Soil Phosphorus

AUS-TDG-LVG-SOP General Moderate confidence

Benchmark Value

15 mg/kg

Direction: Higher is desirable ↑

Form: MaximumOnly

Scoring Curve

This curve shows how a field measurement for this indicator would score across all available benchmark forms in this context.

Evidence & Context

Increasingly detrimental as Olsen P rises above species/community-specific optima; e.g., levels consistently >15 to 20 are likely to reduce native diversity in many temperate grasslands.

Metric Definition:

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

Benchmark Definition:

This benchmark sets a maximum Olsen P level of 15 mg/kg in the top 10 cm of soil, above which native diversity in temperate grasslands is likely to decline.

Justification:

Sustained Olsen P levels above approximately 15 to 20 mg/kg are likely to lead to native biodiversity loss and increased weed invasion.

Sources (1)

Preview of Australian dryland soils are acidic and nutrient-depleted, and have unique microbial communities compared with other drylands - PMC, accessed August 5, 2025,

Australian dryland soils are acidic and nutrient-depleted, and have unique microbial communities compared with other drylands - PMC, accessed August 5, 2025, Journal

How should we manage our soils to increase soil carbon?, accessed May 10, 2026

View Source

Supporting Sources (5)

Additional references from the underlying research that informed this benchmark.

Over-fertilization diminishes the biodiversity of global grasslands - Mongabay

Contextual Support GreyLiterature

Over-fertilization diminishes the biodiversity of global grasslands - Mongabay

View Source

Phosphorus requirements of Australian native plants - ResearchGate, accessed August 4, 2025

Contextual Support Journal

Australian dryland soils are acidic and nutrient-depleted, and have unique microbial communities compared with other drylands - PMC, accessed July 22, 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

3- Build and maintain soil nutrients to improve soil fertility and health in all pasture zones

View Source

What are the optimum nutrient targets for pastures?

Contextual Support GreyLiterature

What are the optimum nutrient targets for pastures?

View Source

Context

Region Australia
Biome Temperate Dry Woodlands & Native Grasslands
Land Use Livestock Grazing & Pasture
Assessment Not Stated
Evidence Type DegradationThreshold

Lifecycle

Status Active
Version 1
Effective From 10 Jun 2026

Notes

Loss of P-sensitive native species, decline in overall native plant biodiversity, increased dominance of P-tolerant (often exotic) species. AssessmentContext defaulted to 'Not Stated' because the source document did not state one.

Related Benchmarks

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