Soil Phosphorus

AUS-TDG-LVG-SOP General Moderate confidence

Benchmark Value

No specific value — see range
Range: 14 to 20 mg/kg
Optimal Range: 14 to 20
Direction: Higher 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.

Evidence & Context

Risk increases with Olsen P, especially at levels >15 to 20, and is highly exacerbated in soils with low PBI (e.g., PBI <50). P loss can occur even at 14 to 17 mg/kg in low PBI soils.

Metric Definition:

Available soil phosphorus measured as Olsen P in the 0-10 cm soil depth.

Benchmark Definition:

This benchmark represents the range of Olsen P in the 0-10 cm soil depth where environmental risk of phosphorus loss to waterways increases, especially in soils with low phosphorus buffering index (PBI).

Justification:

High soil P status increases risk of P leaching and runoff, leading to eutrophication of waterways.

Sources (1)

Preview of What are the optimum nutrient targets for pastures?
What are the optimum nutrient targets for pastures? GreyLiterature

What are the optimum nutrient targets for pastures?

View Source

Supporting Sources (4)

Additional references from the underlying research that informed this benchmark.

Preview of Over-fertilization diminishes the biodiversity of global grasslands - Mongabay
Over-fertilization diminishes the biodiversity of global grasslands - Mongabay
Contextual Support GreyLiterature

Over-fertilization diminishes the biodiversity of global grasslands - Mongabay

View Source
Preview of Phosphorus requirements of Australian native plants - ResearchGate, accessed August 4, 2025
Phosphorus requirements of Australian native plants - ResearchGate, accessed August 4, 2025
Contextual Support Journal

The Big Phosphorus Issue - Australian Native Plants — The Gardeners Lodge, accessed August 1, 2025

View Source
Preview of Phosphorus responses of perennial native pasture species endemic to south-eastern Australia to P application: a review. Crop & Pasture Science, 71(9), 797-815. (Lodge, G. M., Murphy, S. R., & Harden, S., 2020)
Phosphorus responses of perennial native pasture species endemic to south-eastern Australia to P application: a review. Crop & Pasture Science, 71(9), 797-815. (Lodge, G. M., Murphy, S. R., & Harden, S., 2020)
Direct Evidence Journal

Phosphorus fertiliser management for pastures based on native grasses in south-eastern Australia

View Source
Preview of The phosphorus and nitrogen requirements of temperate pasture species and their influence on grassland botanical composition - CSIRO Publishing, accessed August 5, 2025,
The phosphorus and nitrogen requirements of temperate pasture species and their influence on grassland botanical composition - CSIRO Publishing, accessed August 5, 2025,
Contextual Support Journal

Crop and Pasture Science - CSIRO PUBLISHING

View Source

Context

  • Region Australia
  • Biome Temperate Dry Woodlands & Native Grasslands
  • Land Use Livestock Grazing & Pasture
  • Assessment Pristine Reference
  • Evidence Type DegradationThreshold

Lifecycle

  • Status Active
  • Version 1
  • Effective From 25 Mar 2026

Notes

Environmental risk of P loss to waterways increases with Olsen P, especially in low PBI soils.

Related Benchmarks

Other benchmarks in the AUS-TDG-LVG-SOP family.

— mg/kg High
Livestock Grazing & Pasture · Pristine Reference
OptimalRange Active v1
6 mg/kg Moderate
Livestock Grazing & Pasture · Pristine Reference
MaximumOnly Active v1
8 mg/kg Moderate
Livestock Grazing & Pasture · Pristine Reference
MinimumOnly Active v1
6 mg/kg Moderate
Livestock Grazing & Pasture · Pristine Reference
MinimumOnly Active v1
20 mg/kg Moderate
Livestock Grazing & Pasture · Pristine Reference
MinimumOnly Active v1