Soil Potassium

Benchmark Value

120 mg/kg

Thresholds: Lower: —, Upper: 120

Direction: Lower is desirable ↓

Form: UpperThreshold

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 10 benchmarks together — the OptimalRange form drives the primary score, while 9 guard(s) constrain the result.

Contributing Benchmarks

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

Evidence & Context

Detrimental effects can occur if exchangeable potassium exceeds 10% of the soil CEC, which can lead to magnesium deficiency in plants and animals. Furthermore, soil potassium concentrations consistently exceeding approximately 100-120 mg/kg in these typically low to moderate nutrient systems may indicate disturbance or a nutrient imbalance that is unfavorable to native biodiversity and overall ecosystem health.

Metric Definition:

Upper detrimental threshold of soil potassium concentration beyond which ecosystem health is harmed.

Benchmark Definition:

Upper detrimental threshold for potassium in soil.

Justification:

Exceeding 10% of soil CEC in exchangeable potassium can induce magnesium deficiency and nutrient imbalance harmful to native biodiversity.

Sources (3)

Agriculture Victoria. (2024). Understanding soil tests for pastures. Government

Agriculture Victoria. (2024). Understanding soil tests for pastures.

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Preview of Restoring Australia's temperate grasslands and grassy woodlands | Request PDF - ResearchGate, accessed August 6, 2025,

Restoring Australia's temperate grasslands and grassy woodlands | Request PDF - ResearchGate, accessed August 6, 2025, Journal

Prober, S. M., Thiele, K. R., & Loneragan, W. A. (2005). Relationships among soil fertility, native plant diversity and exotic plant abundance inform restoration of forb-rich eucalypt woodlands. Austral Ecology, 30(6), 607-618.

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Preview of Sapsford, S. J., Paap, T., Hardy, G. E. St. J., & Burgess, T. I. (2021). Anthropogenic Disturbance Impacts Mycorrhizal Communities and Abiotic Soil Properties: Implications for an Endemic Forest Disease. Frontiers in Forests and Global Change, 3, 593243.

Sapsford, S. J., Paap, T., Hardy, G. E. St. J., & Burgess, T. I. (2021). Anthropogenic Disturbance Impacts Mycorrhizal Communities and Abiotic Soil Properties: Implications for an Endemic Forest Disease. Frontiers in Forests and Global Change, 3, 593243. Journal

Sapsford, S. J., Paap, T., Hardy, G. E. St. J., & Burgess, T. I. (2021). Anthropogenic Disturbance Impacts Mycorrhizal Communities and Abiotic Soil Properties: Implications for an Endemic Forest Disease. Frontiers in Forests and Global Change, 3, 593243.

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Supporting Sources (2)

Additional references from the underlying research that informed this benchmark.

Preview of Daws, M. I., Standish, R. J., Grigg, A. H., Morald, T. K., & Tibbett, M. (2021). Seeing the forest for the trees: fertiliser increases tree growth but decreases understorey diversity in the Northern Jarrah Forest, southwest Australia. Journal of the Royal Society of Western Australia, 104, 5-9.

Daws, M. I., Standish, R. J., Grigg, A. H., Morald, T. K., & Tibbett, M. (2021). Seeing the forest for the trees: fertiliser increases tree growth but decreases understorey diversity in the Northern Jarrah Forest, southwest Australia. Journal of the Royal Society of Western Australia, 104, 5-9.

Contextual Support Journal

Daws, M. I., Standish, R. J., Grigg, A. H., Morald, T. K., & Tibbett, M. (2021). Seeing the forest for the trees: fertiliser increases tree growth but decreases understorey diversity in the Northern Jarrah Forest, southwest Australia. Journal of the Royal Society of Western Australia, 104, 5-9.

View Source