Contextual Support Journal

Change in Organic Carbon in Forest Plantation Soils in Eastern ..., accessed July 20, 2025,

Preview of Australian Journal of Soil Research - CSIRO Publishing, accessed August 5, 2025

Australian Journal of Soil Research - CSIRO Publishing, accessed August 5, 2025

Contextual Support

Australian Journal of Soil Research - CSIRO Publishing, accessed July 22, 2025

Preview of Biomass harvesting leads to soil acidification: a study of mixed crop–livestock farming systems in Madagascar - CSIRO Publishing, accessed July 20, 2025,

Biomass harvesting leads to soil acidification: a study of mixed crop–livestock farming systems in Madagascar - CSIRO Publishing, accessed July 20, 2025,

Contextual Support Journal

Biomass harvesting leads to soil acidification: a study of mixed crop–livestock farming systems in Madagascar - CSIRO Publishing, accessed July 20, 2025,

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, accessed July 20, 2025,

Preview of Change in Organic Carbon in Forest Plantation Soils in Eastern Australia - ResearchGate, accessed July 25, 2025,

Change in Organic Carbon in Forest Plantation Soils in Eastern Australia - ResearchGate, accessed July 25, 2025,

Contextual Support GreyLiterature

Temperate forests and soils [Chapter 6], accessed July 20, 2025,

Preview of CSIRO Research Publications Repository - Home Page, accessed July 25, 2025,

CSIRO Research Publications Repository - Home Page, accessed July 25, 2025,

Contextual Support Journal

CSIRO Research Publications Repository - Home Page, accessed July 20, 2025,

Preview of Global Trajectories of Forest Soil Acidification: A Scientometric Synthesis of Drivers, Impacts and Sustainable Solutions - MDPI, accessed July 30, 2025,

Global Trajectories of Forest Soil Acidification: A Scientometric Synthesis of Drivers, Impacts and Sustainable Solutions - MDPI, accessed July 30, 2025,

Contextual Support Journal

SOIL CHEMICAL PROPERTIES AND FOREST FLOOR NUTRIENTS UNDER REPEATED PRESCRIBED- BURNING IN - Scion, accessed July 20, 2025,

Preview of Guinto, D. F., et al. (2001). Long-term impacts of prescribed burning on soil chemical properties and forest floor nutrients in two contrasting native eucalypt forests in south-east Queensland. New Zealand Journal of Forestry Science, 31(2), 170-187.

Guinto, D. F., et al. (2001). Long-term impacts of prescribed burning on soil chemical properties and forest floor nutrients in two contrasting native eucalypt forests in south-east Queensland. New Zealand Journal of Forestry Science, 31(2), 170-187.

Contextual Support Journal

NITROGEN RESPONSE AND 15N-LABELLED FERTILISER RECOVERY BY HOOP PINE SEEDLINGS GROWN UNDER GLASSHOUSE CONDITIONS, accessed July 20, 2025,

Preview of Horiba (2018) Soil pH and Nutrient Availability

Horiba (2018) Soil pH and Nutrient Availability

Contextual Support GreyLiterature

Soil Acidity - Land degradation in Australia, accessed July 20, 2025,

Preview of Long-term impacts of harvest residue management on nutrition, growth and productivity of an exotic pine plantation of sub-tropical Australia | Request PDF - ResearchGate, accessed July 20, 2025,

Long-term impacts of harvest residue management on nutrition, growth and productivity of an exotic pine plantation of sub-tropical Australia | Request PDF - ResearchGate, accessed July 20, 2025,

Contextual Support Journal

Long-term impacts of harvest residue management on nutrition, growth and productivity of an exotic pine plantation of sub-tropical Australia | Request PDF - ResearchGate, accessed July 20, 2025,

Preview of Management of Soil, Nutrients and Water in Tropical Plantation Forests - ResearchGate, accessed July 20, 2025,

Management of Soil, Nutrients and Water in Tropical Plantation Forests - ResearchGate, accessed July 20, 2025,

Contextual Support Journal

Management of Soil, Nutrients and Water in Tropical Plantation Forests - ResearchGate, accessed July 20, 2025,

Preview of Management of Soil, Nutrients and Water in Tropical Plantation Forests | ACIAR - Australian Centre for International Agricultural Research, accessed July 20, 2025,

Management of Soil, Nutrients and Water in Tropical Plantation Forests | ACIAR - Australian Centre for International Agricultural Research, accessed July 20, 2025,

Contextual Support

Management of Soil, Nutrients and Water in Tropical Plantation Forests | ACIAR - Australian Centre for International Agricultural Research, accessed July 20, 2025,

Preview of Mapping the Depth-to-Soil pH Constraint, and the Relationship with Cotton and Grain Yield at the Within-Field Scale - MDPI, accessed July 20, 2025,

Mapping the Depth-to-Soil pH Constraint, and the Relationship with Cotton and Grain Yield at the Within-Field Scale - MDPI, accessed July 20, 2025,

Contextual Support Journal

Mapping the Depth-to-Soil pH Constraint, and the Relationship with Cotton and Grain Yield at the Within-Field Scale - MDPI, accessed July 20, 2025,

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

Soil Research - CSIRO PUBLISHING

Preview of Offord, C. A., & Meagher, P. F. (2014). Light and soil pH have a combined effect on the growth and morphology of the critically endangered Wollemi pine (Wollemia nobilis). AoB Plants, 6, plu011.

Offord, C. A., & Meagher, P. F. (2014). Light and soil pH have a combined effect on the growth and morphology of the critically endangered Wollemi pine (Wollemia nobilis). AoB Plants, 6, plu011.

Contextual Support Journal

Growing up or growing out? How soil pH and light affect seedling growth of a relictual rainforest tree | AoB PLANTS | Oxford Academic, accessed July 20, 2025,

Preview of Plant Diversity and Soil Nutrients in a Tropical Coastal Secondary Forest: Association Ordination and Sampling Year Differences - MDPI, accessed July 20, 2025,

Plant Diversity and Soil Nutrients in a Tropical Coastal Secondary Forest: Association Ordination and Sampling Year Differences - MDPI, accessed July 20, 2025,

Contextual Support Journal

Plant Diversity and Soil Nutrients in a Tropical Coastal Secondary Forest: Association Ordination and Sampling Year Differences - MDPI, accessed July 20, 2025,

Preview of Plantation tree growth responses to P, N, K and minor and trace elements on low fertility savanna soils - CSIRO Publishing

Plantation tree growth responses to P, N, K and minor and trace elements on low fertility savanna soils - CSIRO Publishing

Contextual Support Journal

Plantation tree growth responses to P, N, K and minor and trace elements on low fertility savanna soils - CSIRO Publishing, accessed July 20, 2025,

Preview of Regenerative Agriculture—A Literature Review on the Practices and Mechanisms Used to Improve Soil Health - MDPI, accessed August 5, 2025,

Regenerative Agriculture—A Literature Review on the Practices and Mechanisms Used to Improve Soil Health - MDPI, accessed August 5, 2025,

Contextual Support Journal

Regenerative Agriculture—A Literature Review on the Practices and Mechanisms Used to Improve Soil Health - MDPI, accessed July 20, 2025,

Preview of Soil Carbon Pools In Adjacent Natural And Plantation Forests Of Subtropical Australia, accessed July 20, 2025,

Soil Carbon Pools In Adjacent Natural And Plantation Forests Of Subtropical Australia, accessed July 20, 2025,

Contextual Support Journal

Soil Carbon Pools In Adjacent Natural And Plantation Forests Of Subtropical Australia, accessed July 20, 2025,

Preview of SOIL CHEMICAL PROPERTIES AND FOREST FLOOR NUTRIENTS UNDER REPEATED PRESCRIBED- BURNING - Scion Research, accessed March 28, 2026,

SOIL CHEMICAL PROPERTIES AND FOREST FLOOR NUTRIENTS UNDER REPEATED PRESCRIBED- BURNING - Scion Research, accessed March 28, 2026,

Direct Evidence Journal

Soil Carbon Pools in Adjacent Natural and Plantation Forests of Subtropical Australia | Request PDF - ResearchGate, accessed July 20, 2025,

Preview of Soil Group Chapters - G-Misc. - Enviro Data SA, accessed July 13, 2025

Soil Group Chapters - G-Misc. - Enviro Data SA, accessed July 13, 2025

Contextual Support Journal

Australia's State of the Forests Report, accessed July 20, 2025,

Preview of Soil health and stability monitoring in forests - Natural Resources Commission, accessed July 20, 2025,

Soil health and stability monitoring in forests - Natural Resources Commission, accessed July 20, 2025,

Contextual Support

Soil health and stability monitoring in forests - Natural Resources Commission, accessed July 20, 2025,

Preview of Soil Nitrogen Dynamics Under Adjacent Native Forest and ... - NSERL, accessed July 19, 2025,

Soil Nitrogen Dynamics Under Adjacent Native Forest and ... - NSERL, accessed July 19, 2025,

Direct Evidence Journal

Soil Nitrogen Dynamics Under Adjacent Native Forest and Hoop Pine Plantations - NSERL, accessed July 20, 2025,

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

Australian dryland soils are acidic and nutrient‐depleted, and have unique microbial communities compared with other drylands - Arid Ecology Lab

Preview of SoilQuality.org.au. (n.d.). Soil Acidity Factsheet.

SoilQuality.org.au. (n.d.). Soil Acidity Factsheet.

Contextual Support

Soil Acidity | Fact Sheets | soilquality.org.au, accessed July 20, 2025,

Preview of State Soils - Soil Science Australia, accessed July 18, 2025,

State Soils - Soil Science Australia, accessed July 18, 2025,

Contextual Support Journal

Australian dryland soils are acidic and nutrient-depleted, and have unique microbial communities compared with other drylands - PMC, accessed July 20, 2025,

Preview of TROPICAL SOILS | Terrain NRM, accessed July 16, 2025,

TROPICAL SOILS | Terrain NRM, accessed July 16, 2025,

Contextual Support Journal

A Revegetation Guide for Sub-Tropical Forest - Greening Australia, accessed July 20, 2025,

Context

Region Australia
Biome Tropical & Subtropical Rainforests
Land Use Production Forestry
Assessment Not Stated
Evidence Type ReferenceCondition

Lifecycle

Status Active
Version 1
Effective From 10 Jun 2026

Notes

Lower Critical Threshold: 5 pH. Upper Detrimental Threshold: 7.5 pH. Optimal range for nutrient availability and productivity is 5.5 to 6.5 pH. Below pH 5.0, aluminum toxicity impacts ecosystem health; above pH 7.5, micronutrient deficiencies can occur. AssessmentContext defaulted to 'Not Stated' because the source document did not state one.