Physical Characterization of Soils in Two Command Areas of Assam

Physical properties of two soils (Alfisols and Inceptisols) from two different command areas (Shallow Tubewell Command, Alfisols; Deep Tubewell Command, Inceptisols) in the rain shadow belt under Central Brahmaputra Valley Zone (CBVZ) of Assam were studied. The bulk density in Alfisols was higher than Inceptisols and it increased with depth, in both the soils. Soils of STW command registered very low hydraulic conductivity (Ks) values while it was moderate to moderately rapid in DTW command. The surface layer soil of both the command areas contained higher percentage of aggregates less than 0.25 mm. The soils of STW command contained higher water content at all the suction ranges as compared to DTW command. The clay content was the single most dominant factor influencing the physical attributes of soils and it was significantly and positively correlated with bulk density, macro-aggregates, mean weight diameter (MWD), field capacity and permanent wilting point.