Irrigation Requirements for Salinity Management on Perennial Ryegrass Turf.

Use of reclaimed or other saline water sources for turf and landscape irrigation is inevitable in arid regions of the southwestern U.S. However, the use of saline water for turfgrass irrigation requires that salinity in the root zone be maintained at a level that does not adversely impact turf quality. In this study, we combined the line source method of generating a continuous distribution of saline or potable irrigation water, with the application of different quantities of water, thereby providing detailed information on the interaction of water application and salinity on response of perennial ryegrass 'SR 4550' turf maintained as golf course rough. Once established, the turf was irrigated with saline water through alternating irrigation lines creating a continuous distribution between 0.6-4.6 dS/m. In the perpendicular direction, plots were irrigated with different quantities of water (0.9, 1.1, 1.3, and 1.5 times the previous week's reference crop evapotranspiration or ET_o) representing a range from deficit irrigation to leaching. Each plot was further divided into nine strips (1 m x 10 m) parallel to the sprinkler lines for data collection. Soil water tension, soil moisture, salinity, and temperature were monitored continuously at 10 and 20 cm below the soil surface. Leachate was sampled at 20 cm below the surface using suction lysimeters. Turfgrass uniformity, percent turfgrass groundcover, canopy temperature, and dry clipping yield will be evaluated biweekly. Additional soil samples were collected prior to salinity treatments, and throughout the study to assess the change in population size and activity of plant growth promoting rhizobacteria (PGPR) in response to imposed drought and salinity stress. This research will help to develop new guidelines and recommendations regarding irrigation of turf with waters of elevated salinity, and contribute to significant reductions in water use on golf courses and other turf areas where salinity management is a concern.