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Urban Water Quality and Fertilizer Ordinances:Avoiding Unintended Consequences:A Review.... 12 also noted a particularly high degree of plant species could predict when P fertilization could resume.The diversity or richness in urban areas.These studies majority of soils in a North Carolina study did not suggest that urban soils offer potential for using the need P fertilizer(Osmond and Hardy,2004). diversity for the development of sustainable management practices for improving the capacity of Urban soil systems can be responsible for the urban landscape to deliver environmental benefits. significant N losses due to denitrification(Grof iman and Crawford,2003).Their studies in an urban Urban soils can be highly disturbed due to the riparian zone in Baltimore,Maryland,showed strong excavation,grading,soil moving,and construction positive relationships between soil moisture and processes,and fill-soils can take many forms organic matter and denitrification.These authors (USDA-NRCS,2005).Urban soils can be highly suggested taking advantage of these soil properties in compacted during the construction period and the storm water treatment in urban environments. water infiltration rate is reduced in these compacted soils(Gregory et al.,2006).These authors found that The potential for nutrient retention can be great construction activity reduced infiltration rates 70 to for urban soils,especially for lawns.This is because 99%and infiltration rates were typically lower than lawns are typically managed with irrigation and design storm infiltration rate(10 inches per hour) fertilizer to encourage plant growth and development used in northern Florida.Understanding these soil (Pouyat et al.,2010).Plant biomass is converted to formation and transformation processes is important soil organic matter,especially in lawns,and this for developing(after construction)and maintaining organic matter retains nutrients and water. landscapes that achieve the desired aesthetic Unfertilized lawns would reduce their productivity properties yet also do not result in degradation of and reduce their nutrient retention capacity.The key nearby water bodies.Paving and compacted soils can will be to balance the amount of nutrient inputs be facilitators of urban runoff and pollution.In a during the summer with the need to maintain meta-analysis of research studies on the relationship nutrient-assimilation capacity and organic matter between impervious surface and stream water quality, building capacity with reductions in nutrient losses to Schueler et al.(2009),found the impervious cover water bodies. model was supported;stream water quality can be In summary,research shows that urban soils can predicted from impervious cover percentage.Relative be highly disturbed yet maintain a high degree of proportion of open urban turf and landscape areas and capacity to benefit the environment.Urban soils are impervious areas should be considered to minimize highly variable in nutrient-supplying and retention runoff impacts on stream water quality capacities.Urban landscape management,especially (USDA-NRCS,2005).However,municipalities for soil disturbance,fertilization,and irrigation,is a considering regulations regarding limits to critical factor determining whether a soil/landscape impervious cover should first conduct a system will be a nutrient sink or a nutrient source and comprehensive evaluation of receiving water bodies the degree to which it will either retain or release and environmental assessments such as sources and nutrients.Research shows the most effective mitigation because limits may lead to increased approach to reducing nutrient losses will not be a environmental problems(Jones et al.,2005). one-size-fits-all approach,such as a fertilizer ban Plant growth and health are related to soil across all landscapes.Proper fertilization is needed to properties(USDA-NRCS,2005).For example,soils maintain healthy turfgrass that retains nutrients and that are high in organic matter(>3%)may require water. less N than soils with low organic matter(1%or less) because significant amounts of N can be made available from the organic matter in these soils. Urban soils that test high in P content would be unlikely to require additional P fertilization for at least several years,and then a well-calibrated soil test 13 - 19