Interpreting Turfgrass Irrigation Water Test Results

Abstract

T he notion that water quality problems caused by soluble salts arise only-or even primarily-in regions with arid climates is far from the truth. For example, the excessive pumping of fresh water from wells in coastal areas can lead to saltwater intrusion problems. Even in high-rainfall areas the groundwater may contain significant levels of soluble salts derived from underground rock formations of marine origin. Moreover, increasing numbers of golf courses, parks, cemeteries, school campuses, industrial, and commercial turfed sites use potentially saline recycled municipal water for irrigation. The result of this breadth of use is that the effects of excess soluble salts are visible on turfgrass plantings in a wide range of climates. Water analysis and periodic monitoring have thus become key components of sound irrigation management.Water analysis by a commercial laboratory provides data on many parameters, some of which are of little significance for turfgrass irrigation. The most important parameters for turfgrass management are total concentration of soluble salts (salinity); sodium (Na) content; relative proportion of sodium to calcium (Ca) and magnesium (Mg) (Sodium Adsorption Ratio or SAR); chloride (Cl), boron (B), bicarbonate (HCO 3 ), and carbonate (CO 3 ) content; and pH. Other parameters that you are likely to find on a water test report and that you should review are nutrient content (nitrogen, phosphorus, and potassium), chlorine content, suspended solids, and turbidity, though none of these by itself plays a major role in determining the suitability of water for irrigation.

Survey of Irrigation Water for Golf Courses in Southeastern Pennsylvania

“…2). Recycled and well water are typically high in bicarbonates (11), although bicarbonate levels from domestic, recycled, stream, and well water sources in this survey were slightly below the < 90 mg/liter normal range (Fig. 2).…”

“…Although the recycled water pH was below 6.5, the optimum soil pH for turfgrass is considered 6.0 to 7.0 (6). A low or high soil pH can immobilize plant nutrients in the soil (4), and a low or high water pH is a signal that the water should be examined for other potential problems (11). For example, a water pH below 6.5 may indicate excessive iron or sulfate, while a pH above 8.4 could indicate high levels of carbonate, bicarbonate, or sodium.…”

“…Twenty-six parameters were measured or calculated for each sample (Table 1). Data from all irrigation water samples were pooled and the mean, minimum, and maximum values were determined for each parameter (5,14), and the mean value for each parameter was compared to the normal range of irrigation water for turfgrass (3,5,9,11,19,21) and rain water. If the mean value was not within the normal range for turfgrass, that specific parameter was further examined by water source category.…”

“…2). Excessive bicarbonates in water can contribute to an increase in soil pH and more importantly to the development of poor soil permeability (5,11). The bicarbonate ion can combine with calcium or magnesium and precipitate as calcium carbonate or magnesium carbonate, which can often lower the sodium absorption ration (SAR) in soil solution (11).…”

Golf Course Environmental Profile Measures Water Use, Source, Cost, Quality, Management and Conservation Strategies

“…Irrigation water quality, as determined by total dissolved solids (TDS), sodium absorption ratio (SAR), pH, and residual sodium carbonate (RSC) (5), was poorest in the Southwest agronomic region, and TDS and SAR were significantly higher in the Southwest than in all other agronomic regions. In the Southwest and Upper West/Mountain regions, pH was significantly higher than in all the other agronomic regions.…”