Extending the Soil Database of the Dry Zone of Sri Lanka to Cover the Northern Region

Abstract

With the agricultural development in the Northern region of Sri Lanka, there is a need to characterize the soils for land use planning and environmental applications. The objective of this study was to characterize the soils in the Northern region of Sri Lanka to extend the soil data base of the Dry zone, specially the Calcic Red Latasols and Calcic Yellow Latasols, the two major soils occurring in the Jaffna district. These soils were identified, benchmark sites were selected and the landscape features were recorded with soil profile descriptions. Soil physical and chemical properties were studied in each horizon of the soil profile using standard procedures. The excessively drained Calcic Red Latasols occur in all areas other than then depressions of the Karst plains while the Calcic Yellow Latasols which are imperfectly drained occur in depressions of the land unit. The results reveled that Calcic Red latasols show a sandy loam texture while the Calcic Yellow latasols are slightly heavier showing a sandy clay loam texture. The soil eordibility factor of the Calcic Red Latasols and Calcic Yellow Latasols were 0.21 (medium risk) and 0.31 (high risk), respectively. Soil conservation measures to reduce erosion by water are needed for the latter. Both the soils show susceptibility to wind erosion and conservation practices such as mulching is recommended to overcome this problem during the dry periods. The saturated hydraulic conductivity of Calcic Red Latasols was very rapid showing the danger of leaching of inputs as fertilizers and pesticides to ground water easily.