We estimated the height of the capillary fringe (CF) in the soil using a 90-cm long, clear plastic cylinder (4.
RESULTS--Four independent trials indicated the height of the capillary fringe in the pots of soil likely reached the surface of the soil in the treatments [D.
W] = L would have become relatively dry after we ended top-irrigation, because this soil was above the capillary fringe and evaporative rate in the greenhouse, reflecting the regional semiarid climate, was consistently high.
Schade and Hobbie (2005) found no effect from phreatophytic velvet mesquite trees (Prosopis velutina) on surface (0-10 cm) soil moisture in a riparian zone in the Sonoran Desert, but the depth of the water table relative to height of the capillary fringe was not noted.
The capillary fringe (CF), the zone immediately above the water table, is nearly saturated even though it is considered to be part of the vadose (unsaturated) zone.
Solute transport in the capillary fringe and shallow groundwater: Field evaluation.
Fates of nitrate in the capillary fringe and shallow groundwater in a sandy soil drained by ditches.
However, salt build-up in the capillary fringe means that the salinity of the groundwater needs to be relatively low (<5 dS/m), or uptake rate from the watertable low, unless leaching takes place.
The level to which a tree can depress a watertable will depend on the ability of the tree to remove water from that capillary fringe and the rate at which the watertable can respond to this loss.
Leaching of salt accumulated in the capillary fringe of watertable is more likely to occur in the more transmissive soils and in shallower watertables.
The two most common classes are a) NAPLs composed of fuel hydrocarbons that are lighter (LNAPLs) than water and, thus, more easily detected, because they tend to remain within the unsaturated zone or capillary fringe
areas of an aquifer; and b) organic solvent or dense NAPLs (DNAPLs) that tend to migrate deep into formations, becoming entrapped in irregular finger-like structures or pooled on low permeability strata.
In periods when salt accumulates in the root zone between the capillary fringe
and the soil surface, the tree drops its leaf water potential, a mechanism which increases its ability to extract water from the soil.