WATER-QUALITY FROM UNFERTILIZED FLORIDA RANGELAND

Ground water wells from unfertilized Florida rangelands were sampled t o monitor water quality parameters. Ground water was collected (1990-9 2) monthly from three range sites (south Florida flatwoods, slough, an d freshwater pond) at the Southwest Florida Research and Education Cen ter near Immokalee, Florida. Water samples were analyzed for pH, elect rical conductivity, total phosphorus (P), potassium (K), and ammonium- nitrogen (NH4-N); and water table depth was monitored monthly. Levels of nutrients were highly variable during the sampling period. Levels o f P at all three sites exceeded the South Florida Water Management Dis trict's (SFWMD) maximum allowed level (0.18 mg P/L) in surface water r unoff from rangeland. Time series models were useful for predicting (p <0.15) future events for all nutrients and water table depth. Variatio n in water quality, related to its N, P, and K content, was minimized by excavating the ground water wells three times before sampling. Wate r samples continue to be collected from each range site to develop a l ongterm water quality database from unfertilized rangeland.