Evaluation of Experimental Soil Surfactants On a USGA Sand-Based Putting Green.

Hydrophobic conditions of sand-based root zones on golf course putting greens can reduce aesthetics and playability. The objective of this research was to evaluate the efficacy of experimental surfactants for preventing localized dry spot in a sand-based root zone putting green in Wisconsin. Research was conducted on an ‘A-4’ creeping bentgrass (Agrostis palustris L.) grown on a USGA-specification putting green at the O.J. Noer Research and Education Facility in Madison, WI. Treatments consisted of four different surfactants from Aquatrols Corp. (ACA 2978, ACA 2953, Revolution®, and Sixteen90®) and a non-treated control. Effectiveness of each treatment was evaluated upon turfgrass color, quality, percentage of localized dry spot, soil water content and hydrophobic conditions. Turfgrass color was evaluated on a 1-999 scale with a reflectance meter. Visual turfgrass quality was evaluated on a 1-9 scale, with six representing the minimally acceptable level of visual quality. Volumetric soil water content measurements were taken weekly in five random locations within each plot to a 7 cm depth with a time domain reflectometer. Hydrophobicity was determined monthly using the water drop penetration test on three randomly selected soil cores from each plot. Consistent rainfall throughout the duration of the growing season prevented the development of localized dry spot symptoms. Total rainfall over the study period was 49 cm while estimated evapotranspiration (crop coefficient = 0.7) was 44 cm. ACA 2978 applied on a monthly regime had the greatest color rating of 243 and quality rating of 7.9. The lowest color/quality ratings were found in treatments ACA 2953 of 226/7.6 and the control of 227/7.5. However, even the lowest average quality rating was well above acceptable levels. Treatments resulted in large differences in soil water content. The control treatment averaged the greatest soil water content, at 17.5%. Treatments ACA 2978, ACA 2953, and Sixteen90® grouped together at ~14.5% soil water, statistically lower than the control, but statistically greater than the Revolution® treatment which averaged 12.2% soil water content in the upper 7 cm of the soil profile. With the exception of ACA 2978, all surfactants increased the wettability of the soil compared to the non-treated control. These results indicate that during wet periods on well-drained sand putting greens, soil surfactants can be used to decrease soil water content in the upper 7 cm.