Soil Phosphorus

AUS-TMI-AGR-SOP General Moderate confidence

Benchmark Value

70 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. The scoring engine uses 7 benchmarks together — the OptimalRange form drives the primary score, while 6 guard(s) constrain the result.

Evidence & Context

Upper Detrimental Threshold: >70 mg/kg is considered high and indicative of a degraded state. This excess poses a significant risk of nutrient leaching and runoff into sensitive marine ecosystems once the soil's high P-sorption capacity is saturated.

Metric Definition:

Available soil phosphorus level above which ecological degradation and environmental risk occur.

Benchmark Definition:

Maximum available phosphorus level to avoid ecological degradation and pollution risk.

Justification:

Based on the finite P-sorption capacity of volcanic Ferrosol soils and documented environmental impacts of excess phosphorus.

Sources (1)

Preview of AGRICULTURAL AUDIT & LAND USE CAPABILITY ASSESSMENT ..., accessed July 30, 2025,
AGRICULTURAL AUDIT & LAND USE CAPABILITY ASSESSMENT ..., accessed July 30, 2025, Journal

VEGETATION 0}' LORD HOWE ISLAND - Botanic Gardens of Sydney

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Supporting Sources (1)

Additional references from the underlying research that informed this benchmark.

Preview of NORFOLK ISLAND FOOD SECURITY STRATEGY 2023 - 2028 “Growing the local food economy for a resilient, sustainable and healthy com, accessed July 25, 2025,
NORFOLK ISLAND FOOD SECURITY STRATEGY 2023 - 2028 “Growing the local food economy for a resilient, sustainable and healthy com, accessed July 25, 2025,
Contextual Support Journal

NORFOLK ISLAND FOOD SECURITY STRATEGY 2023 - 2028 “Growing the local food economy for a resilient, sustainable and healthy com

View Source

Context

  • Region Australia
  • Biome Tropical & Subtropical Maritime Islands
  • Land Use Agricultural Crop Production
  • Assessment Agricultural Biodiversity Target
  • Evidence Type DegradationThreshold

Lifecycle

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

Notes

Exceeding this threshold disrupts soil biology, suppresses beneficial mycorrhizal fungi, and increases risk of eutrophication in adjacent marine ecosystems.