Is It True That Certain Wetting Agents Remove Organic Coatings from Water-Repellent Sand Particles?.

Soil hydrophobicity is a common problem for golf courses, especially for creeping bentgrass growing on USGA greens. It is believed that hydrophobicity is a result of accumulation of layers of organic substances which form a water-repellent surface. Wetting agents are amphiphilic molecules that have been used as the primary tool for alleviating soil water-repellency. Certain commercialized wetting agents can potentially remove the organic coatings, and this research was aimed to understand this effect. In the laboratory, sands, collected from a USGA green where localized dry spot has been historically observed, were homogenized. Hydrophobicity level of the sand was determined to be strong, as measured by molarity of ethanol test (MED) which yielded an average of 2.1 molar. After packing the hydrophobic sands into PVC pipes, selected wetting agents, including Matador, OARS, and pHAcid were applied at 70 ml to the top of PVC pipes, in addition to a water-only control. Following treatment application, water at pre-determined pore volume of the sand columns were applied to rinse the system three times. Each time the leachate was collected, and the leachate volume as well as the dissolved organic carbon (DOC) and particulate organic carbon (POC) were determined. The solid phase organic carbon on the sands before and after treatments were also determined. Treatments were arranged in a completely randomized design with 3 replications, and the entire experiment was repeated once.  A second experiment also conducted in the laboratory focused on Matador and OARS only in addition to a water-only control. This experiment utilized a similar settings as the first experiment except the wetting agents were applied three times to the same sand columns with three times water rinses following each treatment application. Between each treatment application, the sand columns were dissembled and the undisturbed sand columns were oven dried at 50 ºC. This is an ongoing project and more details will be discussed in presentation.