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2. Sample Site Description and Land Use

Abstract
Introduction
>Site Desc. & Land Use
Methods
Results & Discussion
Conclusions
Acknowledgments
References
Figures, Tables, & Equations
Soil cores were collected from improved pasture (site S5) and semi-native pasture (site 770), within MAERC, and from bordering undeveloped native grassland (Lykes site) (Figure 1). Shallowest soils (0-30 cm) at the three studied sites are composed of predominantly fine- and very fine-grained quartz sand (97-98 percent) with variable amounts of organic matter, primarily in the uppermost 15 cm. Annual rainfall amounts at MAERC average 130 cm and 70% falls during the wet season of June through October. The local water table is high enough at all three locations to cause flooding during major rainfall events, especially during the wet season. At site S5, a regular network of drainage ditches was excavated during the 1970's to lower the water table, thus providing better drained summer pasture for ongoing cow-calf operations.

Improved summer pasture areas, such as at site S5, are planted in bahia grass (Paspalum notatum) and receive a springtime application of fertilizer to sustain adequate growth. For 15-20 years prior to 1987, phosphate-containing fertilizers were applied annually, or at least biannually, at rates of 34-45 kg P2O5 per hectare. Since 1987, only N-based fertilizers such as ammonium sulfate, ammonium nitrate, and calcium nitrate have been applied to these pastures. From 1986 to 2000, for example, ammonium sulfate fertilizer was applied annually or biannually at a rate of 56 kg per hectare. In contrast to fertilized site S5, unfertilized pasture areas, such as site 770 and managed winter pasture W4 (Figure 1), are less well drained and contain mostly native vegetation.

Site S5 is one of 8 adjoining plots of similarly improved summer pasture used for controlled testing of best management practices such as stocking rate and fertilization rate (Figure 1). Each plot is equipped with a flume and automated water sampling equipment designed to monitor runoff water quality during significant rainfall events. Runoff from these sites enters the adjacent Harney Pond Canal (Figure 1), a major drainage that flows into Lake Okeechobee.

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