Excess nutrient loading to water bodies from urban and agricultural landscapes can accelerate eutrophication, which results in excessive algae growth, death of fish and other aquatic species, and degradation of overall water quality (Howarth, 1988). Burkholder et al. (1992) reported surface-water quality degradation at nitrate (NO3−) levels as low as 0.05 to 0.1 mg·L−1. Excessive or poorly timed fertilization of residential landscapes can result in water quality degradation as nutrients, particularly nitrogen (N) and phosphorus (P), are lost in leachate or runoff. For example, Line et al. (2002) reported that the average total N and P exported from a residential setting was 269% and 302%, respectively, greater than from wooded sites. Although fertilizer is not the sole contributor to N exports from residential landscapes it is the most direct and deliberate addition of these nutrients to the urban ecosystem. As such, improving the fertilizer management practices (e.g., application rates, timing of application, and method of application) of consumers and the commercial green industry is an important step in reducing nonpoint nutrient losses from urban landscapes.
Nationwide, state and local lawmakers have addressed environmental concerns surrounding fertilization of urban landscapes by passing a range of season- and/or formulation- specific fertilization bans (mainly for turfgrass) in areas with impaired water bodies that are linked to watersheds that have elevated nutrient loads (e.g., Chesapeake Bay, Gulf of Mexico delta-Mississippi River basin, Florida Everglades). In 2007, the Florida Legislature appointed the Florida Department of Agriculture and Consumer Services to create the Florida Consumer Fertilizer Task Force, which helped to develop recommendations for statewide policies and programs regarding consumer fertilizer use (Hartman et al., 2008). As Florida’s state agencies worked to implement plans for the statewide protection of surface and groundwater, many local governments began to implement their own preventive measures via county and city-wide fertilizer ordinances. As a result of these local actions, several counties and municipalities in the Tampa Bay region (and other areas of Florida) adopted a summer fertilization blackout period with the goal of decreasing nutrient losses during the rainy season (i.e., 1 June to 30 Sept. in Manatee County, FL; Manatee County Florida, 2012). However, the fertilizer blackout period coincides with the period of active plant growth in Florida. The full impact of these fertilizer blackout periods on plant growth and the environment has yet to be evaluated; scientific studies on this topic are limited in the literature.
Beyond directly limiting fertilization, many industry and government organizations have created standards or best management practices (BMPs) that help guide landscape maintenance efforts. For example, the American National Standard Institute’s (ANSI) A300 Tree Care Standard for Fertilization and the Florida-friendly Landscaping™ Green Industries BMP manual (American National Standards Institute, 2011; Florida Department of Environmental Protection, 2010) provide standard recommended fertilizer application rates and other guidelines for maintaining woody ornamentals. Industry consensus and limited research serve as the basis for these published application rates (Shober et al., 2010). Shober et al. (2013) found that annual N application rates of 98 to 195 kg·ha−1 were sufficient to maintain acceptable plant growth [i.e., volume or size index (SI), chlorophyll content, and dry weight] and visual quality of several woody ornamental landscape plant species grown in Florida. Similarly, Werner and Jull (2009) reported annual N application rates of 49 to 146 kg·ha−1 were able to support the healthy growth of young common hackberry (Celtis occidentalis L.) trees in Wisconsin. Both researchers reported optimal fertilizer application rates within the ANSI’s standard recommendation rate range of 49 to 195 kg·ha−1 annually for woody ornamentals (American National Standards Institute, 2011).
Previous research on fertilization of woody ornamentals in the landscape has focused on root growth (Struve, 2002), shoot growth (Gilman et al., 2000; Struve, 2002), and/or aesthetic plant response (Shober et al., 2013, 2014) to fertilizer applications. Yet, few studies have looked at the environmental impacts when applying fertilizers at rates recommended to optimize shoot growth and aesthetics (Rose, 1999; Shober et al., 2010). Among the studies that evaluate the potential for nutrient losses when fertilizing woody ornamentals, Qin et al. (2013) noted that nutrient losses from urban landscapes (containing turfgrass and ornamentals) were reduced when established woody ornamentals were included in fertilized Florida landscapes. In contrast, Erickson et al. (2008) reported that nutrient losses from mixed ornamental plant beds (once fully established) were similar to those from turfgrass monoculture. Our research expands on previously published work to determine the impacts of application rate, method, and timing on woody ornamental health and N leaching from urban residential planting beds. The overall goal of this study was to refine current fertilization standards and BMPs for woody ornamentals by identifying fertilizer rates, application methods, and timing recommendations that account for both the aesthetics of the ornamentals and the potential for nutrient losses to the surrounding environment.
American National Standards Institute2011A300 (Part 2) American national standards for tree care operations: Tree shrub and other woody plant maintenance standards practices (Fertilization). Tree Care Ind. Assn. Inc. Manchester NH
BremnerJ.M.1996Nitrogen p. 1085–1122. In: D.L. Sparks A.L. Page P.A. Hemlke R.H. Loeppert P.N. Soltanpour A. Tabatabai C.T. Johnston and M.E. Sumner (eds.). Methods of soil analysis Part 3: Chemical methods. Soil Sci. Soc. Amer. Madison WI
BroschatT.K.MooreK.A.2010Effects of fertilization on the growth and quality of container-grown areca palm and chinese hibiscus during establishment in the landscapeHortTechnology20389394
BurkholderJ.M.MasonK.M.GlasgowH.B.1992Water-column nitrate enrichment promotes decline of eelgrass Zostera marina: Evidence from seasonal mesocosm experimentsMar. Ecol. Prog. Ser.81163178
de MendiburuF.2014Agricolae: Statistical procedures for agricultural research. R package version 1.1-6
EricksonJ.E.CisarJ.L.SnyderG.H.ParkD.M.WilliamsK.E.2008Does a mixed-species landscape reduce inorganic-nitrogen leaching compared to a conventional St. Augustinegrass lawn?Crop Sci.4815861594
FisherP.R.WikR.M.SmithB.R.PasianC.C.Kmetz-GonzálezM.ArgoW.R.2003Correcting iron deficiency in calibrachoa grown in a container medium at high pHHortTechnology13308313
Florida Department of Environmental Protection2010Florida friendly best management practices for protection of water resources by the green industries. Florida Dept. Environ. Protection Tallahassee. 6 Sept. 2016. <http://fyn.ifas.ufl.edu/pdf/grn-ind-bmp-en-12-2008.pdf>.
GilmanE.WieseC.PazM.ShoberA.ScheiberS.MooreK.BrennanM.2009Effects of irrigation volume and frequency on shrub establishment in FloridaJ. Environ. Hortic.27149–154
HochmuthG.NellT.SartainJ.UnruhJ.B.MartinezC.TrenholmL.CisarJ.2011Urban water quality and fertilizer ordinances: Avoiding unintended consequences—A review of the scientific literature. Univ. Florida Inst. Food Agric. Sci. Gainesville. 6 Sept. 2016. <http://edis.ifas.ufl.edu/ss496>.
HochmuthG.NellT.UnruhJ.B.TrenholmL.SartainJ.2012Potential unintended consequences associated with urban fertilizer bans in Florida-A scientific reviewHortTechnology22600616
KidderG.HanlonE.A.YeagerT.H.MillerG.L.1998IFAS standardized fertilization recommendations for environmental horticulture crops. Univ. Florida Inst. Food Agr. Sci. Gainesville. 6 Sept. 2016. <http://ufdc.ufl.edu/IR00004609/00001>.
LineD.E.WhiteN.M.OsmondD.L.JenningsG.D.MojonnierC.B.2002Pollutant export from various land uses in the upper Neuse River BasinWater Environ. Res.74100108
Manatee County Florida2012Ordinance No. 11–21. Manatee Board of County Commissioners Bradenton. 7 Sept. 2016. <http://www.mymanatee.org/dms/departments/natural-resources/fertilizer-ordinance-archive/Manatee-Co--Final-FertilizerOrd-11-21/Manatee-Co.-Final-Fertilizer-Ord-11.21.pdf>.
MooreK.A.ShoberA.L.GilmanE.F.WieseC.ScheiberS.M.PazM.BrennanM.M.2009Posttransplant growth of container-grown wild coffee, copperleaf, and orange jasmine is affected by irrigation frequencyHortTechnology19786791
MooreK.A.ShoberA.L.HasingG.WieseC.WestN.G.2014Effect of soil type and nitrogen rate on growth of annual and perennial landscape plants in FloridaHortTechnology24724730
MulvaneyR.L.1996Nitrogen: Inorganic forms. In: D.L. Sparks A.L. Page P.A. Hemlke R.H. Loeppert P.N. Soltanpour A. Tabatabai C.T. Johnston and M.E. Sumner (eds.). Methods of soil analysis Part 3: Chemical methods. Soil Sci. Soc. Amer. Madison WI
MylavarapuR.S.d’AngeloW.WilkinsonN.MoonD.2014UF/IFAS Extension soil testing laboratory (ESTL) analytical procedures and training manual. Univ. Florida Inst. Food Agric. Sci. Gainesville. 6 Sept. 2016. <http://edis.ifas.ufl.edu/ss312>.
MylavarapuR.S.SanchezJ.F.NguyenJ.H.BartosJ.M.2002Evaluation of Mehlich-1 and Mehlich-3 extraction procedures for plant nutrients in acid mineral soils of FloridaCommun. Soil Sci. Plant Anal.33807820
PinheiroJ.BatesD.DebRoyS.SarkarD.2014R Core Team (2014) nlme: Linear and nonlinear mixed effects models. R package version 3.1-117. 22 June 2016. <http://CRAN.R-project.org/package=nlme>.
R Core Team2011R: A language and environment for statistical computing. R Foundation for Statistical Computing Vienna Austria. 2013. R Foundation Stat. Computing Vienna Austria
RoseM.A.1999Nutrient use patterns in woody perennials: Implications for increasing fertilizer efficiency in field-grown and landscape ornamentalsHortTechnology9613617
SchoeneG.YeagerT.2006Influence of nitrogen application rate on the magnitude of root and shoot growth flushes of Viburnum odoratissimum Ker-GawlPlant Soil284121128
ShaddoxT.W.UnruhJ.B.TrenholmL.E.2016Nitrate leaching from soluble nitrogen applied to ‘Floratam’ st. augustinegrass and common centipedegrass during dormancyCrop Sci.56837844
ShoberA.L.DavisS.DukesM.D.DennyG.C.BrownS.P.VyapariS.2009aPerformance of Florida landscape plants when irrigated by ET-based controllers and time-based methodsJ. Environ. Hortic.27251256
ShoberA.L.DennyG.C.BroschatT.K.2010Management of fertilizers and water for ornamental plants in urban landscapes: Current practices and impacts on water resources in FloridaHortTechnology2094106
ShoberA.L.MooreK.A.HasingG.S.WieseC.DennyG.C.KnoxG.W.2014Effect of nitrogen fertilization rate on aesthetic quality of landscape-grown vines and groundcoversHortTechnology24604609
ShoberA.L.MooreK.A.WestN.G.WieseC.HasingG.DennyG.KnoxG.W.2013Growth and quality response of woody shrubs to nitrogen fertilization rates during landscape establishment in FloridaHortTechnology23898904
ShoberA.L.MooreK.A.WieseC.ScheiberS.M.GilmanE.F.PazM.BrennanM.M.VyapariS.2009bPosttransplant irrigation frequency affects growth of container-grown sweet viburnum in three hardiness zonesHortScience4416831687
ShurbergG.ShoberA.L.WieseC.DennyG.KnoxG.W.MooreK.A.GiurcanuM.C.2012Response of landscape-grown warm- and cool-season annuals to nitrogen fertilization at five ratesHortTechnology22368375
SmileyE.T.LillyS.J.KelseyP.2013Best management practices: Tree and shrub fertilization. Intl. Soc. Arboriculture Champaign IL
TelenkoD.E.P.ShaddoxT.W.UnruhJ.B.TrenholmL.E.2015Nitrate leaching, turf quality, and growth rate of ‘Floratam’ st. augustinegrass and common centipedegrassCrop Sci.5513201328
U.S. Environmental Protection Agency (USEPA)1993aMethod 350.1. Determination of ammonia nitrogen by semi-automated colorimitry EPA-600/4-79-020. Environ. Monitoring Systems Lab. Office Res. Dev. U.S. Environ. Protection Agency Cincinnati
U.S. Environmental Protection Agency (USEPA)1993bMethod 353.2. Determination of nitrate-nitrite nitrogen by automated colorimetry. Environ. Monitoring Systems Lab. Office Res. Dev. U.S. Environ. Protection Agency Cincinnati
USDA-NRCS2016Official soil series descriptions. Soil Survey Staff National Resources Conservation Serv. Washington. 7 Sept. 2016. <http://www.nrcs.usda.gov/wps/portal/nrcs/detailfull/soils/home/?cid=nrcs142p2_053587>.
WernerL.P.JullL.G.2009Fertilizer uptake, partitioning, and recovery in container-grown common hackberry (Celtis occidentalis) treesArboriculture Urban For.35252262
WernerL.P.JullL.G.2013Fertilizer nitrogen uptake and partitioning in young and mature common hackberry (Celtis occidentalis) treesArboriculture Urban For.398593
ZhangH.HardyD.H.MylavarapuR.WangJ.J.2014Mehlich-3. In: F.J. Sikora and K.P. Moore (eds.). Soil test methods from the southeastern United States. Southern Coop. Ser. Bul. No. 419. Clemson Univ. Clemson. 5 Dec. 2016. <http://www.clemson.edu/sera6/MethodsManualFinalSERA6.pdf>.