Environmental Impact of Irrigating Turf with Type I Recycled Water

As our water reserves diminish, recycled water is increasingly being used for irrigation of turfgrasses. This study was conducted to determine the fate of nutrients contained in Type I recycled water used to irrigate turf and its effect on turf quality. Eighteen plots were randomly assigned to three replications of three irrigation treatments and two grasses. Irrigation treatments included Edwards Aquifer water applied at the evapotranspiration (ET) rate (EA), recycled water applied at the evapotranspiration rate (1XRW), and recycled water applied at 1.1 times the evapotranspiration rate to provide a leaching fraction (LFRW). Grasses included ‘Tifway’ bermudagrass (Cynodon dactylon (L.) Pers. × C. transvaalensis Burtt Davy) and ‘Jamur’ zoysiagrass (Zoysia japonica Steud.). Rain, runoff, leachate, and soil samples were collected and analyzed for total salts, Ca, Cu, Fe, Mg, Mn, N, K, Na, and Zn. The use of San Antonio Water System (SAWS) Type I recycled water had no adverse effect on turf quality but did result in a significant increase in soil electrical conductivity (EC) from 0.2518 dS m⁻¹ in the EA treatment to 0.3132 and 0.3171 dS m⁻¹ in the 1XRW and LFRW treatments, respectively. The Ca content increased from 134 108 and 135 467 mg L⁻¹ in the EA and 1XRW treatments to 142 835 mg L⁻¹ in the LFRW treatment. Na concentrations in the soil were not affected by the use of recycled water. The use of recycled water resulted in increased total salts (EC), Na and nitrate (NO₃) concentrations in leachate passing below 76 cm. The EC increased from 0.425 dS m⁻¹ for the EA treatment to 0.626 and 0.614 dS m⁻¹ for the 1XRW and LFRW treatments, respectively. Na concentrations in leachate increased from 18.33 mg L⁻¹ for the EA treatment to 49.10 and 52.91 mg L⁻¹ for the 1XRW and LFRW treatments, respectively. Runoff water from treatments irrigated with recycled water exhibited a trend of increased EC, Ca, Mn, and Na.