Soil properties (e. g. soil type, organic carbon concentration) influence water pollution in different ways. The tendency for leaching of nitrates is higher in sandy soils than in heavy soils with a high clay content. Leaching of pesticides due to preferential flow or co-transport of colloidal matter is particularly high in clay-rich soils and in general related to soil properties such as soil structure, organic matter content, clay content, iron oxides, as well as soil hydrological processes and management (e. g. time of application) (Estévez et al., 2008).
With increasing concentration of organic matter in soil and the tendency towards mineralisation, the amount of nitrates being susceptible to leaching increases. On the other side, organic matter can serve as energy source for denitrification and thus, under certains circumstances, can decrease nitrate leaching, e. g. in grasslands and peat soils.
In case local information on soil properties with a high resolution are not accessible or suitable, official databases may be used to asses soil properties. Combining the LUCAS topsoil database with land surface parameters from the NASA-Shuttle Radar Topography Mission (SRTM) and data from CORINE land cover 2000, Ballabio et al. (2015) produced maps on European scale for topsoil clay, silt, sand and coarse fragments content, bulk density and derived from that USDA textural classes and available water capacity at a 500 m grid cell resolution.
The soil type may be used as an indicator to estimate nitrogen leaching (most severe in sandy soils) and pesticide leaching (most severe in clay-rich soils due to preferential flow).
For most nonionic compounds, adsorption is correlated with soil organic matter (Bailey, et al., 1970, Wauchope, et al., 2002). Soil organic carbon may be used as indicator for pesticide leaching. A specific parameter is calculated for each pesticide (the Koc) which can be derived by the organic carbon content of a soil to estimate the sorption. Besides the concentration of soil organic matter, sorption of pesticides in the soil is determined by its clay content (Schierholz et al., 2000).
Stassemeyer et al. (2017) used data from the European Soil Database (ESDB): dominant slope class, organic carbon concentraton in top soil layer (0-30 cm), dominant texture class in top and sub soil, parent material, depth of gley horizon, presence, target and type of water management system (Panagos et al., 2012b). The soil organic carbon concentration in the top 1 m was estimated according to an average ratio as described in Kruijne et al. (2011). Topsoil bulk density and field capacity were derived from Ballabio et al. (2016). The K-factor of the modified universal soil loss equation (MUSCLE) was obtained from Panagos et al. (2012a).