In this chapter, a review of soil models is carried out. The number of models within the literature is too high to cover every example in depth, so a selection has been made based on age, stage of development and specificity to soil modelling. In addition, a number of existing soil model reviews have been investigated, to determine the depth of information already available.
- Soil erosion and nutrient loss modelling, the models commonly operate at the catchment scale or smaller and over a relatively short time step. Producing regional scale, long term scenario predictions would require a lot of computational and data resources.
- For models of soil carbon and nitrogen cycling, the spatial and temporal scales vary considerably, as does the complexity of the models applied, meaning that scenarios can be explored at scales from local to national, and daily to multi-annual.
- Crop productivity models can generally be applied at the scales desired, but require significant data resources to implement and operate on short time steps. They also often require specific information about the crops of interest.
- More generally applicable ecosystem/biosphere models have similarities to crop productivity models in that they incorporate information on soils, vegetation, climate and topography/hydrology, but these often take the form of frameworks rather than specific locked models. They are complex and require a lot of data to initialize, often in the form of field measurements of the ecosystem being simulated. They are therefore less relevant to decision making over regional scales than crop productivity models.