Major Soils of the Dry Zone and Their Classification

Abstract

Rainfall is an important climatic factor influencing soil formation in Sri Lanka. Therefore, the major soil types are initially grouped to soils of the Wet, Intermediate, and Dry zones according to major climatic regions. Subsequently, the soils of the Wet and Intermediate zones are grouped according to the elevation, soils occurring in the up, mid and low countries. The Dry zone consists of only the low country and therefore, grouped under soils derived from erosional surfaces, coastal plains, and the flood plains. Near the coastal areas of Dry zone, the landscape is flat and changes to undulating toward Intermediate zone. Sketches showing such landscapes have been included in the chapter. Out of 118 soil series identified and mapped 54 soil series occur in the Dry zone. As the soil maps are too large to include in this book, one page from soil maps is included with references for further reading. Each soil series is classified according to Soil Taxonomy and World Resource Base (WRB-FAO) legend depending on the availability of data. More detail classification was done using the WRB classification as it does not demand detail information as soil moisture regimes which are needed for Soil Taxonomy. The local name used from the 1972 classification which are named as Great Soil Groups are also given in the tables. For each of the physiographic grouping occurring in the given climatic zone one characteristic (benchmark) soil series is described in detail with the color photographs of the landscape and soil profile .