Soil Phosphorus

AUS-TBF-AGR-SOP General High confidence

Benchmark Value

No specific value — see range

Range: 9 to 70 mg/kg

Optimal Range: 9 to 70

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

Based on the comprehensive research from the BFDP project and the BFDC guidelines, along with validation studies, a single reference value for soil phosphorus in the Australian Temperate Broadleaf & Mixed Forests biome under agricultural land use is not scientifically defensible. Instead, a range of target Colwell P values, contingent upon the Phosphorus Buffering Index (PBI) of the soil and the specific agricultural land use, is recommended.

Metric Definition:

Colwell P soil test phosphorus concentration representing plant-available phosphorus in soil.

Justification:

These values are derived from BFDP and BFDC data and represent critical phosphorus levels to achieve 90-95% of maximum yield while balancing environmental health.

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 The development and application of functions describing pasture yield responses to phosphorus, potassium and sulfur in Australia using meta-data analysis and derived soil-test calibration relationships - CSIRO Publishing, accessed August 11, 2025

The development and application of functions describing pasture yield responses to phosphorus, potassium and sulfur in Australia using meta-data analysis and derived soil-test calibration relationships - CSIRO Publishing, accessed August 11, 2025 Journal

The role of regenerative agriculture in sustainable land use - ClimateWorks Australia

View Source

Supporting Sources (1)

Additional references from the underlying research that informed this benchmark.

Making Better Fertiliser Decisions for Cropping Systems in Australia: an overview

Contextual Support Government

Making Better Fertiliser Decisions for Cropping Systems in Australia: an overview

View Source

Context

Region Australia
Biome Tropical and Subtropical Broadleaf Forests
Land Use Agricultural Crop Production
Assessment Agricultural Biodiversity Target
Evidence Type ReferenceCondition

Lifecycle

Status Active
Version 1
Effective From 5 Jun 2026

Notes

No upper detrimental threshold — higher values are always better up to natural saturation. Ranges vary by PBI class from Extremely Low (<15) to Very High (>840).

Related Benchmarks

Other benchmarks in the AUS-TBF-AGR-SOP family.