Soil Phosphorus

AUS-TDG-CON-SOP General Low confidence

Benchmark Value

8 mg/kg

Direction: Higher is desirable ↑

Form: Point

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 11 benchmarks together — the OptimalRange form drives the primary score, while 10 guard(s) constrain the result.

Contributing Benchmarks

OptimalRange Primary OptimalRange Guard OptimalRange Guard MinimumOnly Guard MaximumOnly Guard Point Guard OptimalRange Guard MinimumOnly Guard MaximumOnly Guard OptimalRange Guard MaximumOnly Guard

Evidence & Context

Using Colwell P method: A benchmark of approximately 8 mg/kg (0-10 cm depth) is recommended.

Metric Definition:

Available soil phosphorus concentration measured by Colwell P method at 0-10 cm soil depth

Benchmark Definition:

This benchmark represents the soil phosphorus concentration measured by Colwell P method at which native plant species occurrence peaks in low-phosphorus temperate grassy ecosystems.

Justification:

Derived from the work of Dorrough and Scroggie (2008), indicating native plant species occurrence peaked at this Colwell P level in ungrazed, low-P grassy ecosystems.

Sources (1)

Preview of Individual plant species responses to phosphorus and livestock grazing in temperate grassy ecosystems of Australia (Dorrough and Scroggie, 2008)

Individual plant species responses to phosphorus and livestock grazing in temperate grassy ecosystems of Australia (Dorrough and Scroggie, 2008) Journal

Individual plant species responses to phosphorus and livestock grazing in temperate grassy ecosystems of Australia. Australian Journal of Botany, 56(8), 663-673. (Dorrough and Scroggie, 2008)

View Source

Supporting Sources (2)

Additional references from the underlying research that informed this benchmark.

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)

Contextual Support Journal

Phosphorus fertiliser management for pastures based on native grasses in south-eastern Australia

View Source

Understanding soil tests for pastures | Soil | Farm management ..., accessed May 12, 2025

Direct Evidence Government

Agriculture Victoria. (2025). Understanding soil tests for pastures. Farm Management.

View Source

Context

Region Australia
Biome Temperate Dry Woodlands & Native Grasslands
Land Use Conservation / Protected Natural Areas
Assessment Conservation Target
Evidence Type ReferenceCondition

Lifecycle

Status Active
Version 1
Effective From 9 Jun 2026

Notes

Represents the best available condition of nature for soil phosphorus in conservation areas using Colwell P method.

Related Benchmarks

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