Microbial Biomass Carbon (MBC)

AUS-TSW-LVG-SMB General Moderate confidence

Benchmark Value

No specific value — see range

Range: 470 to 700 mg/kg

Optimal Range: 470 to 700

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 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

An optimal range for MBC is likely to be associated with MBC values in the range of 470-700 mg/kg, corresponding to systems with high perennial grass content and optimal pasture mass (2-4 t DM/ha).

Metric Definition:

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

Benchmark Definition:

This benchmark represents the optimal range of Microbial Biomass Carbon in temperate semi-arid shrublands and open woodlands under livestock grazing, associated with high perennial grass content and optimal pasture mass.

Justification:

The MBC values measured in the high-performing treatments at the Tamworth site provide the quantitative boundaries for this optimal range.

Sources (1)

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

Sustainable Grazing Systems (SGS) Key Program - Final Report

View Source

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 HealthyOperationalRange

Lifecycle

Status Active
Version 1
Effective From 20 Mar 2026

Notes

A high-functioning state is likely associated with MBC values in the range of 470-700 mg/kg, corresponding to systems with high perennial grass content and optimal pasture mass (2-4 t DM/ha). No upper detrimental threshold — higher values are always better up to natural saturation.

Related Benchmarks

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