Characterization Mapping and Topographic Association of Coastal Saline Soils in Aghanashini Estuary of North Canara District Karnataka

Abstract

A study was conducted to assess the physico-chemical characteristics, fertility newlinestatus and their spatial variability in Aghanashini estuary of North Karnataka district, newlineKarnataka. To understand the pattern and spatial association of soil salinity with newlinetopography and land use/ land cover in coastal cultivated soils, the sampling was done newlineat 250 m distance along and across the river course. The results revealed that the soils newlinewere acidic in nature. Electrical conductivity varied from non-saline (0-2 dS m-1) to newlinestrongly saline (gt16 dS m-1). Among the exchangeable cations, calcium was the newlinedominant cation followed by magnesium, sodium and potassium. Sodium ion was the newlinedominant water soluble cation followed by calcium, magnesium and potassium. newlineChloride was the dominant anion followed by sulphate and bicarbonate. The ESP did newlinenot exceed 15 per cent in the study area. Soils were medium to high in organic carbon, newlinelow in available nitrogen and phosphorus, low to medium in available potassium and newlinemedium to high in available sulphur. Among the micronutrients, zinc was sufficient to newlinedeficient in the study area. Variograms for physico-chemical properties (pH, OC and newlineCEC) of the soils were described by spherical model. While, electrical conductivity newlinewas described by an exponential model. Variograms of available nitrogen, phosphorus, newlinepotassium and sulphur exhibited moderate to weak spatial dependency in the study newlinearea. From the relationship between elevation and soil salinity, major portion of newlinestrongly (gt16 dS m-1) and moderately saline (8-16 dS m-1) areas fell under contour newlineelevation of 0 to 25 m above the MSL irrespective of season and year. Slightly, very newlineslightly and non-saline areas were characterized by land contour elevation between 25 newlineand 75 m above MSL. Land use/cover classes such as aquaculture (prawn farming), newlinewet land, mangrove and mud flat exhibited higher soil salinity of gt8 dS m-1. newline