nutrient requirements of warm-season putting...

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NUTRIENT REQUIREMENTS OF WARM-SEASON PUTTING GREEN CULTIVARS DURING GROW-IN AND THEIR DROUGHT RESISTANCE ONCE ESTABLISHED

By

JOHN HUDSON ROWLAND

A DISSERTATION PRESENTED TO THE GRADUATE SCHOOL OF THE UNIVERSITY OF FLORIDA IN PARTIAL FULFILLMENT

OF THE REQUIREMENTS FOR THE DEGREE OF DOCTOR OF PHILOSOPHY

UNIVERSITY OF FLORIDA

2010

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© 2010 John H. Rowland

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To my family

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ACKNOWLEDGMENTS

I would like to thank Dr. John Cisar for providing me the opportunity to obtain my

doctorate, and my additional advisors for their expertise, time, and devotion to the process. I

would like to thank Pamela Michels and my family for their never-ending support, as well as

everyone at the Fort Lauderdale Research and Education Center who helped with my research

project, particularly Brian Steinberg. Donations of sod from Wayne Hanna and Environmental

Turf, fertilizer from Raymond Snyder of Harrell’s, chemicals from Bayardo Herrera of UAP,

sand from John Swaner of Golf Agronomics, soil sensors from Charlie of Toro, and laser-

grading by Kevin Hardy of Ballpark Maintenance were greatly appreciated. Funding from the

Calvin L. Korf Turfgrass Research Endowment helped make this research possible.

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TABLE OF CONTENTS page

ACKNOWLEDGMENTS ...............................................................................................................4

LIST OF TABLES ...........................................................................................................................7

LIST OF FIGURES .........................................................................................................................9

LIST OF ABBREVIATIONS ........................................................................................................17

ABSTRACT ...................................................................................................................................18

CHAPTER

1 INTRODUCTION ..................................................................................................................20

Rationale .................................................................................................................................20 Turfgrass Nutrition .................................................................................................................20 Fate of Nutrients .....................................................................................................................21 Water Requirements ...............................................................................................................22 Water Sources .........................................................................................................................22 Watering Practices ..................................................................................................................23 Water Quality ..........................................................................................................................25

2 ESTABLISHMENT OF WARM-SEASON PUTTING GREEN CULTIVARS AS AFFECTED BY NITROGEN/POTASSIUM FERTILIZATION ..........................................27

Introduction .............................................................................................................................27 Materials and Methods ...........................................................................................................29

Experimental Site ............................................................................................................29 Experimental Design and Statistical Analysis .................................................................30 Fertilizer Treatments .......................................................................................................30 Measurements ..................................................................................................................30

Results and Discussion ...........................................................................................................31 Turfgrass Cover ...............................................................................................................31 Chlorophyll ......................................................................................................................32 Thatch Development .......................................................................................................32 Root Development ...........................................................................................................33 Surface Compressibility and Ball Roll ............................................................................34 Mower Scalping ...............................................................................................................34 Quality and Recovery ......................................................................................................35 Algae ................................................................................................................................36

3 DROUGHT RESISTANCE OF NEWLY-ESTABLISHED WARM-SEASON PUTTING GREEN CULTIVARS AS AFFECTED BY NITROGEN/POTASSIUM FERTILIZATION ...................................................................................................................63

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Introduction .............................................................................................................................63 Materials and Methods ...........................................................................................................65

Experimental Site ............................................................................................................65 Measurements ..................................................................................................................66 Statistical Analysis ..........................................................................................................68

Results and Discussion ...........................................................................................................68 Turfgrass Wilting .............................................................................................................68 Soil Moisture ...................................................................................................................69 Turfgrass Quality .............................................................................................................70 Chlorophyll Levels ..........................................................................................................71 Normalized Difference Vegetative Index ........................................................................71 Drought Resistance Characteristics .................................................................................72

4 DROUGHT RESISTANCE OF WARM-SEASON PUTTING GREEN CULTIVARS SODDED ON SANDY NATIVE SOIL ...............................................................................104

Introduction ...........................................................................................................................104 Materials and Methods .........................................................................................................106

Experimental Site ..........................................................................................................106 Measurements ................................................................................................................107 Statistical Analysis ........................................................................................................108

Results and Discussion .........................................................................................................108 Turfgrass Wilting ...........................................................................................................108 Soil Moisture .................................................................................................................109 Evapotranspiration .........................................................................................................111 Turfgrass Quality ...........................................................................................................111 Chlorophyll Levels ........................................................................................................112 Normalized Difference Vegetative Index ......................................................................113

5 CONCLUSIONS ..................................................................................................................149

APPENDIX

CHAPTER 2 DATA ....................................................................................................................153

CHAPTER 3 DATA ....................................................................................................................166

CHAPTER 4 DATA ....................................................................................................................180

LIST OF REFERENCES .............................................................................................................182

BIOGRAPHICAL SKETCH .......................................................................................................188

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LIST OF TABLES

Table page 2-1 Anova table for turfgrass cover of a USGA-specified research green in experiment 1

at week 13 on 1 January 2009. ...........................................................................................39

2-2 Anova table for turfgrass cover of a USGA-specified research green in experiment 2 at week 9 on 23 September 2009. ......................................................................................43

2-3 Anova table for chlorophyll index of a USGA-specified research green in experiment 1 at week 17 on 29 January 2009. ......................................................................................45

2-4 Anova table for chlorophyll index of a USGA-specified research green in experiment 2 at week 6 on 3 September 2009. .....................................................................................46

2-5 Anova table for thatch depth of a USGA-specified research green at the end of experiment 1.......................................................................................................................47

2-6 Anova table for thatch depth of a USGA-specified research green at the end of experiment 2.......................................................................................................................48

2-7 Anova table for root length of a USGA-specified research green at the end of experiment 1.......................................................................................................................49

2-8 Anova table for root length of a USGA-specified research green at the end of experiment 2.......................................................................................................................50

2-9 Anova table for surface compressibility of a USGA-specified research green in experiment 1 at week 15 on 13 January 2009. ...................................................................51

2-10 Anova table for surface compressibility of a USGA-specified research green in experiment 2 at week 10 on 3 October 2009. ....................................................................52

2-11 Anova table for ball roll distance of a USGA-specified research green in experiment 1 at week 24 on 20 March 2009. ........................................................................................53

2-12 Anova table for ball roll distance of a USGA-specified research green in experiment 2 at week 11 on 9 October 2009. .......................................................................................54

2-13 Anova table for mower scalping of a USGA-specified research green in experiment 1 at week 20 on 19 February 2009. .......................................................................................55

2-14 Anova table for mower scalping of a USGA-specified research green in experiment 2 at week 10 on 1 October 2009. ..........................................................................................56

2-15 Anova table for quality of a USGA-specified research green at the end of experiment 1..........................................................................................................................................57

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2-16 Anova table for quality of a USGA-specified research green at the end of experiment 2..........................................................................................................................................58

2-17 Anova table for recovery of a USGA-specified research green at the end of experiment 1.......................................................................................................................59

2-18 Anova table for recovery of a USGA-specified research green at the end of experiment 2.......................................................................................................................60

2-19 Anova table for algae on a USGA-specified research green in experiment 1 at week 7 on 24 November 2008. .......................................................................................................61

2-20 Anova table for algae on a USGA-specified research green in experiment 2 at week 4 on 22 August 2009. ............................................................................................................62

3-1 Physical properties of USGA-specified soil. .....................................................................73

3-2 Canopy characteristics of warm-season putting green cultivars. .......................................73

3-3 Thatch depth and root length of warm-season putting green cultivars. .............................73

4-1 Physical properties of Hallandale fine sand. ....................................................................114

A-1 Effect of potassium on turfgrass cover. ...........................................................................155

A-2 Effect of potassium on chlorophyll index. .......................................................................156

A-3 Effect of potassium on thatch depth. ................................................................................157

A-4 Effect of potassium on root length. ..................................................................................158

A-5 Effect of potassium on surface compressibility. ..............................................................159

A-6 Effect of potassium on ball roll. .......................................................................................160

A-7 Converted modified stimpmeter ball roll distances. ........................................................161

A-8 Effect of potassium on mower scalping. ..........................................................................162

A-9 Effect of potassium on turfgrass quality. .........................................................................163

A-10 Effect of potassium on turfgrass recovery. ......................................................................164

A-11 Effect of potassium on algal cover. ..................................................................................165

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LIST OF FIGURES

Figure page 2-1 Trends of weekly means for turfgrass cover during grow-in of a USGA-specified

research green in experiment 1 from 2 October 2008 – 16 April 2009. ............................37

2-2 Trends of weekly means for turfgrass cover as affected by N fertilization during grow-in of a USGA-specified research green in experiment 1 from 2 October 2008 – 16 April 2009. ....................................................................................................................38

2-3 Effect of grass*Nitrogen (N) on turfgrass cover of a USGA-specified research green in experiment 1 at week 13 on 1 January 2009. .................................................................39

2-4 Trends of weekly means for turfgrass cover, as affected by N/K fertilization ratio during grow-in of a USGA-specified research green in experiment 1 from 2 October 2008 – 16 April 2009. ........................................................................................................40

2-5 Trends of weekly means for turfgrass cover during grow-in of a USGA-specified research green in experiment 2 from 30 July – 4 November, 2009. ..................................41

2-6 Trends of weekly means for turfgrass cover as affected by N fertilization during grow-in of a USGA-specified research green in experiment 2 from 30 July – 4 November, 2009. ................................................................................................................42

2-7 Effect of grass*N on turfgrass coverage of a USGA-specified research green in experiment 2 at week 9 on 23 September 2009. ................................................................43

2-8 Trends of weekly means for turfgrass cover as affected by N/K fertilization ratio during grow-in of a USGA-specified research green in experiment 2 from 30 July – 4 November, 2009. ................................................................................................................44

2-9 Effect of grass*N on chlorophyll index of a USGA-specified research green in experiment 1 at week 17 on 29 January 2009. ...................................................................45

2-10 Effect of grass*N on chlorophyll index of a USGA-specified research green in experiment 2 at week 6 on 3 September 2009. ..................................................................46

2-11 Effect of grass*N on thatch depth of a USGA-specified research green at the end of experiment 1.......................................................................................................................47

2-12 Effect of grass*N on thatch depth of a USGA-specified research green at the end of experiment 2.......................................................................................................................48

2-13 Effect of grass*N on root length of a USGA-specified research green at the end of experiment 1.......................................................................................................................49

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2-14 Effect of grass*N on root length of a USGA-specified research green at the end of experiment 2.......................................................................................................................50

2-15 Effect of grass*N on surface compressibility, as measured with a Volkmeter, of a USGA-specified research green in experiment 1 at week 15 on 13 January 2009. ...........51

2-16 Effect of grass*N on surface compressibility, as measured with a Volkmeter, of a USGA-specified research green in experiment 2 at week 10 on 3 October 2009. ............52

2-17 Effect of grass*N on ball roll distance of a USGA-specified research green in experiment 1 at week 24 on 20 March 2009. .....................................................................53

2-18 Effect of grass*N on ball roll distance of a USGA-specified research green in experiment 2 at week 11 on 9 October 2009. ....................................................................54

2-19 Effect of grass*N on mower scalping of a USGA-specified research green in experiment 1 at week 20 on 19 February 2009. .................................................................55

2-20 Effect of grass*N on mower scalping of a USGA-specified research green in experiment 2 at week 10 on 1 October 2009. ....................................................................56

2-21 Effect of grass*N on quality of a USGA-specified research green two weeks after verticutting at the end of experiment 1. .............................................................................57

2-22 Effect of grass*N on quality of a USGA-specified research green two weeks after verticutting at the end of experiment 2. .............................................................................58

2-23 Effect of grass*N on recovery of a USGA-specified research green two weeks after verticutting at the end of experiment 1. .............................................................................59

2-24 Effect of grass*N on recovery of a USGA-specified research green two weeks after verticutting at the end of experiment 2. .............................................................................60

2-25 Effect of grass*N for algae on a USGA-specified research green in experiment 1 at week 7 on 24 November 2008. ..........................................................................................61

2-26 Effect of grass*N for algae on a USGA-specified research green in experiment 2 at week 4 on 22 August 2009.................................................................................................62

3-1 Wilting ratings of recently established warm-season putting green cultivars on a USGA-specified research green under 25% ETo irrigation in experiment 1 from 2 May – 16 May 2009. ..........................................................................................................74


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3-4 Wilting ratings of recently established warm-season putting green cultivars on a USGA-specified research green under 25% ETo irrigation in experiment 2 from 18 October – 30 October 2009. ...............................................................................................77



3-7 Soil moisture of a USGA-specified research green under 25% ETo irrigation in experiment 1 from 30 April – 12 May 2009. .....................................................................80



3-10 Soil moisture of a USGA-specified research green under 25% ETo irrigation in experiment 2 from 19 October – 24 October 2009. ...........................................................83



3-13 Quality of recently established warm-season putting green cultivars on a USGA-specified research green under 25% ETo irrigation in experiment 1 from 2 May – 16 May 2009. ..........................................................................................................................86

3-14 Quality of recently established warm-season putting green cultivars on a USGA-specified research green under 50% ETo irrigation in experiment 1 from 2 May – 16 May 2009. ..........................................................................................................................87

3-15 Quality of recently established warm-season putting green cultivars on a USGA-specified research green under 100% ETo irrigation in experiment 1 from 2 May – 16 May 2009. .....................................................................................................................88

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3-16 Quality of recently established warm-season putting green cultivars on a USGA-specified research green under 25% ETo irrigation in experiment 2 from 19 October – 29 October 2009. ...........................................................................................................889

3-17 Quality of recently established warm-season putting green cultivars on a USGA-specified research green under 50% ETo irrigation in experiment 2 from 19 October – 29 October 2009. .............................................................................................................90

3-18 Quality of recently established warm-season putting green cultivars on a USGA-specified research green under 100% ETo irrigation in experiment 2 from 19 October – 29 October 2009. .............................................................................................................91

3-19 Chlorophyll index of recently established warm-season putting green cultivars on a USGA-specified research green under 25% irrigation in experiment 1 from 2 May – 12 May 2009. .....................................................................................................................92

3-20 Chlorophyll index of recently established warm-season putting green cultivars on a USGA-specified research green under 50% ETo irrigation in experiment 1 from 2 May – 12 May 2009. ..........................................................................................................93

3-21 Chlorophyll index of recently established warm-season putting green cultivars on a USGA-specified research green under 100% ETo irrigation in experiment 1 from 2 May – 12 May 2009. ..........................................................................................................94

3-22 Chlorophyll index of recently established warm-season putting green cultivars on a USGA-specified research green under 25% ETo irrigation in experiment 2 from 19 October – 25 October 2009. ...............................................................................................95



3-25 Normalized difference vegetative index (NDVI) of recently established warm-season putting green cultivars on a USGA-specified research green under 25% ETo irrigation in experiment 1 from 2 May – 12 May 2009. ....................................................98

3-26 Normalized difference vegetative index (NDVI) of recently established warm-season putting green cultivars on a USGA-specified research green under 50% ETo irrigation in experiment 1 from 2 May – 12 May 2009. ....................................................99

3-27 Normalized difference vegetative index (NDVI) of recently established warm-season putting green cultivars on a USGA-specified research green under 100% ETo irrigation in experiment 1 from 2 May – 12 May 2009. ..................................................100

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3-28 Normalized difference vegetative index (NDVI) of recently established warm-season putting green cultivars on a USGA-specified research green under 25% ETo irrigation in experiment 2 from 19 October – 25 October 2009. .....................................101



4-1 Wilting ratings of sodded warm-season putting green cultivars under 25% ETo irrigation in experiment 1 from 25 September to 31 October 2009. ................................115

4-2 Wilting ratings of sodded warm-season putting green cultivars under 50% ETo irrigation in experiment 1 from 26 September to 1 November 2009. ..............................116

4-3 Wilting ratings of sodded warm-season putting green cultivars under 100% ETo irrigation in experiment 1 from 31 September to 31 October 2009. ................................117

4-4 Wilting ratings of sodded warm-season putting green cultivars under 25% ETo irrigation in experiment 2 from 14 November to 10 December 2009. ............................118

4-5 Wilting ratings of sodded warm-season putting green cultivars under 50% ETo irrigation in experiment 2 from 14 November to 9 December 2009. ..............................119

4-6 Wilting ratings of sodded warm-season putting green cultivars under 100% ETo irrigation in experiment 2 from 14 November to 10 December 2009. ............................120

4-7 Soil moisture for sodded warm-season putting green cultivars under 25% ETo irrigation in experiment 1 from 20 September to 30 October 2009. ................................121



4-10 Soil moisture for sodded warm-season putting green cultivars under 25% ETo irrigation in experiment 2 from 12 November to 10 December 2009. ............................124



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4-13 Evapotranspiration of sodded warm-season putting green cultivars in experiment 1 from 29 September to 30 October 2009. ..........................................................................127

4-14 Evapotranspiration of sodded warm-season putting green cultivars in experiment 2 from 12 November to 9 December 2009. ........................................................................128

4-15 Comparison of evapotranspiration (ET) calculation methods in experiment 1 from 29 September to 30 October 2009. .......................................................................................129

4-16 Comparison of evapotranspiration (ET) calculation methods in experiment 2 from 12 November to 9 December 2009. ......................................................................................130

4-17 Quality ratings of sodded warm-season putting green cultivars under 25% ETo irrigation in experiment 1 from 20 September to 31 October 2009. ................................131



4-20 Quality ratings of sodded warm-season putting green cultivars under 25% ETo irrigation in experiment 2 from 12 November to 10 December 2009. ............................134



4-23 Chlorophyll index of sodded warm-season putting green cultivars under 25% ETo irrigation in experiment 1 from 20 September to 30 October 2009. ................................137



4-26 Chlorophyll index of sodded warm-season putting green cultivars under 25% ETo irrigation in experiment 2 from 12 November to 10 December 2009. ............................140



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4-29 Normalized difference vegetative index (NDVI) of sodded warm-season putting green cultivars under 25% ETo irrigation in experiment 1 from 20 September to 30 October 2009. ...................................................................................................................143



4-32 Normalized difference vegetative index (NDVI) of sodded warm-season putting green cultivars under 25% ETo irrigation in experiment 2 from 12 November to 10 December 2009. ...............................................................................................................146



A-1 Actual and historical mean air temperatures (°C) in experiment 1 from 20 October 2008 – 16 April 2009. ......................................................................................................153

A-2 Actual and historical mean air temperatures (°C) in experiment 2 from 23 July to 4 November 2009. ...............................................................................................................154

B-1 Comparison of theta meter with grass in place, and removed for direct reading of volumetric water content. .................................................................................................166

B-2 Comparison of theta meter with grass in place and the gravimetric method of determining volumetric water content. ............................................................................167

B-3 Comparison of theta meter with grass removed and the gravimetric method of determining volumetric water content. ............................................................................168

B-4 Actual and historical mean air temperatures (°C) in experiment 1 from 23 April to 16 May 2009. ........................................................................................................................169

B-5 Actual and historical mean air temperatures (°C) in experiment 2 from 9 October to 31 October 2009. ..............................................................................................................170

B-6 Wilting ratings of recently established warm-season putting green cultivars on a USGA-specified research green as affected by nitrogen/potassium ratio (N:K) in experiment 1 from 2 May to 16 May 2009. .....................................................................171

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B-7 Wilting ratings of recently established warm-season putting green cultivars on a USGA-specified research green as affected by nitrogen/potassium ratio (N:K) in experiment 2 from 18 October to 30 October 2009. ........................................................172

B-8 Volumetric water content of recently established warm-season putting green cultivars on a USGA-specified research green as affected by nitrogen/potassium ratio (N:K) in experiment 1 from 30 April to 12 May 2009. ...................................................173

B-9 Quality of recently established warm-season putting green cultivars on a USGA-specified research green in experiment 1 from 2 May to 16 May 2009. .........................174

B-10 Quality of recently established warm-season putting green cultivars on a USGA-specified research green in experiment 2 from 19 October to 29 October 2009. ............175

B-11 Chlorophyll index of recently established warm-season putting green cultivars on a USGA-specified research green as affected by nitrogen/potassium ratio (N:K) in experiment 1 from 2 May to 12 May 2009. .....................................................................176

B-12 Chlorophyll index of recently established warm-season putting green cultivars on a USGA-specified research green as affected by nitrogen/potassium ratio (N:K) in experiment 2 from 19 October to 25 October 2009. ........................................................177

B-13 Normalized difference vegetative index (NDVI) of recently established warm-season putting green cultivars on a USGA-specified research green as affected by nitrogen/potassium ratio (N:K) in experiment 1 from 2 May to 12 May 2009. ..............178

B-14 Normalized difference vegetative index (NDVI) of recently established warm-season putting green cultivars on a USGA-specified research green as affected by nitrogen/potassium ratio (N:K) in experiment 2 from 19 October to 25 October 2009. .179

C-1 Actual and historical mean air temperatures (°C) in experiment 1 from 20 September to 30 October 2009. ..........................................................................................................180

C-2 Actual and historical mean air temperatures (°C) in experiment 2 from 11 November to 12 December 2009. ......................................................................................................181

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LIST OF ABBREVIATIONS

BMP Best management practices

CV Cultivar

ET Evapotranspiration

ETo Potential evapotranspiration

KSAT Saturated hydraulic conductivity

OM Organic matter

PCU Polymer-coated urea

PF PristineFlora

PVC Poly vinyl chloride

SD SeaDwarf

TD TifDwarf

TE TifEagle

USGA United States Golf Association

VWC Volumetric water content

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Abstract of Dissertation Presented to the Graduate School of the University of Florida in Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy

NUTRIENT REQUIREMENTS OF WARM-SEASON PUTTING GREEN CULTIVARS DURING GROW-IN AND THEIR DROUGHT RESISTANCE ONCE ESTABLISHED

By

John Hudson Rowland

May 2010

Chair: John L. Cisar Major: Soil and Water Science

Bermudagrasses [Cynodon dactylon (L.) Pers. x C. transvaalensis Burt Davy] were the

primary warm-season species used on golf greens until improved varieties of seashore paspalum

(Paspalum vaginatum Swartz) and zoysiagrass (Zoysia spp.), with claims of reduced fertilizer

and water requirements, became available. Nitrogen is normally applied at 4.9 g N m⁻² wk⁻¹

during warm-season putting green establishment to ensure rapid turfgrass cover. Potassium,

which reduces turfgrass growth, quality, and tolerance to environmental stresses when deficient,

is often applied at rates equal to or greater than N in an attempt to increase its benefits.

‘TifDwarf’ (TD) and ‘TifEagle’ (TE) bermudagrasses, ‘SeaDwarf’ (SD) seashore paspalum, and

‘PristineFlora’ (PF) zoysiagrass [Zoysia japonica Stued. by Zoysia tenuifolia (L.) Merr.] had

varied levels of N, K, and irrigation applied to compare nutrient and water use requirements.

Cultivars were sprigged at 36.6 m³ haֿ¹ on a USGA-specified sand research green in Sept. 2008

and July 2009. Fertilizer treatments included 1.2, 2.4, 3.7, or 4.9 g N m⁻² wk⁻¹, and a one-time

application of polymer-coated urea (PCU) at 39.1 g N m⁻². Each N treatment coincided with

four N to K fertilization ratios (N:K): 1N:1K, 1N:2K, 1N:3K, or 1N:4K. Within cultivar grow-in

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rate was similar for SD,TD, and TE in both years, and PF in year 2 with 2.4, 3.7, or 4.9 g N m⁻²

wk⁻¹; 1.2 g N m⁻² wk⁻¹ was similar for SD in year 2. There were no significant effects among

N:K. The 2.4 g N m⁻² wk⁻¹ rate was generally considered best for rapid establishment of all

cultivars. Although 1.2 g N m⁻² wk⁻¹ was usually slower to grow-in, it often provided a more

desirable putting surface than 3.7, or 4.9 g N m⁻² wk⁻¹. One application of PCU provided

sufficient cover for all cultivars in 2009. The USGA green was then fertilized with N at 4.9 g

mֿ² 30dֿ¹, and K at 1N:1K, 1N:2K, 1N:3K, or 1N:4K and irrigated at 25, 50 or 100% of potential

evapotranspiration (ETo), as determined by the Blaney-Criddle equation. Treatments were

initiated in April (experiment 1) and Oct. (experiment 2) 2009. All cultivars had objectionable

wilting at 25% ETo, although PF and SD generally had less in exp. 2. TifDwarf and TE had

objectionable wilting at 50% ETo in both exp.’s, while PF was objectionable in exp. 2. Wilting

did not become objectionable at 100% ETo. There were no beneficial effects for increasing N:K.

SeaDwarf appeared to tolerate deficit irrigation the best. A second water use study, which used

identical irrigation treatments and lysimeters to measure evapotranspiration (ET), was conducted

with PF, SD, and TD sodded on Hallandale fine sand (Siliceous, hyperthermic Lithic

Psammaquent). All cultivars had objectionable wilting at 25, 50, and 100% ETo. SeaDwarf had

less wilting than PF in both exp., and TD in exp. 2 at 25% ETo. TifDwarf wilted most at 50%

ETo in exp. 2. PristineFlora had the highest ET, and SD the lowest. Irrigation at 100% ETo was

insufficient for all cultivars on the native soil. PristineFlora and SD provided high quality

putting surfaces and had better drought resistance than TD and TE bermudagrass. SeaDwarf

required the least N during establishment.

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CHAPTER 1 INTRODUCTION

Rationale

Ample amounts of nutrients and water are required to maintain warm-season golf course

greens. When deficient, supplemental applications of fertilizer and irrigation become necessary.

Best management practices, based on sound research results, should be followed by turfgrass

managers to avoid unnecessary applications of nutrients and irrigation, which can pollute and

deplete ground and surface waters.

Turfgrass Nutrition

In addition to providing desirable color and playing conditions, a properly fertilized

sward of turfgrass uses water more efficiently (Christians, 1998), reduces weed populations

(Lowe et al., 2000; Rajaniemi, 2002), and promotes recovery from foot traffic (McCarty and

Miller, 2002), and biotic stresses (Vargas, 1994). The nutrients required in the greatest amounts

and applied most frequently to turfgrass are nitrogen (N), phosphorus (P), and potassium (K). Of

these primary nutrients (i.e., macronutrients), N has the largest influence on turfgrass color, shoot

density and growth (Rodriguez et al., 2001; Snyder et al., 1984). Warm-season golf course

greens require up to 118 g N mֿ² yrֿ¹, depending upon the cultivar, amount of traffic, length of

growing season, soil type, and demands of golfers (Cisar and Snyder, 2003; McCarty and Miller,

2002; Sartain et al., 1999). Lightning, rainwater, and soil organic matter provide only small

amounts of N in comparison to what is required by most warm-season putting green cultivars

(Brady and Weil, 1999; Erickson et al., 2001; FDEP, 2007; Wolf and Snyder, 2003). To

improve putting surfaces, golf course superintendents apply additional N at regular intervals.

Since applications of soluble N >2.4 g N mֿ² can increase leaching and runoff potential, smaller,

more frequent applications are usually recommended (FDEP 2007; Sartain et al., 1999). If

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slow-release N sources are used, applications up to 15 g N mֿ² 90 dֿ¹ can be made without

undesired flushes of growth or increased environmental impacts (Sartain et al., 1999).

Phosphorus enables plants to store and transfer energy during metabolic processes

(Havlin et al., 1999). Since P is not as mobile as N, and occurs naturally in rock, soil and

rainwater, soil solution P is often sufficient for warm-season turfgrass growth. Fertilization with

P is considered unnecessary, and discouraged unless soil and tissue tests determine there is a

deficiency, particularly since excess P can cause a decline in bermudagrass growth due to

reduced tissue N (Sartain et al., 1999), negative environmental effects such as algal blooms, and

increase populations of noxious aquatic plants in surface water bodies (FDEP, 2007).

Potassium is often called the “health element”, as it is thought to improve resistance to

stresses from drought, disease and temperature extremes (Sartain et al., 1999). Since K is highly

soluble and leaches readily in high-sand content greens, it is often considered deficient in soil

tests. Although research has not shown increased benefits with N/K fertilization ratios higher

than 1N:0.5K (Sartain, 1998; Snyder and Cisar, 2000a), K is often applied at rates equal to or

higher than N due to soil test recommendations, and a presumed increase in plant health and

stress resistance. Though K is not yet tagged as an environmentally damaging nutrient, large

applications should be avoided unless deficiency is confirmed by tissue tests or visual symptoms,

such as chlorosis of the older leaves.

Fate of Nutrients

Applied nutrients that go unused by turfgrass or other plants can remain in the soil for

future use, leach into ground water, or enter surface waters as runoff. Nutrient retention in soils

is highly dependent on soil type and organic matter (OM) concentration. Sandy soil generally

has very low cation exchange capacity due to its small surface area and low OM content (Sartain

and Snyder, 1999). Soils that include moderate amounts of clay or organic matter can hold

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appreciable amounts of nutrients on electrostatic exchange sites until the plant needs them due to

larger surface areas. These soils can reduce leaching of nutrients into groundwater, although

runoff into surface waters may increase due to slower infiltration rates. Maintaining a stand of

aquatic plants in retention ponds or along lake banks in areas prone to runoff reduces pollution of

surface waters due to their filtering effect (Figure 1; FDEP, 2007).

Water Requirements

Water is the primary requirement for turfgrass function and survival. Turfgrass water

levels are normally between 75-85 percent by weight, and death occurs when water content is

less than 60 percent (Cisar and Miller, 1999). Without adequate plant moisture, the ability to

transport nutrients and water throughout the transpiration stream is compromised. As soil water

potential decreases below field capacity and nears the permanent wilting point, stomata on

turfgrass leaves close in an attempt to protect against dehydration. The lack of a cooling effect

from the release of water vapor through transpiration leads to a reduction of photosynthesis, and

increased canopy temperature. If stomata remain closed, plant cell metabolism will be

compromised and turfgrass density will decline. If drought conditions persist, turfgrasses can

become permanently wilted and die.

Water Sources

Since water is not always available in sufficient quantities to provide acceptable stands of

turf, supplemental irrigation is often used. Potential water sources include ground water, surface

water, non-potable, reclaimed, and effluent wastewater. Ground water, which is the main source

for public supply, can be acquired by drilling into aquifers found between layers of rock, or the

surficial water table (Barnett, 2007). Surface water bodies, such as stormwater runoff detention

ponds, lakes, rivers, and canals are most often used by golf courses due to the large amounts of

water required and ease of pumping. Reclaimed water from treatment plants has become popular

23

due to its reduced cost and recent fresh water restrictions. Golf courses are well suited for

reclaimed water use, as the dense root systems of turfgrasses filter out nutrients and

contaminants, reducing the likelihood of groundwater contamination.

Watering Practices

Irrigation applications are based on visual drought symptoms, soil moisture levels,

evapotranspiration (ET) rates, predictive models, and turfgrass species. When turfgrass is under

drought stress, leaves lose turgor, margins roll inward, and turn blue-green in color (Cisar and

Miller, 1999). A commonly accepted practice is to apply irrigation when one-half of the leaves

have begun to roll. Another method used to determine the onset of drought is the footprint test.

After walking across an area of turf, if the footprints do not spring back within a few minutes,

irrigation should be scheduled for the next morning unless rainfall is imminent.

Soil moisture levels are evaluated more precisely with devices that measure electrical

resistance and water tension. Theta probes, which measure electrical resistance in the soil, are

portable, easy to use, and require only a few readings per green to determine if irrigation will be

necessary. In most cases, irrigation should not be considered until volumetric water content falls

below 20%. When superintendents encounter ‘hot spots’ on greens, which often occur on highly

sloped sections, a hand syringing of the dry area is preferable to an all-inclusive irrigation. This

practice saves water and helps prevent runoff. Tensiometers measure negative pressure head of

soil water with a vacuum gauge to determine moisture availability, and are often used in

conjunction with automatic irrigation systems. When soil moisture reduces to a set tension

threshold, irrigation will run until soil moisture becomes sufficient. Using this form of irrigation

reduces water use and nitrogen leaching (Snyder et al., 1984). Rain sensors are also used as

circuits in automatic irrigation systems, and will cancel an upcoming irrigation if rainfall has

exceeded a predetermined level.

24

Predictive models use climatological data and empirical procedures to determine

potential ET and net irrigation requirements. McCloud, Thornthwaite, Penman and modified

Blaney-Criddle are commonly used ET estimation methods. The McCloud equation was

developed to reflect turfgrass water use under Florida conditions, and is considered the most

accurate model when mean temperatures are higher than 70° F (Augustin, 1983). The

Thornthwaite equation, which emphasizes temperature and day length, underestimates ET

compared to the McCloud equation. The Penman equation is based upon net radiation, vapor

pressure, and wind speed, but also is considered to underestimate ET (Augustin, 1983). The

modified Blaney-Criddle method is used by most Florida water management districts to allocate

water for golf course irrigation. The Blaney-Criddle method is based on mean temperature,

percent daylight hours, and climatic and consumptive use coefficients (Blaney and Criddle,

1950). Provided the proper crop coefficient is used, and light levels are correct, the model is

considered to accurately estimate ET (Augustin, 1983). Adjustments can be made when changes

in environmental parameters such as solar radiation, wind, or rainfall dictate. The need for

irrigation is increased on sunny days when stomata remain open to increase canopy cooling via

water vapor release. Water requirements also increase when wind velocity is high, as the

external layer of vapor pressure that protects the leaf from dehydration is decreased. If excessive

rainfall occurs, irrigation can be delayed until drought stress becomes evident.

Differences in ET between and within turfgrass species also influence amount and

frequency of irrigation. Warm-season turfgrasses generally require less water to maintain plant

growth compared to cool-season turfgrasses due to differences in their carbon fixation pathways.

Cool-season turfgrasses need to keep their stomata open for longer periods of time to capture

carbon dioxide, and subsequently lose more water through transpiration. The higher water-use

25

efficiency rates and lower carbon dioxide compensation point of warm-season turfgrasses

generally provide higher water-use efficiency (Cisar and Miller, 1999). Differences in

morphological characteristics can also influence the ability of turfgrasses to resist drought as

horizontal leaf orientation, slow vertical leaf growth rate, and high shoot and leaf densities can

impart lower water-use rates (Cisar and Miller, 1999).

Water Quality

The most salt-tolerant warm-season grasses can tolerate irrigation with seawater for short

periods of time, although saline sources are most often mixed with fresh water for prolonged

usage (Zinn, 2004). Since fresh water is a limited resource and high in cost, some golf courses

have turned to saline and reclaimed water for irrigation. Although these sources are a viable

option, they can have a negative effect on turfgrass quality if not managed properly. Suspended

solids and high salinity are of utmost concern on golf course greens, as soil pores can become

clogged with solids, causing reduced infiltration and an anaerobic environment (Cisar and Miller,

1999). Applications of gypsum can flush sodium off the soil exchange complex and replace it

with calcium. The soluble sodium sulfate that is left can then be flushed below the root zone

with fresh water (Cisar et al., 1999).

High bicarbonate levels in irrigation water can affect plant health even if it is low in

sodium and dissolved salts, as calcium and magnesium carbonate precipitate to form lime when

soil pH ≥ 8 (Cisar et al., 1999). Soils can then become sodium dominant, as calcium and

magnesium are no longer exchangeable. Acidifying materials such as ammonium sulfate can

help reduce soil pH when bicarbonate levels are moderate, but injections of stronger acids (e.g.,

sulfuric) into the irrigation system may be needed under extreme conditions (Sartain and Snyder,

1999).

26

Figure 1-1. Vegetation on golf course lake banks creates a filter for nutrient runoff.

27

CHAPTER 2 ESTABLISHMENT OF WARM-SEASON PUTTING GREEN CULTIVARS AS AFFECTED

BY NITROGEN/POTASSIUM FERTILIZATION

Introduction

Proper fertilization of golf course putting greens during establishment provides rapid

turfgrass cover, high quality putting surfaces, and limits environmental impact. Of the primary

nutrients, N is most important for turfgrass culture, and has the greatest influence on color, shoot

density and growth (Rodriguez et al., 2001; Snyder et al., 1984). Nitrogen is often applied at

higher rates (e.g., 4.9 g N m⁻² wk⁻¹) during putting green establishment in an attempt to

overcome leaching losses from increased irrigation, hydraulic conductivity, reduced cation

exchange capacity, turfgrass cover, and root mass (Rodriguez et al., 2001; White, 2003). Slow-

release N sources can provide quality turfgrass with reduced leaching in coarse-textured soils

(Brown et al., 1977; Petrovic, 2004; Snyder et al., 1980), and allow larger applications of N to be

applied less frequently without negative agronomic or environmental effects (Sartain et al.,

1999). Applying soluble N at a rate greater than 2.4 g mֿ² is not recommended due to the

potential for decreased ball roll speeds, root growth, increased flushes of top growth, mower

scalping, mat development, and potential for leaching and contamination of ground water

(FDEP, 2007; Sartain et al., 1999).

Although P does not impart a large influence on turfgrass growth under most conditions,

optimum development of young plants during establishment can be limited if soil and tissue

levels are insufficient (Havlin et al., 1999; Rodriguez et al., 2001; Sartain, 1998). To ensure

adequate availability, P is often incorporated into the root zone prior to planting, or surface

applied as a starter fertilizer (Guertal, 2007; White, 2003). A 1N:0.4P fertilization ratio was

considered optimal for establishment of bermudagrass in sandy soil (Rodriguez et al., 2001).

28

Potassium, which is beneficial for turfgrass quality and growth (McCarty and Miller, 2002;

Snyder and Cisar, 2000), infers increased tolerance to drought, disease, wear, heat (Turner and

Hummel, 1992), and cold (Beard, 1973) at adequate fertilization levels. Although turfgrasses

generally utilize half as much K as N (Turgeon, 1985), and only marginal increases in tissue K

have been observed (Snyder and Cisar, 2000), K is often applied at equal or greater amounts than

N in an attempt to increase stress tolerance (Augustin, 1992; Sartain, 1998).

Hybrid bermudagrasses [Cynodon dactylon (L.) Pers. x C. transvaalensis Burt Davy]

were first used on golf course putting greens when ‘Tiffine’ and ‘Tifgreen’ were released in 1953

and 1956, respectively (Burton, 1991). In 1965, Tifdwarf (TD), a natural mutation of Tifgreen

with smaller, shorter, leaves, stems and internodes, was released (Burton, 1991). Due to its

ability to provide a high quality putting surface at mowing heights below 5 mm, TD was the

standard warm-season greens variety for over thirty years, and is still a highly used cultivar (Foy,

2006). Advances in greens maintenance technology, and increased demand for faster green

speeds necessitated cultivars that provided a denser, smoother surface and tolerated lower

mowing heights (Vermeulen, 1995). TifEagle (TE) bermudagrass, released in 1998, had lower

vertical growth characteristics, increased shoot density, finer texture, and could be mown low

enough (< 3 mm) to produce a putting surface comparable to creeping bentgrass [Agrostis

stolonifera L. var palustris (Huds.) Farw.], the standard cool-season grass for speed and quality

(Busey and Dudeck, 1999; Foy, 1997; Foy, 2006; Hartwiger and O’Brien, 2006; McCarty et al.,

2007). Recently released cultivars of seashore paspalum (Paspalum vaginatum Swartz) and

zoysiagrass [Zoysia japonica Stued. by Zoysia tenuifolia (L.) Merr.] also provide high quality

putting surfaces, and purportedly require 50% less N and water than bermudagrass (Foy, 2006).

SeaDwarf (SD), regarded as the first true dwarf seashore paspalum, was released in 1999, and

29

can withstand mowing heights below 3 mm. Seashore paspalum can also be irrigated with

seawater containing 34,000 ppm dissolved salts, if necessary (Zinn, 2004). The grass subfamily

Chloridoideae, which contains the genera Cynodon and Zoysia, are also tolerant to saline

irrigation due to their ability to secrete salt through leaf glands (Cisar et al., 1999; Marcum,

1999). Zoysia spp. are used in areas where salt stress, limited sunlight, or low temperatures limit

the growth of other warm-season grasses (Foy, 2006; Murray and Engelke, 1983). PristineFlora

(PF), which is an upright, narrow-leafed, “Emerald-type” zoysiagrass (Scully, 2005), approved

for release in 2004 (Scully et al., 2009), provides a high quality putting surface and tolerates

regular mowing at 3 mm.

This study was conducted to evaluate the effects of varied N and K fertilization rates

during grow-in of three warm-season greens grasses sprigged into a USGA-specified sand green.

Materials and Methods

Experimental Site

Two grow-in experiments were performed at the University of Florida Fort Lauderdale

Research and Education Center in Ft. Lauderdale, FL (26º09' N, 80º24' W) on a newly-

renovated, 1440 m² research green, constructed with a United States Golf Association(USGA)-

specified soil mix containing 10 g kgֿ¹ organic matter by weight, from 2008 to 2009 (USGA

Green Section Staff, 2004). A pre-plant application of P in the form of triple superphosphate

was applied at 4.9 g m⁻² in each study. Other nutrients applied prior to sprigging included the

sulfate forms of Fe, Mn, and Mg at 4.9, 1.6, and 1.6 g m⁻², respectively. The green was sprigged

with PF, SD, TD, and TE at 36.6 m³ haֿ¹ in Sept. 2008 (Experiment 1) and July 2009

(Experiment 2). The green was initially mowed at 6.4 mm, with clippings removed, and

gradually lowered to 3.6 mm in experiment 1, and 3.8 mm in experiment 2, as the surface

30

became smoother. Irrigation was applied as needed to maintain healthy turfgrass. Pesticides

were applied on a curative basis, and included chlorothalonil and bifenthrin for algae, brown

patch, leaf spot, green aphid, and sod webworm control. Weeds were removed by hand on a

regular basis due to differing herbicide tolerances among cultivars.

Experimental Design and Statistical Analysis

Cultivar, N, and K treatment factors were arranged in a split-plot, completely randomized

design with three replications. Main plots (cultivar and N) were 4 m by 4 m and sub-plots (K

ratio) were 2 m by 2 m. SAS® (version 9.2) PROC MIXED and the Tukey-Kramer multiple-

comparison procedure were used to determine significant (P

31

weights were determined at the end of each experiment from 10 cm diam. and 20 cm deep cup

cutter cores separated into 0–10 and 10–20 cm deep sections. Thatch was separated from the 0

to 10 cm deep section, oven-dried (60°C), weighed, ashed in a 550°C muffle furnace, and re-

weighed to determine ‘ash-free’ weight (Snyder and Cisar, 2000). Roots were separated from

soil with a 2 mm diam. sieve and garden hose, oven-dried (60°C), weighed, ashed in a 550°C

muffle furnace, and re-weighed to determine ‘ash-free’ weight (Snyder and Cisar, 2000).

Surface compressibility was determined by averaging two readings per sub-plot from a weight-

based thatch displacement instrument (Volk, 1972). Ball roll speed was obtained by averaging

the distance of two golf balls rolled in two opposite directions using a 19-cm modified USGA

stimpmeter (Gaussoin et al., 1995). Visual estimates of mower scalping were rated on a 1-10

scale (10 = complete loss of leaf blades). Two weeks after a 1 cm deep verticutting (0.6 cm

spacing between blades) was performed, turfgrass quality and recovery were visually rated from

1-10 (10 = highest/most). Algae was rated visually from 1-10 (10 = most).

Results and Discussion

Turfgrass Cover

In experiment 1, SD, TD, and TE took 13 weeks to obtain ≥90% cover, while PF required

27 weeks when fertilized with 2.4, 3.7, or 4.9 g N m⁻² wk⁻¹. Cover was reduced for SD, TD, and

TE with 1.2 g N m⁻² wk⁻¹ and PCU (Figures 2-1, 2-2, 2-3; Table 2-1). The 1.2 g N m⁻² wk⁻¹

treatment took 1, 2, and 4 weeks longer to obtain ≥90% cover for SD, TD, and TE, respectively.

There were no significant differences in cover among N/K fertilization ratios (Figure 2-4). In

experiment 2, only PF and TE fertilized with PCU and 1.2 g N m⁻² wk⁻¹ had

32

2.4, 3.7, and 4.9 g N m⁻² wk⁻¹. Unlike the first study, PF had similar cover, at some N rates, to

TD and TE, and 1.2 g N m⁻² wk⁻¹ was similar to the higher weekly N rates for SD. Because

experiment 1 was initiated in cooler autumn temperatures it took several more weeks to achieve

≥90% cover than experiment 2, which was initiated at the peak of summer. Hence, as each

cultivar had similar cover with 2.4, 3.7, and 4.9 g N m⁻² wk⁻¹ in both experiments, the higher

rates were considered excessive and increased potential for nutrient leaching, runoff, and

subsequent contamination of nearby water bodies.

Chlorophyll

In experiment 1, SD, TD, and TE had less chlorophyll when fertilized with 1.2 g N m⁻²

wk⁻¹ compared to the higher weekly N rates (Figure 2-9; Table 2-3). In experiment 2, all

cultivars had less chlorophyll when fertilized with 1.2 g N m⁻² wk⁻¹ compared to the higher

weekly N rates (Figure 2-10, Table 2-4). Though 1N:1K was higher (P=0.042) than 1N:3K in

2008 there were no within cultivar significant differences in chlorophyll among N/K ratios in

either experiment (Tables 2-3, 2-4). The chlorophyll index seemed to be an effective indicator of

N status in relation to turfgrass cover, particularly in experiment 1 (Figure 2-3). This

relationship suggests that reflectance meters can be used during grow-in to optimize growth and

reduce N usage. This is supported by previous studies that found correlations between

reflectance meters and turfgrass clipping yield, leaf hue, darkness and density (Mangiafico and

Guillard, 2005; Trenholm et al., 1999).

Thatch Development

In experiment 1, SD had a shallower thatch depth when fertilized with PCU compared to

4.9 g N m⁻² wkֿ¹ (Figure 2-11; Table 2-5). PristineFlora, and PCU had the shallowest thatch

33

depths among cultivars, and N treatments, respectively. There were no within cultivar

differences among N treatments in experiment 2 (Figure 2-12; Table 2-6), though PF had the

shallowest thatch among cultivars, and PCU had less thatch than 1.2 and 2.4 g N m⁻² wk⁻¹.

There were no significant differences for thatch depth among N/K ratios in either experiment

(Tables 2-5, 2-6). Since thatch accumulation is attributed to accelerated vegetative growth

(Beard, 1973), the slower-growing PCU N treatment likely caused the reduction in thatch depth

in experiment 1. The lack of pronounced differences in thatch depth among N rates was not

entirely unexpected, as previous results have been mixed. Carrow et al. (1987), and Smith

(1979) found no differences in thatch depth, whereas Baldwin (2009), Duble (2000), Snyder and

Cisar (2000), Unruh et al. (2007), and White et al. (2004) reported greater thatch depths with

increased N fertilization rates.

Root Development

In experiment 1, SD fertilized at 4.9 g N m⁻² wkֿ¹ had reduced root development

compared to 1.2, 2.4, and 3.7 g N m⁻² wkֿ¹ (Figure 2-13; Table 2-7). PristineFlora had the

shallowest root system among cultivars. In experiment 2, there were no within cultivar

differences among N treatments, though PF had the shallowest roots among cultivars (Figure 2-

14; Table 2-8). There were no significant differences in root length among N/K ratios in either

experiment (Tables 2-7, 2-8). Excessive N fertilization reportedly increases aboveground tissue

growth and causes a reduction in root growth (Beard, 1973; Christians, 1998). Although the

highest weekly N rate decreased root length in SD in this study, Unruh et al. (2007) reported

both increased and decreased root weights during grow-in of seashore paspalum putting green

cultivars fertilized at 4.9 g N m⁻² 14 dֿ¹.

34

Surface Compressibility and Ball Roll

In both experiments, all cultivars fertilized with 3.7 and 4.9 g N m⁻² wk⁻¹ generally had

increased surface compressibility compared to 1.2 g N m⁻² wk⁻¹ and PCU (Figures 2-15, 2-16;

Tables 2-9, 2-10), although PF was unaffected by N rate in experiment 1. There were no

significant differences in surface compressibility among N/K ratios in either experiment (Tables

2-9, 2-10). The increases in surface compressibility at higher weekly N rates were likely due to

accelerated aboveground growth, as Volk (1972) reported significant regressions of

compressibility (P

35

heights used in these experiments. The increased height of cut in experiment 2 was due in large

part to the tendency of TD to become scalped.

Quality and Recovery

In experiment 1, SD quality was higher two weeks after verticutting when fertilized with

PCU or 1.2 g N m⁻² wk⁻¹, compared to 3.7 and 4.9 g N m⁻² wk⁻¹ (Figure 2-21; Table 2-15).

PristineFlora had higher quality than: TD regardless of N treatment, SD at 2.4, 3.7 and 4.9 g N

m⁻² wk⁻¹, and TE at 2.4 and 4.9 g N m⁻² wk⁻¹. In experiment 2, SD quality was higher when

fertilized with PCU compared to 2.4, 3.7, and 4.9 g N m⁻² wk⁻¹ (Figure 2-22; Table 2-16). All N

treatments for PF had higher quality than TD, and SD fertilized at 3.7 and 4.9 g N m⁻² wk⁻¹; PF

had higher quality than TE at 1.2 and 4.9 g N m⁻² wk⁻¹. There were no significant differences in

quality among N/K ratios in either experiment (Tables 2-15, 2-16). After verticutting, PF was

relatively unscathed due to its minimal thatch development and upright growth habit, while TD,

and SD likely had reduced quality due to growth habit, and thatch density, respectively.

In experiment 1, SD fertilized with PCU and 1.2 g N m⁻² wk⁻¹ had recovered more than

3.7 and 4.9 g N m⁻² wk⁻¹ two weeks after verticutting (Figure 2-23; Table 2-17). PristineFlora

had recovered more than TD. In experiment 2, TD fertilized with PCU had recovered more than

3.7 g N m⁻² wk⁻¹ (Figure 2-24; Table 2-18). SeaDwarf and TD exhibited less recovery than PF.

There were no significant differences in recovery among N/K ratios in either experiment (Tables

2-17, 2-18). Since PF sustained minimal damage after verticutting, it was generally the fastest to

recover. Conversely, since SD and TD were severely damaged from verticutting, more time was

required for recovery.

36

Algae

In experiment 1, PF had reduced algae when fertilized with PCU (Figure 2-25; Table 2-

19). In experiment 2, PF and TD had reduced algae when fertilized with PCU compared to 4.9 g

N m⁻² wk⁻¹ (Figure 2-26; Table 2-20). In both experiments algae was generally higher in PF,

particularly when fertilized with 4.9 g N m⁻² wk⁻¹. There were no significant differences in algae

among N/K ratios in either experiment (Tables 2-19, 2-20).

37

Figure 2-1. Trends of weekly means for turfgrass cover during grow-in of a USGA-specified

research green in experiment 1 from 2 October 2008 – 16 April 2009.

38

Figure 2-2. Trends of weekly means for turfgrass cover as affected by N fertilization during

grow-in of a USGA-specified research green in experiment 1 from 2 October 2008 – 16 April 2009.

39

Figure 2-3. Effect of grass*Nitrogen (N) on turfgrass cover of a USGA-specified research green

in experiment 1 at week 13 on 1 January 2009. Mean estimates with same letter are not statistically different at 0.05 significance level based on the Tukey-Kramer method. PCU=39.1 g N mֿ².

Table 2-1. Anova table for turfgrass cover of a USGA-specified research green in experiment 1

at week 13 on 1 January 2009. Effect Degrees of

freedom F value Probability > F Least significant

difference Grass 3 671.4

40

Figure 2-4. Trends of weekly means for turfgrass cover, as affected by N/K fertilization ratio

during grow-in of a USGA-specified research green in experiment 1 from 2 October 2008 – 16 April 2009.

41

Figure 2-5. Trends of weekly means for turfgrass cover during grow-in of a USGA-specified

research green in experiment 2 from 30 July – 4 November, 2009.

42

Figure 2-6. Trends of weekly means for turfgrass cover as affected by N fertilization during

grow-in of a USGA-specified research green in experiment 2 from 30 July – 4 November, 2009.

43

Figure 2-7. Effect of grass*N on turfgrass coverage of a USGA-specified research green in

experiment 2 at week 9 on 23 September 2009. Mean estimates with same letter are not statistically different at 0.05 significance level based on the Tukey-Kramer method. PCU=39.1 g N mֿ².

Table 2-2. Anova table for turfgrass cover of a USGA-specified research green in experiment 2

at week 9 on 23 September 2009. Effect Degrees of



44

Figure 2-8. Trends of weekly means for turfgrass cover as affected by N/K fertilization ratio

during grow-in of a USGA-specified research green in experiment 2 from 30 July – 4 November, 2009.

45

Figure 2-9. Effect of grass*N on chlorophyll index of a USGA-specified research green in

experiment 1 at week 17 on 29 January 2009. Means with same letter are not statistically different at the 0.05 probability level based on the Tukey-Kramer method. PCU=39.1 g N mֿ².

Table 2-3. Anova table for chlorophyll index of a USGA-specified research green in experiment

1 at week 17 on 29 January 2009. Effect Degrees of



46

Figure 2-10. Effect of grass*N on chlorophyll index of a USGA-specified research green in

experiment 2 at week 6 on 3 September 2009. Means with same letter are not statistically different at the 0.05 probability level based on the Tukey-Kramer method. PCU=39.1 g N mֿ².

Table 2-4. Anova table for chlorophyll index of a USGA-specified research green in experiment

2 at week 6 on 3 September 2009. Effect Degrees of



47

Figure 2-11. Effect of grass*N on thatch depth of a USGA-specified research green at the end of

experiment 1. Means with same letter are not statistically different at the 0.05 probability level based on the Tukey-Kramer method. PCU=39.1 g N mֿ².

Table 2-5. Anova table for thatch depth of a USGA-specified research green at the end of

experiment 1. Effect Degrees of



48

Figure 2-12. Effect of grass*N on thatch depth of a USGA-specified research green at the end of


Table 2-6. Anova table for thatch depth of a USGA-specified research green at the end of




49

Figure 2-13. Effect of grass*N on root length of a USGA-specified research green at the end of


Table 2-7. Anova table for root length of a USGA-specified research green at the end of




50

Figure 2-14. Effect of grass*N on root length of a USGA-specified research green at the end of


Table 2-8. Anova table for root length of a USGA-specified research green at the end of




51

Figure 2-15. Effect of grass*N on surface compressibility, as measured with a Volkmeter, of a

USGA-specified research green in experiment 1 at week 15 on 13 January 2009. Means with same letter are not statistically different at the 0.05 probability level based on the Tukey-Kramer method. PCU=39.1 g N mֿ².

Table 2-9. Anova table for surface compressibility of a USGA-specified research green in

experiment 1 at week 15 on 13 January 2009. Effect Degrees of



52

Figure 2-16. Effect of grass*N on surface compressibility, as measured with a Volkmeter, of a

USGA-specified research green in experiment 2 at week 10 on 3 October 2009. Means with same letter are not statistically different at the 0.05 probability level based on the Tukey-Kramer method. PCU=39.1 g N mֿ².

Table 2-10. Anova table for surface compressibility of a USGA-specified research green in

experiment 2 at week 10 on 3 October 2009. Effect Degrees of



53

Figure 2-17. Effect of grass*N on ball roll distance of a USGA-specified research green in

experiment 1 at week 24 on 20 March 2009. Means with same letter are not statistically different at the 0.05 probability level based on the Tukey-Kramer method. PCU=39.1 g N mֿ².

Table 2-11. Anova table for ball roll distance of a USGA-specified research green in experiment

1 at week 24 on 20 March 2009. Effect Degrees of



54

Figure 2-18. Effect of grass*N on ball roll distance of a USGA-specified research green in

experiment 2 at week 11 on 9 October 2009. Means with same letter are not statistically different at the 0.05 probability level based on the Tukey-Kramer method. PCU=39.1 g N mֿ².

Table 2-12. Anova table for ball roll distance of a USGA-specified research green in experiment

2 at week 11 on 9 October 2009. Effect Degrees of



55

Figure 2-19. Effect of grass*N on mower scalping of a USGA-specified research green in

experiment 1 at week 20 on 19 February 2009. Scalping ratings: 1-10 (1 = none, and 10 = complete loss of leaf blades). Means with same letter are not statistically different at the 0.05 probability level based on the Tukey-Kramer method. PCU=39.1 g N mֿ².

Table 2-13. Anova table for mower scalping of a USGA-specified research green in experiment

1 at week 20 on 19 February 2009. Effect Degrees of



56

Figure 2-20. Effect of grass*N on mower scalping of a USGA-specified research green in

experiment 2 at week 10 on 1 October 2009. Scalping ratings: 1-10 (1 = none, and 10 = complete loss of leaf blades). Means with same letter are not statistically different at the 0.05 probability level based on the Tukey-Kramer method. PCU=39.1 g N mֿ².

Table 2-14. Anova table for mower scalping of a USGA-specified research green in experiment

2 at week 10 on 1 October 2009. Effect Degrees of



57

Figure 2-21. Effect of grass*N on quality of a USGA-specified research green two weeks after

verticutting at the end of experiment 1. Quality ratings: 1-10 (1 = dead, 6 = minimum acceptable, and 10 = best). Means with same letter are not statistically different at the 0.05 probability level based on the Tukey-Kramer method. PCU=39.1 g N mֿ².

Table 2-15. Anova table for quality of a USGA-specified research green at the end of




58

Figure 2-22. Effect of grass*N on quality of a USGA-specified research green two weeks after

verticutting at the end of experiment 2. Quality ratings: 1-10 (1 = dead, 6 = minimum acceptable, and 10 = best). Means with same letter are not statistically different at the 0.05 probability level based on the Tukey-Kramer method. PCU=39.1 g N mֿ².

Table 2-16. Anova table for quality of a USGA-specified research green at the end of




59

Figure 2-23. Effect of grass*N on recovery of a USGA-specified research green two weeks after

verticutting at the end of experiment 1. Recovery ratings 1-10 (10 = completely recovered). Means with same letter are not statistically different at the 0.05 probability level based on the Tukey-Kramer method. PCU=39.1 g N mֿ².

Table 2-17. Anova table for recovery of a USGA-specified research green at the end of




60

Figure 2-24. Effect of grass*N on recovery of a USGA-specified research green two weeks after

verticutting at the end of experiment 2. Recovery ratings 1-10 (10 = completely recovered). Means with same letter are not statistically different at the 0.05 probability level based on the Tukey-Kramer method. PCU=39.1 g N mֿ².

Table 2-18. Anova table for recovery of a USGA-specified research green at the end of




61

Figure 2-25. Effect of grass*N for algae on a USGA-specified research green in experiment 1 at

week 7 on 24 November 2008. Means with same letter are not statistically different at the 0.05 probability level based on the Tukey-Kramer method. PCU=39.1 g N mֿ².

Table 2-19. Anova table for algae on a USGA-specified research green in experiment 1 at week

7 on 24 November 2008. Effect Degrees of



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Figure 2-26. Effect of grass*N for algae on a USGA-specified research green in experiment 2 at

week 4 on 22 August 2009. Means with same letter are not statistically different at the 0.05 probability level based on the Tukey-Kramer method. PCU=39.1 g N mֿ².

Table 2-20. Anova table for algae on a USGA-specified research green in experiment 2 at week

4 on 22 August 2009. Effect Degrees of



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CHAPTER 3 DROUGHT RESISTANCE OF NEWLY-ESTABLISHED WARM-SEASON PUTTING

GREEN CULTIVARS AS AFFECTED BY NITROGEN/POTASSIUM FERTILIZATION

Introduction

Water

nutrient requirements of warm-season putting...

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