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. The scoring engine uses 6 benchmarks together — the OptimalRange form drives the primary score, while 5 guard(s) constrain the result.
Contributing Benchmarks
Evidence & Context
The proposed benchmark for the best available condition is therefore not a single value, but a range that varies with soil texture: Sands / Light Texture: 120-150 mg/kg Sandy Loams / Moderate Texture: 150-200 mg/kg Clay Loams / Moderate Texture: 180-250 mg/kg Clays / Heavy Texture: 200-300 mg/kg
Colwell K test (bicarbonate-extractable potassium) in soil at 0-10 cm depth, representing plant-available potassium.
The benchmark represents the 'Ideal' range for Colwell K (0-10 cm) in well-managed temperate pastures, serving as a proxy for high ecological health and resilience.
This value is from authoritative state government guidelines based on extensive field trials and is specific to clay loam/moderate texture soils; benchmarks for other textures are: Sands/Light (120-150 mg/kg), Sandy Loams/Moderate (150-200 mg/kg), and Clays/Heavy (200-300 mg/kg).
Sources (1)
Understanding soil tests for pastures
View SourceSupporting Sources (24)
Additional references from the underlying research that informed this benchmark.
The Western Australian Rangeland Monitoring System (WARMS) – operating a regional scale monitoring system - ResearchGate, accessed July 24, 2025
View SourceWhat are the optimum nutrient targets for pastures? - Soil Health Knowledgebase
View SourceAustralian dryland soils are acidic and nutrient-depleted, and have unique microbial communities compared with other drylands - PMC
View SourceGippsland Plains Grassy Woodland - Wikipedia
View SourceManaging Grazing to Restore Soil Health, Ecosystem ... - Frontiers
View SourceHow to increase improved pasture yield | Yara Australia
View SourceRestoration of degraded grazing country in the semi-arid areas of NSW
View Source
Long-term rundown of plant-available potassium in Western Australia requires a re-evaluation of potassium management for grain production: a review - CSIRO PUBLISHING | Crop and Pasture Science, accessed July 24, 2025
View SourcePotassium Control of Plant Functions: Ecological and Agricultural Implications - PMC
View Source
What do you see and when? What could this indicate? What test can I do to confirm? - MLA
View SourcePotassium - Tas | Fact Sheets | soilquality.org.au, accessed May 11, 2025,
View SourcePotassium and sulphur - emerging deficiencies in the southern region - GRDC
View SourceRegenerative Agriculture - Nuffield Farming Scholarships
View SourcePotassium for high rainfall pastures - DPIRD's Digital library
View SourcePotassium in the soil - Potash Development Association (PDA)
View SourceSemi-arid woodlands (grassy sub-formation) | NSW Environment, Energy and Science
View SourceTemperate Grasslands - Greening Australia
View SourceUnderstanding soil tests for pastures | Soil | Farm management ..., accessed July 17, 2025,
View SourceSoil Potassium Availability and Role of Microorganisms in Influencing Potassium Availability to Plants - ResearchGate
View SourceSoutheast Australia temperate savanna - Wikipedia
View SourceManaging natural areas | City of Gold Coast, accessed May 19, 2025
View SourceThe role of regenerative agriculture in sustainable land use - ClimateWorks Australia
View Source
How Biodiversity-Friendly Is Regenerative Grazing? - Frontiers
View Source