Soil Organic Carbon (SOC)

AUS-TMI-LVG-SOC General High confidence

Benchmark Value

3.5 %

Direction: Higher is desirable ↑

Form: MinimumOnly

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 2 benchmarks together — the OptimalRange form drives the primary score, while 1 guard(s) constrain the result.

Contributing Benchmarks

OptimalRange Primary MinimumOnly Guard

Evidence & Context

The pivotal finding, stated explicitly in the 2022 report, is that soil analysis from agricultural land on Norfolk Island revealed that optimal soil organic carbon levels are greater than 3.5%.

Metric Definition:

Soil Organic Carbon (SOC) is the measurable carbon constituent of Soil Organic Matter (SOM), representing the carbon content in soil organic matter.

Benchmark Definition:

This benchmark represents the minimum optimal soil organic carbon level for pastures on clay-rich volcanic soils in the Tropical & Subtropical Maritime Islands biome under livestock grazing and pasture land use.

Justification:

This value is based on direct soil analysis from Norfolk Island agricultural land, representing the best available condition for livestock pastures on clay-rich volcanic soils, supported by corroborating data from analogous mainland pasture systems.

Sources (3)

Norfolk Island Environmental Assessment

Norfolk Island Environmental Assessment

View Source

Soil Carbon Sequestration Potential: A review for Australian agriculture - MLA Journal

Soil Carbon Sequestration Potential: A review for Australian agriculture - MLA

View Source

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

Coexistence of shrubs and grass in a semi-arid landscape: a case study of mulga (Acacia aneura, Mimosaceae) shrublands embedded in fire-prone spinifex (Triodia pungens, Poaceae) hummock grasslands - CSIRO PUBLISHING | Australian Journal of Botany

View Source

Supporting Sources (3)

Additional references from the underlying research that informed this benchmark.

Is there a critical level of organic matter in the agricultural soils of temperate regions: A review | Request PDF - ResearchGate

Contextual Support

Is there a critical level of organic matter in the agricultural soils of temperate regions: A review | Request PDF - ResearchGate

View Source

Soil organic matter and carbon sequestration in pastures - FutureBeef, accessed August 5, 2025,

Contextual Support GreyLiterature

Sparling, G. P. (1992). Ratio of microbial biomass carbon to soil organic carbon as a sensitive indicator of changes in soil organic matter. Australian Journal of Soil Research, 30(2), 195-207.

View Source

The Soil Carbon Research Program (SCaRP) - CSIROpedia, accessed July 6, 2025,

Contextual Support Government

Exploring Soil Carbon in the Mallee - Soils Connect, accessed July 6, 2025

View Source

Context

Region Australia
Biome Tropical & Subtropical Maritime Islands
Land Use Livestock Grazing & Pasture
Assessment Not Stated
Evidence Type ReferenceCondition

Lifecycle

Status Superseded
Version 1
Effective From 5 Jun 2026
Effective To 5 Jun 2026

Notes

No upper detrimental threshold — higher values are always better up to natural saturation. The benchmark represents the 'optimal' SOC level for pastures on Ferrosol soils in this biome. AssessmentContext defaulted to 'Not Stated' because the source document did not state one.

Related Benchmarks

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