Risk of nutrient leaching following over‐irrigation of two warm‐season turfgrasses with recycled water

Abstract

Recent climatic shifts have driven increased demand for recycled water as an irrigation source, with many counties in Florida imposing sanctions on irrigation allowances for lawns. Given these sanctions, there is a need to understand the ways this resource may amplify problems due to common lawn care malpractices that still occur, such as overwatering. A greenhouse study was conducted at the UF/IFAS Fort Lauderdale Research and Education Center in the spring of 2022 and 2023 to better understand how recycled water irrigation interacts with granular fertilizer applications on nutrient leaching and performance of “CitraBlue” St. Augustinegrass (Stenotaphrum secundatum [Walter] Kuntze) and “Celebration” bermudagrass (Cynodon dactylon [L.] Pers). Turfgrass was grown within lysimeters filled with Mason sand, fertilized at 49 kg N ha−2 with controlled release (42–0–0) fertilizer or unfertilized, and irrigated with either recycled or potable water. Recycled water was found to significantly increase the amount of orthophosphate in leachate (∼2×) among both grass species in both years, as well as amount of nitrate in leachate (∼4×) from St. Augustinegrass. Bermudagrass systems leached more nitrate based on either fertilizer applications or water source depending on the year. Ammonium leaching was positively influenced by water source among both grass species, with recycled water inducing the most presence of ammonium in bermudagrass. Water source was the main driver of cumulative nutrient presence in the leachate across species. Overuse of recycled water irrigation, despite not affecting turfgrass performance, was markedly associated with increased nutrient levels in the leachate.