Soil Potassium Reactions as Related to Clay Mineralogy of Selected Kentucky Soils

Abstract
Clay mineralogy was related to soil K reactions of Heitt, Eden and Maddox series, representative soils of high K‐supplying power; and Maury, Bedford and Tilsit series, representative soils of low to medium K‐supplying power.Clay fractions of Heitt, Eden and Maddox soils contained more illite than Maury, Bedford and Tilsit clay fractions; thus illite is the probable seat of K‐supplying power.Effects of drying the soils on exchangeable K levels were investigated. Upon drying, fixation was observed when the initial, field‐moist level of exchangeable K was relatively high; release occurred when the initial level was low.The 14Å. vermiculite spacing contained by soils of high K‐supplying power was easily collapsed to 10Å. by K saturation and 100° C. heating, whereas that spacing of soils of low K‐supplying power was affected little by K saturation, requiring 300° C. or higher heating for closure. At least two possible explanations could account for the differences in collapsibility: (a) differences in magnitude, location and origin of interlayer charge; and (b) presence or absence of nonexchangeable Al in interlayer positions.
Funding Information
  • National Science Foundation

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