Digital Soil Mapping

Volume 2 of the series Progress in Soil Science pp 137-150

Homosoil, a Methodology for Quantitative Extrapolation of Soil Information Across the Globe

  • B.P. MallavanAffiliated withMontpellier SupAgro
  • , B. MinasnyAffiliated withFood & Natural Resources, The University of Sydney
  • , A.B. McBratneyAffiliated withFood & Natural Resources, The University of Sydney Email author 

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In many places in the world, soil information is difficult to obtain and can be non-existent. When no detailed map or soil observation is available in a region of interest, we have to extrapolate from other parts of the world. This chapter will discuss the Homosoil method, which assumes homology of soil-forming factors between a reference area and the region of interest. This includes: climate, physiography, and parent materials. The approach will involve seeking the smallest taxonomic distance of the scorpan factors between the region of interest and other reference areas (with soil data) in the world. Using the digital information of soil climate from the Climate Research Unit (CRU) (solar radiation, rainfall, temperature, and evapo-transpiration), topography from the HYDRO1k (elevation, slope, and compound topographic index), and lithology of the world on a 0.5°× 0.5° grid, we calculated Gower’s similarity index between an area of interest and the rest of the world. The rules calibrated in the reference area can be applied in the region of interest realising its limitations and extrapolation consequences.


Global soil mapping Homoclime Climate Map extrapolation Soil forming factors