Soil Phosphorus

AUS-TSW-LVG-SOP General High confidence

Benchmark Value

10 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

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:

Available phosphorus (Colwell-P) concentration in soil

Benchmark Definition:

This benchmark represents the lower critical threshold of available phosphorus in soil needed to maintain productive function in temperate semi-arid grazing systems with low PBI soils (sands).

Justification:

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

Sources (2)

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
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, Journal

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

View Source

Supporting Sources (2)

Additional references from the underlying research that informed this benchmark.

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

Phosphorus - NSW | Fact Sheets | soilquality.org.au, accessed July 22, 2025

View Source
Preview of Indicative Soil Phosphorus Report | LongPaddock | Queensland Government
Indicative Soil Phosphorus Report | LongPaddock | Queensland Government
Contextual Support Government

Indicative Soil Phosphorus Report | LongPaddock | Queensland Government

View Source

Context

  • Region Australia
  • Biome Temperate Semi-Arid Shrublands & Open Woodlands
  • Land Use Livestock Grazing & Pasture
  • Assessment Not Stated
  • Evidence Type DegradationThreshold

Lifecycle

  • Status Active
  • Version 1
  • Effective From 10 Jun 2026

Notes

Below this threshold, pasture and animal productivity are compromised. AssessmentContext defaulted to 'Not Stated' because the source document did not state one.

Related Benchmarks

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