Soil Phosphorus

AUS-TDG-AGR-SOP General Moderate confidence

Benchmark Value

20 mg/kg

Thresholds: Lower: —, Upper: 20

Direction: Higher is desirable ↑

Form: UpperThreshold

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 12 benchmarks together — the OptimalRange form drives the primary score, while 11 guard(s) constrain the result.

Contributing Benchmarks

OptimalRange Primary LowerThreshold Guard UpperThreshold Guard Point Guard LowerThreshold Guard OptimalRange Guard UpperThreshold Guard OptimalRange Guard OptimalRange Guard MinimumOnly Guard MaximumOnly Guard OptimalRange Guard

Evidence & Context

Therefore, an Upper Detrimental Threshold of >20 mg/kg Olsen P (0-10 cm) is proposed.

Metric Definition:

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

Benchmark Definition:

Upper detrimental threshold beyond which soil phosphorus levels pose increased environmental risk.

Justification:

Beyond this level, risks of P loss, eutrophication, and negative impacts on native biodiversity increase substantially.

Sources (4)

Preview of (PDF) Phosphorus accumulation and other changes in soil ...

(PDF) Phosphorus accumulation and other changes in soil ... Journal

Phosphorus Dynamics in the Soil–Plant–Environment Relationship in Cropping Systems: A Review - MDPI

View Source

Preview of The phosphorus saturation degree as a universal agronomic and environmental soil P test

The phosphorus saturation degree as a universal agronomic and environmental soil P test Journal

Soil | Australia state of the environment 2021

View Source

Preview of Why phosphorus is important - NSW Department of Primary Industries, accessed August 4, 2025

Why phosphorus is important - NSW Department of Primary Industries, accessed August 4, 2025 Government

(PDF) Individual plant species responses to phosphorus and ...

View Source

www.agric.wa.gov.au

www.agric.wa.gov.au

View Source

Supporting Sources (3)

Additional references from the underlying research that informed this benchmark.

Preview of Phosphorus fertiliser management for pastures based on native grasses in south-eastern Australia - CSIRO Publishing, accessed August 5, 2025,

Phosphorus fertiliser management for pastures based on native grasses in south-eastern Australia - CSIRO Publishing, accessed August 5, 2025,

Direct Evidence Journal

Phosphorus nutrition of phosphorus-sensitive Australian native ..., accessed May 15, 2025,

View Source

Phosphorus: a finite resource essential for life, critical for agriculture and food security

Contextual Support Journal

Phosphorus: a finite resource essential for life, critical for agriculture and food security

View Source

Phosphorus: a finite resource essential for life, critical for agriculture and food security - CSIRO, accessed August 11, 2025

Contextual Support Government

Nitrogen and Phosphorus Retranslocation of Leaves and Stemwood in a Mature Eucalyptus Forest Exposed to 5 Years of Elevated CO2 - Frontiers, accessed July 19, 2025,

View Source

Context

Region Australia
Biome Temperate Dry Woodlands & Native Grasslands
Land Use Agricultural Crop Production
Assessment Pristine Reference
Evidence Type DegradationThreshold

Lifecycle

Status Active
Version 1
Effective From 24 Mar 2026

Notes

This threshold marks a departure from high environmental health and is associated with legacy P soils and over-fertilization.

Related Benchmarks

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