Microbial Biomass Carbon (MBC)

AUS-TMI-AGR-SMB General Moderate confidence

Benchmark Value

400 mg/kg

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 7 benchmarks together — the OptimalRange form drives the primary score, while 6 guard(s) constrain the result.

Contributing Benchmarks

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

Evidence & Context

The Microbial Biomass Carbon (MBC) measured in the topsoil (0–10 cm) of the Perennial Pasture system at the Pampas site was 400 µg C/g soil.

Metric Definition:

Microbial Biomass Carbon (MBC) is the mass of carbon held within the living component of soil organic matter, consisting primarily of bacteria and fungi.

Benchmark Definition:

Microbial Biomass Carbon (MBC) represents the amount of living microbial carbon in soil organic matter, indicating soil biological health in tropical maritime island agricultural crop production.

Justification:

This value reflects the level of microbial life supported by a stable, permanent-cover system with continuous organic matter inputs, aligning with the core principles of regenerative agriculture.

Sources (1)

Preview of Farming systems can affect soil biology, soil pathogens and system ...

Farming systems can affect soil biology, soil pathogens and system ... Journal

Farming system impact on soil biology and functions

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Supporting Sources (7)

Additional references from the underlying research that informed this benchmark.

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

Contextual Support

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

View Source

Food, Climate & Regenerative Farming FAQ - The Nature Conservancy, accessed May 11, 2025,

Contextual Support

Food, Climate & Regenerative Farming FAQ - The Nature Conservancy

View Source

Hunt and Gather the Island way. - Norfolk Island Stories, accessed July 27, 2025,

Contextual Support

Norfolk Island Environmental Assessment Executive Summary, accessed July 28, 2025

View Source

Lord Howe Island - Wikipedia, accessed July 30, 2025,

Contextual Support GreyLiterature

Lord Howe Island - Wikipedia, accessed August 1, 2025,

View Source

Microbial Biomass Carbon - NSW | Fact Sheets | soilquality.org.au, accessed August 5, 2025,

Contextual Support GreyLiterature

Microbial Biomass | Fact Sheets | soilquality.org.au, accessed July 18, 2025,

View Source

Ratio of microbial biomass carbon to soil organic carbon as a sensitive indicator of changes in soil organic matter - ResearchGate

Contextual Support Journal

Ratio of microbial biomass carbon to soil organic carbon as a sensitive indicator of changes in soil organic matter - ResearchGate

View Source

Preview of Traditional Aboriginal and Torres Strait Islander Land Management Practices: Fire-Stick Farming and Beyond - Welcome To Country - Shop, accessed July 28, 2025

Traditional Aboriginal and Torres Strait Islander Land Management Practices: Fire-Stick Farming and Beyond - Welcome To Country - Shop, accessed July 28, 2025

Contextual Support GreyLiterature

Traditional Aboriginal and Torres Strait Islander Land Management Practices: Fire-Stick Farming and Beyond - Welcome To Country - Shop, accessed July 28, 2025

View Source

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

This benchmark is derived from a proxy mainland subtropical site due to lack of direct data for the target biome. No upper detrimental threshold is identified; higher MBC is better up to natural soil capacity.

Related Benchmarks

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