Conceptual soil-regolith toposequence models to support soil survey and land evaluation

Abstract

Soil maps and the accompanying soil survey report are used to portray the spatial variation of soils in landscapes by indicating what soils, their proportion and their soil properties are likely to occur at a particular location or within a soil map unit. Soil surveyors intuitively understand this soil variation and how it may occur by reading the landscape. However, soil maps and soil survey reports are often too technical and not easily understood by land managers and decision-makers who are not specialist soil scientists. This chapter demonstrates how conceptual soil-regolith toposequence models can be used to describe (supporting soil survey map data and reports), explain (providing an understanding of the processes) and predict (supporting land evaluation) soil spatial variability in a range of complex landscapes. Case studies from Australia and Brunei are provided to illustrate how soil toposequence models are critical to explain, predict and solve practical land use problems, especially in complex soil-landscape environments. These conceptual models provide the following critical data to support land evaluation and ­management decisions by illustrating soil properties that are changing in time and space, which is especially important in salt-affected and acid sulphate soils (e.g. seasonal and climatic changes in occurrences of salt efflorescences), and the most suitable approaches for characterising, monitoring, predicting, managing and displaying soil changes for environmental impact assessments, pollution incidents, waste management and technology support.