Utilization of poor quality waters in the urban landscape has the potential of saving large quantities o f good quality water for higher priority uses. Bennudagrass in particular is well suited to be irrigated with poorer quality water. A two-year field study was conducted to determine the long-term effects o f applying shallow saline aqui&r water to two turfgnss sports fields. The water (0.69-3.4 dSm ') was applied using cyclic irrigation during peak demand months (Mty-Oct). Treatments consisted o f cycling saline water through the existing irrigation systems. Saline substitution o f fiesh water was set at 1,2,3 and 4 times per 7 freshwater irrigation events. Irrigations were applied using an ET feedback system and imposmg a leadm^finction o f 0.15. Turf color and cover, canopy temperature, hulk soQ conductivity, soil moisture, leaf water potential, tissue moisture content and stomatal conductance were monitored on a bimonthly basis during the peak demand months. AU plots except for control, were instrumented with tensiometers and salinity sensors. Soil samples (2430 total samples at the University and 1530 total samples at the high school she) were taken yearty from each plot in a 5 x 5 m

water as a supplemental irrigation source on landscapes would free up potable water for higher priority uses, A 2-yr cyclic irrigation study using shallow saline groundwater lower water tables in contact with structural foundawas conducted on a sports field in southern Nevada [bermudagrass (Cynodon dactylon L. 'Tifway') overseeded with perennial ryegrass tions, reduce the potential of contaminating the primary (Lolium perenne L. 'Champion')]. Shallow groundwater with a salinity aquifer, and reduce the flow of shallow groundwater to of 3.3 dS m Ϫ1 was substituted for municipal water (0.9 dS m Ϫ1) at a the Las Vegas Wash and the Colorado River system. rate of one, two, three, or four times per seven irrigation events during However, such water does contain a significant salt load. the peak water demand periods of 15 May to 15 October. Salinity Salinity in the shallow system varies from 1.8 dS m Ϫ1 in sensors and tensiometers were installed at depths of 10, 25, and 40 cm the central part of the valley to Ͼ10.0 dS m Ϫ1 in the and recorded weekly. Midday leaf xylem water potential, canopy southeastern part of the valley (Dean 1996; Schaan temperature, and turfgrass color and cover ratings were taken on a 2001). bimonthly basis. Soil salinity cycled up (as high as 24 dS m Ϫ1) and Many studies have demonstrated the feasibility of down (baseline values of 4.0-10.0 dS m Ϫ1) in response to substitution using saline water for irrigating agricultural and hortiperiods. However, the duration in which soil salinity exceeded salt tolerance threshold values for bermudagrass were short in all treat-cultural crops (Ayers and Wescot, 1985; Rhoades et al., ments (Ͻ21 d during the 2-yr period at the 10-cm depth). These 1989; Grattan, 1994; Dean et al., 1996; Leskys et al., short durations of threshold values being exceeded combined with 1999). Results from previous investigations into the pothe successful return to baseline soil salinity values during the cyclic tential use of the shallow saline aquifer in the Las Vegas off periods (freshwater only) led to little change in turfgrass color, Valley indicated that bermudagrass is well suited for cover, and plant water status. Freshwater savings as high as 50 cm irrigation with such water if threshold irrigation/potenyr Ϫ1 and a reduction in as many as 62 municipal irrigation days (days tial evapotranspiration (ET o) ratios are not exceeded irrigations took place) during the peak water demand periods oc-(where ET o is generated with an empirical-based equacurred. Results of this experiment indicate that the cyclic irrigation tion such as the Penman Combination equation and strategy is feasible in the urban setting with large turfgrass areas. threshold values relate to a well-defined point where turfgrass color and cover ratings decrease with declining irrigation/ET o ratios) (