Interpretation of digital soil photographs using spatial analysis: II. Application

Abstract

Colour variation in digital photographs of soils was quantified and classified meaningfully, using ArcView Spatial Analyst. This procedure holds great promise for the unbiased and quantitative determination of soil colour properties and statistical correlation with related soil hydrological conditions. The analysis of digital photographs from ten profiles in the Weatherley catchment indicated that diagnostic grey and yellow-brown colours were dominant in all the profiles described for this study. The occurrence of grey increased with depth, at the expense of yellow-brown. This pointed to a wetter subsoil water regime. Diagnostic red dominated in the Bloemdal profile. The occurrence of diagnostic red in profiles of the Longlands, Tukulu, Kroonstad and Katspruit soil forms was associated with the occurrence of Fe oxide mottles. Black classification was used mainly for the elimination of shaded areas from the photographs.