Effect of compaction, tillage and climate change on soil water balance of Arable Luvisols in Northwest Germany

In this study we determined wheeling (external loads of 6.3 Mg by 10 times wheeling) and tillage effects (conventional and conservation tillage) on the soil hydraulic properties of Stagnic Luvisols in Northwest Germany and modeled the soil water balance's reaction on both loading and changing climatic conditions.Due to the mechanical stress applied by loading, physical properties changed distinctly in the top Ap-horizons and the subsequent Eg-horizons at both tillage systems. Especially pore size distributions and soil hydraulic conductivities were affected. The Btg horizons did not show changes due to loading.Soil water balance was measured with soil tensiometers during one growing period and the following autumn and was modeled with Hydrus 1D for loaded and unloaded conditions under winter wheat for three different periods (1991–2000; 2051–2060; 2091–2100) based on a regional A1B climate scenario.At the loaded sites we found an increase of actual transpiration rates in the growing period. As a consequence of stronger drying and changed hydraulic properties, rewetting in autumn and winter was retarded and less complete on average. Furthermore, simulations indicated an increase of the variability of matric potentials. Consequently, compaction might result in a higher drought risk and a higher susceptibility for water logging in spring, which may result in less favorable soil conditions and plant growth.Reactions of soil water balance on changing climatic conditions were comparable for all loading variants and tillage systems. Predicted changes in precipitation (in general: summer −, winter +) and temperature (+) would result in a reduction of transpiration rates in the growing period while the climatic water balance in autumn and winter would increase distinctly.

► We determined wheeling and tillage effects on soil hydraulic properties of Luvisols. ► As a reaction to the mechanical stress applied by loading (6.3 Mg), physical soil properties changed distinctly under all tillage treatments. ► Especially pore size distributions and soil hydraulic conductivities were affected. ► Simulations showed distinct reactions of the soil water balance on both loading and changing climatic conditions.