Wettability of Hydrophobic Sand As Influenced By Wetting Agent Solutions.

Soil hydrophobicity is a common problem on golf course putting greens. Golf course greens consist of a sand based soil layer, which is prone to develop water-repellency, and consequently lead to localized dry spot (LDS). To reduce LDS, golf course superintendents use wetting agents to improve water infiltration and distribution. The objective of this study was to determine effects of commonly used wetting agents for their influences on surface tension and consequently, capability of moving water through the soil profile. A laboratory-based experiment was carried out to evaluate selected wetting agents for their influence on surface tension and wettability on hydrophobic USGA sand at five concentrations of 4x, 2x, 1x, ½ x, and ¼ x of the highest suggested label rates using tap water. Surface tension of the varying concentrations of wetting agent and the tap water were determined by using a tensiometer. Wettability of the wetting agent solutions were determined by using hydrophobic USGA-grade sand which exhibits a steady and severe water-repellency. All wetting agent solutions, regardless of concentration, yielded a surface tension substantially less than the tap water, which was determined to be 47.9 mN m^-1. As expected, an increase of the wetting agent concentration generally led to a reduction of surface tension of the wetting agent solutions. However, wetting agents tested showed a wide range of surface tension at the suggested label rate. For example, Pervade, which is a wetting agent used as a penetrator, showed up to 36% lower surface tension compared to Revolution, a commonly used wetting agent for improving water distribution. This difference in surface tension likely explains the greater water moving capacity of Pervade, compared to Revolution. This is an ongoing experiment; more details will be discussed in the presentation.