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Urban Nutrient Management Research UpdateAmy Shober, Ph.D.Soil & Water Science Department University of Florida Gulf Coast REC1Topics for DiscussionResponse of Landscape Grown Ornamentals to N FertilizationNutrient Leaching from Simulated Mixed Landscapes During EstablishmentNutrient Leaching from Established Mixed Landscapes.Urban Landscapes

Complex systemMany land ownersDiverse vegetationSoil issuesMany questions remainHow much fertilizer do we need?What is the potential for nutrient loss?

3Response of Landscape Grown Ornamentals to Nitrogen fertilizationLandscape FertilizationLevel of MaintenanceN fertilizer recommendationlb 1000 ft-2Basic0-2Moderate2-4High4-6Florida Green Industries BMPs N Fertilizer RecommendationsCurrent N fertilizer recommendations for ornamental plants growing in the landscape is vague. We dont really know how much N or P that ornamental landscape plants need, let alone how much fertilizer is actually being applied in urban landscapes.

Compare to growing corn. For example, if we were to grow 150 bushel corn, we would expect to add 150 lb/ac N.5Research ObjectiveHow much N is needed to grow ornamentals in the landscape?

Research ObjectiveDetermine plant response of selected ornamental plants to N fertilizer in the landscape.

Due to the limited amount of research related to fertilizer N response of landscape grown annual bedding species, we recognize the need to validate existing N rate recommendations for annual bedding species. The objective of this research was to evaluate plant response of selected warm and cool season annuals to N fertilizer applied at five rates in the landscape. The overall goal was to validate, or if necessary, update current N fertilizer recommendations for annual plants grown in the landscape.

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Experimental DesignAnnuals, perennials, vines, groundcovers, and shrubs evaluatedRaised beds with soil fill (no mulch) or field (shrubs only)Data collection over 2 yearsPolymer coated N fertilizer applied at 5 ratesOther nutrients applied based on soil test

Completely randomized design3 beds/treatment (Total 15 beds)4 groups of 3 individual plants/bedTotal 36 plants/treatment

7Nitrogen Fertilizer RatesAnnual N Fertilizer RateAnnuals Total N Applied lb 1000 ft-2 00.0020.6941.3862.10124.20Revisit need to total N

Only put in kg/ha8Data Collection & AnalysisPlant response parametersPlant size index (cm3) = H W1 W2Quality rating (1-5)SPAD (proxy for chlorophyll content)Dry biomass (at harvest)Tissue TKN (at harvest)Measured several plant growth parameters and visual quality ratings. Data analysis was done with standard statistical methods.9

12 lb NPlant Response to N Fertilizer2 lb N4 lb N0 lb N10Regression AnalysisOptimum N rate = 3.5-3.8 lb 1000 ft-2If we follow the traditional method for determining N rate based on growth response, we would use a regression analysis to determine the N rate where we reach the maximum growth, yield, etc. If we do this with our annual species, the statistics tell us that we need to apply N at an annual rate between 10 and 11 lb/1000 sq feet.

153 168 lb/ac

171 kg ha-1 for 150 bushel corn11Plant Quality Response0 lb N/1000 ft212 lb N/1000 ft2

12Plant Quality Response12 lb N/1000 ft24 lb N/1000 ft2

Annuals Fertilizer RatesBased on plant growth and quality response of plants to slow-release N fertilizer in unmulched sandy fill soil.Season and SpeciesOptimum Annual N Rate (lb/1000 ft2)GrowthQualityCool seasonDianthus11 164 6Pansy10 14+4 6Snapdragon10 210 2Warm seasonMelampodium9 160 2Vinca11 17+4 6 Zinnia8 17+0 2Perennials Fertilizer RatesSpeciesOptimum Annual N Rate (lb/1000 ft2)GrowthQualityBush daisy9 114 6Caladium7 12+ 2 4Liriope12+4 6Lantana10 12+12 (0-54 WAP)0 (54-96 WAP)Salvia8 12+12 (0-30 WAP) 0 (30-96 WAP)Based on plant growth and quality response of plants to slow-release N fertilizer in unmulched sandy fill soil.Shrub Fertilizer RatesSpeciesOptimum Annual N Rate (lb/1000 ft2)GrowthQualityIndian hawthornNo growth response0-2 (76 WAP)Knock out roseNo growth response4 (39 WAP)Sweet viburnumNo growth response4 (27 WAP)Based on plant growth and quality response of plants to slow-release N fertilizer in unmulched sandy fill soil.Quality response for viburnum began at 27 WAP, for rose at 39 WAP, and for indian hawthorne at 24-31 (12 lb) and after 76 (0-2 lb).16Preliminary ConclusionWe can reduce N applications by up to 60% if we fertilize to achieve acceptable quality plants compared with optimizing growth response.Most ornamental plants evaluated achieved acceptable quality when fertilized within current IFAS rates.

Results of our annuals research suggests that we can reduce N applications by 60% when we fertilize to achieve acceptable quality plants compared with optimizing growth response.

This reduction in nutrients applied can result in a lower risk of N losses from urban landscapes.17Continuing ResearchScreening of additional species underway in field and fill soils.Quantifying effect of N rate, timing, and application method N leaching.

There are many more species of ornamentals than we can evaluate, but we continue to screen additional species to help us refine N fertilizer recommendations with the hopes we can reduce nutrient inputs to urban landscapes. We are also working to determine the effect of 18Nutrient Leaching From Simulated Residential LandscapesNutrient Losses from Urban Landscapes

Nutrients from lawns & landscapes linked to coastal eutrophicationFocus of regulatory measures (e.g., fertilizer ordinances, bans, and blackouts)

As we discussed earlier, coastal eutrophication is an increasing problem and is, at least in part, related to urban land-based activities. As a result, urban landscapes have been the focus of regulatory measures, such as fertilizer ordinances, fertilizer bans, and or blackout periods. These actions arent based on scientific research, but rather the idea that limiting fertilizer use will improve water quality. But we dont even know what is coming off these landscapes. 20

Florida-Friendly LandscapingFlorida Friendly design courtesy of Dr. Gail Hansen

Right Plant, Right PlaceMore emphasis on using the right plant in the right place which often means replacing turf areas with ornamental plantings. The ideas is that these lower input plants will reduce the potential for nutrient losses.

21Nutrient Leaching from Urban LandscapesWill more nutrients be lost from landscapes with a higher proportion of ornamental plants?

Most studies evaluating nutrient losses from urban landscapes have been conducted in turfgrass systems. In general, these studies did not look at the potential for nutrient losses from ornamental plant beds.

Recently, there has been a lot of interest in comparing the potential for nutrient losses from turf areas vs. ornamental areas. This is partly due to the fact that our major state-wide extension program, called Florida-Friendly Landscaping, touts the use of turf only in areas where is serves a purpose. In other words, they suggest following a Right Plant, Right Place approach. The theory behind this is that turfgrass is high maintenance, requiring a lot of inputs (e.g., water, fertilizer, pesticides). If turf is replaced with Florida-Friendly plants that require lower inputs of fertilizer and water, then the risk for nutrient losses from these landscapes should be reduced. This was all fine and good until researchers set out to quantify nutrient losses from turf monoculture as compared with mixed ornamental landscapes.

Most of the work conducted in Florida has suggested that more nutrients are leached from mixed ornamental landscapes than turf areas. Even some of the work our group did found this. However, we think that there are several things at play with these results. First, we believe that the ornamental landscapes received more fertilizer than needed (we will discuss this in the next section). Second, most of the research was conducted during the first year after planting. Unlike turf, the root systems of container grown ornamentals are confined to the planting hole following transplant into the landscape. For woody plants, it can take up to 6-12 months before root systems are fully established. Therefore, there are no roots to intercept water flow. In addition, fertilizer was broadcast in most of these studies. If there are no roots where fertilizer is placed, then it is subject to leaching losses.

Previous studies also look at the leaching losses from ornamental beds and turf areas seperately.

22Nutrient Leaching During Establishment of Simulated Residential LandscapesResearch ObjectiveTo determine the effect of vegetative cover type on the potential for nutrient losses during the establishment of landscape plants.Therefore, we wanted to24Landscape Plot Installation

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Experimental Design24 Mixed Plots planted in Feb. 2008St. AugustineGalphimiaIndian HawthornFertilizer & water applied based on IFAS recommendationsDrainage collected weekly and analyzed for inorganic N and P.

LiriopeBurford HollyOne time compost application at of 508 m3ha-1 (256 Mgha-1 ). Based on horticultural rates suggested by Bassuk. Approximately 30% by volume.26Drainage DepthP1P2P3P4Phosphorus LoadBars with different letters indicate a significant difference at =0.05 using Tukeys HSD Test.aabbbbaaaaNitrate LoadsBars with different letters indicate a significant difference at =0.05 using Tukeys HSD Test.babababaaaConclusionRisk of nutrient leaching is higher for ornamental beds than for turf during plant establishment. Landowners should prevent applications of nutrients and water to areas of the soil that do not contain plant roots during plant establishment.significant areas of ornamental plant beds do not necessarily leach more nutrients than turfgrass monoculture.

Plant roots of established ornamental species may be the reason that little significant treatment effects were observed.

30Nutrient losses from Established mixed landscapesResearch ObjectiveTo determine the effects of plant cover (turf vs. woody ornamental) on nutrient leaching from established urban landscapes.Therefore, we wanted to32

Materials and MethodsThree landscape treatments established in nine (1113) drainage lysimeters (3 reps)

Three mixed landscape treatments were established in 2007 in drainage lysimeters at the Mid-Florida REC in Apopka (near Orlando). Each treatment was replicated 3 times.

Lysimeters allow for collection and quatification of all drainage water.33Materials and Methods

Treatment 190% Turf10% Ornamental88.9 kg N ha-19.92 kg P ha-1

Treatment 275% Turf25% Ornamental142 kg N ha-118.0 kg P ha-1

Treatment 360% Turf40% Ornamental195 kg N ha-126.0 kg P ha-1Explain treatments.

All plants irrigated with deficit irrigation system (part of a separate research study). All turf fertilized based on IFAS recommendations and ornamentals based on the recommendations of the ESTL. [List total amount of N and P applied per treatment.]34Materials and MethodsDaily subsamples weekly flow-weighted sampleLeachate analyzed for: Nitrate(+nitrite)-N (NOx)Ammonium-N (NH4)Total Kjeldahl N (TKN)Dissolved P (DP)Total P (TP)

We report volume, flow-weighted concentration and loads, but for the purposes of this talk, we will just show volume, concentrations, and cumulative loads over the first 18 weeks.

35Lysimeter DrainageLeachate volume data indicated that rainfall drives leaching events, and that turf was less effective at intercepting and using water than ornamentals.36Cumulative Nutrient LoadsBars with different letters indicate a significant difference at =0.05 using Tukeys HSD Test.Higher leachate volumes collected from the 90% turf treatment did not result in signficiant higher losses of dissolved P or nitrate. However, it appears turf was not as effective as ornamentals at utilizing non nitrate forms of N.37Mass Balance (18 weeks)TreatmentInputOutput% Leached kg ha-1Nitrogen90% Turf89.014.015.475% Turf1426.34.560% Turf1956.63.4Phosphorus90% Turf9.922.323.675% Turf18.01.58.460% Turf26.01.14.1The nutrient mass balance for the first 18 weeks of data collection shows trends that contradict the common idea that adding more nutrients will result in higher nutrient losses. In this study, we showed that even though more N and P was applied as ornamental proportion increased, total N and P losses in leachate were much lower than for the 90% turf treatment. In fact, the 60% turf treatment leached 3.4% of N and 4.1% P, compared with 15.4% N and 23.6% P for the 90% turf treatment.

Round to 1 decmal38ConclusionIncreasing the proportion of established woody ornamentals can improve nutrient use efficiency and decrease N losses in leachate from urban landscapes.

significant areas of ornamental plant beds do not necessarily leach more nutrients than turfgrass monoculture.

Plant roots of established ornamental species may be the reason that little significant treatment effects were observed.

39AcknowledgmentsCooperatorsVimala NairKimberly MooreRichard BeesonGary KnoxGeoff DennyCraig StanleyIFAS Statistics Consulting Service

Graduate studentsZhixuan QinShawna LoperResearch ScientistsGitta ShurbergNancy WestChristine WieseTim DavisFunding AgenciesSouthwest FL WMDFlorida DACs

Questions?

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