Surfactant and polymer-coated sand effects on defi cit irrigated Bermudagrass turf

Abstract

Sand topdressing and soil surfactants are commonly applied to turfgrass areas but it is unclear whether these practices improve visual appearance or reduce hydrophobicity under deficit irrigation. A study was conducted from 2011 to 2013 at New Mexico State University in Las Cruces, NM, to evaluate two topdressing materials and a soil surfactant on deficit irrigated Princess 77 bermudagrass (Cynodon dactylon L.) grown on a loamy sand (mixed, thermic Typic Torripsamment). Treatments consisted of monthly applications of a polymer-coated hydrophilic sand (ACA 3114) or straight sand with or without the soil surfactant and an untreated control. Plots were mowed at 2.0 cm and irrigated at either 70 or 50% of reference evapotranspiration for short grass (ETos). When results were averaged over the research period, plots irrigated at 50% ETos and receiving ACA 3114 or sand topdressing and the soil surfactant exhibited greater green coverage (85.3 and 88.2%, respectively) and better turfgrass quality (6.6 and 6.5, respectively, with 1 = worst, 9 = best) than control plots (71.6% green coverage, quality = 5.1) or plots receiving sand topdressing only (74.7% green coverage, quality = 5.3). Soil repellency in the upper root zone was detected only in 2011, and applications of both ACA 3114 and straight sand topdressing with the soil surfactant on plots irrigated at 50% ETos resulted in lower water drop penetration times (7s and 1s) compared to sand topdressing (12s) only. Our results suggest that bermudagrass quality can be maintained under deficit irrigation if either topdressed with a hydrophilic sand or with straight sand combined with a surfactant.