This project is focused on improving nutrient management recommendations for sod producers as part of Florida’s best management practices (BMPs) program. The goal of this project is to evaluate nitrogen (N) fertilizer rate recommendations for Florida sod growers to achieve yield goals (shorten time to harvest) without negatively impacting water quality. The project was initiated in October 2023 and was conducted at four sod farms across the state and at the West Florida Research and Education Center (WFREC). At each farm, the project was conducted on two grass species. The N fertilizer (70% soluble plus 30% slow release) rates included 0, 120, 190, 260, and 330 lbs N/acre/year, which includes the range of current University of Florida, Institute of Food and Agricultural Sciences (UF/IFAS) recommendations. The annual N rate was split into monthly applications throughout the growing season. At the WFREC location, N applications were also being combined with phosphorus (P) fertilizer applications at 0 and 44 lbs P/acre/year to determine both N and P leaching. The treatments were arranged in a randomized complete block design with four replications. All other normal agronomic practices (irrigation, pesticides, etc.) were followed. Data collection included monthly visual turfgrass quality ratings, visual estimated percent cover, percent green cover via digital image analysis, and normalized difference vegetation index (NDVI). Soil cores and tissue samples were collected at the beginning and end of each growing season to determine soil chemical properties and nutrient concentrations. At harvest, sod samples were also collected to measure nutrient exports from fields. At WFREC, leachate was collected weekly and as needed based on rainfall events. Leachate volumes were measured at each water sampling event and subsamples from the leachate were analyzed for N and P concentrations. Preliminary results indicate that there are treatment differences in percent cover for all grasses. When grass species was combined across sod farms, the N rates of 260 and 330 lbs N/acre/year increased St. Augustinegrass [Stenotaphrum secundatum (Walter) Kuntze] percent cover. Additionally, the yearly rate of 330 lbs N/acre resulted in the greatest bermudagrass percent cover [Cynodon dactylon (L.) Pers. x C. transvaalensis Burtt-Davy]. This experiment is being repeated, and additional analysis will occur after the second harvest cycle has been completed.
