Seasonal and land use dependent variability of soil hydraulic and soil hydrological properties of two Northern German soils

This paper analyses the seasonal and land use induced variability of soil hydraulic and soil hydrological properties such as saturated hydraulic conductivity, unsaturated hydraulic conductivity, infiltration capacity, field capacity and bulk density of two typical Northern German soil types: Podzol and Stagnosol. For both soils, three areas under different land uses were identified within ‘homogeneous’ soil mapping units corresponding with land use classes generally available for regional hydrological model applications: grassland, crops and forest. Seasonal variability of the soil hydrological characteristics was determined by 4 repetitions of all measurements during the year 2006 (March/April, May, July, October). The study reveals that soil hydraulic and soil hydrological properties are influenced by land use, considerably. Statistically significant systematic impacts on bulk density, saturated hydraulic conductivity, infiltration capacity and field capacity were identified. In addition, for all investigated soil hydraulic and soil hydrological properties and characteristics, seasonal variability was detected. Seasonal variability was statistically significant for the minority of the investigated variables, only. Nevertheless, soil hydraulic and soil hydrological properties were not constant over time, as assumed in most hydrological models. The outcome of this study encourages further investigating the seasonal variability of soil hydraulic properties based on a more comprehensive sampling design to account for their spatial variability. Furthermore, the development of hydrological models is recommended in order to include more process understanding in terms of natural variability in the models.