Saifudeen, NGeorge, JosephKAU2020-11-272020-11-271993170390https://krishikosh.egranth.ac.in/handle/1/5810155878MScAn experiment was conducted at the Department of Soil Science and agricultural Chemistry, College of Agriculture, Vellayani with 50 surface soil samples each from Trivandrum, Kazhakuttom and Kottor series to assess the behaviour of soil potassium. Water soluble, available, exchangeable, nitric acid soluble and non – exchangeable potassium in these soils were determined. Sample observations on total potassium from soils with low, medium and high available potassium were also undertaken. In addition, the physical and chemical properties of all the samples were studied through observations on soil separates, pH, electrical conductivity, organic carbon, cation exchange capacity, base saturation and exchangeable forms of calcium, magnesium and sodium. Neutral ammonium acetate (1.0 N) extractable potassium (available form) was found to be positively influenced by water soluble, exchangeable and nitric acid extractable forms of potassium. The organic carbon content positively influenced the available potassium where the soil organic carbon was low viz., Trivandrum and Kazhakuttom series. Cation exchange capacity also had a positive influence on available potassium. Percentage base saturation influenced available potassium positively, except in forest soils. In Trivandrum series 71 percent of nitric acid potassium was available to crops; while the corresponding values were 46 and 51 percent in Kazhakuttom and Kotoor series respectively. The total potassium content was also relatively high in Trivandrum series. The relationship between various forms of soil potassium and also between potassium fractions and other soil components expressed varying trends in soils falling under different fertility classes. This aspect needs further investigation. Quantification of the contribution of different fractions of soil potassium towards crop uptake is suggested as a future line of work. Basic studies on the ionic equilibria in soil solutions which affect potassium exchange and availability in these soils also warrants attention.EnglishThesis