SportsTurf

June 2014

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.

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Field Science | By Dara M. Park and Sarah A. White N early all waters contain trace levels of salts, which dissolve into water as a result of mineral weathering in the earth's surface. In addition, water runoff from urban and agricultural lands during storm and irrigation events can also impact water quality. Salinity, or the presence of salts, within irrigation water can impact plant growth and soil structure. The salinity of water sources vary (Table 1) as do the influence of various trace elements that combine with salts to make up the total salinity or salt presence within your water source. The total salinity of a water source is contributed by cations and anions. Common elements that contribute to salinity include calcium (Ca 2+ ), magnesium (Mg 2+ ), sodium (Na + ), potassium (K + ), chloride (Cl - ), bicarbonate (HCO 3_ ), carbon- ate (CO 3 2- ), sulfate (SO 4 2- ), and others. Natural weather patterNs Salts are commonly found in coastal area soils and water bodies. Fluctuating tides influence fresh surface water sources and soils with shallow groundwater levels. Natural saline aqui- fers can also be close enough to the surface that it is very tricky to determine proper well depth. Further inland are deeper saline aquifers (commonly found out west) that are used alone, and or blended with fresher water for irrigation purposes. Rainfall contains few salts, and is nature's way to remediate soil salt accumulation. Humid regions that are inland from the coast, receive plenty of rainfall and thus the soils do not experience any long-term salt accumulation. Arid climates, where evapotranspiration (ET) demand far exceeds rainfall, are another hot spot for salt issues. As water is lost from the soil via ET, the salts accumulate in the soil profile and near the soil surface. Grasses that naturally grow in arid conditions or in coastal environments are adapted to living under moderate to high salt conditions. For example, bermudagrass, zoysiagrass, and buffalograss all have leaf glands that excrete excess salts. Salt SourceS in irrigation water ›› Storm surge related flooding could directly induce salinity problems in land previously free of such issues via storm water runoff. 34 Sportsturf | June 2014 www.sportsturfonline.com Table 1. Salinity values of various water sources reported for total dissolved salts in parts per thousand (ppt) and parts per million (ppm), and as electrical conductivity (EC) in uS/cm, and mS/cm. ppt ppm (mg/L) μS/cm (μmhos/cm) mS/cm (mmhos/cm, dS/m) Most freshwater streams < 1 < 1000 100-2000 0.1 – 2.0 Distilled water 0.5 -3.0 0.0005 – 0.003 Water supply limit 0.5 500 782 0.782 US salt concentration limits in drinking water 1 1000 1560 1.56 Melted snow 2- 42 0.002 – 0.042 Typical limit for irrigation 2 2000 3130 3.13 Brackish: mild 1 - 5 1000 - 5000 1560 - 7810 1.56 – 7.81 Brackish: moderate 5 - 10 5000 - 10,000 7810 -15,600 7.81 – 15.6 Brackish: heavily 10 - 35 10,000 - 35,000 15,600 – 54,700 15.6 – 54.7 Sea water > 35 > 35,000 55,000 55 Brine > 50 > 50,000 78,100 78.1

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