Evaluation of Surface Tension and Infiltration of Wetting Agents.

Soil hydrophobicity is a reoccurring problem on USGA sand-based greens which causes water repellency as a result of water bypasses the hydrophobic roots zones. Once water repellency has developed, preferential flow occurs causing localized dry spot (LDS), and ultimately leads to plant death. Based on a national survey, 94% of golf course superintendents use wetting agents to combat this problem. Wetting agents are amphiphilic molecules that contain a hydrophobic tail and a hydrophilic head. The hydrophobic tails adhere to the hydrophobic sand surfaces leaving the hydrophilic heads in the soil solution, allowing water molecules to adhere them. This process changes the soil chemistry and allows water to infiltrate into a water repellent soil. Still, the question remains, which is the best wetting agent? Using inappropriate wetting agent can potentially lead to unfavorable playing conditions such as soft surfaces or extremely dry greens. Therefore, the objective of this experiment was to assess different wetting agents for their influences on surface tension and infiltration. A laboratory experiment was performed to determine physical characteristics of various wetting agents at 5 rates (.25x, .5x, 1x, 2x, 4x of the label rate). These properties included surface tension (mN m^-1), solid/liquid contact angel, infiltration rates (mm min^-1) and rewettability using artificially made hydrophobic sand that meets USGA specifications. This experiment is still ongoing and detailed results will be discussed in the presentation.