Microbial Biomass Carbon (MBC)
Benchmark Value
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 7 benchmarks together — the OptimalRange form drives the primary score, while 6 guard(s) constrain the result.
Contributing Benchmarks
Evidence & Context
Therefore, an MBC value of approximately 150 mg/kg is proposed as a lower critical threshold for this context.
Microbial Biomass Carbon (MBC) is the mass of carbon held within the living component of soil organic matter.
A lower critical threshold of 150 mg/kg MBC indicates a level below which soil microbial function and ecological resilience are severely compromised in tropical maritime island agricultural soils.
Values below approximately 150 mg/kg represent a severely degraded, carbon-limited state with impaired ecological function and resilience.
Sources (1)
Farming system impact on soil biology and functions
View SourceSupporting Sources (7)
Additional references from the underlying research that informed this benchmark.
Interim Biogeographic Regionalisation for Australia (IBRA), Version 7 (Regions), accessed July 12, 2025,
View SourceFood, Climate & Regenerative Farming FAQ - The Nature Conservancy
View SourceNorfolk Island Environmental Assessment Executive Summary, accessed July 28, 2025
View SourceLord Howe Island - Wikipedia, accessed August 1, 2025,
View SourceMicrobial Biomass | Fact Sheets | soilquality.org.au, accessed July 18, 2025,
View Source
Ratio of microbial biomass carbon to soil organic carbon as a sensitive indicator of changes in soil organic matter - ResearchGate
View SourceTraditional Aboriginal and Torres Strait Islander Land Management Practices: Fire-Stick Farming and Beyond - Welcome To Country - Shop, accessed July 28, 2025
View Source