Water repellency in forest and grassland soils of Puerto Rico.

摘要

The hydrophobic properties of soils resist or retard surface infiltration, affecting plant growth and surface water distribution. Scientists have found a significant relationship between vegetation cover and hydrophobic behavior of soils. The objective of this thesis was to compare soil hydrophobic behavior in grassland and secondary forests, to obtain better information regarding influence of vegetation cover on hydrophobic properties of soils and in the spatial variability of repellency.; Five areas of grassland cover and 5 areas of nearby secondary forest cover were identified for the study. Methods used to characterize water repellency in soils were water drop penetration time (WDPT) and molarity ethanol droplet test (MEDT). WDPT represents the amount of time a drop of pure water takes to infiltrate the soil surface. MEDT determines the molarity at which liquid surface tension repellency begins to occur.; Water repellency behavior occurs at both vegetation covers.; Using MEDT hydrophobic behavior was detected in almost all surface soils, regardless of vegetation type. (Abstract shortened by UMI.)