Soil Potassium

AUS-TMS-AGR-SOK General Moderate confidence

Benchmark Value

No specific value — see range

Range: 40 to 50 mg/kg

Thresholds: Lower: 40, Upper: —

Optimal Range: 40 to 50

Direction: Higher is desirable ↑

Form: OptimalRange

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 15 benchmarks together — the OptimalRange form drives the primary score, while 14 guard(s) constrain the result.

Contributing Benchmarks

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

Evidence & Context

A Lower Critical Threshold is estimated to be around 40-50 mg/kg exchangeable K.

Metric Definition:

Lower critical threshold of exchangeable potassium concentration in 0-10 cm soil depth below which plant health and productivity are significantly compromised.

Benchmark Definition:

Lower critical threshold for exchangeable potassium indicating onset of significant ecological and agronomic harm.

Justification:

Based on agronomic critical values for wheat (~49 mg/kg Colwell K), native savanna baseline (~46 mg/kg), and analogous savanna systems with low K levels requiring fertilization.