Soil Phosphorus

AUS-TSW-LVG-SOP General High confidence

Benchmark Value

No specific value — see range

Range: 10 to 60 mg/kg

Thresholds: Lower: 10, Upper: —

Optimal Range: 10 to 60

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

Industry guidelines provide well-established minimums for maintaining pasture productivity. For the Colwell P test, these minimums vary with PBI, ranging from 10 mg/kg for very low PBI soils (sands) to 60 mg/kg for very high PBI soils (clays).

Metric Definition:

Lower critical threshold of available phosphorus (Colwell-P) for pasture and animal productivity

Benchmark Definition:

This benchmark defines the lower critical threshold range of available phosphorus in soils varying by Phosphorus Buffering Index, below which pasture and animal productivity are compromised in grazed temperate semi-arid woodlands.

Justification:

These values represent a robust, evidence-based lower critical threshold for the productive function of the grazing system.

Sources (1)

Preview of Critical phosphorus values from the Better Fertiliser Decisions for Pastures project: early insights from validation trials - BioOne Complete, accessed July 28, 2025,

Critical phosphorus values from the Better Fertiliser Decisions for Pastures project: early insights from validation trials - BioOne Complete, accessed July 28, 2025, Journal

Soil nutrient critical limits | MBFP | More Beef from Pastures - MLA

View Source

Supporting Sources (3)

Additional references from the underlying research that informed this benchmark.

A simple phosphorus buffering index for Australian soils - University of Tasmania Open Access Repository Cover sheet

Contextual Support GreyLiterature

Cycling of phosphorus in grazing systems - NSW Department of Primary Industries

View Source

Preview of Critical phosphorus values from the Better Fertiliser Decisions for Pastures project: early insights from validation trials - CSIRO Publishing, accessed August 5, 2025,

Critical phosphorus values from the Better Fertiliser Decisions for Pastures project: early insights from validation trials - CSIRO Publishing, accessed August 5, 2025,

Direct Evidence Journal

Critical phosphorus values from the Better Fertiliser Decisions for Pastures project: early insights from validation trials - CSIRO Publishing

View Source

Indicative Soil Phosphorus Report | LongPaddock | Queensland Government

Contextual Support Government

Indicative Soil Phosphorus Report | LongPaddock | Queensland Government, accessed August 1, 2025

View Source

Context

Region Australia
Biome Temperate Semi-Arid Shrublands & Open Woodlands
Land Use Livestock Grazing & Pasture
Assessment Pristine Reference
Evidence Type DegradationThreshold

Lifecycle

Status Active
Version 1
Effective From 25 Mar 2026

Notes

Below these levels, pasture and animal productivity are compromised. No upper detrimental threshold — higher values are always better up to natural saturation.

Related Benchmarks

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