Environmental Factors Governing Soil Water Repellency Dynamics in a Pinus Pinaster Plantation in NW Spain

Soil water repellency (SWR) is a dynamic property that changes throughout the year. The objective of this work was to identify the environmental factors governing the temporal patterns in SWR in a pine plantation in northwest Spain with a view of predicting its occurrence and persistence. For this purpose, 24 samples were collected from the soil surface (0-5cm) at 25 different times over a 1-year period and analysed for SWR by using water drop penetration time test and soil moisture measurements. Temporal variations in SWR exhibited a well-defined seasonal pattern. The soil surface was largely wettable from late autumn to early spring and extremely water repellent during summer and early autumn. Repellency persistence was rather variable during spring. There was highly significant correlation between SWR and soil moisture content. The moisture range defining the presence or absence of repellency under field conditions was 22-57%. There were also significant correlations with the target variables (maximum temperature, minimum temperature, precipitation and water balance during variably long antecedent periods), with coefficients that increased with increasing length of the antecedent period considered. The moisture content of soil at the time of sampling and the average maximum temperature for the 28days before sampling are the best predictors of occurrence of SWR and its persistence in different seasons. Copyright (c) 2015 John Wiley & Sons, Ltd.