Temporal fluctuations of water repellency in forest soils of Galicia, NW Spain. Do soil samples dried at laboratory reflect the potential soil water repellency?

Water repellency is a widespread property of Pinus pinaster and Eucalyptus globulus forest soils in NW Spain and is particularly severe during the summer dry conditions. The aim of this work was to compare actual water repellency at field-moist samples with potential water repellency after drying at 25 and 105 degrees C in samples collected at different times of year under four forest soils. Also, we investigated whether drying at 25 or 105 degrees C led to repellency values comparable to the highest levels reached under field conditions in the summer with a view to developing an appropriate sampling protocol towards estimating the maximum possible water repellency of a given soil as a key to establishing its environmental effects. The actual and potential water repellency was determined by using the water drop penetration time (WDPT) and molarity of an ethanol drop (MED) tests.