15. Complex Soil Variation over Multiple Scales

Like Swift’s fleas, the soil is organized at multiple spatial scales from the clay particle, interacting with its neighbours and the soil solution according to the laws of electrochemistry, to the continent, at which the properties of the soil are organized according to general climate trends and the contingencies of geological history. Pedometrics can help the soil scientist to understand these processes in so far as it is possible to analyse soil properties into scale-dependent components which can be modelled and visualized. This is done, for example, by the spatially nested sampling introduced by Youden and Mehlich (1937). Geostatistical methods achieve it to some extent, with the use of nested models of regionalization and coregionalization, and methods of analysis to visualize components of different spatial scales (factorial kriging, reference) and scale-dependent correlation between variables (e.g. Goovaerts and Webster 1994). However, geostatistical analysis is primarily undertaken to support spatial prediction; the variogram, while reflecting the influence of processes at multiple spatial scales, is not particularly suited to the interpretation of such processes. For this we must look elsewhere.