Warm Season Turfgrass and Rootzone Quality Under Saline Sprinkler and Drip Irrigation.

Potable water for turfgrass irrigation has been restricted in the arid and semi-arid southwestern USA and alternatives, such as recycled or saline ground water have been promoted. However, information is lacking 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 three year field study (2005-2007) was conducted at New Mexico State University to determine whether adequate turf quality could be maintained when plants were watered with different salinity levels from two types of irrigation systems. Nine warm season grasses received irrigation at three salinities (potable [control], electrical conductivity [EC_w] ≈ 0.6 dS m^-1, moderately saline [EC_w ≈2.0 dS m^-1], and saline [EC_w ≈ 3.1 dS m^-1]) from either a sprinkler or a subsurface drip system. Turf plots were irrigated daily at 100% reference evapotranspiration. Turf quality, spring green-up, and fall color retention was assessed monthly by visual ratings and digital image analysis. Rootzone salinity was measured bi-annually at three depths. Grasses irrigated with potable and moderately saline water exhibited significantly higher quality than those watered with saline water during summer months. Seashore paspalum had highest quality over the entire research period followed by bermudagrass, regardless of the water quality applied. Salinity had no affect on spring green-up or fall color retention. Increases in soil salinity during spring and early summer correlated with an increase in irrigation and the EC_e decrease during late summer and fall can be explained by increased precipitation in July and August. Results suggest that warm season grasses can be sustained with saline water in a transition zone climate under both sprinkler and drip irrigation.