Identifying areas of multiple soil degradation processes at regional scale

Soil compaction and soil erosion by water are among the top 5 threats to agricultural soils in Europe. Soil compaction has a direct impact on soil erosion, for instance by reducing infiltration rates. Therefore, measures directly addressing soil compaction (e.g. optimized field traffic and reduced wheel load) have an impact on soil erosion by water. In addition, measures such as crop rotation management, including cover crop management, allow combined effects on soil erosion and soil compaction. Currently, no evidence at regional scale is available that indicates which measures can generate this co-benefit and which regions having a high risk of soil erosion and compaction can benefit from those measures. Modelling exercises provide the option for generating this information and are tested here in a regional scale case study.

As a first step, we identified cropland with a combined risk of soil compaction and soil erosion by water in Lower Saxony (northern Germany). To this end, we derived typical crop rotations for 2017 to 2021 based on high-resolution crop type maps for three soil regions in the study area. Depending on the crop rotations and farm size, typical machinery equipment was defined and field work dates were derived according to phenological data. This data was combined with three weather scenarios using real observational data (dry: 2020, wet: 2017, intermediate: 2004). We employed the USLE (Universal Soil Loss Equation) and the SaSCiA-model (Spatially explicit Soil Compaction risk Assessment) to model soil erosion and soil compaction risk for the different weather scenarios and the three typical crop rotations in the soil regions. The results help to identify regions with combined risk for soil erosion and soil compaction. The next step will be the analysis of measures addressing both degradation processes.