An exploratory model of soil structure dynamics: concepts, scope and initial applications

In this presentation, the development, scope and concepts underlying a phenomenological model of soil structure dynamics embedded in a new soil-crop simulation model (USSF; Uppsala model of Soil Structure and Function) will be described. This model accounts for seasonal soil structure dynamics (e.g. tillage/consolidation, surface sealing, swell-shrink) as well as those occurring at much longer (i.e. decadal and centennial) time-scales arising from processes such as microbial-mediated soil aggregation, macro-faunal activity and root growth. The USSF model couples these descriptions of soil structure dynamics with modules for crop growth, soil hydrology and organic matter cycling at the scale of the soil profile. This means that the model can be used to evaluate the effects of soil structure dynamics driven by changes in climate or land management (e.g. soil degradation or regeneration) on the soil water balance, crop growth and stocks of soil organic matter. To finish, some initial applications of the USSF model will be presented, followed by a brief discussion of some important current limitations as well as future prospects.