Abstract
Three transects on gently sloping terrains around Khon Kaen were laid for soil investigation and sampling to analyze not only the soil characteristics but also the nature of the soil materials. Four pedons for each transect to the depth of ca. 2 m were described and soil samples were taken horizonwise. Soil samples were subjected to various analyses for characterizing materials. All the soils were invariably sandy throughout the profile. Clay content tended to increase towards the subsoil. Lessivage or clay translocation appeared to contribute to this phenomenon, particularly in the pedons on the upper slope. Soil fertility was very low, reflecting the highly siliceous, sandy nature of the soil materials. The soils on the upper slope of a transect were relatively more weathered, judging from the presence of iron oxide forms. However, kaolinite and quartz-rich clay mineralogy and highly siliceous total chemical composition were features common to all the soils regardless of slope positions in a transect. The soil materials were much too weathered for these characterization techniques to be effective in discriminating the degree of weathering.
