Florida Lawn


Width of Vegetative Buffer Strips Influences Fertilizer and Nutrient Movement from Turfgrass Systems


By Ryan Adams, M. S. Student, Jason Kruse, Ph.D., University of Florida/IFAS, Gainesville, Florida and J. Bryan Unruh, Ph.D., University of Florida/ IFAS West Florida Research & Education Center , Milton, Florida


Recently, numerous regulations and ordinances have been


enacted to reduce fertilizer applications in an effort to reduce nutrient leaching and runoff. In nearly every case, there are restrictions placed on the distance from the edge of a body of water that must be left unfertilized to serve as a buffer strip. However, there has been little research conducted to evaluate the effect of various widths of the unfertilized buffer strips in an effort to identify the optimal width that will minimize direct application of fertilizers to the body of water, reduce nutrient runoff, and minimize erosion of the soil surface. This study was devel- oped to evaluate the ‘performance of various buffer strip widths and their influence on nutrient runoff in an urban landscape comprised of hybrid bermu- dagrass. Starting in 2011, we will evaluate the influence of non-fertilized buffer strip width on the fate of nitrate nitrogen and ortho-phosphate applied to a sloped bermudagrass site located at the University of Florida Plant Science Research and Education Unit located in Citra, Florida. The sloped site was segmented into fifty two individual


(4.6’ by 40’) plots running perpendicular to the slope. Each plot is separated by an L-shaped aluminum flashing material that runs the length of the plot. A v-shaped collection weir is situated at the bottom of each runoff plot. Runoff water flows through the weir into a collection container. Plots will be maintained using typical bermudagrass management practices found on golf course fairways. Runoff will be generated using an above ground irrigation system with a design capacity of 2” per hour. Irrigation heads will be installed 6’ above the turf allowing water droplets to reach terminal velocity before impacting the turf surface. Appropriate pressure regulation is integral to the system design. Three nitrogen fertilizer sources will be evaluated and will


include: 16 16


1) 100% quick-release; 2) 100% slow-release; and 3) 50%:50% quick-release:slow-release.


Each fertilizer treatment will be placed at interval distances


which are: 1.) 0 – 10’; 2.) 5’ – 15’; 3.) 10’ – 20’; and 4.) 20’ – 30’ from the down-slope collection point. Four replications of each fertilizer source by distance combination will be used along with four untreated plots for comparison purposes. To augment the runoff


study, leaching trials will be conducted at the West Florida Research and Education Center in Jay. Nine fertilizer sources will be applied at excessive application rates and irrigated with an exces- sive amount of water creating a “worst-case” scenario. Following application, leach- ate will be evacuated at 4, 8, 12, 24, 48, 96, 168, and 336 hours. Samples will be ana- lyzed for nitrate-nitrogen using


accepted laboratory procedures. Percolate volumes will also be measured from each plot to allow for flow-weighted analysis. Turf visual quality parameters will be assessed periodically throughout the study. At least four runs of the experiment will be conducted. Completion of the project should result in a better understanding of the influence of unfertilized buffer strips on nutrient movement in bermudagrass turf in Florida. It is expected that the best preventative buffer strip distance will be identified and that information related to the proper manage- ment of these buffer strips will be useful to turf managers.


Dr. Bryan Unruh is a professor and associate center director for the UF/ IFAS West Florida Research & Education Center in Milton. He can be reached at 850-995-3720, ext. 108 or by emailing jbu@ufl.edu.


Dr. Jason Kruse is an assistant professor in the UF/IFAS Environmental Horticulture Department specializing in sports turf management. He can be reached at 352-273-4569 or by emailing jkk@ufl.edu.


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