Urban Nutrient Management Research Update Amy Shober, Ph.D. Soil & Water Science Department University of Florida Gulf Coast REC

Topics for Discussion 1.Response of Landscape Grown Ornamentals to N Fertilization 2.Nutrient Leaching from Simulated Mixed Landscapes During Establishment 3.Nutrient Leaching from Established Mixed Landscapes.

Urban Landscapes Complex system –Many land owners –Diverse vegetation –Soil issues Many questions remain –How much fertilizer do we need? –What is the potential for nutrient loss?

RESPONSE OF LANDSCAPE GROWN ORNAMENTALS TO NITROGEN FERTILIZATION

Landscape Fertilization Level of Maintenance N fertilizer recommendation lb 1000 ft -2 Basic0-2 Moderate2-4 High4-6 Florida Green Industries BMPs N Fertilizer Recommendations

Research Objective How much N is needed to grow ornamentals in the landscape? Research Objective –Determine plant response of selected ornamental plants to N fertilizer in the landscape.

Experimental Design Annuals, perennials, vines, groundcovers, and shrubs evaluatedAnnuals, perennials, vines, groundcovers, and shrubs evaluated Raised beds with soil fill (no mulch) or field (shrubs only)Raised beds with soil fill (no mulch) or field (shrubs only) Data collection over 2 yearsData collection over 2 years Polymer coated N fertilizer applied at 5 ratesPolymer coated N fertilizer applied at 5 rates Other nutrients applied based on soil testOther nutrients applied based on soil test

Nitrogen Fertilizer Rates Annual N Fertilizer Rate Annuals Total N Applied –––––––– lb 1000 ft -2 ––––––

Data Collection & Analysis Plant response parameters –Plant size index (cm3) = H × W1 × W2 –Quality rating (1-5) –SPAD (proxy for chlorophyll content) –Dry biomass (at harvest) –Tissue TKN (at harvest)

12 lb N Plant Response to N Fertilizer 2 lb N 4 lb N 0 lb N

Regression Analysis Optimum N rate = lb 1000 ft -2

Plant Quality Response 0 lb N/1000 ft 2 12 lb N/1000 ft 2

Plant Quality Response 12 lb N/1000 ft 2 4 lb N/1000 ft 2

Annuals Fertilizer Rates Based 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 ft 2 ) GrowthQuality Cool season Dianthus11 – 164 – 6 Pansy10 – 14+4 – 6 Snapdragon10 – 210 – 2 Warm season Melampodium9 – 160 – 2 Vinca11 – 17+4 – 6 Zinnia8 – 17+0 – 2

Perennials Fertilizer Rates SpeciesOptimum Annual N Rate (lb/1000 ft 2 ) GrowthQuality Bush daisy9 – 114 – 6 Caladium7 – 12+2 – 4 Liriope12+4 – 6 Lantana10 – (0-54 WAP) 0 (54-96 WAP) Salvia8 – (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 Rates SpeciesOptimum Annual N Rate (lb/1000 ft 2 ) GrowthQuality Indian hawthornNo growth response 0-2 (76 WAP) ‘Knock out’ roseNo growth response 4 (39 WAP) Sweet viburnumNo growth response 4 (27 WAP) Based on plant growth and quality response of plants to slow-release N fertilizer in unmulched sandy fill soil.

Preliminary Conclusion We 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.

Continuing Research Screening of additional species underway in field and fill soils. Quantifying effect of N rate, timing, and application method N leaching.

NUTRIENT LEACHING FROM SIMULATED RESIDENTIAL LANDSCAPES

Nutrient Losses from Urban Landscapes Nutrients from lawns & landscapes linked to coastal eutrophication Focus of regulatory measures (e.g., fertilizer ordinances, bans, and blackouts)

Florida-Friendly Landscaping™ Florida Friendly design courtesy of Dr. Gail Hansen “Right Plant, Right Place”

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

NUTRIENT LEACHING DURING ESTABLISHMENT OF SIMULATED RESIDENTIAL LANDSCAPES

Research Objective To determine the effect of vegetative cover type on the potential for nutrient losses during the establishment of landscape plants.

Landscape Plot Installation

Experimental Design 24 Mixed Plots planted in Feb Mixed Plots planted in Feb – St. Augustine – Galphimia – Indian Hawthorn Fertilizer & water applied based on IFAS recommendations Fertilizer & water applied based on IFAS recommendations Drainage collected weekly and analyzed for inorganic N and P. Drainage collected weekly and analyzed for inorganic N and P. − Liriope − Burford Holly

Drainage Depth P1P2P3P4

Phosphorus Load Bars with different letters indicate a significant difference at α=0.05 using Tukey’s HSD Test. aa b b b b a a a a

Nitrate Loads Bars with different letters indicate a significant difference at α=0.05 using Tukey’s HSD Test. b a b a b a b a a a

Conclusion Risk 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.

NUTRIENT LOSSES FROM ESTABLISHED MIXED LANDSCAPES

Research Objective To determine the effects of plant cover (turf vs. woody ornamental) on nutrient leaching from established urban landscapes.

Materials and Methods Three landscape treatments established in nine (11’×13’) drainage lysimeters (3 reps)

Materials and Methods Treatment 1 90% Turf 10% Ornamental 88.9 kg N ha kg P ha -1 Treatment 2 75% Turf 25% Ornamental 142 kg N ha kg P ha -1 Treatment 3 60% Turf 40% Ornamental 195 kg N ha kg P ha -1

Materials and Methods Daily subsamples →weekly flow-weighted sample Leachate analyzed for: –Nitrate(+nitrite)-N (NO x ) –Ammonium-N (NH 4 ) –Total Kjeldahl N (TKN) –Dissolved P (DP) –Total P (TP)

Lysimeter Drainage

Cumulative Nutrient Loads Bars with different letters indicate a significant difference at α=0.05 using Tukey’s HSD Test.

Mass Balance (18 weeks) TreatmentInputOutput% Leached –––––– kg ha -1 ––––– Nitrogen 90% Turf % Turf % Turf Phosphorus 90% Turf % Turf % Turf

Conclusion Increasing the proportion of established woody ornamentals can improve nutrient use efficiency and decrease N losses in leachate from urban landscapes.

Acknowledgments Cooperators –Vimala Nair –Kimberly Moore –Richard Beeson –Gary Knox –Geoff Denny –Craig Stanley IFAS Statistics Consulting Service Graduate students –Zhixuan Qin –Shawna Loper Research Scientists –Gitta Shurberg –Nancy West –Christine Wiese –Tim Davis Funding Agencies –Southwest FL WMD –Florida DACs

Questions?