Phosphorus Removal in Sod Production Systems in Florida

February, 2010
Maria L. Silveira - Range Cattle Research & Education Center, Soil & Water Scientist


From economic and environmental perspectives, effective nutrient management strategies should consider the balance between inputs and outputs in the system. Nutrient budgets (inputs versus outputs) can help farmers evaluate efficiency and improve resource utilization. This is particularly true for phosphorus fertilization. Besides the environmental issues related to unnecessary phosphorus application, phosphorus fertilizer represents an expensive input in forage systems in Florida, thus sound P management programs may help reducing production costs.

Nutrient budgets can be calculated in a variety of ways. Typically, it is relatively easy to estimate phosphorus outputs in a typical cow-calf system when harvested crop is exported as hay or silage. However, limited information is available on the amounts of P removed when turfgrass sod is produced. In sod systems, the above- and below-ground plant biomass is removed along with a significant portion of soil. Significant amounts of phosphorus can also be exported when sod is harvested. To sustain adequate yields, phosphorus needs to be applied to supply the crop nutrient requirements to sod grown on soils from which the previous sod crop has been harvested.

A study was conducted at the Range Cattle Research and Education Center, Ona, FL to evaluate P removal rates in different sod production systems in central and south Florida. Fifty-two (52) pieces of sod were collected in April, 2009 from 6 producers in 26 locations throughout central and south Florida. In the laboratory, each sod piece was divided into three compartments: above- and below-ground plant biomass, and soil pool and total phosphorus was determined in each fraction. Phosphorus removal rates varied from 60 to 500 pounds of P per acre assuming that the entire ACRE was harvested. These rates correspond to approximately 140 to 1,160 lb of P2O5 per acre per cut. The lowest P removal rate observed in the study occurred in a field receiving no P fertilization. Greater P removal rates were obtained in fields receiving biosolids application. The greatest percentage of the total P removed with sod was found in the soil pool Averaged across the 52 samples, P removed with the soil represented 54% of the total P removed, while above-ground and below-ground plant biomass accounted for 6% and 40% of the total P removed, respectively. Caution should be exercised when harvesting sod to minimize soil losses and, consequently, high P removal rates. For additional information on this study please refer to IFAS publication entitled “Phosphorus Removal rates from Sod Production Systems” (available at http://edis.ifas.ufl.edu/SS521).

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