Post‐application irrigation effect on surfactant efficacy applied to a sand‐based putting green

Abstract Soil surfactants are applied to recreational turfgrass areas like golf course putting greens to help improve water infiltration, distribution, and uniformity. Most commercially available surfactant labels recommend immediate post‐application irrigation (PAI) to maximize product efficacy. However, many turfgrass managers may forgo PAI due to potential concerns of excess surface wetness, reduced surface firmness, or time constraints with golf play. A field study was conducted in 2024 to evaluate the effect of immediate PAI for two surfactant chemistries ([polyoxyalkylene polymer [PP] [8.0 L ha −1 ] and a blend of alkoxylated ethylene oxide‐propylene oxide adducts/nonionic polyols [AEPA] [6.4 L ha −1 ]) on a sand‐based creeping bentgrass ( Agrostis stolonifera L.) research green in West Lafayette, IN. Surfactants were initially applied on May 30, 2024 and reapplied every 14 days for a total of nine applications and received either immediate PAI with 0.5 cm water or scheduled nightly irrigation approximately 18 h after application across the study area. Visual turfgrass quality, percentage of turfgrass stress, soil volumetric water content (VWC), and water droplet penetration time (WDPT) were measured. Both surfactants improved seasonal quality and reduced stress/wilt with or without immediate PAI. Compared to the non‐treated control, the surfactants increased VWC and reduced WDPT in the upper 0–1 cm in early September. Immediate PAI increased average VWC and reduced WDPT in late summer compared to the non‐treated control. This 1‐year field study reinforces the value of immediate PAI to maximize surfactant efficacy and turfgrass health, especially during late‐summer stress.