A study was conducted in New Mexico from 2005 to 2007 to investigate the effects of two potable water-saving strategies: irrigating with saline water and using subsurface systems, on changes in rootzone salinity and quality of nine warm-season and seven cool-season turfgrasses. Plots were irrigated using either sprinklers or subsurface drip with water of one of three salinity levels (0.6 dS m-1, 2.0 dS m-1, 3.5 dS m-1). Turf plots were rated monthly for quality during the growing seasons. Warm-season grasses were assessed bi-annually for spring and fall color. Green cover on cool-season plots was determined using digital image analysis. Soil samples were collected bi-annually (June and November) and analyzed for electrical conductivity (EC), sodium (Na), and Sodium Adsorption Ratio (SAR) at depths of 0-10 cm, 10-20 cm, and 50-60 cm. Generally, changes in soil EC, Na content, and SAR reflected seasonal changes in irrigation and natural precipitation for both grasses. Electrical conductivity and Na values in 0-20 cm peaked in June of 2005 and 2006 and dropped to lower levels after the summer rainy season.
With the exception of moderately saline irrigated plots in 2005, summer EC on warm-season grasses did not differ between drip and sprinkler irrigated plots for any of the three water qualities. Electrical conductivity, Na, and SAR at a rootzone depth of 0-20 cm were highest in June 2006 reaching 4.7 dS m-1, 1024 ppm, and 16.1, respectively. For most of the warm-season grasses tested, EC, Na, or SAR values showed no significant relationship with turf quality. Drip irrigation resulted in earlier green-up than sprinkler irrigation but had no effect on summer quality or fall color retention. Most of the warm-season grasses included in this study maintained an acceptable quality level when drip-irrigated with saline water.
Electrical conductivity and Na values were highest (6.1 dS m-1 and 943 ppm, respectively) in June of 2006 on drip irrigated plots of cool-season grasses at depths of 0-10 cm. Electrical conductivity was higher in drip irrigated plots than sprinkler irrigated plots on four of the six sampling dates. Irrigation type and water quality did not affect EC and Na at soil depths of 50-60 cm. For four of the seven grasses tested, EC, Na, or SAR values showed a significant but weak relationship (0.18 < r2 < 0.27) with turf quality, indicating that more than one stressor affected visual ratings. With the exception of tall fescue [Festuca arundinacea (Schreb.)], cool-season grasses could not be maintained at acceptable quality levels when irrigated with saline water from either a sprinkler or a subsurface drip system. Based on these findings, with the exception of tall fescue, warm-season grasses appear to be the logical choice for turf areas irrigated with saline water from either a drip or a sprinkler system.
Keywords: turfgrass, saline water, grasses, saline irrigation
Hardcopy or CD of report available from: New Mexico Water Resources Research Institute, NMSU, Box 30001, MSC 3167, Las Cruces, NM 88003 http://wrri.nmsu.edu/publish/order.html