Microbial Biomass Carbon (MBC)

AUS-ASC-AGR-SMB General Low confidence

Benchmark Value

450 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 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 this synthesis, a tentative MBC reference value for the "best available condition" in Australian alpine/subalpine agricultural systems under sustained best-practice regenerative management (0-10 cm) is proposed as 450 mg C/kg dry soil.

Metric Definition:

Microbial Biomass Carbon (MBC) measured in mg C/kg dry soil in the topsoil (0-10 cm), ideally reflecting peak growing season values.

Benchmark Definition:

This benchmark represents the carbon content within living soil microorganisms in the top 10 cm of soil under alpine and subalpine agricultural crop production in Australia, reflecting the best available condition achievable with regenerative management during the peak growing season.

Justification:

The benchmark is derived from synthesis of broader Australian agricultural data, estimations from soil organic carbon conversions, and principles of regenerative agriculture, reflecting the best available condition achievable under alpine/subalpine agricultural systems with regenerative management.

Sources (7)

Preview of Carbon stocks in Tasmanian soils - ResearchGate
Carbon stocks in Tasmanian soils - ResearchGate Journal

Carbon stocks in Tasmanian soils - ResearchGate

View Source
Preview of Farming system legacy impacts on the storage and persistence of soil organic carbon and understanding the different types carbon in northern cropping systems – science that value adds in field farming systems research - GRDC
Farming system legacy impacts on the storage and persistence of soil organic carbon and understanding the different types carbon in northern cropping systems – science that value adds in field farming systems research - GRDC Government

Farming system legacy impacts on the storage and persistence of soil organic carbon and understanding the different types carbon in northern cropping systems – science that value adds in field farming systems research - GRDC

View Source
Preview of Global Climate Change Effects on Soil Microbial Biomass Stoichiometry in Alpine Ecosystems - MDPI, accessed August 28, 2025,
Global Climate Change Effects on Soil Microbial Biomass Stoichiometry in Alpine Ecosystems - MDPI, accessed August 28, 2025, Journal

Global Climate Change Effects on Soil Microbial Biomass Stoichiometry in Alpine Ecosystems - MDPI

View Source
Preview of Interpreting Microbial Biomass Carbon | Fact Sheets | soilquality.org ...
Interpreting Microbial Biomass Carbon | Fact Sheets | soilquality.org ... Government

Microbial Biomass | Fact Sheets | soilquality.org.au

View Source
Preview of Local Land Services
Local Land Services Government

Microbial Biomass Carbon - 0 - 10cm | Victoria | Examine ...

View Source
Preview of ResearchOnline@JCU - James Cook University, accessed on June 7, 2025
ResearchOnline@JCU - James Cook University, accessed on June 7, 2025 Journal

Variation in soil microbial biomass in the dry tropics: impact of land-use change

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, 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

Context

  • Region Australia
  • Biome Alpine and Subalpine Complex
  • Land Use Agricultural Crop Production
  • Assessment Not Stated
  • Season peak growing season
  • Evidence Type ReferenceCondition

Lifecycle

  • Status Active
  • Version 2
  • Effective From 3 Jun 2026

Notes

Lower Critical Threshold: 200 mg/kg. The benchmark is an aspirational target within an optimal range of 350-700 mg/kg, with no well-defined upper detrimental threshold. AssessmentContext defaulted to 'Not Stated' because the source document did not state one.

Related Benchmarks

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

450 mg/kg Low
Agricultural Crop Production · Not Stated · peak growing season
Point Superseded v1
800 mg/kg Low
Agricultural Crop Production · Not Stated
MaximumOnly Rejected v1