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 13 benchmarks together — the OptimalRange form drives the primary score, while 12 guard(s) constrain the result.
Evidence & Context
A conservative estimate for the lower critical threshold zone can be established at < 250 mg/kg.
Microbial Biomass Carbon (MBC) as the total carbon in living microbial cells in soil.
This benchmark defines the lower critical threshold of microbial biomass carbon below which soil microbial communities are too small or inactive to support core ecosystem functions in the target biome under livestock grazing.
Inferred from studies showing MBC in heavily degraded grazing sites can be 75-85% lower than in healthy controls and from low biological function values in production-focused agricultural systems.
Sources (1)
grazing impacts on the spatial distribution of soil microbial biomass around tussock grasses in a tropical grassland - Publication : USDA ARS
View SourceSupporting Sources (2)
Additional references from the underlying research that informed this benchmark.
Loss of Soil Carbon Associated with a Short-Duration Flood in a ...
View SourceMicrobial biomass and microbial biodiversity in some soils from New South Wales, Australia | Request PDF - ResearchGate
View Source