The Use of Image Analysis in the Micromorphological Study of Old Cultivated Soils: an Evaluation Based on Soils from the Island of Papa Stour, Shetland

This paper presents data from the first part of a major project designed to investigate the micromorphology of cultivated soils. In particular, the initial phase of the project is concerned with an investigation into methods for the identification and quantification of cultivation features in soil thin sections using image analysis techniques. In 1993 a range of soil samples of known cultivation contexts were taken from an abandoned farm at Olligarth which is located on the small island of Papa Stour, to the immediate west of Mainland Shetland. Cultivation on this farm was carried out using a delling spade until the late 1940s. Samples from four contrasting sites at Olligarth (Site 6: a planticrue, Site 7: the kale yard, Site 8: small fields, and Site 9: heathland) were subsequently analysed for total phosphate, organic content expressed as loss on ignition. Image analysis and traditional soil micromorphology were undertaken on samples from these sites. Results from the image analysis, traditional micromorphological analysis and chemical analysis for each site were compared. Overall it was found that image analysis can contribute significantly to micromorphological description and interpretation of old cultivated soils. However, image analysis should not be seen as providing a replacement for the standard description of thin sections. Instead, the use of image analysis in the study of ancient cultivated soils should not be undertaken in isolation. Other forms of analyses (phosphate, pollen, organic matter, traditional micromorphology) should be undertaken in combination with image analysis in order to investigate the formation of cultivated soils. ? 1996 Academic Press Limited