Microbial Biomass Carbon (MBC)

AUS-TSW-LVG-SMB General Moderate confidence

Benchmark Value

700 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 11 benchmarks together — the OptimalRange form drives the primary score, while 10 guard(s) constrain the result.

Contributing Benchmarks

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

Evidence & Context

Based on this evidence, the value of 700 mg/kg is selected as the primary "best-on-offer" reference value for Microbial Biomass Carbon in this land use context.

Metric Definition:

Microbial Biomass Carbon (MBC) represents the total carbon contained within the living cells of soil microorganisms.

Benchmark Definition:

This benchmark represents the highest measured Microbial Biomass Carbon value in temperate semi-arid shrublands and open woodlands under livestock grazing, reflecting a high ecological function and best-on-offer soil biological activity.

Justification:

This value is chosen because it represents the highest documented state of soil biological activity achieved within a realistic, well-managed, and productive grazing system.

Sources (1)

Sustainable Grazing Systems (SGS) Key Program - Final Report Journal

Sustainable Grazing Systems (SGS) Key Program - Final Report

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Supporting Sources (3)

Additional references from the underlying research that informed this benchmark.

functions-of-soil-organic-matter-and-the-effect-on-soil-properties.pdf.pdf, accessed July 19, 2025,

Contextual Support Journal

The biodiversity cost of carbon sequestration in tropical savanna - PMC - PubMed Central

View Source

Impact of agricultural land use on distribution of microbial biomass and activity within soil aggregates - ResearchGate

Contextual Support Journal

Plant responses to livestock grazing frequency in an Australian temperate grassland, accessed August 8, 2025,

View Source

Preview of Managing grazing to increase ground cover in rangelands: using remote sensing to detect change - CSIRO Publishing, accessed July 18, 2025,

Managing grazing to increase ground cover in rangelands: using remote sensing to detect change - CSIRO Publishing, accessed July 18, 2025,

Contextual Support Journal

Guppy, C.N., Waters, C.M., Hacker, R.B., et al. (2024). Managing grazing to increase ground cover in rangelands: using dynamic regional comparison to document property-scale change. Rangeland Journal.

View Source

Context

Region Australia
Biome Temperate Semi-Arid Shrublands & Open Woodlands
Land Use Livestock Grazing & Pasture
Assessment Pristine Reference
Evidence Type ReferenceCondition

Lifecycle

Status Active
Version 1
Effective From 20 Mar 2026

Notes

No upper detrimental threshold — higher values are always better up to natural saturation. This benchmark represents the highest measured MBC value in a temperate woodland grazing system under best-practice management (fertilized and oversown with perennials). It is an aspirational target reflecting high ecological function.

Related Benchmarks

Other benchmarks in the AUS-TSW-LVG-SMB family.