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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62 GOLF COURSE MANAGEMENT 10.18 columns. After 24 hours, sand columns were then washed at the pore volume of 2 ounces of water three times at 30-minute intervals (Figure 2). All leachates collected from application of the wetting agents and the sequential washes were acidified using sulfuric acid to remove inorganic carbons. e organic carbons in the soluble forms in the leachates (termed dissolved organic carbon) and in the insoluble forms in the leachates (termed particulate organic carbon) were then determined. e underlying rationale for this measurement is that all organic compounds contain carbon; therefore, determining the organic carbon in the leachates is an indirect measurement for the amount of organic compounds that could be potentially washed off from the hy - drophobic sands. e amount of dissolved organic carbon was quantified by using a Shimadzu TOC- VWP analyzer equipped with an autosam - pler ASI-V. e particulate organic carbon was evaluated by first separating the particu - late organic matter from the leachates using a centrifuge before determining the mass of the particulate organic matter via combustion. Solid phase organic carbon in the sand profiles before and after treatment was determined by Application/wash flow chart the objective of this research was to investigate whether selected wetting agents could remove hydrophobic organic coatings from sand sur - faces. Materials and methods Sand was collected from areas where lo- calized dry spot had been documented on a 7-year-old USGA green at the Turf Research Facility at the University of Missouri in Co - lumbia, Mo. e degree of hydrophobicity was determined to be moderate, based on the molarity of ethanol droplet test. Once bench- dried, sand was separated from plant debris before homogenization and packed into PVC columns. After being packed to uniformity, all columns contained the same amount of sand with a uniform bulk density and poros - ity, which was equivalent to a pore volume of 2 ounces (58 milliliters). Wetting agents ap - plied included Matador (ENP Investments) and OARS and a surfactant named pHAcid (Numerator Technologies), as well as dis - tilled, deionized water as a control. All three wetting agents were mixed with water at the highest label-suggested rates and applied to the sand columns at 2.36 ounces (70 millili - ters), which was greater than the pore volume and ensured complete saturation of the sand of publications on this topic. As of Aug. 21, 2018, a search of the term "wetting agent" in the Turfgrass Information File ( http://tic.msu. edu ) produced 1,438 records. Despite the wide use of and interest in wet - ting agents in our turf community, many ques- tions have yet to be answered (5, 7-11). One of the questions brought up by Keith Karnok, Ph.D. — one of the foremost authorities on soil water repellency (1) — concerns whether certain wetting agents can live up to the ad - vertising and remove organic coatings from the soil particles (9). Removal of the organic coatings can ultimately reverse the soil's wa - ter-repellent condition and, consequently, will allow the turf manager to move away from regular application of wetting agents through - out the growing season — until organic acids accumulate on the sand surface again. eoretically, reversal of water repellency is possible because humic acids are soluble in high-pH solutions such as sodium hydroxide (NaOH), and fulvic acid can be dissolved in both acidic and basic solutions. A field experi - ment on a USGA green found that sequential applications of NaOH at 0.1 M over three days removed substantial amounts of humic substances and reduced soil hydrophobicity levels from strong to moderate (6). However, application of NaOH increased soil pH from 5.9 to 8.3 and resulted in variable levels of phytotoxicity on creeping bentgrass (Agrostis stolonifera L.). Another approach is to use wax-dependent metabolizing bacteria such as Streptomyces species (13), Rhodococcus species (12) and Mycobacterium species (2). However, this bioremediation approach was discovered to be time-consuming, and results were in - consistent depending on the environmental conditions. Alternatively, some wetting agents with strong amphiphilic properties have been found to be capable of concentrating and extracting hydrophobic organic compounds from water in the laboratory (4). In the turf market, some commercial compounds claim to remove or - ganic coatings from the hydrophobic sand sur- face. For example, a product called OARS (or- ganic acid removal system; Aqua-Aid), which (based on the label information) contains 80% polyoxyalkylene polymers and 10% po - tassium salt of alkyl substituted maleic acid, is being promoted for such a purpose. Until this study, however, there was no research-based evidence to evaluate such an effect. erefore, Figure 2. Flow chart representing application of wetting agents and three sequential washes. 70 ml wetting agent treatment 58 ml water 1st wash 58 ml water 2nd wash 58 ml water 3rd wash

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