Hydrological conditions outweigh soil texture, temperature, and terrain in German agricultural land use

Abstract

Background The availability of fertile land suitable for agriculture is limited. In the European Union, political demand for self-sufficiency in staple food production currently competes with increasing ambitions for nature restoration and green energy. Meanwhile, the overall agricultural area shrinks due to land sealing. This makes an efficient use of land area essential. Aims With Germany as a case study, we determined which soil, terrain, and climate properties govern current agricultural land use and historic land-use change (LUC) to inform future land-use decisions. Methods Using data from the 3104 sites of the German Agricultural Soil Inventory, we defined land-use categories based on 100-year histories for permanent cropland, permanent grassland, and conversions between cropland and grassland. Conditional inference forest models used static edaphoclimatic variables to predict land-use type likelihood. Results Low precipitation, deep groundwater, or Luvisol or Cambisol soils favored the centennial continuous use of land as cropland. High precipitation, shallow groundwater, or Gleysol/Fluvisol/Histosol soils favored permanent grassland. LUC sites showed drivers similar to their destination permanent land use. For example, the likelihood of cropland-to-grassland conversion increased with higher precipitation and showed sharp increases, especially on land with mean annual precipitation >900 mm y−1, whereas slope terrain was of secondary importance. Conclusions Land use in Germany largely depends on factors related to hydrological properties (i.e., precipitation and drainage properties) rather than soil texture, temperature, and terrain per se. The patterns outlined in this study provide novel insights into how differences in site properties affect land use and can be used to inform future LUC priorities