Soil Organic Carbon (SOC)

AUS-TMI-AGR-SOC General Moderate confidence

Benchmark Value

No specific value — see range

Range: 1.9 to 2.2 %

Thresholds: Lower: 1, Upper: —

Optimal Range: 1.9 to 2.2

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 10 benchmarks together — the OptimalRange form drives the primary score, while 9 guard(s) constrain the result.

Contributing Benchmarks

OptimalRange Primary OptimalRange Guard MinimumOnly Guard LowerThreshold Guard OptimalRange Guard Point Guard LowerThreshold Guard OptimalRange Guard OptimalRange Guard Point Guard

Evidence & Context

Functional Range Summary: Lower Critical Threshold: Evidence from tropical agroecosystems suggests a critical threshold of 1.0–1.2% SOC. Below this range, soil function, nutrient cycling, and crop response to inputs are significantly compromised. Optimal Range: Research on tropical Ferralsols identifies an optimal range of 1.9–2.2% SOC for achieving high agronomic efficiency and crop yields, representing a state of high soil health and productivity.

Metric Definition:

Soil Organic Carbon concentration in the top 0–10 cm of soil

Benchmark Definition:

This benchmark defines the soil organic carbon concentration in the top 0–10 cm of soil for tropical maritime island agricultural crop production. Values below 1% indicate compromised soil health and productivity, while an optimal range of 1.9–2.2% supports high agronomic efficiency and ecosystem resilience.

Justification:

The benchmark represents a 'best-on-offer' condition for the top 0–10 cm of soil under regenerative agricultural crop production. Due to a lack of direct studies in Australia's tropical island territories, this value is a scientifically justified proxy derived from analogous mainland tropical systems.

Sources (3)

Preview of (PDF) Soil Organic Carbon – Role in Rainfed Farming Systems With ...

(PDF) Soil Organic Carbon – Role in Rainfed Farming Systems With ...

Soil Organic Carbon – Role in Rainfed Farming Systems With Particular Reference to Australian Conditions - ResearchGate, accessed July 16, 2025,

Preview of Addressing the rundown of nitrogen and soil organic carbon - GRDC, accessed July 25, 2025,

Addressing the rundown of nitrogen and soil organic carbon - GRDC, accessed July 25, 2025, Journal

CRITICAL SOIL ORGANIC CARBON RANGE FOR OPTIMAL CROP RESPONSE TO MINERAL FERTILISER NITROGEN ON A FERRALSOL | Experimental Agriculture - Cambridge University Press

Preview of Soil Organic Carbon Thresholds and Nitrogen Management in Tropical Agroecosystems: Concepts and Prospects - ResearchGate, accessed July 25, 2025,

Soil Organic Carbon Thresholds and Nitrogen Management in Tropical Agroecosystems: Concepts and Prospects - ResearchGate, accessed July 25, 2025, Journal

Soil Organic Carbon Thresholds and Nitrogen Management in Tropical Agroecosystems: Concepts and Prospects - ResearchGate, accessed August 28, 2025,

Supporting Sources (37)

Additional references from the underlying research that informed this benchmark.

Preview of a comparisonof the soils of tropical latin america ano tropical australia

a comparisonof the soils of tropical latin america ano tropical australia

Contextual Support Journal

Queensland Soil Monitoring Program | State of the Environment Report 2020, accessed July 20, 2025,

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

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

Contextual Support Journal

Norfolk Island Agricultural Audit and Land Capability Assessment Report

Preview of Australia's bioregions (IBRA) - DCCEEW, accessed July 15, 2025

Australia's bioregions (IBRA) - DCCEEW, accessed July 15, 2025

Contextual Support

Interim Biogeographic Regionalisation for Australia (IBRA), Version 7 (Regions), accessed July 12, 2025,

Preview of Can best agricultural practices saturate the organic carbon in tropical soils? - ResearchGate

Can best agricultural practices saturate the organic carbon in tropical soils? - ResearchGate

Contextual Support GreyLiterature

Can best agricultural practices saturate the organic carbon in tropical soils? - ResearchGate, accessed July 19, 2025

Preview of Carbon farming | CottonInfo

Carbon farming | CottonInfo

Contextual Support GreyLiterature

Carbon farming | CottonInfo

Preview of Characteristics and Drivers of Soil Organic Carbon Saturation Deficit in Karst Forests of China - MDPI

Characteristics and Drivers of Soil Organic Carbon Saturation Deficit in Karst Forests of China - MDPI

Contextual Support Journal

Mapping soil organic carbon fractions for Australia, their stocks, and uncertainty - BG

Preview of Climate of Australia - Wikipedia, accessed July 13, 2025

Climate of Australia - Wikipedia, accessed July 13, 2025

Contextual Support GreyLiterature

Climate of Australia - Wikipedia

Preview of Common soil types | Environment, land and water - Queensland Government, accessed August 9, 2025

Common soil types | Environment, land and water - Queensland Government, accessed August 9, 2025

Contextual Support Government

Australian Soil Classification edition 3 - CALCAROSOLS

Preview of Common soil types | Environment, land and water | Queensland ...

Common soil types | Environment, land and water | Queensland ...

Contextual Support Government

Phosphorus nutrition of phosphorus-sensitive Australian native ...

Preview of critical soil organic carbon range for optimal crop response to mineral fertiliser nitrogen on a ferralsol - ResearchGate

critical soil organic carbon range for optimal crop response to mineral fertiliser nitrogen on a ferralsol - ResearchGate

Contextual Support GreyLiterature

critical soil organic carbon range for optimal crop response to mineral fertiliser nitrogen on a ferralsol - ResearchGate

Preview of critical soil organic carbon range for optimal crop response to mineral fertiliser nitrogen on a ferralsol - ResearchGate, accessed August 3, 2025,

critical soil organic carbon range for optimal crop response to mineral fertiliser nitrogen on a ferralsol - ResearchGate, accessed August 3, 2025,

Contextual Support

CRITICAL SOIL ORGANIC CARBON RANGE FOR OPTIMAL CROP ...

Preview of Ecological Regions Of Australia - WorldAtlas, accessed July 27, 2025,

Ecological Regions Of Australia - WorldAtlas, accessed July 27, 2025,

Contextual Support GreyLiterature

Ecological Regions Of Australia - WorldAtlas, accessed July 28, 2025

Preview of Enhancing Organic Carbon Content in Tropical Soils: Strategies for Sustainable Agriculture and Climate Change Mitigation - ResearchGate

Enhancing Organic Carbon Content in Tropical Soils: Strategies for Sustainable Agriculture and Climate Change Mitigation - ResearchGate

Contextual Support Journal

AGRICULTURAL AUDIT & LAND USE CAPABILITY ASSESSMENT - Norfolk Island Regional Council

Preview of Growing soil organic carbon in dryland agricultural systems - CSIRO Publishing, accessed July 6, 2025,

Growing soil organic carbon in dryland agricultural systems - CSIRO Publishing, accessed July 6, 2025,

Contextual Support Journal

(PDF) Seasonal changes in microbial function and diversity ...

Preview of HOW TO MEASURE AND INTERPRET RESULTS IN RELATION TO SOIL ORGANIC CARBON - Grains Research and Development Corporation (GRDC), accessed August 5, 2025,

HOW TO MEASURE AND INTERPRET RESULTS IN RELATION TO SOIL ORGANIC CARBON - Grains Research and Development Corporation (GRDC), accessed August 5, 2025,

Methodology Source GreyLiterature

HOW TO MEASURE AND INTERPRET RESULTS IN RELATION TO SOIL ORGANIC CARBON - Grains Research and Development Corporation (GRDC)

Preview of Is there any optimum range for organic carbon found in tropical soils? - ResearchGate

Is there any optimum range for organic carbon found in tropical soils? - ResearchGate

Contextual Support Journal

Is there any optimum range for organic carbon found in tropical soils? - ResearchGate

Preview of Lord Howe Island Palms

Lord Howe Island Palms

Contextual Support GreyLiterature

Lord Howe Island supports a once-contiguous population of palm trees. Two soil types emerged on the - Chegg

Preview of Managing soil organic carbon in tropical agroecosystems: evidence from four long-term experiments in Kenya - Agritrop

Managing soil organic carbon in tropical agroecosystems: evidence from four long-term experiments in Kenya - Agritrop

Contextual Support Journal

Managing soil organic carbon in tropical agroecosystems: evidence from four long-term experiments in Kenya - Agritrop

$Preview of Mapping soil organic carbon fractions for Australia, their stocks, and uncertainty - BG, accessed July 6, 2025,$

Mapping soil organic carbon fractions for Australia, their stocks, and uncertainty - BG, accessed July 6, 2025,

Contextual Support Journal

Pedogenic controls of soil organic carbon stocks and stability beneath montane Norway spruce forests along a precipitation gradient - PMC, accessed March 28, 2026,

Preview of National Soil Strategy, accessed August 3, 2025,

National Soil Strategy, accessed August 3, 2025,

Contextual Support

Grazing management for soil carbon in Australia: A review, accessed July 28, 2025,

Preview of Norfolk Island Plant Communities - Jerry Coleby-Williams

Norfolk Island Plant Communities - Jerry Coleby-Williams

Contextual Support Journal

Norfolk Island Plant Communities - Jerry Coleby-Williams

Preview of Regenerative agriculture in Australia: the changing face of farming - Frontiers

Regenerative agriculture in Australia: the changing face of farming - Frontiers

Contextual Support GreyLiterature

The Longest Paddock: Cattle on Norfolk Island, accessed July 28, 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 August 28, 2025,

Preview of Responses to controlled release potassium fertilisers in agriculture following phosphate mining - CSIRO PUBLISHING | Soil Research, accessed July 30, 2025,

Responses to controlled release potassium fertilisers in agriculture following phosphate mining - CSIRO PUBLISHING | Soil Research, accessed July 30, 2025,

Contextual Support Journal

Healthy Land Ecosystems | TSRA State of the Environment

Preview of Soil carbon | Environment, land and water - Queensland Government

Soil carbon | Environment, land and water - Queensland Government

Direct Evidence Journal

Soil carbon | Environment, land and water - Queensland Government

Preview of Soil carbon saturation: Linking concept and measurable carbon pools

Soil carbon saturation: Linking concept and measurable carbon pools

Contextual Support Journal

The six rights of how and when to test for soil C saturation - Copernicus.org

Preview of Soil Carbon Saturation: What Do We Really Know? - PMC - PubMed Central

Soil Carbon Saturation: What Do We Really Know? - PMC - PubMed Central

Contextual Support

Soil Carbon Saturation: What Do We Really Know? - PMC - PubMed Central

Preview of Soil Carbon Sequestration Potential: A review for Australian agriculture - MLA, accessed August 5, 2025,

Soil Carbon Sequestration Potential: A review for Australian agriculture - MLA, accessed August 5, 2025,

Contextual Support Journal

Spatial distribution of soil microbial activity and soil properties ..., accessed August 13, 2025,

Preview of Soil Carbon Snapshot - Agriculture Victoria, accessed August 5, 2025,

Soil Carbon Snapshot - Agriculture Victoria, accessed August 5, 2025,

Contextual Support Journal

Baseline map of organic carbon in Australian soil to support national carbon accounting and monitoring under climate change - PubMed Central, accessed July 28, 2025,

Preview of Soil organic carbon and total nitrogen under Leucaena leucocephala pastures in Queensland - ResearchGate

Soil organic carbon and total nitrogen under Leucaena leucocephala pastures in Queensland - ResearchGate

Direct Evidence Journal

Comparison of no-tillage and conventional tillage in the development of sustainable farming systems in the semi-arid tropics - ResearchGate, accessed May 11, 2025,

Preview of Soil organic carbon is at risk in a large part of European agricultural land - EU Science Hub

Soil organic carbon is at risk in a large part of European agricultural land - EU Science Hub

Contextual Support Government

Soil carbon | Environment, land and water - Queensland Government, accessed July 19, 2025

Preview of Soil Organic Carbon Thresholds and Nitrogen Management in Tropical Agroecosystems: Concepts and Prospects - JRC Publications Repository, accessed August 3, 2025,

Soil Organic Carbon Thresholds and Nitrogen Management in Tropical Agroecosystems: Concepts and Prospects - JRC Publications Repository, accessed August 3, 2025,

Direct Evidence GreyLiterature

Soil Organic Carbon Thresholds and Nitrogen Management in Tropical Agroecosystems: Concepts and Prospects - JRC Publications Repository

Preview of Soil organic matter in dryland systems – management and opportunities - GRDC

Soil organic matter in dryland systems – management and opportunities - GRDC

Contextual Support Government

Soil Respiration and Carbon Balance Under Cover Crop in a no-Till Tropical Fruit Orchard - Frontiers, accessed July 28, 2025,

Preview of The Stories Beneath the Soil: Norfolk Island's Unique Flora and Its Secrets

The Stories Beneath the Soil: Norfolk Island's Unique Flora and Its Secrets

Contextual Support Government

The Stories Beneath the Soil: Norfolk Island's Unique Flora and Its Secrets

Preview of The Stories Beneath the Soil: Norfolk Island's Unique Flora and Its Secrets, accessed July 25, 2025,

The Stories Beneath the Soil: Norfolk Island's Unique Flora and Its Secrets, accessed July 25, 2025,

Contextual Support GreyLiterature

Geology - Norfolk Island Flora & Fauna Society

Preview of Too Much Organic Matter - Maine Organic Farmers and Gardeners Association

Too Much Organic Matter - Maine Organic Farmers and Gardeners Association

Contextual Support GreyLiterature

Study shows some urban gardens contain too much organic matter | Newsroom

Preview of Tropical Forests and Grasslands (Savanna) - Soils 4 Teachers

Tropical Forests and Grasslands (Savanna) - Soils 4 Teachers

Contextual Support GreyLiterature

Tropical Forests and Grasslands (Savanna) - Soils 4 Teachers

Context

Region Australia
Biome Tropical & Subtropical Maritime Islands
Land Use Agricultural Crop Production
Assessment Pristine Reference
Evidence Type ReferenceCondition

Lifecycle

Status Active
Version 1
Effective From 19 Mar 2026

Notes

Lower Critical Threshold: 1 %. No upper detrimental threshold — higher values are always better up to natural saturation. The optimal range of 1.9–2.2% SOC is associated with high agronomic efficiency and productivity. [Migration] Original wider evidence range: 1 – 2.2 (retained OptimalRange: 1.9 – 2.2)

Related Benchmarks

Other benchmarks in the AUS-TMI-AGR-SOC family.