Amelioration of water repellency in highly managed soils and the enhancement of turfgrass performance through the systematic application of surfactants

Water repellency is a common phenomenon in highly managed golf course soils. Considerable speculation exists on the cause of water repellency, yet little definitive research has been conducted to elucidate those factors contributing to its cause. In golf course soils, water repellency has been managed through the prophylactic application of surfactants to turf areas exhibiting visual symptoms, commonly referred to as localized dry spots (LDS) and characterized as irregular areas of stressed and declining turf. Soils in affected areas are often dry, have poor infiltration rates, and are non-wettable. The problem may be observed on fairways but is more prevalent on sand-based tees and greens. While surfactants have been used commonly as management tools, few studies have evaluated them beyond the traditional use as materials to eliminate LDS. This study evaluated the effectiveness of a new surfactant formulation (Primer 604) for amelioration and management of soil water repellency (as measured using water drop penetration time [WDPT]), improvement in a range of turf performance parameters (turf quality, area affected by LDS, percent wilt under stress), and estimation of available soil water. Thirty-six sand-based tees on a course with a history of severe water repellency were treated with 0, 125, or 185 ml of surfactant (in 8 l of water) per 100 m2. Treatments were applied monthly for three months and ratings were taken over a four-month period beginning with the initial treatment applications. At study initiation, all tees exhibited LDS symptoms. Surfactant treatment significantly reduced soil water repellency as compared to the untreated control. Reduction in soil water repellency lasted for a minimum of one month. After two surfactant treatments, turf quality was improved and both LDS and afternoon turf wilting were nearly eliminated on treated tees, while severity increased in the untreated controls. Reduction in water repellency corresponded with enhanced turf performance ratings. Based on visual assessment of soil core samples, estimated hydration uniformity and available water were improved in treated soils. Systematic treatment with Primer 604 reduced soil water repellency, enhanced turf performance, improved uniformity of turf, and increased available water in soils.