Soil–landscape variability: mapping and building detail information for soil management

AbstractThe study of soil–landscape relationships at a detailed scale (1:10 000) and its use for soil management was less common in developing countries. The study was conducted in western Ethiopia with the aim to explain the soil variability across landscapes, classify soils into mapping units and produce a map of these soils. This study was performed based on a discrete model of spatial variation. Five soil reference groups: Vertisols, Cambisols, Fluvisols, Luvisols and Leptosols were identified in the study site. Distribution of the soil reference groups was determined by landscape position. Variation in soil texture, colour,pH, exchangeable acidity, organic carbon, total nitrogen, available phosphorus (av. P), carbon to nitrogen ratio (C/N), exchangeable potassium (K), calcium (Ca), magnesium (Mg), sodium (Na) and cation exchange capacity (CEC) was observed within and among soil mapping units (SMUs). Variability was considerably high for exchangeable Ca andCEC. Factor analysis result indicated that variation in soil properties within land unit was comparatively highest in Leptosols ofSMU9 (88.87%) and lowest in Vertisols ofSMU1 (60.82%). Moderate‐to‐fine scale mapping of soil properties helps to build detail information for soil management. Grouping fields into mapping units that require more or less similar management measure would be an important soil–landscape concept. As a result, mapping units could be used as cost‐effective means of treating variable field so as to optimize the forecasted benefits.