Extent and persistence of water repellency in north‐western Spanish soils

Abstract

AbstractThe aim of this work was to examine the distribution and persistence of water repellency in soils of different texture in the Spanish humid region as a function of land use and management. At 34 locations, samples of soil under different land uses (maize crop, grassland, Pinus pinaster forest and Eucalyptus globulus forest) and various geological materials were collected from the surface layer (0–5 cm). In addition, P. pinaster and E. globulus forest soil samples were collected at four different depths (0–5, 5–10, 10–20 and 20–40 cm) at 10 of the previous locations. Water repellency was determined by using the water drop penetration time (WDPT) test on field‐moist samples (actual WDPT) collected during summer and was compared with the values for samples dried at 25 and 105 °C (potential WDPT).Based on the results, the prevailing vegetation and land use dictate the development and persistence of surface water repellency in the studied soils. The E. globulus forest soil samples were found to be the most water repellent, followed by the P. pinaster forest samples (73 and 64%, respectively, with actual WDPT > 6 h); on the other hand, 79% of the field‐moist samples from soils under maize and 71% of those under grass were non‐repellent. The influence of vegetation on water repellency was found to be related to the type and content of soil organic matter. Each type of vegetation resulted in significant differences in surface water repellency between soils with sandy‐loam texture and also between soils with loam or silt‐loam texture; repellency was higher in the samples with coarser textures. The persistence of water repellency decreased with increasing soil depth, the decrease being more marked in the finer‐textured soils than in the coarser ones and also in the pine forest soils than in the eucalypt forest soils. The water repellency of most of the samples dried at 25 and 105 °C was similar to that of the field‐moist samples collected during the dry period (r = 0·90, p < 0·01). Copyright © 2007 John Wiley & Sons, Ltd.