Transport of Nutrients and Managment Practicse in Sod Production in Lake Okeechobee Watershed.

Sod producers were surveyed in the Lake Okeechobee Watershed to determine their production, nitrogen (N) and phosphorous (P) fertilizer practices to evaluate the current parameters used in models in South Florida. Annual N and P fertilizer inputs varied greatly among farms, grasses and soil types. Bahiagrass received the least N and P compared to any other grass on an annual basis.  Production of St. Augustinegrass on sand received more N and P inputs compared to St. Augustinegrass production on muck. Similarly, zoysiagrass production on sand soils received more N input compared to zoysiagrass produced on muck. Approximately 86% of every acre was actually being harvested from the sod farm for St. Augustinegrass, bermudagrass, or zoysiagrass with much less (65%) for bahiagrass. The thickness of sod cut from surveyed farms was approximately 2.54 cm. Harvest cycle duration varied by grass species. Only bermudagrass was capable of producing two harvests per year. Zoysiagrass and St. Augustinegrass harvest generally produced one harvest per year. Total P (TP) and Total N (TN) in sod samples varied greatly between grasses and grass and soil combinations. Overall, St. Augustinegrass preceded by zoysiagrass had the greatest TP of the grasses that were produced on sand and muck soils. Bahiagrass produced on sand had the lowest TP followed by bermudagrass.  Overall zoysiagrass and St. Augustinegrass produced on muck soils had the highest TN with zoysiagrass produced on sand having the lowest TN. Exports of TP from sod farms were greater from sand soils than muck soils. Nitrogen exports were the greatest from sod producers of zoysiagrass on muck soils and the lowest from St. Augustinegrass produced on muck.  From the results of the survey and N and P analysis of sod, it appears that several key criteria used in the models used in South Florida, have changed since it was first developed.