Grewal, K.S.Shankar, Vivek2016-11-212016-11-212006http://krishikosh.egranth.ac.in/handle/1/86691The present investigation was carried out to investigate the “Potassium adsorption and desorption kinetics” on surface soil samples, collected from five locations in Haryana, widely varying in their physico-chemical properties. Adsorption of potassium was investigated on the collected soil samples using 60 and 120 mg K kg-1 soil, for different time intervals ranging from 0, 1, 2, 4, 8, 12, 24, 36, 48, 60 and 72 hours. Adsorption of potassium was found to be significantly affected by soil texture. Fine textured Kaul soil, having higher amount of clay adsorbed more amount of potassium than coarse textured soils in both the treatments. The adsorption of K was found to be an instantaneous phenomenon. Significant adsorption was observed only in the first hour of incubation for the two treatments. At subsequent time intervals, the adsorption of potassium increased but it was statistically non-significant. All the five tested adsorption kinetic models viz. zero order, first order, power function, parabolic diffusion and Elovich were adequate in describing the kinetics of K adsorption in all the soils, however, the parabolic diffusion equation in 60 mg K kg-1 treated soils and zero-order in 120 mg K kg-1 treated soils were found to be the best. CEC of the soil was found to be the -iibest predictor of ‘a’ and ‘b’ parameters of the best fit zero order model. Except pH, none of the soil property significantly correlated with ‘b’ parameter of parabolic diffusion equation. Desorption of non exchangeable potassium was studied on all soil samples at three different temperatures i.e. 20ºC, 30ºC and 40ºC using 0.01M citric acid, 0.01M oxalic acid and 0.01M malic acid as extractants for time intervals 0, 1, 2, 4, 12, 24, 36, 48, 60, 96 and 192 hours with each extractants at desired temperature. Desorption of non-exchangeable potassium in different soils increased significantly with increase in temperature from 20ºC to 40ºC and also with time of incubation of the extractants. The soils were first made free of NH4OAc extractable K. Maximum amount of non-exchangeable K was desorbed in Kaul soil having highest amount of clay. Amongst the three extractants, 0.01M oxalic acid extracted the highest amount of non-exchangeable K followed by malic acid and least by citric acid in all the soils at all the temperatures. For potassium untreated soils, power function model best described the non-exchangeable K desorption, where as Elovich model was found to give the best fit in majority of K treated soils. CEC and silt content of K untreated soils and CEC, OC and clay content of K treated soils were found to be significantly correlated with ‘b’ parameters of the best fit kinetic models.enPotassium, Adsorption, Desorption, Kinetic models, Temperature, Organic acid, Soil physical propertiesThesis