Soil Phosphorus

AUS-TMS-CON-SOP General Low confidence

Benchmark Value

10 mg/kg

Direction: Higher is desirable ↑

Form: MaximumOnly

Scoring Curve

This curve shows how a field measurement for this indicator would score across all available benchmark forms in this context.

Evidence & Context

Levels consistently >5-10 mg/kg in typically P-poor TMS soils (e.g., Kandosols, Tenosols) may lead to negative ecological outcomes, including favoring invasive species over natives and potential P toxicity to sensitive native plants.

Metric Definition:

Available phosphorus (Bicarbonate-extractable P, 0-10 cm depth) in soil

Benchmark Definition:

This benchmark defines the upper detrimental threshold for available phosphorus in Australian Tropical Monsoonal Savanna soils, above which negative ecological impacts such as invasive species dominance and toxicity to native plants may occur.

Justification:

Sustained increases above natural background levels can lead to negative ecological outcomes including invasive species proliferation and toxicity to native plants.

Sources (2)

Management practices in the Northern Jarrah Forest, southwest Australia: fertiliser increases tree growth but decreases understo Journal

Management practices in the Northern Jarrah Forest, southwest Australia: fertiliser increases tree growth but decreases understo

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Phosphorus toxicity in the Proteaceae - ResearchGate Journal

Phosphorus toxicity in the Proteaceae - ResearchGate

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Supporting Sources (1)

Additional references from the underlying research that informed this benchmark.

www.publications.qld.gov.au, accessed May 16, 2025,

Direct Evidence Journal

The Soils of Cape York Peninsula. Cooktown and Weipa Sections. Land Resource Survey and Evaluation.

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Context

Region Australia
Biome Tropical Monsoonal Savannas
Land Use Conservation / Protected Natural Areas
Assessment Pristine Reference
Evidence Type DegradationThreshold

Lifecycle

Status Active
Version 1
Effective From 10 Jun 2026

Notes

It is crucial to distinguish natural P-rich soil patches from anthropogenic enrichment. The reference value of <5 mg/kg represents the upper limit of the typical natural range for many TMS soils supporting high ecological health.

Related Benchmarks

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