Field evaluation of perennial ryegrass cultivars for use with effluent water irrigation

Fresh water is a scarce resource that needs to be conserved. Landscape irrigation, a large portion of the outdoor water use, can be accomplished with water of less-than-potable quality. The use of effluent water generated from residential graywater in landscapes would go a long way toward conserving potable water for other essential uses. The objectives of this study were to evaluate the effect of effluent versus fresh water irrigation on the performance of 11 lawn-height perennial ryegrass (Lolium perenne L.) cultivars in the Willamette Valley of Oregon, USA, and determine the effects of effluent water irrigation on soil and tissue analyses. A two-year field trial was established in October 2015 on native soil, and the experimental design was an 11 by 2 strip-plot design with three replications. Synthetic effluent water (water-softening salt, two laundry detergents, and a chelating agent) was applied twice-weekly over perennial ryegrass plots in the summers of 2016 and 2017, and compared to a freshwater control. Small reductions in turf density and color were observed with effluent water irrigation only in June and July of 2017. Our results suggest that effluent water is a viable alternative to freshwater irrigation in the summer of Willamette Valley, where there is little to no precipitation. However, the accumulation of Na, Cl, and B in the soil and plant tissue indicates that future research is warranted to determine any long-term effects from effluent water irrigation on turfgrass and soil health.