Soil Potassium

AUS-TMI-FOR-SOK General Moderate confidence

Benchmark Value

50 mg/kg
Thresholds: Lower: —, Upper: 50
Direction: Higher is desirable ↑
Form: LowerThreshold

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 6 benchmarks together — the OptimalRange form drives the primary score, while 5 guard(s) constrain the result.

Contributing Benchmarks

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

Evidence & Context

For sandy soils, which are common in the target biome, potassium levels below 50 mg/kg are classified as "Low".

Metric Definition:

Available potassium level in soil below which forest health and long-term productivity are likely compromised

Benchmark Definition:

Critical lower threshold of soil potassium below which ecological function is impaired.

Justification:

Based on general soil health guidelines for Australian agricultural systems on similar soil types.

Sources (1)

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

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

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Supporting Sources (39)

Additional references from the underlying research that informed this benchmark.

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Australian climate zones - | YourHome, accessed July 13, 2025
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Australian climate zones - | YourHome, accessed July 13, 2025

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Christmas and Cocos Islands tropical forests - Wikipedia, accessed July 30, 2025,
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Norfolk Island - Wikipedia

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Climate & Seasons | Australian Wildlife Journeys, accessed July 30, 2025,
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Soil erosion as a resilience drain in disturbed tropical forests

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Cocos (Keeling) Islands - 2022 World Factbook Archive - CIA, accessed July 30, 2025,
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Cocos (Keeling) Islands - 2022 World Factbook Archive - CIA, accessed July 30, 2025

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Conservation | Norfolk Island National Park | Parks Australia, accessed August 3, 2025,
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Deforestation - Norfolk Island Flora & Fauna Society, accessed July 30, 2025,
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Deforestation - Norfolk Island Flora & Fauna Society, accessed July 30, 2025

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Establishment of critical nutrient levels in soil and plant for eucalyptus - Semantic Scholar, accessed July 30, 2025,
Direct Evidence Journal

Establishment of critical nutrient levels in soil and plant for eucalyptus

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Fact sheets: Norfolk Island plant communities - Invasive Species Council, accessed July 30, 2025,
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Fact sheets: Norfolk Island plant communities - Invasive Species Council, accessed July 30, 2025

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Preview of Flora of the Cocos (Keeling) Islands - Wikipedia, accessed July 30, 2025, )_Islands
Flora of the Cocos (Keeling) Islands - Wikipedia, accessed July 30, 2025, )_Islands
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Flora of the Cocos (Keeling) Islands - Wikipedia, accessed July 30, 2025, )_Islands

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Preview of History & culture | Pulu Keeling National Park | Parks Australia, accessed July 30, 2025,
History & culture | Pulu Keeling National Park | Parks Australia, accessed July 30, 2025,
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History & culture | Pulu Keeling National Park | Parks Australia, accessed July 30, 2025

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How does the nutrient cycle work in a tropical rainforest? - Quora, accessed July 30, 2025,
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How does the nutrient cycle work in a tropical rainforest? - Quora, accessed July 30, 2025

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Incredible Great Barrier Reef Islands For Your Holiday - Visitor's Guide - Queensland, accessed July 30, 2025,
Contextual Support

Incredible Great Barrier Reef Islands For Your Holiday - Visitor's Guide - Queensland, accessed August 2, 2025

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Inquiry into forestry and mining operations on the Tiwi Islands, accessed July 30, 2025,
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BIODIVERSITY CONSERVATION ON THE TIWI ISLANDS, NORTHERN TERRITORY: Part 3. Management and planning for biodi

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List of islands of Australia - Wikipedia, accessed July 30, 2025,
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List of islands of Australia - Wikipedia

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Lord Howe Island - Wikipedia, accessed July 30, 2025,
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Lord Howe Island - Wikipedia

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Lord Howe Island subtropical forests | EBSCO Research Starters, accessed August 3, 2025,
Contextual Support

Norfolk Island Plant Communities - Jerry Coleby-Williams

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Lord Howe Island Subtropical Forests | One Earth, accessed July 30, 2025,
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Norfolk Island - Wikipedia, accessed July 30, 2025,
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Norfolk Island National Park | Parks Australia, accessed July 30, 2025,
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Norfolk Island National Park | Parks Australia, accessed July 30, 2025

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Patterns in potassium dynamics in forest ecosystems - PubMed, accessed August 11, 2025,
Contextual Support Journal

Soil Fertility (Part III) - Properties and Management of Soils in the Tropics

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Plant nutrients in the soil - NSW Department of Primary Industries, accessed July 18, 2025,
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POTASSIUM AND MAGNESIUM IN LEAF AND TOP SOIL AFFECTED BY TRIPLE SUPERPHOSPHATE FERTILISATION IN AN ACACIA MANGIUM PLANTATION - JOURNAL OF TROPICAL FOREST SCIENCE, accessed July 30, 2025

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The intact and the imperilled: contrasting mammal population trajectories between two large adjacent islands - CSIRO Publishing, accessed July 30, 2025,
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These 21 Beautiful Tropical Islands Are Closer Than You Think | Travel Insider - Qantas, accessed August 3, 2025
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Context

  • Region Australia
  • Biome Tropical & Subtropical Maritime Islands
  • Land Use Production Forestry
  • Assessment Not Stated
  • Evidence Type DegradationThreshold

Lifecycle

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

Notes

Potassium levels below this threshold indicate significant risk of compromised forest health and productivity in the typically leached soils of the biome. AssessmentContext defaulted to 'Not Stated' because the source document did not state one.

Related Benchmarks

Other benchmarks in the AUS-TMI-FOR-SOK family.

— mg/kg Moderate
Production Forestry · Not Stated
OptimalRange Active v1
250 mg/kg Moderate
Production Forestry · Not Stated
UpperThreshold Active v1