2.2. Soil texture, saturated hydraulic conductivity, and total SOM content
The texture of the soil samples from young and mature olive tree
plots (RM1 and RM2, respectively) was determined by the hydrometer
method (Gee and Bauder, 1986). Total SOM in 36 soil samples from RM1
and 35 samples from RM2 was determined by reduction of excess chromic
acid after oxidation of soil carbon (Allison, 1935). The 71 samples
used for SOM content determination were chosen from the 108 samples
used for the WDPT tests (Section 2.3.1) to represent the different
degrees of repellency, location, soil color, etc. The saturated hydraulic
conductivity, Ks, was determined by measuring the flux in a saturated
column (ELE International Inc., TRI-FLEX 2 Permeability Test System,
Pelham, AL) of disturbed soil for different head gradients.