Soils analyzed in this study. (a) The physicochemical properties of the three selected soils, a Fluvisol, a Dystic Cambisol and a Folic Histosol, are indicated alongside an image of the soil profile used for the installation of the columns. C/N ratio (C/N) was calculated using the carbon and nitrogen contents. The soil horizon in which the columns were placed is represented by the colored bands. (b) Geographical location of the three soils in Switzerland. (c) Close view of columns in the Fluvisol.