The occurrence and alleviation by surfactants of soil-water repellency on sand-based turfgrass systems

Even with routine irrigation, soil water-repellency on sand-based turfgrass systems can occur. This study evaluated three commercially available surfa ctants alone or in combination in 1996, four experimental surfactant formul ations in 1997, and four commercially available surfactants and one experim ental surfactant in 1998 for their effect on reducing soil-water repellency in mature Cynodon dactylon X Cynodon transvaalensis cv. Tifdwarf sand-base d greens, The treatments in 1996 were a commercial standard AquaGro (AG), a nd two new products, Primer (P) and Aqueduct (AD), applied as liquids at th e rates 250, 190 and 250 ml per 100 m(2), respectively, and a control. Comb ination treatments of P + AG, and P + AD were also applied at standard rate s. Surfactants were evaluated for their effect on turfgrass quality and per cent dry spot incidence through a period of drought that induced soil-water repellency symptoms and subsequently through a period of recovery. Water d rop penetration time (WDPT), on the soil cores were determined. Data were a nalyzed for statistical significance (P < 0.05) by automated ANOVA procedur es. Results in 1996 demonstrated that during a period of drought, P or AD g enerally provided both significantly (P < 0.05) higher turfgrass quality an d reduced percent dry spotting than AG and the control. Primer or AD signif icantly (P < 0.05) reduced WDPT. Furthermore, during a recovery period foll owing the drought, P or AD provided significantly (P < 0.05) higher turfgra ss quality than untreated controls. Combinations of P + AG or P + AD did no t provide significantly higher quality turfgrass or less percent dry spots than individual applications of either P or AD. The second experiment in 19 97 consisted of four experimental surfactant formulations of (ACA 1257, ACA 1313, ACA 1455, and ACA 1457), and a control applied at the recommended ra te of 250 mi per 100 m(2) weebly, to plots. As in 1996, surfactants were vi sually evaluated for turfgrass quality and percent dry spot incidence and s oil cores for WDPT. Results demonstrated that ACA treatments generally prov ided significantly (P < 0.10) higher turfgrass quality and reduced percent dry spotting than the untreated control. In 1998, for the third experiment, on a green with extensive soil-water repellency, AD, P, Cascade, LescoFlo, and an experimental surfactant (N-07/05) were applied to alleviate soil-wa ter repellency symptoms. The four commercially available surfactants perfor med well and provided statistically equivalent (P < 0.01) and better turfgr ass quality and percent dry spot reduction than the untreated control. The N-07/05 treatment improved turfgrass quality and reduced dry spots compared to the untreated plots as well, but on most dates did not pet-form as well as the commercial standards. (C) 2000 Elsevier Science B.V. All rights res erved.