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 surfactants alone or in combination in 1996, four experimental surfactant formulations in 1997, and four commercially available surfactants and one experimental surfactant in 1998 for their effect on reducing soil-water repellency in mature Cynodon dactylon X Cynodon transvaalensis cv. Tifdwarf sand-based greens, The treatments in 1996 were a commercial standard AquaGro (AG), and two new products, Primer (P) and Aqueduct (AD), applied as liquids at the rates 250, 190 and 250 ml per 100 m(2), respectively, and a control. Combination treatments of P + AG, and P + AD were also applied at standard rates. Surfactants were evaluated for their effect on turfgrass quality and percent dry spot incidence through a period of drought that induced soil-water repellency symptoms and subsequently through a period of recovery. Water drop penetration time (WDPT), on the soil cores were determined. Data were analyzed for statistical significance (P < 0.05) by automated ANOVA procedures. Results in 1996 demonstrated that during a period of drought, P or AD generally provided both significantly (P < 0.05) higher turfgrass quality and reduced percent dry spotting than AG and the control. Primer or AD significantly (P < 0.05) reduced WDPT. Furthermore, during a recovery period following the drought, P or AD provided significantly (P < 0.05) higher turfgrass quality than untreated controls. Combinations of P + AG or P + AD did not provide significantly higher quality turfgrass or less percent dry spots than individual applications of either P or AD. The second experiment in 1997 consisted of four experimental surfactant formulations of (ACA 1257, ACA 1313, ACA 1455, and ACA 1457), and a control applied at the recommended rate of 250 mi per 100 m(2) weebly, to plots. As in 1996, surfactants were visually evaluated for turfgrass quality and percent dry spot incidence and soil cores for WDPT. Results demonstrated that ACA treatments generally provided 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-water repellency symptoms. The four commercially available surfactants performed well and provided statistically equivalent (P < 0.01) and better turfgrass 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 reserved.