Soil Phosphorus

AUS-TMI-AGR-SOP General High confidence

Benchmark Value

No specific value — see range
Range: 30 to 70 mg/kg
Thresholds: Lower: 30, Upper: 70
Optimal Range: 30 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. 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

The benchmark and its associated functional thresholds are presented below. Indicator Name Reference Value Unit Source Title Source URL or DOI Confidence Level Short Notes Soil Phosphorus 30 - 70 mg/kg Agricultural Audit and Land Use Capability Assessment for Norfolk Island High This benchmark represents the optimal range for available phosphorus in the volcanic Ferrosol soils of Norfolk Island, a key example of the target biome.

Metric Definition:

Available phosphorus measured by standard soil tests such as Colwell-P or Olsen-P, representing the labile P pool available for plant uptake in volcanic Ferrosol soils.

Benchmark Definition:

Optimal range for available phosphorus in volcanic Ferrosol soils to balance crop nutrient needs and ecological health.

Justification:

Derived from an agricultural assessment aimed at promoting sustainable, regenerative food production on Norfolk Island, tailored to volcanic Ferrosol soils with high P-fixation capacity.

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

Norfolk Island Agricultural Audit and Land Capability Assessment Report

View Source

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 Pristine Reference
  • Evidence Type ReferenceCondition

Lifecycle

  • Status Active
  • Version 1
  • Effective From 24 Mar 2026

Notes

Lower Critical Threshold: <30 mg/kg is deficient and compromises crop health and productivity. Upper Detrimental Threshold: >70 mg/kg indicates a degraded state with risks of nutrient leaching and disruption of soil biology, including suppression of beneficial mycorrhizal fungi.

Related Benchmarks

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

30 mg/kg High
Agricultural Crop Production · Pristine Reference
MinimumOnly Active v1
70 mg/kg High
Agricultural Crop Production · Pristine Reference
MaximumOnly Active v1