Soil Potassium
Benchmark Value
Scoring Curve
This curve shows how a field measurement for this indicator would score across all available benchmark forms in this context.
Evidence & Context
A synthesized value of 150–250 mg/kg (Colwell K) is proposed for loamy soils, with adjustments necessary based on soil texture (e.g., 120–200 mg/kg for sandy loams).
Soil Potassium (Colwell K, typically for 0-10 cm soil depth)
This benchmark represents the optimal soil potassium range for loamy soils in temperate dry woodlands and native grasslands under agricultural crop production, reflecting high fertility and ecological functionality.
This range is positioned towards the upper end of what is considered "Ideal" or "Adequate" for productive agricultural systems on loamy soils and overlaps with the lower to mid-range of available K (110–270 mg/kg) found in open, grassy areas of little-grazed native temperate woodlands, which serve as an ecological reference. It significantly exceeds typical agronomic critical deficiency levels.
Sources (3)
Soil fertility in grazing systems: Manage potassium to manage nitrogen - Crops and Soils, accessed July 28, 2025,
View SourceUnderstanding soil tests for pastures
View SourceScanlan, C. A., et al. (2013). Soil Quality: 10 Plant Nutrition. CCMA Soil Health Knowledge Base.
View SourceSupporting Sources (2)
Additional references from the underlying research that informed this benchmark.
Long-term rundown of plant-available potassium in Western Australia requires a re-evaluation of potassium management for grain production: a review - CSIRO Publishing, accessed July 17, 2025,
View Source
Regenerative agriculture – Case studies from Western Australia, accessed May 10, 2025
View Source