Soil Organic Carbon (SOC)

AUS-TMI-LVG-SOC General High confidence

Benchmark Value

1.5 %

Range: 3.5 to 6 %

Optimal Range: 3.5 to 6

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

Contributing Benchmarks

OptimalRange Primary MinimumOnly Guard UpperThreshold 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) content in soil, representing the carbon constituent of 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, indicating healthy soil carbon content for sustainable grazing.

Justification:

The value is derived from direct soil samples from the target biome and land use, defined as optimal in a government environmental assessment, and corroborated by analogous mainland pasture systems.

Sources (3)

Norfolk Island Environmental Assessment

Soil Organic Carbon May Decline Under Climate Change: A Case Study in Mexican Forests, accessed July 19, 2025

View Source

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

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

Potential for soil carbon sequestration in Northern Australian grazing lands: A review of the evidence

View Source

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, Journal

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

View Source

Supporting Sources (2)

Additional references from the underlying research that informed this benchmark.

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

Contextual Support GreyLiterature

A farmer's guide to increasing Soil Organic Carbon under pastures - NSW Department of Primary Industries

View Source

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

Contextual Support Government

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

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 19 Mar 2026

Notes

The benchmark represents the optimal SOC level for pastures on clay-rich volcanic soils in this biome. The lower critical threshold is <1.5% SOC, below which soil stability is compromised. No upper detrimental threshold is identified; ecological benefits continue up to the soil's natural carbon saturation capacity. ConsistencyResolver applied 2026-03-23 00:16 UTC: BenchmarkValue 3.5 → 1.5 (check: MinAboveMax, rationale: Swap the MinimumOnly benchmark's value to 1.5 to represent the lower critical threshold, consistent with Notes stating <1.5% SOC is degraded.)

Related Benchmarks

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