Soil Potassium

AUS-TMS-AGR-SOK General Moderate confidence

Benchmark Value

150 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 5 benchmarks together — the OptimalRange form drives the primary score, while 4 guard(s) constrain the result.

Evidence & Context

The primary concerns with excessively high K levels (potentially >150-200 mg/kg without commensurate benefits) relate to induced nutrient imbalances (especially with magnesium and calcium) and economic inefficiency.

Metric Definition:

Upper detrimental threshold for exchangeable potassium in the 0-10 cm soil depth

Benchmark Definition:

Threshold above which excessive potassium may cause nutrient imbalances and economic inefficiency.

Justification:

Based on risk of cation imbalances in low CEC soils and economic considerations.

Sources (1)

Preview of Fertilisation with P, N and S requires additional Zn for healthy plantation tree growth on low fertility savanna soils - ResearchGate
Fertilisation with P, N and S requires additional Zn for healthy plantation tree growth on low fertility savanna soils - ResearchGate Journal

Fertilisation with P, N and S requires additional Zn for healthy plantation tree growth on low fertility savanna soils - ResearchGate

View Source

Supporting Sources (2)

Additional references from the underlying research that informed this benchmark.

Preview of Soil potassium—crop response calibration relationships and ...
Soil potassium—crop response calibration relationships and ...
Direct Evidence Journal

Soil Survey of the Kurnturlpara Area, Warumungu Aboriginal Land Trust

View Source
Preview of Soil Research - CSIRO PUBLISHING
Soil Research - CSIRO PUBLISHING
Contextual Support Journal

Soil Research - CSIRO PUBLISHING

View Source

Context

  • Region Australia
  • Biome Tropical Monsoonal Savannas
  • Land Use Agricultural Crop Production
  • Assessment Conservation Target
  • Evidence Type DegradationThreshold

Lifecycle

  • Status Active
  • Version 1
  • Effective From 8 Jun 2026

Notes

No direct K toxicity threshold identified; concerns are indirect and related to nutrient imbalances and inefficiency.