The interaction between soil structure and soil processes is a key driver of soil functions - it influences, among other things, carbon turnover, water-holding capacity, material fluxes, and root growth. In agricultural soils, soil structure is regularly disrupted by tillage practices such as plowing or cultivating. To assess the impact of these agricultural practices on plant growth and soil functions, the effect of tillage on soil structure must be precisely analyzed. The initial state of the soil is relevant here: what is the soil’s texture, how long ago was the last disturbance, and what is the moisture content at the time of tillage?
Simulation models can be used to predict these effects. An international research team led by ETH and agroscope Zurich, in collaboration with BGR, has now developed a new mathematical model to predict changes in soil structure following tillage. It allocates the energy introduced by tillage to three processes: the plastic deformation of the soil, the displacement of existing particles, and the creation of a new surface from the resulting fragments (see figure). This makes it possible to simulate both different types of tillage and their effects under varying moisture levels and soil types. For example, at higher moisture contents, more energy is channeled into plastic deformation, since fragmentation is no longer possible under those conditions.
The model was tested using several independent datasets from the scientific literature that cover a broad spectrum of soil types, tillage methods, and conditions - the results demonstrate its broad applicability. Details can be found in the accompanying publication in the journal “Soil & Tillage Research”.
The next step is to integrate the developed model into agroecosystem models. The systemic soil-plant model BODIUM is well-suited for this purpose, as it is one of the few models that takes the dynamics of the soil structure into account. Following its implementation in BODIUM, tests are planned on existing long-term experiments and field sites in Germany and Switzerland to validate predictions of the effects of the changing soil structure on soil functions. The goal is to support long-term advisory services for sustainable tillage practices.