Soil Nitrogen

AUS-TSW-AGR-SON General Moderate confidence

Benchmark Value

1000 mg/kg
Direction: Higher is desirable ↑
Form: MinimumOnly

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 2 benchmarks together — the OptimalRange form drives the primary score, while 1 guard(s) constrain the result.

Evidence & Context

A Lower Critical Threshold is identified not as a simple value, but as a state of persistent negative nitrogen balance, leading to the degradation of soil capital. This is indicated by TSN levels below approximately 1000 mg/kg for heavier soils and 400 mg/kg for sands.

Metric Definition:

Total Soil Nitrogen (TSN) concentration below which persistent negative nitrogen balance leads to soil degradation

Benchmark Definition:

Lower critical threshold of TSN indicating persistent negative nitrogen balance and soil degradation in loam and clay soils under agricultural crop production.

Justification:

Based on nutrient budget studies and soil health surveys indicating that TSN levels below 1000 mg/kg for loam/clay soils correspond to a state of negative nitrogen balance and degradation.

Sources (1)

Preview of Opportunities for improving soil carbon and nitrogen stocks in low and medium rainfall cropping systems - GRDC, accessed July 6, 2025,
Opportunities for improving soil carbon and nitrogen stocks in low and medium rainfall cropping systems - GRDC, accessed July 6, 2025, Government

Soil health stocktake Queensland - GRDC

View Source

Supporting Sources (1)

Additional references from the underlying research that informed this benchmark.

Preview of Strategic tillage of a long-term, no-till soil has little impact on soil characteristics or crop growth over five years
Strategic tillage of a long-term, no-till soil has little impact on soil characteristics or crop growth over five years
Contextual Support Journal

Strategic tillage of a long-term, no-till soil has little impact on soil characteristics or crop growth over five years

View Source

Context

  • Region Australia
  • Biome Temperate Semi-Arid Shrublands & Open Woodlands
  • Land Use Agricultural Crop Production
  • Assessment Not Stated
  • Evidence Type DegradationThreshold

Lifecycle

  • Status Active
  • Version 1
  • Effective From 5 Jun 2026

Notes

This threshold marks the point at which the system transitions from sustainable management to degradation due to nitrogen mining. AssessmentContext defaulted to 'Not Stated' because the source document did not state one.