Soil Nitrogen

AUS-TMS-AGR-SON General Moderate confidence

Benchmark Value

960 mg/kg
Range: 700 to 1200 mg/kg
Thresholds: Lower: 500, Upper: —
Optimal Range: 700 to 1200
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 10 benchmarks together — the OptimalRange form drives the primary score, while 9 guard(s) constrain the result.

Contributing Benchmarks

OptimalRange Primary OptimalRange Guard Point Guard LowerThreshold Guard OptimalRange Guard UpperThreshold Guard OptimalRange Guard Point Guard LowerThreshold Guard OptimalRange Guard

Evidence & Context

The proposed benchmark for total soil nitrogen, representing a high level of environmental health under such management, is 960 mg/kg in the 0-10 cm soil layer.

Metric Definition:

Total soil nitrogen concentration in the top 0-10 cm soil layer under best-practice sustainable or regenerative agricultural crop production.

Benchmark Definition:

Total soil nitrogen concentration in the topsoil (0-10 cm) representing best available condition under sustainable or regenerative agricultural crop production in tropical monsoonal savannas.

Justification:

This benchmark is based on a long-term study at Warra, Queensland, demonstrating nitrogen accretion through legume leys in a cropping system, considered relevant to tropical monsoonal savannas despite being subtropical. Confidence is moderate due to limited direct tropical monsoonal savanna data.

Sources (1)

Preview of Comparison of legume-based cropping systems at Warra, Queensland. I. Soil nitrogen and organic carbon accretion and potentially mineralisable nitrogen.
Comparison of legume-based cropping systems at Warra, Queensland. I. Soil nitrogen and organic carbon accretion and potentially mineralisable nitrogen.

Comparison of legume-based cropping systems at Warra, Queensland. I. Soil nitrogen and organic carbon accretion and potentially mineralisable nitrogen.

View Source

Supporting Sources (4)

Additional references from the underlying research that informed this benchmark.

Preview of Review of C:N Ratios in Vegetation, Litter and Soil Under Australian Native Forests and Plantations - DCCEEW
Review of C:N Ratios in Vegetation, Litter and Soil Under Australian Native Forests and Plantations - DCCEEW
Contextual Support Journal

Review of C:N Ratios in Vegetation, Litter and Soil ... - DCCEEW

View Source
Preview of Soil Nitrogen Supply | Fact Sheets | soilquality.org.au, accessed July 25, 2025,
Soil Nitrogen Supply | Fact Sheets | soilquality.org.au, accessed July 25, 2025,
Contextual Support Government

Soil Nitrogen Supply | Fact Sheets | soilquality.org.au, accessed May 11, 2025,

View Source
Preview of Soil organic carbon and total nitrogen under Leucaena ..., accessed May 11, 2025,
Soil organic carbon and total nitrogen under Leucaena ..., accessed May 11, 2025,
Contextual Support Journal

Soil organic carbon and total nitrogen under Leucaena ..., accessed May 11, 2025,

View Source
Preview of Soil organic carbon and total nitrogen under Leucaena leucocephala pastures in Queensland - ResearchGate
Soil organic carbon and total nitrogen under Leucaena leucocephala pastures in Queensland - ResearchGate
Contextual Support Journal

Comparison of no-tillage and conventional tillage in the development of sustainable farming systems in the semi-arid tropics - ResearchGate, accessed May 11, 2025,

View Source

Context

  • Region Australia
  • Biome Tropical Monsoonal Savannas
  • Land Use Agricultural Crop Production
  • Assessment Pristine Reference
  • Evidence Type ReferenceCondition

Lifecycle

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

Notes

Lower Critical Threshold: 500 mg/kg. Optimal range: 700-1200 mg/kg. No upper detrimental threshold — higher values are always better up to natural saturation.