Microbial Biomass Carbon (MBC)

AUS-AMR-AGR-SMB General Moderate confidence

Benchmark Value

400 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.

Evidence & Context

The analysis of regional data, long-term trial results, and broader ecological principles culminates in the recommendation of a Microbial Biomass Carbon (MBC) benchmark of 400 mg/kg for the 'best available condition' of agricultural crop production in Australia's Arid Mountain Ranges & Uplands biome.

Metric Definition:

Microbial Biomass Carbon (MBC) is a measure of the carbon contained within the living component of soil organic matter (SOM), which is composed predominantly of bacteria and fungi.

Benchmark Definition:

This benchmark represents the best available condition for Microbial Biomass Carbon in agricultural crop production soils of Australia's Arid Mountain Ranges & Uplands, indicating a high level of soil biological function.

Justification:

This value is scientifically justified as it represents a state of high biological function that is demonstrably superior to the current regional average for low-rainfall cropping systems (338 mg/kg). It also signifies a meaningful transition from a state typical of conventionally cultivated soils (<400 mg/kg) to one with enhanced ecological resilience.

Sources (1)

Preview of Regenerative opportunities for building soil biological resilience – a ..., accessed May 11, 2025
Regenerative opportunities for building soil biological resilience – a ..., accessed May 11, 2025 GreyLiterature

Regenerative opportunities for building soil biological resilience – a case study in the low-rainfall zone in Southern Australia - GRDC

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Supporting Sources (2)

Additional references from the underlying research that informed this benchmark.

Preview of Growing soil organic carbon in dryland agricultural systems - CSIRO Publishing, accessed July 6, 2025,
Growing soil organic carbon in dryland agricultural systems - CSIRO Publishing, accessed July 6, 2025,
Contextual Support Journal

Regenerative agriculture in Australia: the changing face of farming - Frontiers, accessed July 8, 2025

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Preview of Prospects for summer cover crops in southern Australian semi-arid cropping systems | Request PDF - ResearchGate
Prospects for summer cover crops in southern Australian semi-arid cropping systems | Request PDF - ResearchGate
Contextual Support

Prospects for summer cover crops in southern Australian semi-arid cropping systems | Request PDF - ResearchGate

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Context

  • Region Australia
  • Biome Arid Mountain Ranges & Uplands
  • Land Use Agricultural Crop Production
  • Assessment Not Stated
  • Evidence Type ReferenceCondition

Lifecycle

  • Status Active
  • Version 1
  • Effective From 4 Jun 2026

Notes

Lower Critical Threshold: 150 mg/kg. No upper detrimental threshold — higher values are always better up to natural saturation. The upper boundary is a management consideration related to water availability. AssessmentContext defaulted to 'Not Stated' because the source document did not state one.