Work to update the University of Florida /IFAS sod production fertilizer recommendations is underway, thanks to funding received from a 2023 state legislative appropriation.
Current sod fertilization recommendations are based on rate studies conducted in 2007, and although the EDIS publication resulting from that work – “Fertility Considerations for Sod Production” (SL-52) – was reviewed in 2017, this did not include new information or research. Sod producers have long been concerned that the recommendations do not address new grasses, new products, updated production methods, or on-farm “real world” testing – concerns shared by producers from many other Florida agricultural commodities.
“Many of the UF/IFAS fertilizer and nutrient management recommendations are decades old,” said Thomas Obreza, Professor of Soil, Water, and Ecosystem Sciences and Director, UF/IFAS Nutrient Management Program. “Since that time, better plant genetics have increased yield potential, and technology has improved production practices. Our recommendations need to be brought up to date to align with current conditions.”1
The need for updated data became critically important after the passage of the 2020 Clean Waterways Act (SB 712), which requires producers to report annual applications of nitrogen and phosphorus to the Florida Department of Agriculture and Consumer Services Office of Ag Water Policy (FDACS – OAWP) during Implementation Verification visits. The data will be aggregated and submitted to the Florida Department of Environmental Protection. It also became particularly critical for sod producers, as the Sod BMP manual was one of the first to be fast-tracked for revision and adoption by the end of 2023.
In 2022, the Florida Legislature approved an appropriation directing funds to the University of Florida to be utilized for “nutrient management research…to result in recommendations on best management practices for supplying fertilizer to the crop to achieve maximum yield and quality goals of growers while minimizing nutrient inefficiencies to the environment.”2 The legislature initially targeted five priority crops: tomatoes, potatoes, citrus, grain corn and green beans. And given the number of commodities produced in Florida – well over 300 – and the limitations of funding, it seemed unlikely that sod research would be prioritized, but we’re pleased to report that work has already begun.
Dr. A. J. Lindsey with the Environmental Horticulture Department is serving as principal investigator for the project, entitled “Developing Optimal Nitrogen Fertilizer Recommendations for Sod Producers in Florida”. He is working in conjunction with Dr. Bryan Unruh (UF/IFAS West Florida Research & Education Center); Dr. Emma Matchem (Agronomy – Gainesville) and Prissy Fletcher (St. Johns County Extension).
The one-year project, funded at roughly $200,000, seeks to quantify nitrogen and phosphorus rates for the various species under different fertilization regimens on farm locations throughout the state (taking into consideration soil types and climate variations). The focus will be on achieving yield goals (shortening time to harvest) without negatively impacting water quality. Additional lysimeter work on nitrogen and phosphorus leaching will be conducted at the UF/IFAS West Florida Research & Education Center in Jay, Florida.
The project will also consider the publication’s designated growing zones, which currently reference only “North”, “Central”, and “South” Florida. These designations were created for simplicity’s sake and do not necessarily reflect climate variations that can significantly affect production. Winter conditions in the Florida Panhandle (Pensacola) area, for example, can vary widely from those of the northeast coast (Jacksonville) although both are designated “North” Florida.
“We’re look at utilizing USDA Hardiness Zones, which might better reflect conditions such as the impact that soil temperatures have on dormancy,” Unruh explained.
Because funding is based on annual legislative appropriations, all proposals are designed in one-year increments. Researchers may reapply for continued funding if funding is available. Unruh said he felt that the ideal length of time for this type of work for sod would be 3-4 years, noting that ongoing projects should have a good chance of receiving funding for subsequent work should the legislature continue to fund this important research.
The UF/IFAS sod fertilization recommendations are not included in the sod BMP manual, but are incorporated by reference, meaning growers and field representatives conducting implementation verification visits are to refer to the current version of the publication for guidance. If updates are made to the recommendations, the BMP program will automatically reference the new rates. The Sod BMP manual is in revision with the goal of having it adopted by rule by December 31, 2023.
Learn more about this project and other projects which are currently underway online at https://bmp.ifas.ufl.edu/about/research-projects/.
With so many agricultural crops in Florida needing this type of research, we are extremely grateful for those who advocated on our behalf to get sod included in the funding for FY 23-24, and to the researchers who quickly prepared a proposal and are already at work!
1 Source: “UF/IFAS begins research to update best management practices for key Florida crops”, June 27, 2022, https://blogs.ifas.ufl.edu/news.
2 Source: UF/IFAS Nutrient Management Program – Nutrient Management Research, https://bmp.ifas.ufl.edu/about/.