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Urban Water Quality and Fertilizer Ordinances:Avoiding Unintended Consequences:A Review.... 10 New research at UF/IFAS(accepted for allowed time for nutrient uptake by the turfgrass, scientific peer-reviewed publication)has shown that reducing the N concentration in the runoff to the leaching from turfgrass is greater in the spring and concentration in the rain water(Erickson et al., fall than in the summer.In a Florida DEP-funded 2001).Bare-soil areas are most prone to soil erosion project,Trenholm et al.(2011)found that more that carries nutrients with the displaced soil. fertilizer is lost from fertilizer applications made during the time of year when the turfgrass is not Buffer strips consisting of healthy turf grass are actively growing and that the lowest leaching levels used to capture,filter,and reduce nutrient runoff were during the period of active growth(summer). (Cole et al., 1997; Steinke et al.,2007).Buffer strips The following are some results from the multi-year as small as 2 feet wide have reduced runoff, study: compared with no buffer strips.Dense turf vegetation reduces runoff by creating"tortuous pathways"that 1.As St.Augustinegrass matured after the first reduce runoff rate thus enhancing infiltration.Water establishment year,NO3-N leaching in the can be filtered of its sediment and nutrient load by summer was minimal,even at very excessive turf shoots and roots.For example,doubling the application rates.No significant correlation with number of turfgrass shoots in a lawn reduced the N rate and NO3-N leaching was found. amount of runoff by 67%(Easton and Petrovic, 2004).Weedy,unhealthy lawns had three times more 2.Zoysiagrass was more prone to leaching at high N runoff than a healthy,dense turf(Easton,2004; N rates.Less N was needed for zoysiagrass Easton,2006). health and quality than for St.Augustinegrass. Research summarized above shows that healthy 3.Greater disease pressure leads to less healthy turf turfgrass plays a major role in absorbing nutrients, and more NO -Nleaching. especially in the periods of active growth.Further, 4.There was greater NO3_Nleaching in spring and research shows that nutrient-deficient turfgrass is less fall. effective than healthy turfgrass at reducing runoff volume and nutrient losses.The research shows that 5.All cultural practices,including fertilization and the mass of a healthy turfgrass root system plays a irrigation,are important to reduce nutrient losses large role in removing nutrients from the soil,and from turfgrass. that a healthy plant is required to produce a healthy root system. 6.Even at high application rates imposed in this study,NO3-Nleaching did not exceed 1.3%of Iron and N are two essential nutrients for plants the applied N in St.Augustinegrass. (Barber, 1984;Epstein and Bloom,2005).Deficiency of either nutrient shows up as yellowing of the 7.Turfgrass quality and health were adequate with turfgrass.Fe is involved in the synthesis of the current UF/IFAS fertilizer recommendations. chlorophyll and N is part of the chlorophyll molecule, Effectiveness of healthy turfgrass in which gives plants their green color(Marschner, preventing soil and nutrient losses by 1995).Iron can be rendered unavailable to turfgrass in high-pH(>7.2)soil at certain times in the year erosion (Carrow et al.,2001;Turgeon,2008).Reduced Erosion in urban landscapes can be a serious availability of Fe occurs in spring when the high-pH problem resulting in loss of topsoil and the associated soils are cool and the root system is not very active in nutrients.Reducing the velocity of runoff water with absorbing Fe,as it is recovering from winter dense,healthy turfgrass will increase infiltration and dormancy(Carrow et al.,2001).Iron yellowing result in groundwater recharge(Blanco-Canqui et al., ("iron chlorosis")also can occur in the summer when 2004;2006;Easton and Petrovic,2004).Healthy turfgrass is growing rapidly(possibly just after a turfgrass captured runoff that contained nutrients and nitrogen application).In this situation not enough displaced soil from a 10%slope.Capturing the runoff iron is available from the soil to meet the rapid 13-1'l