Effect of Surfactant on Fingered Flow in Laboratory Golf Greens

Preferential flow in golf greens causes turfgrass quality deterioration and shortens solute travel time. Little is known how surfactants affect the flow pattern in golf greens. This study visualizes the changes in flow patterns and compares leaching of a nonadsorbed and an adsorbed chemical as a result of the addition of a nonionic surfactant in a simulated United States Golf Association (USGA) putting green profile in a twodimensional sand slab chamber. The USGA putting greens have three distinct layers that become coarser with depth. The addition of the surfactant changed the unstable preferential flow pattern to a uniform flat wetting front in the first 11 cm. Below this, small perturbations occurred, and at a depth of 17 cm, the wetting front became unstable and formed six fingers. After the first 17 cm, the infiltration process was not affected by the addition of the surfactant. Water infiltrated into the second layer as a wavy front and developed a single finger at the third layer. After the irrigation was stopped and water reapplied, the water followed the same pathways established during the first infiltration cycle. Chloride moved two times more slowly in the surfactant-treated profile compared with the nontreated profile. A second application of the surfactant at the same rate did not alter the flow patterns. The study showed that surfactants can provide an inexpensive way to decrease the travel velocity of the pollutants and increase the efficacy of water and applied chemicals through coarse-textured turfgrass profiles.