Soil Nitrogen

AUS-TDG-CON-SON General High confidence

Benchmark Value

No specific value — see range
Range: 1000 to 2000 mg/kg
Thresholds: Lower: 1000, Upper: 2500
Optimal Range: 1000 to 2000
Direction: Lower is desirable ↓
Form: OptimalRange

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 3 benchmarks together — the OptimalRange form drives the primary score, while 2 guard(s) constrain the result.

Contributing Benchmarks

OptimalRange Primary OptimalRange Guard Point Guard

Evidence & Context

Based on these findings from high-quality reference sites, a general benchmark range of 1000 - 2000 mg/kg total nitrogen in the 0-10 cm topsoil layer is proposed as representative of the "best available condition" for these temperate dry woodlands and grasslands under conservation management.

Metric Definition:

Total soil nitrogen concentration in the 0-10 cm topsoil layer

Benchmark Definition:

This benchmark represents the total soil nitrogen concentration in the top 0-10 cm of soil for temperate dry woodlands and native grasslands under conservation management in Australia. The range 1000-2000 mg/kg reflects the best available condition for ecological health in these areas.

Justification:

The benchmark range (1000-2000 mg/kg total N) is derived from topsoils (0-10cm) of little-grazed Eucalyptus albens and E. melliodora woodland remnants in NSW, representing high ecological health. Levels below ~1000 mg/kg total N may indicate degradation or very infertile parent materials, while sustained total N significantly above 2000 mg/kg, or conditions leading to high N availability (e.g., high nitrate), can be detrimental, favoring invasive species and reducing native biodiversity.

Sources (1)

Preview of Prober, S. M., Lunt, I. D., & Thiele, K. R. (2002). Determining reference conditions for management and restoration of temperate grassy woodlands: relationships among trees, topsoils and understorey flora in little-grazed remnants. Australian Journal of Botany, 50(6), 687–697.
Prober, S. M., Lunt, I. D., & Thiele, K. R. (2002). Determining reference conditions for management and restoration of temperate grassy woodlands: relationships among trees, topsoils and understorey flora in little-grazed remnants. Australian Journal of Botany, 50(6), 687–697. Journal

Prober, S. M., Lunt, I. D., & Thiele, K. R. (2002). Determining reference conditions for management and restoration of temperate grassy woodlands: relationships among trees, topsoils and understorey flora in little-grazed remnants. Australian Journal of Botany, 50(6), 687–697.

View Source

Supporting Sources (10)

Additional references from the underlying research that informed this benchmark.

Preview of Determining reference conditions for management and restoration of temperate grassy woodlands: relationships among trees, topsoils and understorey flora in little-grazed remnants - CSIRO PUBLISHING | Australian Journal of Botany, accessed August 12, 2025,
Determining reference conditions for management and restoration of temperate grassy woodlands: relationships among trees, topsoils and understorey flora in little-grazed remnants - CSIRO PUBLISHING | Australian Journal of Botany, accessed August 12, 2025,
Direct Evidence Journal

Soil and Landscape Grid National Soil Attribute Maps - Total Nitrogen (3" resolution) - Release 2 - CSIRO Data Access Portal, accessed May 19, 2025,

View Source
Preview of Identifying ecological barriers to restoration in temperate grassy woodlands: soil changes associated with different degradation states - ResearchGate, accessed August 5, 2025,
Identifying ecological barriers to restoration in temperate grassy woodlands: soil changes associated with different degradation states - ResearchGate, accessed August 5, 2025,
Contextual Support Journal

(PDF) Identifying ecological barriers to restoration in temperate grassy woodlands: soil changes associated with different degradation states - ResearchGate, accessed August 4, 2025,

View Source
Preview of Impacts of Land Use on Soil Nitrogen-Cycling Microbial Communities - PubMed Central, accessed May 19, 2025,
Impacts of Land Use on Soil Nitrogen-Cycling Microbial Communities - PubMed Central, accessed May 19, 2025,
Contextual Support Journal

Impacts of Land Use on Soil Nitrogen-Cycling Microbial Communities - PubMed Central, accessed May 19, 2025,

View Source
Preview of Investigating the Zonal Response of Spatiotemporal Dynamics of Australian Grasslands to Ongoing Climate Change - MDPI, accessed May 19, 2025,
Investigating the Zonal Response of Spatiotemporal Dynamics of Australian Grasslands to Ongoing Climate Change - MDPI, accessed May 19, 2025,
Contextual Support Journal

Investigating the Zonal Response of Spatiotemporal Dynamics of Australian Grasslands to Ongoing Climate Change - MDPI, accessed May 19, 2025,

View Source
Preview of openresearch-repository.anu.edu.au, accessed May 19, 2025,
openresearch-repository.anu.edu.au, accessed May 19, 2025,
Contextual Support Journal

openresearch-repository.anu.edu.au, accessed May 19, 2025,

View Source
Preview of Prober, S. M., & Thiele, K. R. (2005). Ecological and anthropomorphic factors permitting low-risk assisted colonization in temperate grassy woodlands.
Prober, S. M., & Thiele, K. R. (2005). Ecological and anthropomorphic factors permitting low-risk assisted colonization in temperate grassy woodlands.
Direct Evidence Journal

(PDF) Determining reference conditions for management and restoration of temperate grassy woodlands: relationships among trees, topsoils and understorey flora in little-grazed remnants - ResearchGate, accessed May 19, 2025,

View Source
Preview of Restoring Australia's temperate grasslands and grassy woodlands | Request PDF - ResearchGate, accessed August 12, 2025,
Restoring Australia's temperate grasslands and grassy woodlands | Request PDF - ResearchGate, accessed August 12, 2025,
Contextual Support

Restoring Australia's temperate grasslands and grassy woodlands | Request PDF - ResearchGate, accessed May 19, 2025,

View Source
Preview of Restoring ecological function in temperate grassy woodlands: Manipulating soil nutrients, exotic annuals and native perennial grasses through carbon supplements and spring burns | Request PDF - ResearchGate, accessed May 12, 2025
Restoring ecological function in temperate grassy woodlands: Manipulating soil nutrients, exotic annuals and native perennial grasses through carbon supplements and spring burns | Request PDF - ResearchGate, accessed May 12, 2025
Contextual Support Journal

Increasing and declining native species in urban remnant grasslands respond differently to nitrogen addition and disturbance, accessed May 19, 2025,

View Source
Preview of Soil and Landscape Grid National Soil Attribute Maps - Total Nitrogen (3" resolution) - Release 2 - CSIRO Data Access Portal, accessed August 5, 2025,
Soil and Landscape Grid National Soil Attribute Maps - Total Nitrogen (3" resolution) - Release 2 - CSIRO Data Access Portal, accessed August 5, 2025,
Contextual Support Government

Geology | Norfolk Island National Park | Parks Australia, accessed August 2, 2025

View Source
Preview of www.environment.vic.gov.au, accessed May 19, 2025,
www.environment.vic.gov.au, accessed May 19, 2025,
Contextual Support Journal

www.environment.vic.gov.au, accessed May 19, 2025,

View Source

Context

  • Region Australia
  • Biome Temperate Dry Woodlands & Native Grasslands
  • Land Use Conservation / Protected Natural Areas
  • Assessment Conservation Target
  • Evidence Type ReferenceCondition

Lifecycle

  • Status Active
  • Version 1
  • Effective From 24 Mar 2026

Notes

The benchmark range reflects natural spatial variability including higher N under tree canopies (fertile island effect). High total N with high available N (nitrate) is detrimental, favoring invasive species. The range is linked to low available N and healthy nitrogen cycling.