Soil Salinity and Turf Performance Under Saline Irrigation

In the arid and semi-arid southwestern USA potable water for turfgrass irrigation has been restricted and alternatives, such as recycled or saline ground water have been promoted. However, little information is available on the long term sustainability of turfgrasses exposed to salinity, particularly in transition zones where plants face additional stresses of both heat and cold. A five year field study (2005-2009) was conducted at New Mexico State University to determine whether adequate turf quality could be maintained when plants were watered with saline water. Nine warm season grasses received irrigation with either saline (EC_w ≈ 3.1 dS m^-1) or potable water (control, EC_w ≈ 0.6 dS m^-1). Turf plots were irrigated daily at 100% reference evapotranspiration throughout the growing period. Turf quality was assessed monthly by visual ratings and digital image analysis. Rootzone salinity was measured bi-annually at three soil depths. Higher soil EC, sodium content (Na), and sodium adsorption ratio (SAR) in the top 0-10 and 10-20 cm during spring and early summer correlated with an increase in irrigation. Lower EC during late summer and fall could be explained by increased precipitation in July and August. At the 50-60 cm soil depths SAR was the only parameter that changed over time. With the exception of ‘Princess 77’ and ‘SeaDwarf’, all grasses exhibited significantly higher quality under irrigation with potable water than with saline water during summer months. Seashore paspalum cultivars ‘Sea Spray’ and ‘SeaDwarf’ had highest quality over the entire research period followed by bermudagrasses ‘Princess 77’ and ‘Rivera’, regardless of the water quality applied. Our results suggest that warm season grasses can be sustained with saline water in a transition zone climate.