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Excerpts from Chesapeake Bay Urban Nutrient Management Study <br /> Recent research indicates that lawns are highly retentive of fertilizer N under typical <br /> application rates and lawn conditions. Groffman et al (2004) found approx 75% of <br /> fertilizer N was retained in urban lawns monitored in Baltimore. Kaushal et al (2011) <br /> used N isotopic ratio signatures to show watershed export of nitro en is not directl <br /> ro ortional to fertilizer inputs in Baltimore watersheds. <br /> Raciti et al (20o8) and Raciti et al (2o11b) demonstrated residential lawns have a high <br /> capacity for both carbon and nitrogen storage in plant biomass, thatch and soils. <br /> Denitrification in fertilized urban soils is significant at certain times of the year, with a <br /> loss up to 0.30 lbs/l000 sf/year, nearly all of which occurred during less than 5% of the <br /> growing season when soils are saturated and air temperatures are warm (Raciti et al, <br /> 2011a).A lawn's capacity for N storage and transient seasonal conditions supporting <br /> high de-nitrification rates may explain why other research studies found relatively low N <br /> export, despite significant N fertilizer inputs. <br /> Table 2 Core Urban Nutrient Management Practices for the Chesapeake Bay <br /> 1 Consult with the local extension service, master gardener or certified applicator to get <br /> technical assistance to develop an effective urban nutrient management plan for the <br /> property. <br /> 2 Maintain a dense vegetative cover of turf grass to reduce runoff, prevent erosion, and <br /> retain nutrients <br /> 3 Choose not to fertilize, OR adopt a reduce rate/monitor approach OR the small fertilizer <br /> dose approach. <br /> 4 Retain clippings and mulched leaves on the yard and keep them out of streets and storm <br /> drains <br /> 5 Do not apply fertilizers before spring green up or after grass becomes dormant <br /> 6 Maximize use of slow release N fertilizer during the active growing season <br /> 7 Set mower height at 3 inches or taller <br /> 8 Immediately sweep off any fertilizer that lands on a paved surface <br /> 9 Do not apply fertilizer within 15 to 20 feet of a water feature(depending on applicable <br /> state regulations) and manage this zone as a perennial planting, meadow,grass buffer or <br /> a forested buffer <br /> 10 Employ lawn practices to increase soil porosity and infiltration capability, especially <br /> along portions of the lawn that convey or treat stormwater runoff. <br />