Golf Course Management

AUG 2019

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 08.19 Products for alleviating irrigation salinity stress on bermudagrass turf Some programs can successfully alleviate symptoms of salinity stress and improve soil conditions. Using saline or recycled water in combi- nation with turfgrass species that have a high tolerance to salinity is a common strategy for reducing fresh water consumption. Recent estimates are that 13% of the golf courses in the United States use recycled water for irri - gation (3). is percentage is higher in areas that are particularly affected by drought conditions. For example, using data from 2006, researchers estimated that more than one-third of golf courses in the southwestern United States irrigate with recycled water (4). Factors that affect water quality include: concentration of soluble salts (or electrical Marco Schiavon, Ph.D. James Baird, Ph.D. conductivity, EC); relative proportion of so - dium to other cations (sodium adsorption ratio, SAR); and concentration of toxic ele - ments (for example, boron). As plant roots uptake water through osmosis (that is, water moves from a less concentrated solution to a more concentrated solution), excessive amounts of soluble salts can cause the plant to work harder to absorb water from soil, and symptoms of drought can be visible even though soil moisture is adequate. In the past, leaching salts from the root zone was considered the most important management practice for alleviating salt stress (1). Leaching consists of applying sup - plemental water in addition to normal irri- gation practices to help move salts below the root zone. Still, in the southwestern United States, incorporating a leaching fraction into regular irrigation management may be not possible for golf courses, especially when turf is actively growing. Because evapotrans - piration (ET) rates are high during the hot summer months, irrigation run times may be too long to maintain playable course con - ditions. Excessive sodium in irrigation water may lead to dispersion of soil particles and con - sequent deflocculation, especially in heavier clay soils, resulting in plugging of soil pores, decreased water infiltration and oxygen, and loss of rooting (2). e sodium adsorption ratio of irrigation water should be 6 or lower to avoid soil structural deterioration, but golf course superintendents in drier areas may often deal with higher levels of SAR. Calcium dislocates sodium from ex - change sites on soil colloids, preventing soil structure deterioration and defloccula - tion. Because of its low cost and accessibil- ity, gypsum has been historically the most commonly used product to limit sodium hazards. Another strategy is the application of soil surfactants to increase soil wettability and eliminate soil water repellency. Surfac - tants allow water to penetrate hydrophobic root zones by altering surface water tension. Several calcium-based products and wetting agents have been commercially available for salinity management, and overall, turf man - agers are inundated with a plethora of salin- ity alleviation products, many of which have not been tested under unbiased, replicated experiments on turf. The salinity alleviation study area at University of California, Riverside. Tifway II hybrid bermudagrass sod was installed in August 2012. Turf was irrigated with saline water from adjacent storage tanks, and commercial and experimental products were applied from April to October in 2013 and 2014. Photo was taken on Sept. 11, 2014. Photos by Marco Schiavon

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