Benefits of a soil surfactant on putting greens under dry and wet conditions

Abstract

AbstractSoil surfactants are applied to alleviate soil water repellency (SWR). The ability of surfactants to improve turfgrass quality under dry conditions is well documented, but less information exists about their role in situations with water surplus. Our objective was to study responses to monthly application of the surfactant Qualibra® (20 L ha–1) under dry and wet conditions on a sand‐based green covered with creeping bentgrass. Dry conditions implied irrigation to field capacity (FC) once a week (FC1) in 2014 (a year with warm and dry weather from May through July) and deficit irrigation to 60% of FC once a week (DEF1) in 2015 (May through July cool and wet). Wet conditions implied excessive irrigation twice a week (EX2) with 50% more water than needed to replenish FC. The surfactant decreased the average soil water content of the surface 7.5 cm of the root zone from 0.193 to 0.168 m3 m–3 in 2014 and from 0.191 to 0.171 m3 m–3 in 2015. In 2015, the reduction in SWC was stronger with EX2 than with DEF1 irrigation, and this was accompanied by less organic matter accumulation on plots receiving EX2 irrigation. The surfactant reduced the water drop penetration time (WDPT) regardless of irrigation treatments, but improved turfgrass quality only with DEF1 irrigation in 2015. A harder playing surface due to Qualibra® was not observed in 2014 and only at one out of six observations with EX2 irrigation in 2015. We conclude that surfactants imply various benefits depending on water supply.