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Comparison of cumulative NO 3-N leached (g m-2 ) from St. Augustinegrass with 40 g kg-1 soil organic matter (SOM) to St. Augustinegrass with 100 g kg
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Home lawn fertilization has been implicated as a potential source of nitrogen (N) contamination to fragile watersheds in southern Florida. A field-scale study evaluating the effect of N sources and rates, and irrigation scheduling on performance and N leaching from St. Augustine grass lawns was conducted in South Florida. Vadose zone nitrate-N and...
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Citations
... Quiroga-Garza et al. (2001) reported that QRN-treated plots had lower nitrate leaching levels than SRN treatments under long-day conditions in 'Tifgreen' bermudagrass, although the trend was reversed under short-day conditions. Park (2006) observed no difference in the quantity of N leached from st. augustinegrass in southern Florida as a result of N source. Nitrogen was applied at a rate of 1 lb/1000 ft 2 N as urea N, SCU-N, a 50:50 mixture of SCU and urea, or a 25:75 mixture of urea and IBDU. ...
Best management practices (BMPs) for Florida's green industries have been established since 2002. BMPs for nonagricultural industries such as commercial lawn care were developed in 2002 by the Florida Department of Environmental Protection (FDEP), the University of Florida Institute of Food and Agricultural Sciences (UF/IFAS), and other parties. The BMP educational program, delivered primarily by UF/IFAS extension in partnership with the FDEP, began in 2003 as a voluntary program. As a result of increasing concerns regarding lawn fertilization and potential harmful effects on ground and surface waters, several local governments throughout the state require commercial fertilizer applicators to have a certificate of completion in a BMP educational program. The BMP program emphasizes appropriate fertilization practices to reduce nonpoint source pollution, including proper rates, timings, and application of fertilizers. Research done on fate of fertilizer applied to turfgrass demonstrates that a properly maintained lawn provides an effective means for uptake of nutrients. Some of the factors that have been shown through research to increase the opportunity for nutrient leaching include nitrogen (N) application at higher than recommended rates, excess rainfall after fertilization, and fertilization at a time when turf is not actively growing. Research results vary regarding N source and the difference in nitrate leaching resulting from N source. To provide concise research-based information for lawmakers and elected officials in Florida, there is currently a large research project underway to further quantify nutrient leaching under a variety of circumstances. Results of this research should form the basis for future regulations regarding fertilizer applications.
... Studies of residential fertilization (e.g., Cisar et al. 2004) have shown strong covariance between applied loads and resulting leachate concentrations (Morton et al. 1988), but with peak observed nitrate concentrations of 2.6 mg/L at nearly 250 kg/ha/yr application rates. Confounding factors in estimating loads are irrigation rate, which varies widely for urban lawns, and the quantity of soil organic matter (Park 2006). Park (2006) found only weak differences in loading between standard mineral fertilizers and slow release varieties, contrary to findings in Cisar et al. (2001). ...
... Confounding factors in estimating loads are irrigation rate, which varies widely for urban lawns, and the quantity of soil organic matter (Park 2006). Park (2006) found only weak differences in loading between standard mineral fertilizers and slow release varieties, contrary to findings in Cisar et al. (2001). Similar work in row crop fields (e.g., Hubbard and Sheridan (1989) for the SE Coastal Plain) supports the elevated concentrations predicted by the modeling output in Table 4. Tree crops (peaches, citrus, pecans) have been studied for groundwater nutrient enrichment. ...
Summary A discussion of the effects of nutrients on springs biota and ecosystems of necessity requires an understanding of the manner and mechanism of nutrient delivery. Moreover, as evidence accumulates for particular consequences of nutrient and contaminant loading, understanding how those loads can be attenuated is crucial. This chapter focuses on nutrient loading to springsheds, with an emphasis on processes of transport and attenuation that are germane to their delivery to springs. It starts by describing the flowpaths and hydrogeology of Florida's karst systems, with an emphasis on intrinsic vulnerabilities to nitrogen loading in particular. A discussion about land use and land cover change, and the sources of nutrient pollution, follows. Nitrogen loading is by far the most well studied spring contaminant, but examination of other changes that have occurred in springs, including changes in flow, dissolved oxygen, hardness and conductivity that have been documented within and across springs is informative. Attention is also set on the future of nutrient loading, including the potential saturation of phosphorus along subsurface flowpaths, with important implications for the timeline of nutrient load reduction. Finally, the state of our understanding of springsheds as closed systems of water and solutes is examined, with an emphasis on areas of uncertainty that are relevant questions for future research. The Literature: What is Known From this review of the existing literature on nutrient loading there are four essential areas for which managers can proceed with relative certainty: • Complex flowpaths and a wide distribution of residence times characterize the hydrogeology of the Floridan Aquifer. The timeline and source area of water delivered to springs is of critical importance to springshed management, but these physical attributes are poorly constrained in karst systems. The presence of large conduits, uneven limestone porosity, complex potentiometric gradients and shallow relief make the delineation of springsheds an area of active research. • Karst landscapes are vulnerable to pollutants from anthropogenic activities at the surface. The implications of this are profound for land use planning. In particular, it is clear that the risks of aquifer contamination are greatly attenuated in regions of the state and springshed where regional confining layers (e.g., Hawthorn Formation) limit the rate of interaction between surface and Floridan Aquifer waters. Nitrogen (in nitrate form) is particularly problematic because it is effectively inert, and therefore readily transported,
... This increase in N leaching was not seen in the samples collected at the subsequent collection dates in each FCs. Park (2006) found that regardless of season and N sources in all cycles, NO 3 -N leaching peaked shortly after fertilization and did not follow any consistent trend. Other studies have also found similar results (Petrovic, 2004;Johnston et al., 2003;Geron, et al., 1993, Sheard et al., 1985. ...
