Microbial Biomass Carbon (MBC)

AUS-TGP-AGR-SMB General Moderate confidence

Benchmark Value

191 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 7 benchmarks together — the OptimalRange form drives the primary score, while 6 guard(s) constrain the result.

Evidence & Context

The original value of 229 kg C/ha (0-10 cm) was converted to ~191 mg/kg using a standard bulk density of 1.2 g/cm³.

Metric Definition:

Microbial Biomass Carbon (MBC) concentration in topsoil (0-10 cm) under best practice continuous cropping system.

Benchmark Definition:

Benchmark value for Microbial Biomass Carbon representing best available condition for continuous cropping with no-till and stubble retention in temperate grassy woodlands agricultural crop production.

Justification:

Selected due to scientific rigor, relevance to temperate Australian agricultural zone, and quantitative data from a long-term trial.

Sources (1)

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

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

View Source

Supporting Sources (2)

Additional references from the underlying research that informed this benchmark.

Preview of Altered soil microbial community at elevated CO2 leads to loss of soil carbon | PNAS, accessed August 5, 2025
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, accessed July 28, 2025,

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,
Direct Evidence

Soil microbial biomass carbon and CO2? - ResearchGate, accessed July 18, 2025,

View Source

Context

  • Region Australia
  • Biome Temperate Grassy Woodlands & Plains
  • Land Use Agricultural Crop Production
  • Assessment Pristine Reference
  • Evidence Type ReferenceCondition

Lifecycle

  • Status Active
  • Version 1
  • Effective From 17 Mar 2026

Notes

Represents a target for high-performing continuous cropping; not the ecological maximum achievable in the biome.

Related Benchmarks

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