Potassium Exchange Equilibria and Yield Responses of Oats, Barley, and Corn on Selected Quebec Soils

Abstract

Abstract Potassium:calcium + magnesium activity ratios were used to calculate availability indices on eight Quebec soils. These were compared to available potassium measurements and related to yield responses of oats ( Avena sativa L. ), barley ( Hordeum vulgare L. ), and corn ( Zea mays L. ) to potassium fertilizers in field experiments. Crop growth did not change the potential buffering capacities (PBC K ) of two selected soils, which indicated that the quantity‐intensity relation regulated the release of potassium although the activity ratio was greatly reduced. The potassium potential was obtained by multiplying the total amount of exchangeable potassium (−ΔK°) with the potential buffering capacity to place soils on a comparative basis. The potassium potential fully defined the quantity‐intensity relation and correlated more closely to crop responses than the activity ratio measurement, the PBC K , or the available potassium determination.