Microbial Biomass Carbon (MBC)

AUS-AMR-CON-SMB General Moderate confidence

Benchmark Value

No specific value — see range
Range: 0 to 0.05 ratio
Optimal Range: 0 to 0.05
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 3 benchmarks together — the OptimalRange form drives the primary score, while 2 guard(s) constrain the result.

Contributing Benchmarks

OptimalRange Primary Point Guard Point Guard

Evidence & Context

A widely supported heuristic suggests that in a healthy soil, MBC constitutes up to 5% of the total soil organic carbon (SOC). Therefore, the optimal range for a given site is best assessed by comparing its actual MBC to this attainable potential (i.e., MBC/SOC ratio approaching 0.05).

Metric Definition:

Ratio of Microbial Biomass Carbon (MBC) to Soil Organic Carbon (SOC)

Benchmark Definition:

This benchmark defines the optimal ratio of Microbial Biomass Carbon to Soil Organic Carbon, indicating efficient microbial carbon use in soils of the arid mountain conservation biome.

Justification:

This ratio provides a powerful diagnostic tool for assessing soil health and functional efficiency of the microbial community relative to the site's potential.

Sources (1)

Preview of Interpreting Microbial Biomass Carbon | Fact Sheets | soilquality.org.au, accessed August 28, 2025,
Interpreting Microbial Biomass Carbon | Fact Sheets | soilquality.org.au, accessed August 28, 2025, Government

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

View Source

Supporting Sources (28)

Additional references from the underlying research that informed this benchmark.

Preview of (PDF) Tradeoffs between pasture production and plant diversity and soil health attributes of pasture systems of central Queensland, Australia - ResearchGate
(PDF) Tradeoffs between pasture production and plant diversity and soil health attributes of pasture systems of central Queensland, Australia - ResearchGate
Direct Evidence Journal

(PDF) A global analysis of soil microbial biomass carbon, nitrogen and phosphorus in terrestrial ecosystems - ResearchGate, accessed August 3, 2025

View Source
Preview of A global analysis of soil microbial biomass carbon, nitrogen and phosphorus in terrestrial ecosystems
A global analysis of soil microbial biomass carbon, nitrogen and phosphorus in terrestrial ecosystems
Contextual Support

Soil Carbon Sequestration Potential: A review for Australian agriculture - MLA, accessed August 3, 2025

View Source
Preview of A scenario calculator for effects of grazing land management on carbon stocks in Australian rangelands | Request PDF - ResearchGate, accessed August 3, 2025
A scenario calculator for effects of grazing land management on carbon stocks in Australian rangelands | Request PDF - ResearchGate, accessed August 3, 2025
Contextual Support Journal

Topsoil microbial biomass carbon pool and the microbial quotient under distinct land-use types across China, accessed July 20, 2025

View Source
Preview of Aridity structures the microbial potential for carbon cycling and mediates the impact of mammal bioturbation at the continental scale - Western Sydney University, accessed August 3, 2025
Aridity structures the microbial potential for carbon cycling and mediates the impact of mammal bioturbation at the continental scale - Western Sydney University, accessed August 3, 2025
Contextual Support Journal

Increasing aridity reduces soil microbial diversity and abundance in global drylands - PNAS, accessed August 3, 2025

View Source
Preview of Climate dictates microbial community composition and diversity in Australian biological soil crusts (biocrusts) - PMC - PubMed Central, accessed August 3, 2025
Climate dictates microbial community composition and diversity in Australian biological soil crusts (biocrusts) - PMC - PubMed Central, accessed August 3, 2025
Contextual Support

soil quality for crop production and ecosystem health - SPADA UNS, accessed August 3, 2025

View Source
Preview of Denitrification and associated N2O emissions are limited by phosphorus availability in a grassland soil | Request PDF - ResearchGate, accessed August 3, 2025
Denitrification and associated N2O emissions are limited by phosphorus availability in a grassland soil | Request PDF - ResearchGate, accessed August 3, 2025
Contextual Support

Denitrification and associated N2O emissions are limited by phosphorus availability in a grassland soil | Request PDF - ResearchGate, accessed August 3, 2025

View Source
Preview of Effects of Phytoremediation on Microbial Biomass, Composition, and Function in a Sulphide-Rich Tailing From a Metal-Contaminated Region - Frontiers, accessed August 3, 2025
Effects of Phytoremediation on Microbial Biomass, Composition, and Function in a Sulphide-Rich Tailing From a Metal-Contaminated Region - Frontiers, accessed August 3, 2025
Contextual Support Journal

Effects of Phytoremediation on Microbial Biomass, Composition, and Function in a Sulphide-Rich Tailing From a Metal-Contaminated Region - Frontiers, accessed August 3, 2025

View Source
Preview of en.wikipedia.org, accessed August 3, 2025
en.wikipedia.org, accessed August 3, 2025
Contextual Support GreyLiterature

Flinders Ranges - Wikipedia, accessed August 3, 2025

View Source
Preview of Evaluation of long-term soil management practices using key indicators and soil quality indices in a semi-arid tropical Alfisol - CSIRO PUBLISHING | Soil Research, accessed August 3, 2025
Evaluation of long-term soil management practices using key indicators and soil quality indices in a semi-arid tropical Alfisol - CSIRO PUBLISHING | Soil Research, accessed August 3, 2025
Contextual Support Journal

Evaluation of long-term soil management practices using key indicators and soil quality indices in a semi-arid tropical Alfisol - CSIRO PUBLISHING | Soil Research, accessed August 3, 2025

View Source
Preview of Improving Fox Management Strategies in Australia - PestSmart, accessed August 3, 2025
Improving Fox Management Strategies in Australia - PestSmart, accessed August 3, 2025
Contextual Support Journal

Stable isotopic evidence for increased terrestrial productivity through geological time - PMC, accessed August 3, 2025

View Source
Preview of Interactions between climate change, fire regimes and biodiversity in Australia: A preliminary assessment - Murdoch Research Portal, accessed August 3, 2025
Interactions between climate change, fire regimes and biodiversity in Australia: A preliminary assessment - Murdoch Research Portal, accessed August 3, 2025
Contextual Support Journal

Northern Territory Capacity to Progress Environmentally Sustainable Agricultural Production, accessed August 3, 2025

View Source
Preview of Microbe Biomass in Relation to Organic Carbon and Clay in Soil - MDPI, accessed August 28, 2025,
Microbe Biomass in Relation to Organic Carbon and Clay in Soil - MDPI, accessed August 28, 2025,
Contextual Support Journal

Trends in Microbial Community Composition and Function by Soil Depth - PMC

View Source
Preview of Microbial Biomass and Activity in Salt Affected Soils under Arid Conditions - ResearchGate, accessed August 3, 2025
Microbial Biomass and Activity in Salt Affected Soils under Arid Conditions - ResearchGate, accessed August 3, 2025
Contextual Support GreyLiterature

Microbial Biomass and Activity in Salt Affected Soils under Arid Conditions - ResearchGate, accessed August 3, 2025

View Source
Preview of Microbial Biomass Carbon - NSW | Fact Sheets | soilquality.org.au, accessed August 5, 2025,
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
Preview of Microbial community composition and activity in paired irrigated and non-irrigated pastures in New Zealand - CSIRO Publishing, accessed August 3, 2025
Microbial community composition and activity in paired irrigated and non-irrigated pastures in New Zealand - CSIRO Publishing, accessed August 3, 2025
Contextual Support Journal

Microbial community composition and activity in paired irrigated and non-irrigated pastures in New Zealand - CSIRO Publishing, accessed August 9, 2025,

View Source
Preview of Microbial impact on initial soil formation in arid and semiarid environments under simulated climate change - Frontiers, accessed August 3, 2025
Microbial impact on initial soil formation in arid and semiarid environments under simulated climate change - Frontiers, accessed August 3, 2025
Contextual Support Journal

Aridity differentially alters the stability of soil bacterial and fungal networks in coastal and inland areas of Australia - PMC, accessed July 29, 2025

View Source
Preview of Nature Conservation and Nature-Based Tourism: A Paradox? - MDPI, accessed August 3, 2025
Nature Conservation and Nature-Based Tourism: A Paradox? - MDPI, accessed August 3, 2025
Contextual Support Journal

Nature Conservation and Nature-Based Tourism: A Paradox? - MDPI, accessed August 3, 2025

View Source
Preview of Seasonal Dynamics of Soil Microbial Biomass C, N and P along an Altitudinal Gradient in Central Himalaya, India - MDPI, accessed August 28, 2025,
Seasonal Dynamics of Soil Microbial Biomass C, N and P along an Altitudinal Gradient in Central Himalaya, India - MDPI, accessed August 28, 2025,
Contextual Support Journal

Fact Sheets Biological Indicators - Soil Quality

View Source
Preview of Soil and Landscape Grid of Australia - CSIRO, accessed July 30, 2025,
Soil and Landscape Grid of Australia - CSIRO, accessed July 30, 2025,
Contextual Support

Soil and Landscape Grid of Australia - CSIRO, accessed August 1, 2025

View Source
Preview of Soil carbon sequestration in rangelands a critical review of the impacts of major management strategies - CSIRO Publishing, accessed August 5, 2025,
Soil carbon sequestration in rangelands a critical review of the impacts of major management strategies - CSIRO Publishing, accessed August 5, 2025,
Contextual Support

Soil carbon sequestration in rangelands a critical review of the impacts of major management strategies - CSIRO Publishing, accessed May 13, 2025,

View Source
Preview of Soil condition | NSW State of the Environment, accessed August 10, 2025,
Soil condition | NSW State of the Environment, accessed August 10, 2025,
Contextual Support Government

The relationships between land management practices and soil condition and the quality of ecosystem services delivered from agri - DAFF, accessed July 28, 2025,

View Source
Preview of Soil condition | NSW State of the Environment, accessed August 3, 2025
Soil condition | NSW State of the Environment, accessed August 3, 2025
Contextual Support

Soil condition | NSW State of the Environment, accessed August 3, 2025

View Source
Preview of Soil microbial biomass—what do the numbers really mean? - ResearchGate, accessed August 28, 2025,
Soil microbial biomass—what do the numbers really mean? - ResearchGate, accessed August 28, 2025,
Contextual Support

Soil microbial biomass carbon and CO2? - ResearchGate, accessed July 18, 2025,

View Source
Preview of Soil microbial diversity–biomass relationships are driven by soil carbon content across global biomes - PMC - PubMed Central, accessed August 3, 2025
Soil microbial diversity–biomass relationships are driven by soil carbon content across global biomes - PMC - PubMed Central, accessed August 3, 2025
Contextual Support GreyLiterature

(PDF) Response of respiration and nutrient availability to drying and ...

View Source
Preview of Soil microbial diversity–biomass relationships are driven by soil carbon content across global biomes | The ISME Journal | Oxford Academic, accessed August 3, 2025
Soil microbial diversity–biomass relationships are driven by soil carbon content across global biomes | The ISME Journal | Oxford Academic, accessed August 3, 2025
Contextual Support Journal

Priority threat management for Pilbara species of conservation ..., accessed August 3, 2025

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Preview of Sustainable travel toolkit - Tourism NT, accessed August 3, 2025
Sustainable travel toolkit - Tourism NT, accessed August 3, 2025
Contextual Support Journal

Sustainable travel toolkit - Tourism NT, accessed August 3, 2025

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Preview of TERN - Australia's Terrestrial Ecosystem Research Network, accessed July 30, 2025,
TERN - Australia's Terrestrial Ecosystem Research Network, accessed July 30, 2025,
Contextual Support GreyLiterature

The Great Western Woodlands TERN SuperSite: ecosystem monitoring infrastructure and key science learnings, accessed May 19, 2025

View Source
Preview of The relationships between land management practices and soil condition and the quality of ecosystem services delivered from agri - DAFF, accessed July 22, 2025,
The relationships between land management practices and soil condition and the quality of ecosystem services delivered from agri - DAFF, accessed July 22, 2025,
Contextual Support Journal

Maintaining groundcover to reduce erosion and sustain production - NSW Department of Primary Industries

View Source

Context

  • Region Australia
  • Biome Arid Mountain Ranges & Uplands
  • Land Use Conservation / Protected Natural Areas
  • Assessment Pristine Reference
  • Evidence Type HealthyOperationalRange

Lifecycle

  • Status Retired
  • Version 1
  • Effective From 19 Mar 2026
  • Effective To 20 Mar 2026

Notes

Optimal range is a functional concept rather than a fixed numeric value, reflecting site-specific attainable microbial biomass. No upper detrimental threshold — higher values are always better up to natural saturation.

Related Benchmarks

Other benchmarks in the AUS-AMR-CON-SMB family.

340 mg/kg Moderate
Conservation / Protected Natural Areas · Conservation Target
Point Active v1