Department of Agriculture
Master of Science
Localized dry spots (LDS) associated with water repellent (i.e., hydrophobic) soils have detrimental effects on the survival, playability, and aesthetic value of creeping bentgrass (Agrostis palustris) used for golf course putting greens. The development of water-repellent soils, using molarity of ethanol water droplet tests to determine soil hydrophobicity, wetting agent evaluations, and water retention based on percent organic matter were investigated. Greenhouse, field, and laboratory studies were conducted at Western Kentucky University beginning in 2000 and ending in 2001. The greenhouse study was initiated to investigate the type of soil most capable of producing a hydrophobic condition. Using hydrophilic sand as a base, excised bentgrass roots, organic matter, and humate materials were incorporated into containers with live bentgrass turf. The field study, originally developed in 2000 to evaluate rates of Naiad wetting agent applied to established LDS due to hydrophobic soil, was modified to include Primer wetting agent in 2001. This study also compared the efficiency of MED testing based on soil sample size. Soil samples taken using a .63 cm in diameter soil probe were found not to differ from those measuring 1.27 cm in diameter. The laboratory study was designed to incorporate both hydrophilic and hydrophobic soil treatments, which were harvested from an experimental green. Both soils had differing amounts of organic matter, a Michigan peat moss, mixed in based on volumetric and weight calculations. Primer wetting agent was applied to half of the replicates from each soil type and weighed daily. Upon averaging the daily weights of the replicates within each treatment mix, those replicated receiving Primer wetting agent did not hold significantly more moisture when compared to those that did not receive applications. Furthermore, the hydrophobic soil did not differ in moisture retention whether receiving the wetting agent or not. There were significant differences in the amount of moisture held in the differing amounts of organic matter; however, this did not occur across soil type. The treatments containing 20% organic matter by weight held significantly more water in comparison to the other treatments. The same was true in both the hydrophobic and hydrophilic soils. The results of this particular study suggest that wetting agents do not cause construction mixes to retain excess water when containing differing amounts of organic matter.
Elmore, Whitney, "Field and Laboratory Studies on the Development and Control of Soil Water Repellency of Sand Root Zone Mixes" (2001). Masters Theses & Specialist Projects. Paper 655.