Effect of Repeated Application of Wetting Agents on Hydrophobicity of USGA Green.

Hydrophobicity is a common problem on golf course putting greens, and wetting agents are the primary tool that superintendents use to battle with this issue. Some wetting agents in the turf market can potentially remove the hydrophobic coatings from the sand surface, and consequently transform water-repellent sand to wettable medium. The objective of this research was to evaluate these wetting agents for their effect on hydrophobicity of USGA sand following repeat applications. A PVC pipe based infiltration system was utilized where hydrophobicity sands, collected from a USGA green and homogenized, were packed uniformly into 7.6 cm soil columns. Selected wetting agents were applied from the top of the sand columns at label suggested rates, before rinse the sand columns with water at the pre-determined pore-volume of the sand columns 24 hours later. The rinsing was performed 3 times after wetting agent application before subject the undisturbed sand columns to oven drying at 50ºC.  This entire application-triple rinse-drying process was repeated three times for each wetting agent. Leachates from each wetting agent application and rinse were collected from the bottom of the sand columns, and leachate volume and dissolved and particulate organic carbon (DOC and POC) were determined. The hydrophobicity and solid phase organic carbon on the sands were also determined before and after treatment applications. The experiment design was a split-split-plot with three replications. The two wetting agents, OARS and Matador, in addition to a water-only control, were whole-plot variable, each time of wetting agent application served as the sub-plot variable, and each rinsing/washing event was the sub-subplot variable. The entire experiment were repeated once. Prior to treatment application, hydrophobicity of the sands were determined to be strong based on a 2.2 M Molarity of Ethanol Droplet (MED) test. After three sequential treatment applications and following rinses, sands treated with OARS demonstrated extreme hydrophobicity with MED determined to be 4.3 M. In comparison, sands treated with Matador transformed to be wettable medium with no hydrophobicity (MED at 0 M). Sand columns treated with water showed an increased hydrophobicity, and after one drying event, water by itself failed to penetrate into the sands. No changes were found in the solid phase of organic carbon on the sand before or after water-only treatment. However, both OARS- or Matador-treated sands showed 26% or 13% increase of solid phase organic carbon, respectively. More details of leachate volume, DOC and POC will be discussed in the presentation.