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<br /> Y P
<br /> of lawns. In an effort to reduce the plied N within 48 hours following grasses,runoff was reduced three-
<br /> amounts of suspended solids and nu- application (Bowman et al. 1989). fold when infiltration increased
<br /> trients in urban runoff and to comply as shoot density increased in
<br /> with the U.S.Clean Water Act,some •According to sales data, Scotts response to fertilization (Easton
<br /> states and municipalities have enacted Miracle-Gro estimates that about and Petrovic 2004).
<br /> legislation restricting lawn fertiliza- 50%of U.S.homeowners fertilize
<br /> tion.For example,in 2005,Minnesota the lawn (Augustin 2007). On •Returning clippings to the lawn
<br /> became the first state to ban most turf average, the number of annual as it is mowed does not appear to
<br /> applications of P-containing fertilizers. fertilizer applications of about 50 contribute to P runoff(Bierman
<br /> Michigan,North Carolina,Virginia, lbs.N per acre per application was et al, 2010).
<br /> Washington and Wisconsin have,or 1.8, including an estimated 10
<br /> are considering,enacting similar bans. million lawns receiving profes- •Surface roughness coefficients
<br /> In January 2011,New Jersey passed sional lawncare treatments.This are commonly used by civil engi-
<br /> the most restrictive law (The New frequency of application of N is neers to predict the potentialof
<br /> Jersey Fertilizer Law,A2290) to date, much lower than that usually rec- surfaces to contribute to overload
<br /> limiting applications of both N and P ommended by most University water flow.High coefficient values
<br /> to lawns. Extension turf professionals. reflect a potential for less runoff.
<br /> According to research conducted In a simulated rainfall experiment,
<br /> within the last 20 years,stormwater run • In 1999,it was estimated that the pavement had a low roughness ,
<br /> off from a healthy,dense lawn growing atmosphere deposits 0.36 lbs.P per coefficient (about 0.01);Short
<br /> on soils of even moderate compaction acre per year (UN Environment grass prairie,a value of 0.15;and
<br /> and slope rarely occurs.In all but very Programme 1999). both bluegrass and bermuda-
<br /> intense rainfall occurrences,stormwater grass sod,a value of about 0,4
<br /> runoff from a healthy,dense lawn is at •In Wisconsin,a conventionally (Engman 1986).
<br /> or near zero.Most notable exceptions recommended lawn fertilization
<br /> include 1) very steep slopes,2) satu- program of 130 lbs.N per acre •Most or all of the runoff from
<br /> rated or 3) frozen soils and 4) severe per year,using a 27:1.3 N:P ferti- lawns can occur when soils are
<br /> soil compaction. lizer,.would supply 6.2 lbs. P per frozen or saturated (Kussow 2008;
<br /> acre per year.Researchers at the Steinke et al. 2007).A study eval-
<br /> A research summary University of Wisconsin (Soldat uating the effect of prairie and
<br /> This summary is based on a much more and Petrovic 2008) found a range turf buffer strips on runoff from
<br /> comprehensive article by Drs.Stier and of 0 to 17 lbs.P per acre per year concrete slopes revealed that a
<br /> Soldat,titled"Lawns as a Source of reported in turf field-plot research vegetative buffer twice the size of
<br /> Nutrient Runoff in Urban Environ- projects,with typical losses from the sloped (5%) concrete area
<br /> ments," published in the Fall 2011 established turf of about 0.4 lbs. reduced annual runoff by more
<br /> issue of the Watershed Science Bulletin, P per acre per year.This com- than 60%, compared to a 1:1
<br /> journal of the Association of Watershed pares to annual P losses from concrete-to-buffer design (Steinke
<br /> and Stormwater Professionals (the native prairies of about 0.18 lbs. et al. 2007). However, the 1:1
<br /> references cited below are listed on P per acre,from conventionally concrete-to-buffer design was
<br /> page 34). tilled agricultural systems of about effective,allowing less than 1.5%
<br /> 1.69 lbs.P per acre and from con- of precipitation to run off during
<br /> •According to a three-year struction sites of more than 11.5 non-frozen conditions.Most of
<br /> study conducted in the area of lbs.P per acre (Daniel et al. 1979; the runoff from both prairie and
<br /> Baltimore,Maryland,N deposits Sharpley 1995). turf plots occurred when soils
<br /> from the atmosphere averaged were frozen,at which time runoff
<br /> 10 lbs.per acre,compared to 12.8 • In many cases,runoff is reduced totals for both types of vegetation
<br /> lbs. per acre from fertilizers, as as the stand density of a lawn were similar.
<br /> potential inputs to the watershed increases.The contiguous mass
<br /> (Grollman et al. 2004). or matrix of aerial shoots of turf- • Many naturalized areas in a home
<br /> grass plants creates a"tortuous landscape have a rough texture
<br /> • Kentucky bluegrass and peren- pathway,"slowing the flow of water and are capable of retaining pre-
<br /> nial ryegrass are able to absorb and allowing greater infiltration cipitation.A properly designed
<br /> 70% to 80% of an application of (Linde et al. 1995;Kussow 2008). and sized, bermed rain garden
<br /> 50 lbs.soluble N per acre within In one investigation conducted (flat-bottomed depression planted
<br /> 24 hours and almost all of the ap- on a mixture of cool-season turf- with trees,shrubs and native veg
<br /> Journal of the Virginia Turfgrass Council 3 l
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