Soil Nitrogen

AUS-TMI-CON-SON General Moderate confidence

Benchmark Value

6500 mg/kg

Range: 6500 to 6500 mg/kg

Optimal Range: 6500 to 6500

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.

Evidence & Context

The proposed 'best-on-offer' benchmark for total soil nitrogen in conservation areas on volcanic-derived soils (Krasnozems) within the Tropical & Subtropical Maritime Islands biome is 6,500 mg/kg.

Metric Definition:

Total soil nitrogen content in the top 10 cm of soil in conservation areas on volcanic-derived soils (Krasnozems).

Benchmark Definition:

This benchmark represents the mean total nitrogen content in the top 10 cm of volcanic-derived soils in conservation areas within the Tropical & Subtropical Maritime Islands biome, indicating a high-quality soil nitrogen level for these ecosystems.

Justification:

This benchmark is a proxy value derived from a large-scale study of 17 intact subtropical rainforest sites on volcanic (basaltic) soils on the Australian mainland, which serve as a high-fidelity analogue for the target conservation areas.

Sources (1)

Preview of Influence of environmental conditions and some soil chemical properties on the carbon and nitrogen contents of some tropical Australian rainforest soils - CSIRO PUBLISHING | Soil Research, accessed August 2, 2025

Influence of environmental conditions and some soil chemical properties on the carbon and nitrogen contents of some tropical Australian rainforest soils - CSIRO PUBLISHING | Soil Research, accessed August 2, 2025 Journal

Influence of environmental conditions and some soil chemical properties on the carbon and nitrogen contents of some tropical Australian rainforest soils - ResearchGate, accessed August 2, 2025

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Supporting Sources (5)

Additional references from the underlying research that informed this benchmark.

Christmas Island National Park - Wikipedia, accessed July 30, 2025,

Contextual Support GreyLiterature

Cocos Island - Wikipedia, accessed August 2, 2025

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Geology | Norfolk Island National Park | Parks Australia, accessed July 30, 2025,

Contextual Support Government

Geology - Lord Howe Island Museum, accessed August 2, 2025

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Interim Biogeographic Regionalisation for Australia - Wikipedia, accessed August 2, 2025

Contextual Support GreyLiterature

Interim Biogeographic Regionalisation for Australia - Wikipedia, accessed August 2, 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

Soil and Landscape Grid of Australia - CSIRO, accessed July 30, 2025,

Contextual Support

Soil and Landscape Grid of Australia - CSIRO, accessed August 1, 2025

View Source

Context

Region Australia
Biome Tropical & Subtropical Maritime Islands
Land Use Conservation / Protected Natural Areas
Assessment Conservation Target
Evidence Type ReferenceCondition

Lifecycle

Status Active
Version 1
Effective From 25 Mar 2026

Notes

No upper detrimental threshold — higher values are always better up to natural saturation. This benchmark applies ONLY to conservation areas on islands of volcanic origin (e.g., Lord Howe Island, Norfolk Island) with Krasnozem soils. It is NOT applicable to islands with calcareous or atoll-derived soils (e.g., Christmas Island, Cocos (Keeling) Islands). Levels significantly below this benchmark would indicate a compromised ecosystem, and levels significantly exceeding this benchmark are considered detrimental due to anthropogenic nitrogen loading.