Golf Course Management

JUL 2013

Golf Course Management magazine is dedicated to advancing the golf course superintendent profession and helping GCSAA members achieve career success.

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gcm ex t ra The presence of water-repellent soil can be determined by conducting a water-droplet-penetration time test. If the droplet stays on the surface of the soil core more than fve seconds, the soil is considered hydrophobic. the exact chemical makeup of their wetting agents. Although there may be standard chemistries shared by wetting agents that can be grouped or categorized to some extent, many have additional proprietary chemistries that could, in fact, infuence performance. Second, even under strict testing procedures as used in this nationwide study, there are variables that will affect wetting agent performance even more than the unique chemistry of the wetting agent itself. tion time), regardless of the category of chemistry. In other locations, wetting agents in different classifcation categories performed the same in terms of both phytotoxicity and reducing soil water repellency. Likewise, wetting agents in the same category sometimes performed differently from each other among locations or even within a location from one year to the next. There were more similarities than differences among the wetting agents tested. So the questions are: Why so much variation? Why didn't the wetting agents within the same chemical classifcation perform similarly throughout all locations or even within the same location from year to year? There are two reasons for the differences in performance within the same classifcation. First, the wetting agent classifcation system does not take into account that companies do not publish Variables affecting wetting agent performance What variables can have a greater effect on wetting agent performance than the chemistry itself? Some possibilities are: rates of application, amount of carrier water, amount of irrigation applied after application, time between wetting agent application and irrigation afterward, time of day of application, soil type, degree of soil water repellency, depth of water repellency, amount and types of thatch, mat and/ or soil organic matter content, turfgrass species, air temperature, soil temperature, sunlight, etc. These are just the somewhat obvious variables. What about soil pH, water pH, irrigation water quality, formulation, spreader/sprayer calibration, irrigation system uniformity? There are probably many more. 76 GCM July 2013 Conclusion It is recommended that the decision to purchase a particular wetting agent (or any product for that matter) should be based on feld performance and not on the purported chemistry and/or claims made about the product. Turf managers should always insist on university test results to support claims and be sure to conduct their own on-site evaluations. GCM Keith Karnok (kkarnok@uga.edu) is a professor in the department of crop and soil sciences at the University of Georgia, Athens.

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