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Understanding the dynamics of potassium (K) and its availability is fundamental in its efficient use as an important nutrient. The objectives of present study were to compare standard K extraction methods for extractable K and kinetics of K adsorption on five different textured soils. The soils were analyzed for physico-chemical properties, extractable K contents and kinetics of K adsorption. The soils had variable contents of soluble (8-52mg kg-1), exchangeable (13-215mg kg-1), fixed (488-1836mg kg-1), structural (2936-26362mg kg-1) and total K (3438-28517mg kg-1). Except soluble K, the amount of K in different forms was significantly (P?0.05) correlated with clay contents, electrical conductivity (EC), cation exchange capacity (CEC) and calcium carbonate in soils. Different methods variated the extracted K in different textured soils. Mehlich-III, ammonium acetate, AB-DTPA, and calcium chloride extracted K was maximum in sandy clay loam (298mg kg-1, 267mg kg?1, 226mg kg-1, and 113mg kg-1) and lowest was in loamy sand (33mg kg-1, 24mg kg-1, 30mg kg-1, and 24mg kg-1) respectively. Elovich and power function models best explained the K kinetics adsorption, as rate of adsorption constants were negatively correlated with sand contents in the soil type. Pearson correlation showed that the extractability of K by different methods and kinetics of K adsorption were dependent on soil texture EC, CEC and calcium carbonate contents. Hence, soil physico-chemical properties should be considered in recommending rate of K fertilization along with crop K demand and soil extractable K.
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