Soil Phosphorus

AUS-TDG-LVG-SOP General Moderate confidence

Benchmark Value

8 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.

Evidence & Context

For general native pastures, including more P-responsive native species: Victorian government agricultural guidelines classify Olsen P levels <9 mg/kg as "Low — except for native pastures" and <8 mg/kg as "Low" for dryland pastures more broadly.

Metric Definition:

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

Benchmark Definition:

This benchmark sets a minimum Olsen P level of 8 mg/kg in the top 10 cm of soil to avoid low phosphorus conditions detrimental to general native pastures including more phosphorus-responsive species.

Justification:

Olsen P levels consistently below approximately 5 to 8 mg/kg could be considered critically low for maintaining vigor and desired composition of pastures including fertility-tolerant native grasses.

Sources (1)

What are the optimum nutrient targets for pastures? GreyLiterature

What are the optimum nutrient targets for pastures?

View Source

Supporting Sources (5)

Additional references from the underlying research that informed this benchmark.

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,

Contextual Support Journal

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

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Over-fertilization diminishes the biodiversity of global grasslands - Mongabay

Contextual Support GreyLiterature

Over-fertilization diminishes the biodiversity of global grasslands - Mongabay

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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

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

Levels below this range may lead to reduced vigor and persistence of desirable native grasses, increased bare ground, erosion risk, and a shift to less desirable 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.