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 MaintenanceN fertilizer

recommendation

lb 1000 ft-2

Basic 0-2

Moderate 2-4

High 4-6

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 evaluated

• Raised beds with soil fill (no mulch) or field (shrubs only)

• Data collection over 2 years• Polymer coated N fertilizer applied at

5 rates• Other nutrients applied based on soil

test

Nitrogen Fertilizer Rates

Annual N Fertilizer

Rate

Annuals Total N Applied

–––––––– lb 1000 ft-2 ––––––0 0.002 0.694 1.386 2.1012 4.20

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

0 2 4 6 8 10 12 140

5000

10000

15000

20000

25000

f(x) = − 39.809278866 x² + 879.84847471 x + 7843.214616R² = 0.642808522417848

f(x) = − 150.27184415 x² + 3067.6429152 x + 3036.2174931R² = 0.870848357203755

Year 1

Annual N Rate (lb/1000 ft2)

Siz

e I

nd

ex (

cm

3)

Regression Analysis

Optimum N rate = 3.5-3.8 lb 1000 ft-2

Plant Quality Response

0 lb N/1000 ft2 12 lb N/1000 ft2

Plant Quality Response

12 lb N/1000 ft2 4 lb N/1000 ft2

Annuals Fertilizer Rates

Based on plant growth and quality response of plants to slow-release N fertilizer in unmulched sandy fill soil.

Season and Species

Optimum Annual N Rate (lb/1000 ft2)

Growth Quality

Cool season

Dianthus 11 – 16 4 – 6

Pansy 10 – 14+ 4 – 6

Snapdragon 10 – 21 0 – 2

Warm season

Melampodium 9 – 16 0 – 2

Vinca 11 – 17+ 4 – 6

Zinnia 8 – 17+ 0 – 2

Perennials Fertilizer Rates

Species Optimum Annual N Rate (lb/1000 ft2)

Growth Quality

Bush daisy 9 – 11 4 – 6

Caladium 7 – 12+ 2 – 4

Liriope 12+ 4 – 6

Lantana 10 – 12+12 (0-54 WAP)0 (54-96 WAP)

Salvia 8 –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 Rates

Species Optimum Annual N Rate (lb/1000 ft2)

Growth Quality

Indian hawthorn

No growth response

0-2 (76 WAP)

‘Knock out’ rose

No growth response

4 (39 WAP)

Sweet viburnum

No 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. 2008– St. Augustine– Galphimia– Indian Hawthorn

• Fertilizer & water applied based on IFAS recommendations

• Drainage collected weekly and analyzed for inorganic N and P.

− Liriope− Burford Holly

0 10 20 30 40 50 600.0

0.5

1.0

1.5

2.0

2.5

3.0

0123456789

Orna-mental

Turf

Week

Dra

inag

e (

cm

)

Rain

fall (

cm

)

Drainage Depth

P1

P2

P3

P4

Phosphorus Load

P1 P2 P3 P4 Annual0

0.10.20.30.40.50.60.70.80.9

Ornamental

Turf

Period

DR

P L

oad

(kg

/ha)

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

a ab

b b

b

a

a

a

a

Nitrate Loads

P1 P2 P3 P4 Annual0

1

2

3

4

5

6

7

8

9OrnamentalTurf

Period

NO

3+

NO

2-N

Lo

ad

(kg

h

a-1

)

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

b

a

ba ba

b

a

aa

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 190% Turf

10% Ornamental

88.9 kg N ha-1

9.92 kg P ha-1

Treatment 275% Turf

25% Ornamental

142 kg N ha-1

18.0 kg P ha-1

Treatment 360% Turf

40% Ornamental

195 kg N ha-1

26.0 kg P ha-1

Materials and Methods• Daily subsamples

→weekly flow-weighted sample

• Leachate analyzed for: – Nitrate(+nitrite)-N (NOx)

– Ammonium-N (NH4)– Total Kjeldahl N (TKN)– Dissolved P (DP)– Total P (TP)

Lysimeter Drainage

0 10 20 30 40 500

10

20

30

40

50

60

70

80

020406080100120140160180200

60% Turf

75% Turf

Week

Vo

lum

e (

mm

)

Rain

fall (

mm

)

Cumulative Nutrient Loads

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

TKN NOx DRP0

1

2

3

4

5

6

7

8

9 60% Turf75% Turf90% Turf

Nu

trie

nt

Lo

ad

(kg

ha-1

)

a

aba

b

a

a

b

a

b

Mass Balance (18 weeks)Treatment

Input Output % Leached

–––––– kg ha-1–––––

Nitrogen

90% Turf 89.0 14.0 15.4

75% Turf 142 6.3 4.5

60% Turf 195 6.6 3.4

Phosphorus

90% Turf 9.92 2.3 23.6

75% Turf 18.0 1.5 8.4

60% Turf 26.0 1.1 4.1

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?