Golf Course Management

OCT 2018

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

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60 GOLF COURSE MANAGEMENT 10.18 Enzhan Song, Ph.D. Keith W. Goyne, Ph.D. Robert J. Kremer, Ph.D. Stephen H. Anderson, Ph.D. Xi Xiong, Ph.D. This research was funded in part by the United States Golf Association. Do some wetting agents remove organic coatings from water- repellent sand particles? A laboratory study confirmed for the first time that certain wetting agents can remove organic coatings that cause soil water repellency. Figure 1. Representative scanning electron microscopy images of hydrophobic sand (left) and a clean sand grain that has never been used. Scales in micrometers (10 -6 meter) are on the lower right corner of each image. Note the layers of organic coatings on the sand grain in the left panel, and the clean surface on the sand grain in the right panel. The hydrophobic sand grain was collected from a 7-year-old USGA green where localized dry spot has been documented. The hydrophobicity level was determined to be severe based on the water droplet penetration test, which had a result of >2,500 seconds. Photos and figures by Enzhan Song Soil water repellency, also referred to as soil hydrophobicity, slows water infiltration into the soil profile and, in some cases, causes water to bypass hydrophobic areas, ultimately lead - ing to localized dry spot (LDS). is undesir- able soil condition is a widespread issue, but is more common on sand-based growing media such as USGA greens, because the specific surface area of sand particles is much smaller than that of other soil minerals (7). Wetting agents and hydrophobicity Soil hydrophobicity is believed to be caused by the formation of complex organic acids, such as humic acid and fulvic acid, which coat the surface of sand particles (Figure 1). ese organic acids are formed during the natural decomposition of soil organic matter over time (14). Wetting agents that contain both hydrophobic (oil-loving) and hydrophilic (wa - ter-loving) groups in their molecules are the primary management tool for controlling soil water repellency. e desire for control of soil hydrophobicity and improvement of soil water retention has led to a widespread use of wet - ting agents in the turf industry. A 2006 survey found that 98% of golf course superintendents who responded had experience with wetting agents (5). Within the scientific community, there is also a high level of interest among turf researchers, as evidenced by the number

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