Variation in water content and wetting patterns in Dutch water repellent peaty clay and clayey peat soils

The variation in water content of grass-covered peaty clay and clayey peat soils was studied at six sites in the Netherlands. The topsoils were water repellent during dry spells. When the topsoils were dry, they could only absorb water with difficulty, which is illustrated by wetting rate measurements. Precipitation could flow rapidly through shrinkage cracks towards the subsoil, bypassing the matrix of the peat. However, the measurements revealed that preferential flow was not limited to macropore flow: irregular, fingerlike wetting patterns were also formed in the soil matrix. Due to these typical wetting patterns, soil water content varied over short distances at all sites at all sampling dates.