SportsTurf

October 2013

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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detrimental to both turf and soils. Sodium in irrigation water can be absorbed by roots and foliage, and foliar burning can occur if sufficient amounts accumulate in leaf tissue. SODIUM ABSORPTION RATIO (SAR) The relative concentrations of sodium, calcium, and magnesium are important determinants of irrigation water quality. Calcium and magnesium play a major role in maintaining structure of clay-containing soils. If water with excess sodium and low calcium and magnesium is applied frequently to clay soils, the sodium will tend to displace calcium and magnesium on clay particles, resulting in breakdown of structure and reduced permeability. SAR is used to assess the relative concentrations of sodium, calcium, and magnesium in irrigation water and provide a useful indicator of its potential damaging effects on soil structure and permeability. Typically a SAR value below 3.0 is considered very safe for turfgrasses. Over time, water with a SAR of 9.0 or above can cause significant structural damage to clay soils. Sandy soils are not as susceptible to structure and permeability problems, and can tolerate higher SAR values (up to 10 in most cases). NUTRIENTS IN IRRIGATION WATER Irrigation water contains plant nutrients in varying concentrations. Depending on concentrations, nutrients can influence fertility programs and have an environmental impact on ground and surface water. Nitrogen has a significant influence on plant growth, and may present a hazard for drinking water sources if nitrate levels are 10 ppm or more. Phosphorus concentrations should be as low as possible (lower than 1.0 ppm) to avoid causing algal blooms in holding ponds and phosphorus loading in surface streams and lakes. Guidelines for nutrient concentrations are provided in Table 1. n Dr. Peter Landschoot is a professor of turfgrass science at Penn State. He is the resident extension turfgrass management specialist in Pennsylvania. CHLORIDE Chloride contributes to salinity of irrigation water, and when concentrations are high enough, can be toxic to plants. Turfgrasses are not particularly sensitive to chloride, and can tolerate levels up to 100 ppm. Turfgrasses can sustain injury when irrigated with water containing >355 ppm of chloride. Grounds managers should be aware that some ornamental plants are sensitive to chloride concentrations above 70 ppm. BORON Boron is essential for plant growth at very low concentrations. However, it can be quite toxic to some ornamental plants at concentrations as low as 1 to 2 ppm in irrigation water; with symptoms appearing as necrosis on margins of older leaves. Turfgrasses are more tolerant of boron, but to be safe, it's best to use irrigation water with boron concentrations < 2 ppm for watering sports turf. www.stma.org SportsTurf 19

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