Microbial Biomass Carbon (MBC)

AUS-TGP-AGR-SMB General Moderate confidence

Benchmark Value

No specific value — see range

Range: 200 to 600 mg/kg

Optimal Range: 200 to 600

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 16 benchmarks together — the OptimalRange form drives the primary score, while 15 guard(s) constrain the result.

Contributing Benchmarks

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

Evidence & Context

Based on the available data, a defensible optimal range for a high-functioning cropping system in the Temperate Grassy Woodlands biome can be proposed as 200 mg/kg to 600 mg/kg.

Metric Definition:

Optimal functional range of Microbial Biomass Carbon for a high-functioning cropping system.

Benchmark Definition:

Range representing healthy nutrient turnover and resilience in cropping systems within temperate grassy woodlands under agricultural crop production.

Justification:

Supported by balanced carbon and nutrient inputs and observed data from cropping and diverse systems.

Sources (3)

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

Interpreting Microbial Biomass Carbon | Fact Sheets | soilquality.org.au

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

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

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Soil microbial biomass carbon (SMBC) under different cropping systems... - ResearchGate Journal

Soil microbial biomass carbon (SMBC) under different cropping systems... - ResearchGate

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Supporting Sources (6)

Additional references from the underlying research that informed this benchmark.

Altered soil microbial community at elevated CO2 leads to loss of soil carbon | PNAS, accessed August 5, 2025

Direct Evidence

Altered soil microbial community at elevated CO2 leads to loss of soil carbon | PNAS

View Source

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

Direct Evidence GreyLiterature

www.soilquality.org.au

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Procedure for Soil Respiration (CO2 Evolution from Rewetting a Dried Soil) - Soil Fertility, accessed July 9, 2025

Direct Evidence GreyLiterature

Tool 6.7 Soil health benchmarks and guidelines for managing ...

View Source

Soil microbial biomass—what do the numbers really mean? - ResearchGate, accessed August 28, 2025,

Direct Evidence GreyLiterature

Responses of soil labile organic carbon stocks and the carbon pool management index to different vegetation restoration types in the Danxia landform region of southwest China - PMC - PubMed Central

View Source

Soil microbial biomass, activity and nutrient cycling as indicators of soil health.

Contextual Support GreyLiterature

Soil microbial biomass, activity and nutrient cycling as indicators of soil health., accessed August 5, 2025

View Source

Soil organic carbon thresholds control fertilizer effects on carbon accrual in croplands worldwide - PMC

Contextual Support Journal

Soil organic carbon thresholds control fertilizer effects on carbon accrual in croplands worldwide - PMC

View Source

Context

Region Australia
Biome Temperate Grassy Woodlands & Plains
Land Use Agricultural Crop Production
Assessment Not Stated
Evidence Type HealthyOperationalRange

Lifecycle

Status Active
Version 1
Effective From 4 Jun 2026

Notes

Operating within this range signifies robust biological activity and good soil structure. No upper detrimental threshold — higher values are always better up to natural saturation. AssessmentContext defaulted to 'Not Stated' because the source document did not state one.

Related Benchmarks

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