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Urban Water Quality and Fertilizer Ordinances:Avoiding Unintended Conseauences:A Review.... 8 Leached N averaged 0.23%of the total N applied P.Turf scientists recommend returning grass over two years for Kentucky bluegrass(Miltner et al., clippings to the lawn so the nutrients can be recycled. 1996).Total recovery of N was 64 and 81%for Fertilizer N was rapidly converted to non-mineral Spring and Fall,pointing to potential gaseous losses forms within 3 weeks of application and the loss of N of N.Research shows that the active growth period is was mostly due to volatilization and denitrification the time when the grasses have the greatest ability to (Starr and DeRoo, 1981).Fertilizer N,accounted for take up nutrients,due to larger,denser,and more by direct measurement,was 76%where clippings actively growing root and shoot systems.Following were returned and 64%where clippings were not recommended fertilization practices helps maintain returned.Clippings management affected N healthy turfgrass with a strong,expansive root system fertilization,turf growth,and quality in a study in to absorb nutrients,especially during periods of active Connecticut by Kopp and Guillard(2002).These growth in the summer.Recommended fertilization scientists found that returning grass clippings did not rates lead to dense turf growth that prevents erosion decrease turf quality,but did result in an increase in N and slows overland transport of water and nutrients uptake and recovery.These research reports show that (Easton and Petrovic,2004).Nitrate leaching was returning clippings to the lawn is an important aspect three times greater from turfgrass that had been killed of good N and P management in the turfgrass than when Kentucky bluegrass turfgmss was living system. (Jiang et al.,2000).The latter authors stressed the importance of living turf roots in stabilizing nitrate-N Fertilizers can be supplied in soluble(fast)or in the turf-soil ecosystem. slow-or controlled-release forms.Controlled-release fertilizers have been shown to be effective for Root biomass of warm-season grasses declines producing healthy turfgrass(Sartain, 1981;2008; in the fall(Figure 2).Bushoven and Hull(2001) Petrovic, 1990)and reducing the potential for showed that the nitrate assimilative capacity of roots nutrient losses(Saha et al.,2007; Snyder et al., 1984) correlates with greater dry matter allocation to root from lawn grasses.Similarly,research also shows mass by the whole plant.This greater nitrate that properly managed soluble N sources can result in assimilative capacity was correlated with increased N low leaching losses.This result was observed by uptake efficiency in one of the two grass species Sartain(2008)and Quiroga-Garza et al.(2001).The studied.Bermudagrass roots were more competitive latter authors found that highly insoluble N sources than the soil microbial population for assimilating reduced N leaching losses but had negative impacts on nutrients(Wherley et al.,2009).Grass(annual turf growth and health.These authors,however, bluegrass and bentgrass)with greater above-ground pointed out that a trade-off between turf color and N biomass also had greater root biomass that,in turn, leaching may be important,i.e.,lighter green turf led to more N uptake(Pare et al.,2006).Bowman et color is associated with reduced N leaching losses, al.(1998)showed that deep-rooted turf resulted in which may be an important consideration in the less nitrate-N leaching losses than a shallow-rooted turfgrass system.They determined that proper N turf.Nitrogen uptake efficiency was greater with fertilization and irrigation practices,even with increased amounts of finer,fibrous roots,while soluble N sources,can avoid risks of N leaching amounts of thick roots had little impact on N uptake losses.These latter two conclusions suggest the rate(Sullivan et al.,2000).Increased rhizome length importance of a rigorous homeowner education had a negative relationship with N uptake efficiency. program about fertilizer sources and application in These studies showed that management practices that the overall management of fertilizer in the urban lead to better root development,especially deeper environment. root expansion and more fibrous roots can be important in controlling fertilizer N leaching. UF/IFAS research showed that leaching was negligible during the summer months from St. Management of turf clippings is important for N Augustinegrass grown with a commercial fertilizer management in the turfgrass system.Turfgrass containing 62%soluble/38%controlled-release N at a clippings are a large repository of assimilated N and 1.0 lb N/1000 sq.ft.rate(Erickson et al.,2001).The ( 3- Is