SportsTurf provides current, practical and technical content on issues relevant to sports turf managers, including facilities managers. Most readers are athletic field managers from the professional level through parks and recreation, universities.
Issue link: https://read.dmtmag.com/i/484138
www.stma.org April 2015 | SportsTurf 37 I rrigation water quality is usually a minor concern for sports turf manag- ers in the northeastern United States. However, in some areas contaminants in ground and surface water may pose a threat to turf and soil quality. Also, as the demand for potable water increases, sports turf managers may have to con- sider alternatives sources, such as recycled or effluent water. If you suspect poor or marginal irrigation water quality, it's advisable to test your water through a reputable lab. Results from water test laboratories can be confusing. Reports often list up to 20 different quality factors with numbers having unfamiliar units. Fortunately, in the majority of cases you only need to be familiar with a few of these to determine if your water is suitable for use on turf. The four most important factors to con- sider when evaluating the quality of your irrigation water are: pH, bicarbonate, electrical conductivity or soluble salts, and sodium absorption ratio. pH The pH of irrigation water should be determined in a laboratory and listed in your test report. Water with a pH in the range of 6.0 to 7.0 is most desirable for use on sports turf in northern climates. Alkaline or high pH (> 8.0) water can be a problem if used for spray tank mixing with certain pesticides. Alkaline water can reduce the effectiveness of some insecti- cides, herbicides, and fungicides if present in your spray tank for several hours. One way to deal with this problem is to adjust your tank water to a lower pH with acidifying adjuvants. Labels of pesticides that are unstable in alkaline water often contain information on pH buffering of tank water. Depending on how much you irrigate and the type of soil at your facility, the pH of your irrigation water may not have a large influence on soil pH. Mineral soils typically have high buffering capacity against rapid and drastic changes in pH, so periodic applications of alkaline irriga- tion water may not result in a high soil pH. For example, the pH of irrigation water at Penn State's turf research facility ranges from 8.2 to 8.4, but the pH of the soil is about 6.8. The best way to monitor pH of your soil is through a soil test. BicarBonate and carBonate Bicarbonate and carbonate are common constituents of irrigation water, and can influence soil properties and turfgrass performance if concentrations are high enough. If bicarbonate and carbonate levels are high (>120 and 15 ppm, respec- tively), these ions can react with calcium and magnesium in soil to form calcium carbonate and magnesium carbonate (lime). In soils with high amounts of sodium (soils in some areas of the western US or soils treated with high-sodium effluent water or seawater), high bicarbonate and carbonate concentrations can reduce the amount of free calcium and magnesium in soil, allowing sodium to compete for and occupy negatively-charged sites on clay particles. Excess sodium in clay results in destruction of soil structure and reduced water percolation though the soil profile. Most soils in the northeastern US are not high in sodium, so high bicarbonate IrrIgatIon water qualIty for sports turf In the northeast IRRIGATION & DRAINAGE ■ By Dr. Pete LanDschoot aBoVe: In some areas contaminants in ground and surface water may pose a threat to turf and soil quality. rIGht: Measuring electrical conductivity.