Introduction

Up to now, studies of soil dispersion have concentrated on the factors affecting soil dispersion but do not address the effects of mixed mineral suites and reasons soils did not disperse. For that reason, the Southeastern region soil mineralogy workgroup initiated a study of the water dispersibility of some typical regional soils. This portion of the study examines by scanning electron microscopy (SEM) the properties of that part of the soils which did not disperse. By direct examination of the coarse particles it is hoped to gain some knowledge of the factors which prevent dispersion and leaching. Examination of the grain morphology of sand and silt fractions was also undertaken to obtain some insight into the severity of soil weathering.

The high magnification and increased depth of field available through the use of scanning electron microscopy (SEM) especially when combined with energy dispersive X-ray spectroscopy (EDS) can provide valuable data in the study of soils and impurities in them. The interpretations obtained by use of a SEM in soil mineralogy studies are in part subjective and rest on the experience of the operator in studying many samples from different locations.

Scanning electron microscopy has been applied to the study of sediments and soils extensively in the last 20 years (see for example, Berner and Holdren, 1979; Nahon and Colin, 1982; White and Dixon, 1995; White et al. 1982; Wilson and Pittman, 1977) but has not been applied to the examination of soil dispersion.