Fig. 2. Neumann plot (_LVcos_E vs. _LV, where _LV is the liquid–vapor surface tension and _E is the experimentally derived contact angle)_. Filled and open points are _E measured by means of the Wilhelmy plate method (WPM) and the weight-gain capillary rise method (CRM), respectively. The logistic curves (Eq. [21]) were calculated from the combined data of WPM and CRM. The leftmost point in each graph represents the assumed data _E = 0 for pure ethanol. OR = orange orchard cover soil; PN = pine cover soil; EP = eucalyptus cover soil; LCh and PCh = organic matter extracted from leonardite and sphagnum moss, respectively, with chloroform; and LEt and PEt = organic matter extracted from leonardite and sphagnum moss, respectively, with ethanol.