Mapping K dynamics in apple orchards’ soils of Northern Punjab, Pakistan

Apple is highly sensitive to K deficiency and occurrence of K deficiency in the arid and semi-arid tracts was expected therefore a survey was carried out for examining and mapping of K dynamics in the soils of apple producing region of Murree. Eleven apple orchards were selected randomly and samples were collected from five different sites per orchard. One hundred and ten soil samples were collected from the surface (0-15 cm) and sub-surface (15-30 cm) soils. In the surface soils Ks (Soluble K) constituted 0.064 to 0.41 percent of the total K. Sub-surface soil contained Ks that was 0.03 to 0.24 percent of the total K indicating a gradual decrease in plant available K content with the increasing depth. Exchangeable potassium (Ke) constituted about 0.17 to 0.68 and 0.11 to 0.38 percent of total K in the surface and sub- surface soils. Non exchangeable K (Kne) ranged from 0.13 to 0.54 percent with the mean value of 0.29 ± 0.13 constituting about 13.35 to 47.27 percent of total K in the surface soils whereas 31 to 41 percent in the subsurface soils. Surface and subsurface soil contained 14.25 to 75.02 percent of total potassium (Kt) in the form of mineral potassium (Km).