Combining multiple methods for automated soil delineation: from traditional to digital

Abstract

Context Soil maps are a fundamental tool for agriculture development and for land management planning. Digital soil mapping (DSM) consists of a group of techniques based on geotechnologies and statistics/geostatistics that helps soil specialists to map soil types and properties. Aims Four DSM strategies were applied in south-east Brazil. The goal was to visually delineate soil polygons with support of different strategies. Methods The delineation started with aerial photographs, followed by a bare soil image composition. Afterwards, it was added layers with landscape characterisation derived from digital terrain covariates and clustering analysis. Finally, digital clay content map from A and B horizons were used to produce a soil texture gradient raster (clay content increasing in depth). Key results The increasing number of polygons proved that the addition of covariates increased the detail level of the soil map, enhancing visualisation of the landscape variation, resulting on a map that substantially improved both national and state soil inventories. Conclusions We concluded that combining simple geotechnological tools might be of great utility for increasing detailed soil information proper for farmers and decision making. Implications Therefore, new soil information will be available for end users, supporting land management, food production sustainability, and soil conservation.