Differential nitrate leaching and mass balance of ¹⁵N-labeled nitrogen sources applied to turfgrass and citrus

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Title:
Differential nitrate leaching and mass balance of ¹⁵N-labeled nitrogen sources applied to turfgrass and citrus
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xiii, 112 leaves : ill. ; 29 cm.
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English
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Brown, Eric A., 1967
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Soil and Water Science thesis, Ph.D   ( lcsh )
Dissertations, Academic -- Soil and Water Science -- UF   ( lcsh )
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bibliography   ( marcgt )
theses   ( marcgt )
non-fiction   ( marcgt )

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Thesis:
Thesis (Ph.D.)--University of Florida, 2003.
Bibliography:
Includes bibliographical references.
Statement of Responsibility:
by Eric A. Brown.
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Printout.
General Note:
Vita.

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University of Florida
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oclc - 81549569
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AA00017662:00001


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DIFFERENTIAL NITRATE LEACHING AND MASS BALANCE OF SN-LABELED
NITROGEN SOURCES APPLIED TO TURFGRASS AND CITRUS














By

ERIC A. BROWN


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


2003
































This dissertation is dedicated to my parents for their love and support.
















ACKNOWLEDGMENTS

I with to express my appreciation to Dr. Jerry B. Sartain, the chairman of my

supervisory committee. Dr. Sartain gave me the opportunity to work in the turfgrass

fertility laboratory and also gave me the mentoring I needed to achieve the goal of

obtaining the Doctor of Philosophy degree. I am also grateful to the other members of

my supervisory committee, Drs. George H. Snyder, Donald A. Graetz, John L. Cisar,

Grady L. Miller, and G. William Easterwood, for their guidance, assistance and

encouragement.

Thanks go to Hydro-Agri North America for providing the funding for the research

that gave me the opportunity to fulfill my goal of obtaining the Doctor of Philosophy

degree. Special thanks go to Ed Hopwood Jr., manager of the turfgrass laboratory, for

assistance and encouragement. Thanks go to my fellow graduate students in the Soil and

Water Science Department. Finally, thanks go to my parents, Dr. Max A. and Sally A.

Brown, for their encouragement and support.
















TABLE OF CONTENTS
Page

ACKNOWLEDGMENTS ............................................................. ................................

L IST O F T A B L E S .................................................. ..... .......... .................................. vii

LIST OF FIGURES ........................................ ..................................................... xi

A B ST R A C T ................................................................ ................................... xii

CHAPTER

1 IN TRO D U C TIO N ..................................................................................................... 1

2 LITERATURE REVIEW .......................................................................................... 4

Introduction.......................................................................................... ................ 4
Nitrogen in a Turfgrass Environment............................................... ...................5
Nitrogen in a Citrus Environment......................................................................... 8
Influence of C a ........................................................................ ............................9
Influence ofN Form ............................................................................................... 12
Influence of pH ...... .................................................................................... 16
Nitrogen Isotope Techniques......................... ............................... .................20
N nitrogen Partitioning .......................................................................... ..................22

3 METHODS AND MATERIALS..........................................................................26

L ysim eter setup ................................................................................................. ..........26
Plant Collections and Analysis.......................... ......................................... .....28
S and M ixes ........................................ ..... ............................................................29
F fertilizers ......................................................................... .............................. 32
E xperim mental Studies........................ ............................................. ........................34
Turfgrass Glasshouse 2000..........................................................................34
Statistical analysis ........................................ ............ ....................... 35
N -balance ........................................ ..... ... ... ............................... 35
Turfgrass Glasshouse 2001..................................................36
Turfgrass Field Grow-in 2001 .......................................................................38
Turfgrass Field Overseed 2001 .....................................................................39
Citrus Glasshouse 2001 ..................... .................................... ............ 40
Mass Balance Calculations......................................................................................42



iv










4 GLASSHOUSE 2000 TURFGRASS STUDY .........................................................44

Influence of Sand Type and Fertilizer Source on Dry Matter Tissue (Clippings)......44
Nitrogen Uptake (Clippings) and Total Dry Matter Accumulation as Influenced
by Sand T ype ...................................................................................................45
Total N Uptake as Influenced by Sand Type and Fertilizer .....................................45
Nitrogen Retained in the Soil as Influenced by Sand Type and Fertilizer .................46
Leachate pH as Influenced by Sand Type by Fertilizer Interaction .........................47
Leachate EC as Influenced by Sand Type and Fertilizer....................................48
Total N leached as Influenced by Sand Type and Fertilizer.......................................50
M ass Balance Calculations................................................................................ ...52

5 GLASSHOUSE 2001 TURFGRASS STUDY .........................................................54

Tissue Dry Matter as Influenced by Sand Type and Fertilizer.................................54
Total Soil N as Influenced by Sand Type and Fertilizer ..........................................55
N Tissue Uptake as Influenced by Sand Type and Fertilizer ...................................56
Total Dry Matter Production as Influenced by Sand Type and Fertilizer ..................57
Total N Uptake as Influenced by Sand Type by Fertilizer.......................................58
Total N Leached as Influenced by Sand Type and Fertilizer ...................................59
Leachate pH as Influenced by Sand Type and Fertilizer...................................61
Leachate Electrical Conductivity as Influenced by Sand Type and Fertilizer............63
M ass Balance Calculations................................................................................ ...64

6 FIELD TURF GROW-IN STUDY ................................................ ....................... 66

Total N Leached as Influenced by Fertilizer Source ..........................................66
Soil N as Influenced by Fertilizer Source.............................................................. 67
Leachate pH as Influenced by Fertilizer Source....................................................68
Dry Matter Tissue and N Uptake by Tissue as Influenced by Fertilizer Source........70
Total Dry Matter as Influenced by Fertilizer Source.............................................71
Total N Uptake as Influenced by Fertilizer Source ............................................72
Percent Cover as Influenced by Fertilizer Source ..............................................73
Leachate EC as Influenced by Fertilizer Source....................................................74
M ass Balance Calculations...................................................................................76

7 FIELD TURF OVERSEED STUDY.............................. ..................................78

Total N Leached as Influenced by Fertilizer Source ..........................................78
Soil N as Influenced by Fertilizer Source................................................................79
Dry Matter Tissue (Clippings) as Influenced by Fertilizer Source...........................80
Total N Uptake as Influenced by Fertilizer Source ........................................81
Total Dry Matter as Influenced by Fertilizer Source..........................................82
Color Rating as Influenced by Fertilizer Source ................................................82
Leachate pH as Influenced by Fertilizer Source....................................................83
Leachate EC as Influenced by Fertilizer Source.......................................... ...........84
Tissue Mn Concentration as Influenced by Fertilizer Source ..................................85










Tissue Fe Concentration as Influenced by Fertilizer Source......................................86
M ass Balance Calculations................................................ .............................86

8 GLASSHOUSE 2001 CITRUS STUDY ...................................................................88

Nitrogen Leached as Influenced by Sand Type.................................................88
Nitrogen Retention in the Soil .................................................................. .......90
Influence of Sand Type and Fertilizer on Ca, Fe, and Mn concentration in the
leaves ................. .............. ................................ ......... ..........................................90
Leaf P Concentration as Influenced by Sand Type ......................................... .....92
Total P Leached as Influenced by Sand Type by Fertilizer......................................93
Leachate pH as Influenced by Sand Type by Fertilizer........................... .............94
Electrical Conductivity as Influenced by Sand Type and Fertilizer ...........................95
Total Dry Matter as Influenced by Sand Type and Fertilizer...................................96
Calcuim Nitrate with Tropicoate Prill Coating Versus Calcium Nitrate with No
Prill C eating ........................................ .......................................................... ... .....98
Mass Balance Calculations...................................................... ...................99

9 C O N C LU SIO N S.................................... ............................................. .. ................. 101

R EFER EN C ES ............................... ... ...... ............................ ........................ 103

BIOGRAPHICAL SKETCH .............................................................................112















LIST OF TABLES


Table page

3-1. Organic matter and sand size analysis of sand mixes.................................... ...30

3-2. Physical analysis of sand mixes.................................................. .................... 30

3-3. CEC and ammonium-oxalate extractable Fe + Al analysis of sand mixes................31

3-4. Analysis of variance (ANOVA) table used for the determination of statistical
differences in the analysis for effects of sand type and N fertilizer source for the
turfgrass glasshouse 2000 study........................................ ...............................35

3-5. Analysis of variance (ANOVA) table used for the determination of statistical
differences in the analysis for effects of sand type and N fertilizer source for the
turfgrass glasshouse 2001 study ....................... ........ .................................. ....38

3-6. Analysis of variance (ANOVA) table used for the determination of statistical
differences in the analysis for effect N fertilizer source for the turfgrass field
grow -in 2001 study............................................... .......................................... 39

3-7. Analysis of variance (ANOVA) table used for the determination of statistical
differences in the analysis for effect fertilizer source for the turfgrass field
overseed 2002 study. ................................................................................................40

3-8. Analysis of variance (ANOVA) table used for the determination of statistical
differences in the analysis for effects of sand type and N fertilizer source on
citrus 2001 study. ............................................. ........................................... 4 1

4-1. Tissue dry matter clippings weight for all harvests for glasshouse 2000 turfgrass
study as influenced by sand type and fertilizer ......................................................44

4-2. Nitrogen uptake in clippings and total dry matter accumulation for the glasshouse
2000 turfgrass study as influenced by sand type......................................................45

4-3. Total N uptake for glasshouse 2000 turfgrass study as influenced by sand type
and fertilizer. ...................... ............................ .......... .......................................4 6

4-4. Nitrogen retained in the soil for glasshouse 2000 turfgrass study as influenced by
sand type by fertilizer ......................................... ........ .......... ........................ 47










4-5. Leachate pH taken 98 DASt for glasshouse 2000 turfgrass study as influenced by
sand type by fertilizer interaction............................................. ............... ..... 48

4-6. Leachate electrical conductivity taken 98 DASt for glasshouse 2000 turfgrass
study as influenced by sand type and fertilizer. ..............................................49

4-7. Total N Leached for glasshouse 2000 turfgrass study as influenced by sand type
and fertilizer. .................................................. ....................... ........................ 50

4-8. Mass balance and percent 5N recovered for the turfgrass glasshouse 2000 study....53

5-1. Total tissue dry matter weight for all harvests for glasshouse 2001 turfgrass study
as influenced by sand type and fertilizer.............................................................55

5-2. Total N retained in the soil for glasshouse 2001 turfgrass study as influenced by
sand type and fertilizer. ......................................................................................56

5-3. Nitrogen uptake by the harvested tissue for glasshouse 2001 turfgrass study as
influenced by sand type and fertilizer......................................................................57

5-4. Total dry matter for glasshouse 2001 turfgrass study as influenced by sand type
and fertilizer. ................................................ .................. ..............................58

5-5. Total N uptake for glasshouse 2001 turfgrass study as influenced by sand type by
fertilizer. .................................. .................. ............................................... 59

5-6. Total N leached for glasshouse 2001 turfgrass study as influenced by sand type by
fertilizer. ...... .......................... ... ........................................................................6 0

5-7. Leachate pH taken 98 DASt for glasshouse 2001 turfgrass study as influenced by
sand type by fertilizer ......................................................................................... 62

5-8. Leachate electrical conductivity taken 98 DASt for glasshouse 2001 turfgrass
study as influenced by sand type by fertilizer.............................................63

5-9. Mass balance and percent N recovered for the turfgrass glasshouse 2001 study.......65

6-1. Total N leached for field grow-in 2001 turfgrass study as influenced by fertilizer
so u rce ..................................................................................... .............................6 7

6-2. Soil N (KCI Extractable) for field grow-in 2001 turfgrass study as influenced by
fertilizer source...................................... ................ ............................................68

6-3. Leachate pH taken 52 days after sprigging for field grow-in 2001 turfgrass study
as influenced by fertilizer source. ....................................... .................. ............70

6-4. Dry matter tissue and N uptake by tissue for field grow-in 2001 turfgrass study as
influenced by fertilizer source......................................................................... 70



vlll










6-5. Total dry matter for field grow-in 2001 turfgrass study as influenced by fertilizer
source. ........................................ ........ ................... ..... ... .. ....................72

6-6. Total N uptake for field grow-in 2001 turfgrass study as influenced by fertilizer
source. ........................................ ..... ................. ............................................72

6-7. Percent cover for field grow-in 2001 turfgrass study as influenced by fertilizer
source. ................................................ ................................................ .............. 74

6-8. Leachate EC for field grow-in 2001 turfgrass study as influenced by fertilizer
source. .......................... ............................................. .......... ........................ ......75

6-9. Mass balance and percent 5N recovered for the turfgrass field grow-in 2000
study. ............................................................... ............... .......................... ........77

7-1. Total N leached for field overseed 2002 turfgrass study as influenced by
fertilizer source .............................................. .............. ........................ ......... 79

7-2. Soil N (KCI extractable) for field overseed 2002 turfgrass study as influenced
by fertilizer source.............................................................................................. 80

7-3. Dry matter tissue for field overseed 2002 turfgrass study as influenced by
fertilizer source ............................ ......... ...... ... ................................................. 81

7-4. Total N uptake for field overseed 2002 turfgrass study as influenced by
fertilizer source...................................................................................................81

7-5. Total dry matter for field overseed 2002 turfgrass study as influenced by
fertilizer source...................................................................................................... ..82

7-6. Color rating for field overseed 2002 turfgrass study as influenced by fertilizer
source. ...................................... ......... ..... ............ ....... ................. .....83

Leachate pH for field overseed 2002 turfgrass study as influenced by fertilizer source...84

7-8. Leachate EC for field overseed 2002 turfgrass study as influenced by fertilizer
source .................................................................................................................84

7-9. Tissue Mn concentration for field overseed 2002 turfgrass study as influenced
by fertilizer source.............................................................................. ................ 85

7-10. Tissue Fe concentration for field overseed 2002 turfgrass study as influenced
by fertilizer source ............................ .. ... ................ ........ ... ..................86

7-11. Mass balance and percent N recovered for the turfgrass field overseed 2002
study ........................ ... .......... ......... .................... ....... ..................... .87

8-1. Total N leached for glasshouse 2001 citrus study as influenced by sand type...........89










8-2. Influence of sand type by fertilizer on Ca, Fe, and Mn concentration in the
leaves for the glasshouse 2001 citrus study. ..................................................92

8-3. Leaf P concentration in the leaves for glasshouse 2001 citrus study as
influenced by sand type ..................................................................................... 93

8-4. Total P leached for glasshouse 2001 citrus study as influenced by sand type by
fertilizer. .................................................................................. ...................... 94

8-5. Leachate pH collected 198 DAI for glasshouse 2001 citrus study as influenced
by sand type by fertilizer ............................................................................... ....95

8-6. Leachate EC collected 198 days after initiation for glasshouse 2001 citrus study
as influenced by sand type and fertilizer....................................................96

8-7. Total dry matter weight for glasshouse 2001 citrus study as influenced by sand
type and fertilizer. .............................................................................................. 97

8-8. Total N uptake for glasshouse 2001 citrus study as influenced by sand type and
fertilizer. ........................................ ............................. .............................. 98

8-9. Root dry matter weight and N uptake into roots for glasshouse 2001 citrus
study as influenced by sand type and fertilizer .................................... .... 98

8-10. Mass balance and percent 5N recovered for the citrus glasshouse 2001 study. ...100
















LIST OF FIGURES


Figure page

4-1. Total N03--N and Ca leached from (a) coated sand, (b) uncoated sand turfgrass
glasshouse 2000 study ....................................................................................... 52

5-1. Total N03'-N and Ca leached from (a) coated sand and (b) uncoated sand for the
turfgrass glasshouse 2001 study...........................................................................61

7-1. Soil N (KC1 extractable) retained vs. % NH4 content of fertilizer source ...............80

8-1. Total NO3--N and Ca leached from (a) coated sand, (b) uncoated sand for the
citrus 2001 study. .......................... ..... ............................. ......................89

8-1. C continued. ................................... ....................... ....... ...... .......... ......... 90
















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

DIFFERENTIAL NITRATE LEACHING AND MASS BALANCE OF "N-LABELED
NITROGEN SOURCES APPLIED TO TURFGRASS AND CITRUS

By

Eric A. Brown

August 2003

Chair: Jerry B. Sartain
Major Department: Soil and Water Science

Most crops including turfgrass and citrus require nitrogen (N) fertilization in order

to maintain the desired level of quality and productivity. However, potential leaching

losses of N present environmental and economic concerns. It has been suggested that

nitrate (NO3)-N can be retained by soil cation exchange in the form of a CaNO3 ion pair.

Objectives of this research were (1) to determine the leaching potential and utilization of

5 soluble 15N labeled sources, ammonium nitrate-NH4N03 = AN, potassium nitrate-

KNO3 = KN urea-CO(NH2)2 = urea, ammonium sulfate-(NH4)2SO4 = AS, and calcium

nitrate-5Ca(N03)2NH4N0310H20 = CN in turfgrass and citrus systems through mass

balance studies; (2) to identify components responsible for differential leaching and

utilization of applied '5N; and (3) to determine the influence of Ca-2 on N03- retention,

leaching, and utilization of applied 1N. Ammonium-N applied in nutrient sources AN,

AS, and urea lowered the pH of the soil system and resulted in increased percent cover

and color ratings during turfgrass field studies due to increased Mn uptake. All N sources









were equally effective in supplying N to plants except when NO3- sources KN and CN

were used with leachate pH > 6.5 in turfgrass field studies and in the glasshouse when AS

exhibited lower coverage and higher leaching rates than the other sources. Total N

recovery for all N sources was 72% based on N studies with 56% in plant, 4% in soil,

and 12% in leachate. Unaccounted N was presumed to be lost to volatilization and

denitrification. No difference in N leached or N retained in the soil was observed due to

the presence of the proposed CaNO3+ ion pair. These studies suggest that fertilizing with

N03--N sources increases the growth media and leachate pH which may result in negative

influences on growth and quality ofturfgrasses due to Mn availability that do not exist

when NH4+-N sources are used. Additionally, in low exchange capacity sandy growing

media, it does not appear that the formation of the proposed Ca(NO3)+ ion pair reduces

the potential leaching loss of NO3N-N supplied through the application of calcium nitrate

fertilizer.













CHAPTER 1
INTRODUCTION

Nitrogen (N) is needed by every living organism for survival. Crops and landscape

areas often need N fertilization in order to obtain desired yield and/or quality. However,

excess N in bodies of water can cause eutrophication, the process by which water

becomes enriched in dissolved nutrients (such as nitrates and phosphates) that stimulate

the growth of aquatic plant life, usually resulting in the depletion of dissolved oxygen and

a general degradation of water quality. For this reason, N that is applied to agronomic

crops and turfgrass has been closely scrutinized and monitored to reduce the amount of N

that ends up in runoff or leachate.

Potential leaching losses of N present environmental and economic concerns.

Nitrogen losses deprive turfgrass and crops of an essential nutrient and serve as a

potential pollutant to surface and ground waters. Turfgrass fertilization is receiving more

attention from an environmental perspective due to the overall quantity of fertilizer

required to maintain acceptable quality. Due to the cultural practices involved in golf

course management and the unique nutritional requirements of turfgrasses, fertilizer

application rates are often higher than those typically utilized on an agronomic crop

(Sartain, unpublished data, 1996).

There are numerous N materials commercially available to managers to supply

needed N. This study compared soluble sources of '5N [ammonium nitrate-NH4NO3.

potassium nitrate-KNO3, ammonium sulfate-(NH4)2S04, urea-CO(NH2)2, and calcium

nitrate-5Ca(NO3)2 NH4NO310H20] to identify materials that are capable of supplying the









required nutrients while minimizing the quantity lost due to leaching. Through the use of

the 15N-labeling technique, the differential nitrate leaching and mass balances were

quantified.

In a report to Hydro Agri North America on the retentive and mobile characteristics

of CN, Sartain (unpublished data, 1996) reported no differences due to N source on the

quantity of N03-N leached; however N source did not influence the quantity of calcium

(Ca) leached suggesting that the Ca as applied in the CN was being retained by the soil

against leaching losses. Large differences in N03-N leaching losses relative to N source

were not observed, but based on the lack of apparent Ca movement through the

lysimeters treated with CN and the somewhat larger quantity of unaccountable N03-N in

these lysimeters, it could be hypothesized that the N03-N is being retained along with the

Ca in the form of Ca(NO3)+ ion pair. Limitations in the analytical techniques employed

in the study did not allow for verification of this theory.

The literature reveals a number of studies that have been conducted employing CN

as a N source. These studies have been carried out on an array of soils under varying

environmental conditions, but a clear and objective comparison of CN with other N

sources relative to N retained in the soil, leached, and taken up by plants under varying

soil and environmental conditions has not been reported. A series of laboratory,

glasshouse, and field experiments were conducted in Gainesville, Florida, from July 2000

to March 2002 to clarify these points.

The objectives of the studies were (1) to determine the leaching potential and

utilization of 5 soluble 1N labeled sources, AN, KN, urea, AS, and CN in varying soil

and environmental conditions including turfgrass and citrus systems through mass









balance studies; (2) to identify components responsible for differential leaching and

utilization of applied '5N; (3) to determine the influence of Ca+2 on NO3- retention,

leaching, and utilization of applied 15N; (4) to evaluate the influence of Tropicoate M prill

coating on CN retention, leaching, and utilization.

The objectives of the studies were (1) to determine the leaching potential and

utilization of 5 soluble 15N labeled sources, NH4NO3, KNO3, CO(NH2)2, (NH4)2SO4, and

5Ca(N03)2NH4N0310H20 in varying soil and environmental conditions including

turfgrass and citrus systems through mass balance studies; (2) to identify components

responsible for differential leaching and utilization of applied 15N; (3) to determine the

influence of Ca'2 on NO3- retention, leaching, and utilization of applied 15N; (4) to

evaluate the influence of TropicoateTM prill coating on 5Ca(NO3)2 NH4NO310H20

retention, leaching, and utilization.














CHAPTER 2
LITERATURE REVIEW

Introduction

Nitrogen (N) is an important nutrients in turfgrass culture. Maintaining a high

quality turfgrass often requires the application of large quantities of N for plant uptake

(Snyder et al., 1984; Sartain, 1988). One of the primary goals of N management is to

improve N use efficiency. Low N efficiency can be due to N losses from soil/plant

systems through leaching and/or gaseous losses volatilizationn and denitrification) during

the growing season (Bock, 1984). Other pathways for N loss include immobilization (the

conversion of inorganic N ions, N03- and NH4+, into organic forms) and NH4" fixation by

clay minerals.

As microorganisms decompose carbonaceous organic residues in the soil, they may

demand more N than is contained in the residues themselves. The microorganisms then

incorporate mineral N ions into their cellular components, leaving the soil solution

temporarily devoid of N03 and NH4+ ions (immobilization of N) (Tisdale et al., 1999).

Due to the size of the NH4+ ion, it can become entrapped within cavities in the crystal

structure of certain clay minerals and fixed in the rigid part of a crystal structure and held

in nonexchangable form, where it can be released only slowly to higher plants and

microorganisms. Ammonium fixation by clay minerals is generally greater in subsoil

than in topsoil, due to the higher clay content of subsoils (Brady and Weil, 2000).

There is a growing concern about nitrate (NO3-) pollution in surface and ground

waters. Leaching of NO3 can have economic as well and environmental consequences.







5


Applied N that is not taken up by the desired crop represents lost value to the nutrient

manager, and its presence in drinking water supplies in excess of Environmental

Protection Agency (EPA) standards of 10 mg N L-' (45 mg NO3 L-') presents human

health hazards. The major human and animal health issue associated with the

consumption of excessive N03-N from drinking water is methemoglobinemia or "blue

baby syndrome" (Pierzymski et al., 1994). Additionally, increased levels of N in water

bodies can contribute to eutrophication, a general degradation of water quality caused by

accelerated growth of algae and depletion of dissolved oxygen.

Nitrogen in a Turfgrass Environment

The fate of N in a turfgrass environment includes several major categories of the N

cycle. These include 1) plant uptake; 2) soil retention and microbial immobilization; 3)

runoff and leaching into groundwater and surface waters; and 4) losses to the atmosphere

(Petrovic, 1990). Nitrogen can also undergo numerous soil reactions including

mineralization, immobilization, nitrification, denitrification, and volatilization (Tisdale et

al., 1999). Considerable potential exists in Florida for leaching of N applied to

bermudagrass (Cynodon sp.) turf due to factors such as high N fertilization rates used,

excessive irrigation, abundant rainfall, and generally sandy soils (Snyder et al., 1980).

Snyder et al. (1980) reported it is reasonable to assume that most of the N that

leached from urea fertilization or from urea based slow-release sources was in the NO3

form because urea is rapidly hydrolyzed to NH4' in warm wet soils, and NH4+ is rapidly

oxidized to N03" via nitrification. Snyder et al. (1980) concluded that the reason more

N03- was leached from Ca(N03)2 than from urea was due to N volatilization of surface

applied urea. Volk (1959) listed six conditions that favor volatilization losses from urea:

1) low soil cation-exchange capacity; 2) high rates of urea application; 3) high









temperatures; 4) high pH, 5) application to a moist surface which then dries out; and 6)

the presence of a grass sod. Volk reported that losses from urea solution were similar to

those from dry urea for turf but were much less for bare soils (soils with no plants).

Losses of N as NH3 during 7 days following surface application of urea-N were 20 to

30% for 4 different grass sods.

The high sand content of United States Golf Association (USGA) golf greens

creates a rootzone potentially prone to N leaching. Johnston and Golob (2003) conducted

research on the floating green at the Coeur d'Alene (Idaho) Resort Golf Course where the

green is essentially a large sand-based lysimeter. The green has a USGA-recommended

rootzone with bentgrass (Agrostis solonifera L.) Total recovered N was 59% (11% in

leachate and 48% in clippings over the three year study. Nitrate-N in the leachate ranged

from 0 to 3.1 ppm and NH4-N ranged from 0 to 0.6 ppm. Low leachate N

concentrations and efficient plant uptake of N suggests low potential for negative

environmental impact from N fertilization to USGA golf green systems under conditions

similar to those studied by Johnston and Golob.

Keeney and Nelson (1982) reported that NO3 is highly soluble and a very mobile

plant nutrient. Nitrate's qualities of mobility help increase plant uptake but also make it

very susceptible to leaching through the soil. Soil type also greatly affects NO3- leaching

rates. Soils have vertical and horizontal variability in their chemical, physical and

biological properties (Keeney, 1986). Kinjo and Pratt (197 la) reported a positive

correlation between the amount of NO3- adsorbed and the content of amorphous

inorganic materials extractable with 0.5 M NaOH. In an additional study, Kinjo and Pratt

(197 Ib) showed that a competition existed between the common anions of CI, NO3,









S042-, and H2P04- for anion adsorption sites. It was reported that C1 showed a slight

preference over NO3-, while S042- and H2P04- were greatly preferred over N03-. The

effect of adding S042- and N03- in the same column was an increase in the rate of

movement of N03- (Kinjo and Pratt, 197 1c).

Bolan et al. (1993) reported the effect of Ca2+ on the adsorption of SO42- in

variable-charge soils. It was found that S042- adsorption increased with increasing

adsorption of Ca2 The increase in SO42- adsorption per unit increase in Ca2+ adsorption

was 12 times more in soils containing Fe and Al hydrous oxides as the major variable-

charge component than in soil dominated by organic matter. In soils containing Fe and Al

hydrous oxides, specific adsorption of Ca2+ increased the positive charge and thereby

induced further adsorption of S042-. Increase in positive charge accounted for up to 75%

of the increase in S042- adsorption and the remaining increase was attributed to the

coadsorption of Ca and S042- as a CaSO40 ion pair. Investigation of whether the ion

pairs CaNO3 or Ca(N03)20 could lead to increased N03- retention in soil systems has not

been done. Increased concentrations of Ca2+ and NO3' will push the equilibrium reaction

towards the formation of more CaN03 or Ca(N03)20 ion pairs in the soil solution

(Lindsay, 2001).

The movement and transport of Ca(N03)2 is affected by soil mineralogy and

chemistry. Retention of Ca(N03)2 seems to be a common phenomenon in variable charge

subsoils (Qafoku and Sumner, 2001). The magnitude of Ca(NO3)2 retention was higher

in subsoils with appreciable anion exchange capacity (AEC) and an equivalent amount of

CEC.









Nitrogen in a Citrus Environment

Alva and Paramasivam (1998) developed N best management practices for citrus in

sandy Entisols to increase N uptake efficiency and to minimize N03 leaching below the

rooting depth. Improved management of irrigation and fertilizer placement and timing of

application contributed to minimized leaching of NO3- below the root zone.

Paramasivam and Alva (2001) reported that NO3" leaching in an entisol during citrus

production occasionally peaked at 12 to 100 mg L-', but at the highest rates of applied N,

concentrations mostly remained below 10 mg L-'. Nitrogen losses in a citrus rootstock

system were found to be lower using controlled-release fertilizers than from soluble

fertilizers (Dou and Alva, 1998).

Nitrogen transformations of NH4NO3 and Urea in an entisol and spodisol under

citrus production showed that during a 7 day incubation, the percentage transformation of

NH4-N into N03-N was 33 to 41%. Greater than 95% of the urea applied was hydrolyzed

to NH4- within 4 to 7 days (Khakural and Alva, 1996).

Lea-Cox et al. (2001) measured '5N uptake, allocation and leaching losses from a

citrus rootstock system. Newly developing spring leaves and fruit formed dominant

competitive sinks for '5N, accounting for between 40 and 70% of the total 15N taken up

from the treatments. Nitrogen-use efficiency declined with increasing N rate, irrespective

of rootstock. Willis et al. (1990) found that NO3 and NH4+ concentrations fluctuated

seasonally and increased at 15 and 46 cm depths after fertilization and rainfall. More

NO3 leaching was found when granular fertilizer was applied 5 times/year compared

with the 10 or 30 time/year liquid treatments.

Leher and Bar-Akiva (1979) studied N03-N uptake under Mn-deficiency stress

conditions. They reported that Mn-deficient plants absorbed more NO3- than control









plants. The authors stated that they have no experimentally proven explanation for the

apparently more efficient use of N by Mn-deficient lemon seedlings, except to postulate

that Mn deficiency in citrus may inhibit the Hill reaction similar to triazine herbicides,

which causes an increase in N assimilation and protein synthesis in plants.

Influence ofCa

Calcium in the soil solution occurs as a relatively large, divalent ion which readily

enters the apoplast and is bound in an exchangeable form in cell walls and on the exterior

surface of the root plasmalemma (Kirkby and Pilbeam, 1984). Calcium occurs in the

cytoplasm and chloroplasts in very low concentrations and appears to have a limited role

as an enzymatic cofactor. Kirkby and Pilbeam (1984) reported that the soil solution

usually provides an adequate supply of Ca to plants, but other factors exist that can

contribute to Ca deficiencies within the plant. Simonne et al. (2001) suggested that

Ca(N03)2 enhances lettuce crunchiness and should be used even though NH4NO3 may be

a less costly N material.

Bache (1984) in describing the role of Ca in buffering soils states that Ca2- is the

soluble cation that occurs in the largest amount in most soils. Calcium does not take part

directly in the proton transfer reactions involved in pH-buffering, but it provides the

cation charge balance for the reactions. Bache reported that Ca is the complementary

cation in formulations of chemical potential for many other ions in soils. They concluded

that pH changes associated with buffering are produced by leaching of Ca2- from soil, or

by adding Ca2> to soil in liming materials.

Van Miegroet and Cole (1984) suggested that the presence of large amounts of

mobile N03- in solution triggered accelerated cation leaching, causing a selective

redistribution of primarily exchangeable Ca2+ from the A to the B horizon. Sartain









(1985) reported that acidity promoted bennudagrass thatch accumulation except with

addition of Ca(OH)2. Horst et al. (1986) reported that the addition of Ca to the fertilizer

formulation apparently enhanced N utilization in bermudagrass. They noted that color,

quality, and verdure were improved and persisted longer with the addition on Ca to urea

N sources. A treatment consisting of a 1:4 ratio of Ca(N03)2 to urea as [Ca(N03)2

4CO(NH2)2] had color scores greater than urea alone at every evaluation in research

conducted in 1979. Urea + Ca(N03)2 scored higher than ammonium sulfate in 16 out of

21 ratings and was greater (p<0.05) in 9 of 16 ratings. Root and rhizome production was

higher with the urea + Ca application which supports the hypothesis that Ca enhanced N

absorption is allocated to increased dry matter production. Two mechanisms have been

identified for increased dry matter production with added Ca and NH4 -forming N

sources including urea. Urea and NH4 -forming N sources amended with Ca reduced N

losses (Fenn et al., 1981) from surface applied fertilizer. Second, there is increased

NH4I-N uptake by plants from the soil solution when associated with Ca in solution

(Viets, 1944), leading to increased plant production. Jacobson et al. (1960) reported that

polyvalent cations such as Ca*2 often exert a positive influence of the absorption of

monovalent cations.

Fenn and Feagley (1999) measured Ca-stimulated NH4+ absorption using isotopic

nitrogen (15N) in greenhouse trials. As Ca2+ ion concentrations in solution were

increased, an increase in '5NH4* absorption was obtained in all plant species tested. The

observation that divalent cations such as Ca2+ and Mg2* stimulate root absorption of

monovalent cations, such as K' or NH4- is now referred to as the "Viets Effect."









Increased NH4t is associated with enhanced photosynthetic rates as well as increased

proportions of new metabolites translocated to nutrient sinks.

Leggett and Gilbert (1967) determined that Ca2 influences root plasmalemma

functions through exterior adsorption. Morre and Brocker (1976) concluded that Ca2-

saturation of the plasmalemma beneficially increased membrane thickness and the lack of

adequate Ca usually less than 40 to 80 ug L leads to membrane leakiness. The

integrity of the plasmalemma is maintained by the presence of extra Ca2, leading to

greater turgor pressure and nutrient retention in cells which produce greater gro\ ith

potential in plants. Calcium also has been shown to provide some protection to plant

roots against soil acidity (Barker et al., 1966; Bartlett, 1965). The higher the soil solution

Ca2- concentration, the less the deleterious effect that acidity has on plant growth. Fenn

et al. (1991, 1994) found preferential increases of beet and onion root bulb yields with

increasing Ca2 additions at a constant rate of NH4+. Metabolites went preferentially to

the roots and bulbs showing that the primary pattern of translocation of N compounds

changed from the leaves to the roots or bulbs. Horst et al. (1986) observed a synergistic

association of Ca2+ and NH4 in bermudagrass growth process, but observed no extra

benefit for Ca2> with NO3-.

Jacobson et al. (1960) postulated that the presence of Ca2> in the solution creates a

barrier probably at the cell surface. This barrier was effective in blocking Li' and H and

determines the relative amounts of the cations reaching the absorption site. The

stimulating effect of Ca2- is considered by Jacobson et al. to be essentially a blocking of

interfering ions whereas the Viets effect describes the effect of Ca2 as stimulating uptake

ofmonovalent cations such as NH4+ and K'.









Many physiological processes in plant cells are linked with Ca2" ions including cell

division and elongation, protoplasmic and chloroplast streaming, secretion of cell wall

material, and functioning of a number of enzymes, as well as transport of carbohydrates

and other respiratory substrates on the plasmalemma and tonoplast (Tikhaya and

Tazabaeva, 1986). Fenn and Feagley (1999) theorized that the placement of Ca2-

precipitating N fertilizers (urea, NH3, and phosphate species) near roots may cause

membrane dysfunction, whereas including Ca with these N fertilizers enhances more

normal absorption of available NH4L.

Solution Ca2> concentrations well above those considered adequate resulted in

increased plant growth in an NH4I environment (Fenn et al., 1987). Ammonium

absorption increased in plants with increasing Ca in the soil solution up to 13 mmol Ca2-

L-'. Further, when an NH4+ fertilizer is used where leaching could move N03- below the

root zone, the use of Ca2- with NH4 fertilizer could improve N use efficiency. Increased

amounts of Ca2+ in the nutrient solution of calcareous sand were related to increases in

plant dry matter weights.

Influence of N Form

Plant uptake of N in the NH4+ verses the NO3- form will have consequences on the

pH of the surrounding soil solution. Plants can modify their rhizosphere through nutrient

uptake from the rhizosphere, rhizo-deposition, and plant root exudates (El-Shantnawi and

Makhadmeh, 2001). Dejaegere et al. (1981) reported that NH4 nutrition leads to

acidification of the NH4- solution while N03- nutrition leads to a slow alkalinization of

NO3" solutions. Ammonium nutrition leads to an excess of about 70 H- for every 100

ions taken up in the medium while N03- nutrition leads to a deficit of 22 H+ ions in the

medium. Riley and Barber (1969) reported an accumulation of HC03- and an increase in









pH of the root-soil interface environment of soybean roots was related to the NO3- level

of the soil solution. This effect was attributed to a greater uptake of anions than cations

by the plant so that HCO3- release maintained electrical neutrality. It was concluded that

the HCO3" accumulation and pH increases at the root surface and in the rhizoplane soil

are closely associated with the N03" supply and uptake by the plant roots.

In further research, Riley and Barber (1971) reported that fertilization of soybeans

with NH4'-N decreased the pH of the rhizocylinder (roots plus strongly adhering soil);

fertilization with NO3- increased the rhizocylinder pH. Results for soybeans grown with

NH4+ and NO3- treatments at four initial soil pH levels showed that the P content of the

shoots and roots was closely correlated with the pH of the rhizocylinder, but not the pH

of the bulk soil. It was suggested that the increased availability of P from the soil where

NH4+ was used was mainly due to the effect of the N source on the pH of the rhizosphere

soil.

Macklon and Sim (1980) performed a study to quantify Ca uptake in tomato plants

when supplied with NH4' and NO3" in solution. Ammonium nutrition resulted in a

reduction of Ca concentration in the xylem sap and of calcium content in the stems and

leaves compared with the NO3- fed plants. This effect was attributed to the less negative

trans-root electrical potential measured in NH4n-fed plants and the resultant reduction of

inward driving force on passively moving divalent cations.

Lawson (2000) measured the effect on turf quality from the application of

(NH4)S04 vs. NH4NO3 on Festuca rubra/Agrostis tenuis Sibth turf combination and

reported that differences in turf quality between the two N sources resulted mainly from

the differential effects on soil pH. Measurements of botanical composition showed









(NH4)2S04 application to cause an increase in Agrostis content of the turf and a decrease

in Festuca content, and the effects being enhanced by the application of lime. The

NH4NO3 application caused a large increase in the Poa annua L. content of the turf and

was exacerbated by the application of lime. Ammonium sulfate treated turf was less

infected with Microdochium nivale and produced a greater rooting depth than NI l4NO3.

Calcium nitrate or lime was used by Towers et al. (2002) to manipulate pH and they

found reduced incidence of grey leaf spot compared to perennial ryegrass treated with

(NH4)2SO4. Plots treated with (NH4)2SO4 or urea sustained 7 to 65% more disease than

turf fertilized with Ca(NO3)2.

Ammonium nutrition has been reported to reduce Mn uptake by plants due to

cation absorption competition (Cox and Reisenauar, 1977). Manganese toxicity

developed in muskmelons when the N source was NO3 in a Mn and N solution (Elamin

and Wilcox, 1986).

Mancino and Troll (1990) compared leaching losses of N03-N and NH4-N from

'Penncross' creeping bentgrass growing on an 80/20 sand to peat soil mixture. Nitrogen

sources included CN, AN, AS, urea, urea formaldehyde, and isobutylidene diurea.

Nitrate represented the major portion of leached N, with NH4+ losses being negligible.

There were no differences between sources at these application levels as total leaching

losses were 0.5% of the applied N. In another study using higher application rates, CN

and AN leached 2.8% and 4.13% of applied N, respectively.

Bailey (1998) found that when perennial ryegrass was supplied with different ratios

of 'N-labelled NH4" and NO3- -N (20:80, 50:50, and 80:20, with a nitrification inhibitor),

followed by sequential destructive harvests (to simulate a grazing situation), both forms









of N were absorbed at almost equal rates until the supply of the minor N component in

each treatment was almost exhausted. It was suggested that the uptake of N in perennial

ryegrass was characterized by matching of NH4 and N03- -N absorption rates by plants,

thus maximizing the advantages and minimizing the disadvantages associated with the

exclusive use of either form of N, thereby optimizing the potential for vegetative and

reproductive regeneration. Plants grown with NH4+ and NO3- -N at a ratio of 50:50

accumulated more root carbohydrate than those in the other two treatments and clearly

were in the best position to re-mobilize root carbohydrate and initiate shoot regeneration.

In another study by Bailey (1999), the ratio of 5N-labelled NH4+ and NO3- -N

(20:80, 50:50, and 80:20, with a nitrification inhibitor) was supplied to creeping bent to

determine the effects on N absorption, assimilation, and plant growth. Results indicated a

lack of plant preference in regards to NH4+ and N03- -N absorption, but suggest that the

processes of N absorption storage, and assimilation were actually best synchronized

when the two forms of N were supplied in equal proportions. Supplying plants with

different combinations of NH4 and NO3- -N produced distinctive differences in plant

morphology. In the high NO3- treatment, plants preferentially partitioned resources into

shoot and stolon formation, whereas in the high NH4+ treatment, resources were

preferentially partitioned into root production. Changes in plant morphology might be

adaptations to aid species survival in environments associated with a predominance of

either N form such as situations in which creeping bent might be out-competed for vital

canopy positions by faster growing species such as perennial ryegrass.

In a study comparing N leaching in bermudagrass turf, Snyder et al. (1980)

reported that quality turfgrass, coupled with minimal N leaching, resulted from









fertilization with slow-release N sources. Leaching losses from urea were lower than

Ca(NO3)2 and this was attributed to volatilization losses. At 8 g N m2 NO3 -N

concentration of the leachate averaged 2.4 and 1.4 ppm for Ca(N03)2 and IBDU,

respectively, well below the 10 ppm standard set for drinking water. Geron et al. (1993),

in a study on the establishment methods and fertilization practices on N03- leaching from

turfgrass, found that different N sources and ferilizer programs did not result in greater

NO3 -N percolate losses compared to unfertilized turfgrass plots.

Nitrate-N readily moves with the wetting front following irrigation (Bauder and

Montgomery, 1980). They concluded that NO3- leaching from N fertilizers under

irrigation may be minimized by timely applications of NH4 based fertilizers and low

volume irrigations to minimize leaching below the crop root zone.

Influence of pH

Micronutrient availability is related to pH of the soil system. Elements such as Mn

and Fe become increasingly less available to the soil solution and thus plants as pH

increases above the 6.5 to 7.0 range (Brady and Weil, 2000). Micronutrient deficiency

can cause chlorosis in plants. Micronutrient deficiency chlorosis, also called bicarbonate

induced chlorosis by Lucena (2000), describes the effect of bicarbonate, NO3- and other

environmental factors on Fe deficiency chlorosis. Bicarbonate in the soil solution is quite

mobile and can be a strong pH buffer. Lucena reported that the formation of Fe(II) from

the Fe(III) in the rhizosphere and ferric reductase activity of plant roots declines sharply

at high pH values. Nitrate can be acquired by the roots along with a proton cotransport

that increases the pH outside the root plasmalemma, but a redox effect is also important.

From a thermodynamic point of view, electrons released by the plant can be taken










directly by nitrate instead of Fe(III), or the Fe(II) can be oxidized by the NO3. If NO3 and

NO2 reductions occur in the rhizosphere, microsite pH increases at the root surface.

Solution reactions whether outside or inside the plant can reduce plant available

levels of Mn and Fe. Apoplastic pH controls the entry of Mn2+ and Fe2+ to the cytosol in

leaves in a similar way that occurs in the root. Bicarbonate in the nutrient solution could

act as a buffer in the leafapoplast. Nitrate uptake in the meristem also produces a pH

increase, with the same effect as the bicarbonate. Also, NO3 is an oxidant that could

reduce the availability of the electrons for the Mn reduction for membrane transport

(Lucena, 2000).

Rates of 3.3 to 7.3 kg N acre-' of IBDU applied to ryegrass resulted in chartreuse

yellow turf color (Volk and Dudeck, 1976). Rates of 2.2 kg N acre'' ofIBDU resulted in

chartreuse green turf color. Sartain (personal communication, 2003) found similar results

and concluded that continuous exclusive use of IBDU can raise soil pH to levels that are

conducive to micronutrient deficiency, resulting in a yellowing of turf color. Tissue

analysis showed an excellent inverse correlation with Mn content suggesting that the

IBDU was increasing soil solution pH resulting in lower tissue Mn content and poor color

for the turf (Volk and Dudeck, 1976).

Ammonium nutrition produces a pH reduction around the roots of plants which can

increase Mn solubility and increase its uptake (Smiley,1974). Snyder et al. (1979)

reported that manganese (Mn) deficiency of 'Tifgreen' bermudagrass (Cynodon X

magenissii Hurcombe) turf has been observed in South Florida when soil pH exceeded 7

as a result of irrigation with alkaline water. Adequate Mn nutrition was obtained even in

the absence of Mn fertilization when soil pH was maintained below 7 with acid-forming









N sources. Although this seems to contradict the findings by Cox and Reisenauar (1977),

the effect observed by Snyder et al. (1979) was pH related while the effect observed by

Cox and Reisenauar was due to cation absorbtion competition. It was concluded that this

treatment was very suitable for turfgrass, since considerable N is commonly used in

turfgrass production.

Research conducted on non-fertile acid strip-mined soils has found that

bermudagrass is a suitable plant species for revegetation. Bermudagrass was found to

tolerate acidic conditions as low as pH 3.4 (Lundberg et al., 1977). The pH of 4.5 was

found to be the best for dry matter production, but it was noted that bermudagrass can

tolerate low pH levels with increasing vigor down to pH of 3.4 (Sartain, 1985). Lundberg

et al. (1977) theorizes that if it were not for the abundance of toxic metals such as Mn.

Cu, and Al in the soils used, that lower pH levels would not have a deleterious effect on

growth. Sandy soils such as those used in a USGA specification golf green, having low

levels ofMn, Cu, and Al, could possibly have pH levels below 3.4 and still be

productive.

Snyder et al. (1979) reported that soil pH resulting from Ca(N03)2 fertilization was

reported around 7 and increased to around 7.5 by the third year of the study. In contrast,

acid-forming fertilizer (NH4)2SO4 was used to successfully bring the soil pH values

below 5, when it was decided to substitute NH4NO3 for (NH4)2SO4 to keep the pH values

above 5 (Snyder et al.,1979; Sartain, 1985). Manganese deficiencies were pH-induced

rather than attributable to insufficient total Mn in the soil and were responsible for

severely limited turf appearance and growth.









Snyder et al. (1979) concluded that the best method of alleviating the Mn

deficiency was through reducing soil pH. Elemental sulfur (S) could be used, but pH

maintenance in a favorable range can probably be achieved most economically by

choosing N sources with the proper degree of potential acidity with the understanding

that some Mn will eventually need to be applied to the soil as the total Mn is depleted.

Sartain (1985) reported that maximum growth rates for bermudagrass occurred at

pH less than 4.0. Acidity promoted thatch accumulation, except in the presence of

applied Ca as Ca(OH)2. It was concluded that AS as a N source can produce a high

quality, rapid growing bermudagrass under putting green conditions. Primary long-term

disadvantages of using AS are excessive thatch accumulation and leaching of plant

nutrients (Smith 1979 and Sartain 1985). Incidence of Stellaria media and Poa annual

during the cool-season growth period can be minimized by maintaining the soil pH

between 4.5 and 5.0 and acceptable overseeding with ryegrass can be achieved. Varco

and Sartain (1986) reported that application of S resulted in a reduction in stand of Poa

annua possibly due to reduced germination as a result of decreased pH brought on by

applied S. It was concluded that annual bluegrass infestation ofturfgrasses may be

reduced by limiting P applications and maintaining the soil pH near 5.0, but the infested

turfgrass must be tolerant of these conditions. Thompson et al. (1992) reported that the

onset of summer patch, patch development, bulk soil and rhizosphere pH were greatly

reduced by application of NH44 -N to Kentucky bluegrass. Hill et al. (2002) reported that

lime may be applied along with (NH4)2SO4, to maintain acceptable soil pH levels and

turf quality, without reducing the effectiveness of (NH4)2SO4 for the control of summer

patch in Kentucky bluegrass.









Nitrogen source has an affect on turfgrass appearance and growth when N was

applied via fertigation (Snyder and Burt, 1985). Soil pH from highest to lowest was

reported in the order NaNO3 > NH4NO3 > urea > NH4CI. Turfgrass growth and

appearance were adversely affected by Mn deficiency in all treatments except NH4CI.

Manganese deficiencies were ameliorated with repeated Mn fertilizations, but clipping

weights were found to be negatively correlated to soil pH during the final year of the

study.

Malhi et al. (2000) suggests that periodic monitoring of the soil pH is important

when soluble N sources are used for extended periods of time. Soil was acidified and the

concentration of soil extractable Al, Fe, and Mn was increased by N application. The Mn

concentration in forage increased markedly in response to reduced soil pH from the acid

forming fertilizers. Soil acidification was found to be greatest with AS, followed by AN

and urea which were the same. Malhi et al. (2000) reported that pH was not changed by

CN and was found to be the highest. Snyder and Burt (1985) found similar results from

N fertilizer applications and concluded that N3O sources can raise the soil pH to levels

that are undesirable. Long term (3 year) application of CN on bahiagrass resulted in an

increase in soil pH and a response to added Fe and Mn (J.B. Sartain, personal

communication, 2003).

Nitrogen Isotope Techniques

Fate of fertilizer N applied to experiments can be estimated by measuring the

difference in plant N uptake between treated and check plots or by isotopic methods. The

difference method has often been used in field experiments to estimate fertilizer N

recovery by crops, however isotopic tracers afford distinction between fertilizer N and

soil N and allow the researcher to directly determine fertilizer N recovery (Schindler and









Knighton, 1999). The use of 5N in soil fertility research has two primary drawbacks (i)

the 1N enriched material is very expensive and is thus limited to small greenhouse or

microplot investigations and (ii) fertilizer N recovery interpretations are complicated by

the fact that 15N undergoes biological interchange when applied to the soil system. It has

been advised that studies involving fertilizer N recovery should include control plots and

to calculate fertilizer N recovery by both isotopic and difference methods (Jansson,

1958). This reduces the chance of making erroneous interpretations due to the

mineralization-immobilization turnover and biological interchange processes.

Nitrogen isotope analysis has been useful in the routine measurement of

transformation rates of N-containing compounds in agricultural and natural ecosystems.

The stable isotopes 14N and 15N are commonly used as tracers. They occur naturally in a

relatively fixed abundance with about 273 atoms of mass 14 for each atom of mass 15

(Hauck, 1973). Nitrogen tracers are materials that contain an unusually high or low

content of either 14N or 15N. The use of isotopes has been very helpful in elucidating

specific pathways and demonstrating that certain reactions are possible (Knowles and

Blackburn, 1993). Determining the quantity of applied 15N-labelled N fertilizer

recovered in the leachate, soil, and plant material components (verdure, tissue, roots,

stems, and leaves) can be achieved using 15N enriched treatment materials.

Hauck (1973) reported that data from 1N tracer studies obtained over a variety of

experimental conditions indicate first year recoveries of applied 5N ranging from 30-

70%, with 10-40% remaining in the soil, 5-10% lost through leaching, and 10-30% not

found and presumably lost via volatilization and/or denitrification. Pasture ecosystems

had 70-90% N accounted for due to increased levels of 5N being recovered in the t r,!L.










Nitrogen Partitioning

Martinez and Guiraud (1990) in discussing the fate of 15N fertilizer applied to

winter wheat reported the recovery of total fertilizer showed an uptake by plants of 65%

while immobilization in the soil was 21%. Measurement of losses indicated that leaching

was very low during the vegetative cycle (1%). Nitrogen not accounted for was assumed

to be lost by denitrification. The 15N labeled tracer analysis showed overall recoveries of

labeled N of 91.7% and 97% for two rotation cropping systems and concluded that this

showed the ecological importance of a catch crop in reducing N leaching as well as its

efficient use of fertilizer in the plant-soil system from the particular rotation.

Frank et al. (2001) reported recovery of 15N labeled N from fertilizer treatments of

24 and 49 kg N ha'' rates on Kentucky bluegrass was 95 and 73% of applied N,

respectively, and concluded that the majority of applied N is either retained in the soil or

taken up by the turf. Miltner et al. (1996) reported recovery of 15N labeled urea applied

to Kentucky bluegrass to be 0.23% in leachate and total 15N recovery to be up to 81%.

Rapid uptake and immobilization of 15N labeled N was observed over the 2 year

experiment leading to the conclusion that a well-maintained turf intercepts and

immobilizes N quickly making leaching an unlikely avenue of N loss from a turf system.

Blue (1974) reported N uptake efficiency was in the 40 to 50% range through the

first 4 years of N fertilization and after that increased to 65 to 75% on Pensacola

bahiagrass and concluded that N leaching is not a major loss route when N is applied to

perennial grass pastures at biologically useable rates.

Brown and Volk (1966) reported that there were no differences in total recovery of

labeled N in plants plus soil between ureaform and NH4NO3. A greater proportion of

labeled NH4NO3-N was recovered in the plants than labeled ureaform-N, however









approximately 15 to 20% of the ureaform material remained apparently unchanged in the

soil after 1 year.

Concern for environmental welfare has promoted the development and

implementation of best management practices (BMPs) for golf courses. A major area of

concern on golf courses is the application of fertilizer to potentially highly leachable

sand-based putting greens. Lee et al. (2003) found no evidence that N fertilization or the

ecology of the bermudagrass system posed inherent risks to water quality and the

environment. Results indicate that soil NO3-N levels were consistently low (1 to 4 mg

kg-' soil). Levels were relatively uniform with depth and across several landscape

positions. The soil NO3- levels under fertilized fairways were similar to those in adjacent

nonfertilized natural areas, indicating minimal influence from turf management practices.

Nitrogen released from mineralization is synchronized with bermudagrass growth,

keeping soluble N in the soil plant system rather than being lost via leaching.

Johnston and Golob (2003) found that low leachate N concentrations and efficient

plant uptake of N suggested a low potential for negative environmental impact of N

applications on golf greens. Using a floating green at Coeur d'Alene Resort Golf Course

(Idaho), N was quantified in the leachate from the green and taken up by the plant.

Nitrate-N levels were never found to be excessive in the leachate even after as much as

5.0 g N m-2 was applied. Leachate NO3-N levels were only close to 3 mg N L'- one time

in three years and averaged about 1.5 mg N L ', well below EPA standards.

Denitrification can account for N lost from soil systems (Petrovic, 1990). The term

denitrification describes the microbial process where nitrate is reduced to gaseous N

compounds such as nitrous oxide (NO) and nitrogen (N2). Microbial denitrification is









equivalent to aerobic oxidation with NO3 replacing oxygen as the ultimate oxidizing

agent, where NO3 instead of oxygen serves as the final hydrogen (or electron) acceptor

(Bremner and Shaw, 1958). Horgan et al. (2002) reports that recovery of applied N is

typically low in turfgrass systems and cites denitrification as the reason. Total emission

of 'N from fertilizer applied to Kentucy bluegrass as N2 or N20 was 19.0% for the

turfgrass and 7.3% for bare soil. Corresponding values for total recovery of '5N were

70.6 and 84.2% respectively.

Denitrification occurs during the hydrologic process of USGA greens, further

diminishing the negative impact from the system. Greens built to USGA specification

have a textural discontinuity at 30 cm depth that helps keep the root zone more highly

saturated with water than if there was uniform textural continuity below that depth

(USGA Green Section Staff, 1993). Moisture retention by soil underlain by gravel was

much greater than in similar depths of a uniform soil (Miller and Bunger, 1963).

Moisture content of the soil above the layer increased as the layer was approached. The

moisture content of the soil underlain by gravel changed very little after the first few days

following irrigation whereas the uniform soil moisture moved downward throughout the

observation period.

Bermudagrass can be very efficient in N utilization from fertilizers. Bowman et al.

(2002) reported 63% N recovery for Meyer zoysiagrass and 84% N recovery for hybrid

bermudagrass. Leaching losses were high following the first application, ranging from

48 to 100% of the N03-N and 4 to 16% of the NH4-N applied. Nitrate loss from

subsequent applications was reduced substantially, while NH4+ leaching was essentially

eliminated.









Risks of NO3-N losses in bermudagrass can be avoided by proper fertilization and

irrigation programs, even when a highly soluble N source is used (Quiroga-Garza et al.,

2001). Total leaching losses through a bermudagrass system represented a minimal

fraction (<1%) of the total applied N.

Shaddox and Sartain (2002) reported in a study to determine the influence of eight

N management regimes on establishment of Tifway 419 bermudagrass that N loss via

leaching during establishment can be reduced by following a progressive-type application

regime without adversely affecting tissue uptake or coverage rate. By applying N at low

rates when turf density is low and increasing N rates as turf density increases, N leaching

can be minimized without sacrificing grow-in performance. Using combinations of

controlled release and readily soluble N forms has been demonstrated to show a

significant reduction in leaching of NO3 compared to the use of soluble forms alone

(Parabasivam and Alva, 1997).














CHAPTER 3
METHODS AND MATERIALS

This research consisted of three glasshouse and two field studies conducted at the

University of Florida, Gainesville, Fl. Turfgrass glasshouse and field research projects

were conducted at the Turfgrass Envirotron, 1282 Hull Road, while a citrus experiment

was conducted just down the road from the Envirotron in an isolated glasshouse.

Lysimeter setup

The mobility of N from selected N sources on native Florida sand soils and USGA

root zone mixes was evaluated using lysimeters. A lysimeter is a device for measuring

the percolation of water through soils and for determining the soluble constituents

removed in the drainage or leachate. All experiments were set up using polyvinyl

chloride (PVC) pipe material formatted to the function of a lysimeter. Each lysimeter

was 45 cm tall and 15 cm internal diameter with a porous bottom of Typar Landscape

fabric and closed by a 5 cm deep PVC end cap. Lysimeters have the flexibility to be used

in the glasshouse or placed out in the field under the soil surface where a suction pump

can be used to evacuate leachate solution. Leachate can be collected in the glasshouse by

means of gravity or by suction. Leachates from the turfgrass glasshouse studies were

collected by gravity while the turfgrass field studies and the citrus study leachates were

collected with a suction pump to aid in collection. The suction pump was used to allow

for the evacuation of the macropores (40 cm tension) from the citrus soils as to more

accurately replicate field conditions.









River rock pea gravel was rinsed with tap water and placed in the bottom of each

lysimeter to form a 15 cm layer. The sand and pea gravel were tested with a Mehlich I

extraction to insure they did not have appreciable Ca content, so that indigenous soil Ca

would not interfere with tracking applied Ca (Hanlon et al., 1994a). Sands and

amendments were air dried in a glasshouse, weighed, and mixed by weight for the root

zone materials of desired composition. Root zone media that included peat were mixed

in a cement mixer for ten minutes before being placed in the lysimeters to insure

uniformity of mixing. The dry weight of soil placed into each lysimeter was recorded so

total nutrient retention could be calculated from core samples taken at the completion of

the study. The lysimeters were placed in the glasshouse and field settings in a

randomized complete block fashion. Glasshouse units were supported on a wooden

frame suspended approximately 30 cm above the glasshouse floor. Field lysimeters were

implanted in an experimental USGA putting green with hoses connected to the bottom

for leachate collection.

The saturated soils were allowed to drain for 24 hours and weighed to give an

estimate of "pot water holding capacity." Overhead irrigation was applied to the

turfgrass studies while the citrus experiment was maintained by hand application of

water. Care was taken not to irrigate in excess of the pot water holding capacity, as this

would result in undesirable loss of leachate. Lysimeters were weighed and brought back

to pot water holding capacity on an as needed basis during alternate weeks between

collection of leachates. Urea-N analysis of leachate and soil extraction were measured as

described by Bremner (1982). Nitrate-N and NH4I-N in leachate and soil extraction were

determined by colorimetric method using a Rapid Flow Analyzer Aikenm 300 series









(Alkem Corporation, Clackamas, Oregon) at the Analytical Research Laboratory,

Gainesville, Florida.

Plant Collections and Analysis

Clippings for dry matter production were taken biweekly on the turfgrass

glasshouse studies once the dry matter production reached harvestable quantities,

approximately 28 days after sprigging (DAS) for turfgrass grow-in studies. Turfgrass was

clipped at approximately 7.5 mm cutting height by hand held scissors. Verdure

(vegetative material above the soil left after tissue harvest) and roots were collected at

termination and washed free of soil. Citrus leaves, stems, and roots were collected at the

end of the study. All plant material was dried at 700C for a period of 48 hours, ground to

2mm mesh size and ashed and analyzed for P, K, Ca, and Mg (Hanlon et al., 1994b).

Tissue from turfgrass overseed study was also analyzed for Mn and Fe. Glasshouse

lysimeters were maintained at near optimum moisture, but to induce leaching an

additional V2 pore volume of excess water (ca. 500 mL) was added every two weeks.

Field lysimeters were maintained under normal irrigation and maintenance practices as

are used for the entire research green. Additional irrigation was added for the grow-in

phase by use of a lawn sprinkler connected to a garden hose and applied as needed to

keep the vegetative sprigging material moist through the critical early stages of

establishment.

Total N in plant material was measured by total Kjeldahl N (TKN) analysis

following the procedure as described by Horneck and Miller (1998). Digestion of 200

mg oven dried leaf tissue was performed in 50 mL digestion tubes to which 150 mg of

digest catalyst Kel-Pak (1.0g K2SO4 and 0.3g CuSO4) and 3 mL concentrated H12SO4









were added. The mixture was mixed on a vortex shaker and heated on a Tecator

Digestion System 40-1016 Digester to 3700C for approximately 2 h until clear. The

digest was allowed to cool and then diluted to 50 mL with deionized water and vortexed.

Total N in the digest was determined by automated colorimetric procedure (Baethgen and

Alley, 1989) using an Alkem 300 series Rapid Flow Analyzer.

Sand Mixes

Different sand mixes were used in the evaluation of N source fertilizers. A total of

five sand mixes were used as follows: Coated sand, USGA uncoated sand, USGA

uncoated sand plus 15% by volume peat, USGA sand (Envirogreen), and the E horizon

uncoatedd fine sand) of an area spodosol (hyperthermic, uncoated Typic

Quartzipsamments) was used for the uncoated material in the citrus study (Table 3-1).

Organic matter content and sand size analysis revealed that three of the sands met

USGA's specifications for particle size distribution and the coated sand was very close to

achieving specifications but contained too much fine sand. The uncoated fine sand had a

much finer texture. Physical analysis of sand mixes is provided in Table 3-2 and chemical

analysis (CEC and ammonium-oxalate extractable Fe + Al) in Table 3-3. Oxalate

extractable Fe and Al were determined using methods described by McKeague and Day

(1966).

Harris et al. (1996) distinguished between sands having 'clean' (coating free) or

uncoated sand (UCS) and 'slightly coated' grains. Sands are classified as uncoated by

the United States Department of Agriculture if the contain < 5% silt plus clay. The

terminology 'slightly coated' is used for sand that contains < 5% silt plus clay, but have

clay coatings. For simplicity the term coated sand (CS) will be substituted for slightly










coated sand. Sand-grain coatings in sandy coastal plain soils of the southeast USA

consist mainly of silt and clay, bound by relatively low amounts of metal oxides.

Table 3-1. Organic matter and sand size analysis of sand mixes.
Sand
----------------------------------------------------- Silt
Fine Very Very +
Sample OM gravel coarse Coarse Medium Finet fine Clay
..........................................................................................................
------------------------% by weight------------------------
Coated sand -- 0.0 0.0 5.8 65.1 25.2 3.7 0.2
USGA uncoated sand -- 0.1 3.2 24.5 43.3 24.3 4.6 0.0
USGA uncoated sand 1.55 0.0 0.4 53.3 41.3 3.8 1.0 0.2
plus 15% peat ( by vol.)
USGA sand (Envirogreen) 0.33 0.1 5.5 28.9 40.5 22.7 2.2 0.1
Uncoated fine sand -- 0.0 0.2 4.7 31.4 37.8 24.9 1.0

USGA 1-5% <10% >60% <20 <5% <8%
Specifications (2-4 ideally) ---
<10%
t Based on USGA range of 0.25 0.15 mm.

Table 3-2. Physical analysis of sand mixes.
Pore Space

Sample Ksatt BDI PD# Total Microft MacrotWWHC

cm hr- g/cc--- -------%------ %


Coated sand
USGAt uncoated sand
USGA uncoated sand
plus 15% peat ( by vol.)
USGA sand (Envirogreen)
Uncoated fine sand


47.1
71.3
120.1


1.69
1.71
1.51


2.63
2.60
2.50


35.4
34.4
40.1


18.3
18.4
14.7


17.5
16.0
25.4


10.8
10.8
9.7


59.0 1.71 2.58 33.8 16.9 16.9 9.9
10.7 1.73 2.60 33.7 30.3 3.4 17.5


USGA recommendation -- 35-55 15-25 15-30 --
t United States Golf Association
+ saturated hydraulic conductivity
USGA recommendations for Ksat are 15-30 (normal) and 30-60 (accelerated) cm hr'
1 bulk density
# particle density
tt micropores (small pores that retain water at 30 cm tension)
I+ macropores (large pores that contain air at 30 cm tension)
water holding capacity at 30 cm tension, by weight.










Harris et al. (1996) found that some morphological and taxonomic distinctions

among sandy coastal plain soils fortuitously reflect the presence, absence, and abundance

of sand-grain coatings, all of which influence relative phosphorus (P) adsorption and

retention capacity. The 'presence vs. absence' distinction was concluded to be relatively

discrete and readily observable. An absence of coatings is indicated by light gray or

white colors (e.g. Munsell chroma < 2 and value >7) and the dominance of bare (clean)

quartz sand grains as observed under a hand lens. The coatings, when present, and be

seen via their color, opacity, and rough surface textural appearance as superimposed on

the vitreous quartz surface. Coatings are often ensconced in crevices, and do not

necessarily occupy a high proportion of the grain surface. Grain components include

kaolointe, hydroxy-interlayered vermiculite, gibbsite, goethite, and Fe & Al

oxyhydroxides.

Table 3-3. CEC and ammonium-oxalate extractable Fe + Al analysis of sand mixes.

oxalate extractable
CECt Fe Al Total
cmol charge kgl' soil ---------mg kg'-----
Coated sand 1.076 148 181 329
USGA uncoated sand 0.851 11 23 34
USGA uncoated sand 1.430 8 15 23
plus 15% peat ( by vol.)
USGA sand (Envirogreen) 1.266 32 17 49
Uncoated fine sand 1.237 20 81 101
tCEC values measured by the compulsive exchange method (Gillman, 1979).

Soil samples were collected at the end of each study by taking a single core sample

(3.0 cm diameter) from each lysimeter at termination of the glasshouse studies and three

cores (3.0 cm diameter) from each plot at termination of the field studies. Soil samples

were air-dried and screened through a 2.0 mm sieve. Inorganic exchangeable soil N was









determined using a 5 g sub-sample of air dried soil extracted with 50 mL of 2 M KCI in a

100 mL plastic test tube and shaken for 60 min on a mechanical reciprocating shaker at

low speed (140 strokes min-1). Soil was analyzed for pH (2:1 water to soil ratio) and

electrical conductivity using an Accumet Model 20 pH/mV/conductivity meter.

Mehlich I extractions were used to determine soil P, K, Ca, Mg (Hanlon et al., 1994a).

Fertilizers

A total of five N fertilizers were evaluated. For simplicity, fertilizers will be

denoted as follows; ammonium nitrate-NH4NO3 = AN, potassium nitrate -KN3 = KN,

urea-CO(NH2)2 = urea, ammonium sulfate-(NH4)2S04 = AS, and calcium nitrate-

[5Ca(NO3)2 NH4NO310H20] = CN. All fertilizer sources were used in their pure

chemical state except CN which has some NH4' content added during the manufacturing

process to neutralize acidity (G.W. Easterwood, personal communication, 1999).

Fertilizer sources were enriched to minimum 5% '5N to enhance tracking of applied N

fertilizer.

Ammonium nitrate used in agriculture contains between 33 and 34% N and

provides equal amounts of N in the NH4+ and NO3 forms. It is hygroscopic and care

must be taken to prevent caking and physical deterioration in storage and handling. The

AN prill is often coated with MgCl2 which prevents adsorption of water from the

atmosphere. Ammonium sulfate is produced mainly as a by-product of the Bessemer

process: 2NH3 + H2S04 -- (NH4)2S04. Advantages of AS are its low hygroscopicity and

chemical stability. It is a good source of both N and S. The strongly acid-forming

reaction of AS in soil can be advantageous in high-pH soils and for acid requiring crops.

Ammonium sulfate can be undesirable in acidic soils already in need of liming and its










relatively low N content (21% N) often render it too expensive to use as an N source

(Tisdale et al., 1999).

Urea has a relative high nutrient content (46% N) and is an economical choice for

the supply of N. Urea applied to soil is hydrolyzed by the enzyme urease to NH4*. Urea

hydrolysis proceeds rapidly in warm, moist soils, with most of the urea transformed to

NH4- in several days (Tisdale et al., 1999). Potassium nitrate (13% N) contains two

essential nutrients (N and K) and is manufactured by reaction of concentrated HNO3 with

KCI. It has a moderate salt index, negligible Cl- content, and alkaline reaction in soil

which make it appropriate for intensively grown crops such as tomatoes, potatoes,

tobacco, leafy vegetables, citrus, peaches, and other crops (Tisdale et al., 1999). Calcium

nitrate is produced by treating CaCO3 with HNO3. It is extremely hygroscopic and is

prone to liquification in humid conditions. Coating CN prills with a moisture barrier

such as TropicoateT and storage in moisture proof bags is necessary to ensure product

stability. Calcium nitrate is a useful fertilizer for vegetable production and other crops

that are prone to Ca deficiencies. It is sometimes used in foliar sprays for celery,

tomatoes, and apples. On sodium (Na) affected soils, CN can be used as a Ca 2 source to

displace Na on cation exchange sites (Tisdale et al., 1999).

All of these N fertilizer sources are commonly used in agriculture to supply N to

plants. These sources offer a readily available source of N and are susceptible to

leaching. Readily soluble N sources provide a flush of growth, but may be more prone to

leaching and runoff than slow-release forms (Wang and Alva, 1996). Best manuaem, ntI

practices recommend using combinations of readily available (water soluble) N sources

in combination with controlled or slow release sources to supply initial green up and a









continual amount of N as the plant needs it, thus minimizing N lost to leaching or runoff.

Fertigation is a method of using inexpensive soluble sources of N to mimic the benefits

of controlled release materials through the irrigation system. Treatments for the turfgrass

field studies were applied via a boom sprayer. Since all the N sources used were readily

soluble, it was determined that frequent applications of fertilizer was the best method to

establish the turfgrass during a grow-in scenario which mimics the normal practice of

using fertigation. Water was applied after the treatments to insure that fertilizer entered

the rootzone.

Experimental Studies

Turfgrass Glasshouse 2000

A glasshouse experiment was established on July 27, 2000 and lasted 16 weeks

ending in November 18, 2000. Turfgrass sprigs, (vegetative material consisting of

stolons and rhizomes used for reproduction), were applied to lysimeters filled with two

different soil mixes (CS and UCS) at 5 g moist sprigs lysimeter'1. The CS mix was used

to simulate a typical golf fairway condition, thus no peat was added to the mix and was

sprigged with Tifsport bermudagrass. The UCS mix was used to simulate golf green

conditions fitting USGA specifications containing 15% peat by volume and was .priLed

with 'Tifdwarf bermudagrass. Soil mixes were blocked as main plots in the glasshouse

and analyzed together as a split-plot experimental design. For both soils, there were 7

treatment units with 5 replications or 'blocks' for a randomized complete block analysis.

Four treatment units were direct comparison of treatments at a single x rate (AN, KN,

Urea, and CN). In addition to the comparison treatments an additional set of CN

treatments of 0, 0.5x, 1.0x, and 2.0x were employed. These additional 4 treatments were

included in each block for the purpose of quantifying Ca2 and NO3" in the leachate and









through the use of regression analysis identifying the mechanism of any differential

nitrate leaching.

The objectives of this study were to (1) to determine the N leaching potential and

utilization of 5N labeled sources; AN, KN, urea, and CN in turfgrass golf fairway and

USGA golf green scenarios through mass balance studies; (2) to differentiate retention,

leaching and plant utilization of 5N from CS vs. UCS; (3) to identify components

responsible for any differential leaching and utilization of applied "N; (4) to determine

the influence of Ca2 on NO3- retention, leaching, and utilization of applied 15N.

Statistical analysis

Statistical analysis was performed using SAS for Analysis of Variances (SAS

Institute, 1987). Single degree of freedom contrasts were generated to separate the means

based on the general linear model procedure. A standard analysis of variance (ANOVA)

table was used for the determination of statistical differences in the analysis of effects of

sand type and fertilizer source as a split plot design is shown in Table 3-4.

Table 3-4. Analysis of variance (ANOVA) table used for the determination of statistical
differences in the analysis for effects of sand type and N fertilizer source for the
turfgrass glasshouse 2000 study.
Source DF
Replication 4
Main-plot factor (sand) 1
Error (sand) 4
Subplot factor (fertilizer) 3
sand x fertilizer 3
Error (fertilizer) 24
Total 39

N-balance

Mass balance of 'N applied was designed to be measured beginning with a grow-

in and continuing on into a maintenance phase. It has been observed that maintenance

phase turfgrass leaches minimal amounts of N, thus included in this study was an









addition of a simulated rain event before scheduled treatment applications. This

experiment was designed to mimic real world conditions, thus leaching events were

conducted with deionized water (pH 5.5). Sands were selected to represent soils found in

Florida that are generally sandy and may or may not have sand grain coatings.

More N can potentially leach during establishment ofturfgrass than during

maintenance of turfgrass because N is generally applied in higher rates during a grow-in

and reduced after roots and plants have established. Initially, plants were fertilized with

5.0 g N m-2 wk-1. The maintenance phase N rate was reduced to treatment application

every other week. Treatments were applied in liquid aliquots to lysimeters and were in

the ratio 1:1:1 N-P-K initially and were progressively brought to a 4:1:2 N-P-K ratio by

the maintenance phase. The N source was the treatment variable, the K source was KC1,

and the P source was H3P04. Micronutrients and S (as sulfate) were applied together by

applying a commercially available micronutrient solution at a rate of 11.2 kg Fe ha'

(10.0 lbs Fe acre').

Ten treatment applications of 5.0 g N m-2 were applied with 7 leaching events. A

total of 0.91 g N lysimeter- was applied over the study. During the maintenance phase,

leaching events occurred mid-way between treatment applications (1 week after

fertilization).

Turfgrass Glasshouse 2001

The turfgrass glasshouse 2001 study began July 13, 2001 and ended November 1,

2001. It was a replication of the experiment from the previous year with two exceptions.

The urea treatment was replaced with AS to allow for the evaluation of the NH4 source

of N and because of its widely used nature in the turfgrass industry. The USGA









specification golf green UCS media did not include an addition of peat. Amendments are

occasionally omitted from USGA mixes for monetary and time considerations.

Objectives of this study were to (1) to determine the N leaching potential and

utilization of "N labeled sources; AN, KN, AS, and CN in turfgrass golf fairway (CS)

and USGA golf green (UCS) scenarios through mass balance studies; (2) to differentiate

retention, leaching and plant utilization of 5SN from CS vs. UCS; (3) to identify

components responsible for any differential leaching and utilization of applied '"N; (4) to

determine the influence of Ca+2 on NO3- retention, leaching, and utilization of applied

'5N.

The study consisted of two sands, CS and UCS, four N source treatments, with four

replications. Turfgrass sprigs (vegetative material consisting of stolen and rhizomes

used for reproduction) were applied to lysimeters filled with two different soil mixes CS

and UCS at 5 g moist sprigs lysimeter-. The CS mix was used to simulate typical Florida

golf fairway conditions and was sprigged with Tifsport bermudagrass. The UCS mix was

used to simulate golf green conditions and conformed to USGA specifications (however,

no addition of peat was added) and was sprigged with Tifdwarf bermudagrass. Soil

mixes were divided in the glasshouse and analyzed together as a split-plot experimental

design. For both soils, there were 7 treatment units with 4 replications or 'blocks' for a

randomized complete block analysis. Four treatment units were direct comparison of

treatments at a single x rate (AN, KN, AS, and CN). In addition to the comparison

treatments were CN treatments of 0, 0.5x, 1.0x, and 2.0x. These additional 4 treatments

were included in each block for the purpose of quantifying Ca-2 and N03" in the leachate










and through the use of regression analysis identifying the mechanism of any differential

nitrate leaching.

An ANOVA table was used for the determination of statistical differences in the

analysis of effects of sand type, and fertilizer source (Table 3-5). Single degree of

freedom contrasts were used to separate mean differences.


Table 3-5. Analysis of variance (ANOVA) table used for the determination of statistical
differences in the analysis for effects of sand type and N fertilizer source for the
turfgrass glasshouse 2001 study.
Source DF
Replication 3
Main-plot factor (sand) 1
Error (sand) 3
Subplot factor (fertilizer) 3
Sand x fertilizer 3
Error (fertilizer) 18
Total 31


Turfgrass Field Grow-in 2001

The turfgrass field study was initiated July 9, 2001, on the USGA specification

Envirogreen, Gainesville, FL and ended October 29, 2001. The purpose of the study was

to evaluate '5N sources AN, KN, urea, and CN during bermudagrass grow-in and

subsequent maintenance phase on a USGA golf green under field conditions with regard

to N leached, N retained in the soil, and N taken up by the turfgrass. Grow-in conditions

require frequent irrigation that can initially move N past the sprigging material, while the

established turfgrass with its dense rooting and healthy microbial community, is much

more efficient in N use.

Sixteen inground lysimeters were arranged in a randomized complete block design

having four N treatments and four replications. Plots were 1 m2. Leachates were

collected approximately twice per week to remove solute from the bottom of the









lysimeters from accumulation from green irrigation and rainfall. Similar nutrient rate

programs were used in the field study as those used in the glasshouse studies (5.0 g N m-2

week-' for 7 weeks during grow-in phase and a reduction to 2.5 g N m-2 week-' for the 9

week maintenance phase). Nutrients were applied initially in a 1-1-1 N-P-K ratio and

reduced to a 4-1-2 N-P-K ratio by the maintenance phase. A total of 57.5g N meter2 was

applied. An ANOVA table was used for the determination of statistical differences in the

analysis of effects of sand type, and fertilizer source (Table 3-6).

Treatments were applied in liquid form with a hand held boom sprayer. Early in

the experiment the weekly treatments were applied in one-week doses, however lack of

overall growth led to the application of treatments broken over several days to mimic

something similar to a fertigation application. The fact that N sources used were 100%

soluble and no slow-release sources were used meant that irrigation or rain could leach N

below the vegetative sprigging material very quickly. A total of 57.5g N plot-' was

applied during turfgrass grow-in.

Table 3-6. Analysis of variance (ANOVA) table used for the determination of statistical
differences in the analysis for effect N fertilizer source for the turfgrass field grow -in
2001 study.
Source DF
Fertilizer 3
Replication 3
Error 9
Total 15


Turfgrass Field Overseed 2001

A eight week field evaluation of direct comparison treatments at a single N rate

(AN, KN, AS, and CN) began January 22, 2002. The purpose of the study was to

evaluate 5SN sources AN, KN, AS, and CN during established perennial ryegrass scenario









on a USGA golf green under field conditions with regard to N leached, N retained in the

soil, and N taken up by the turfgrass. Bermudagrass was overseeded with perennial

ryegrass for quick establishment and winter tolerance. Four treatment applications were

made, each followed two weeks later by tissue harvest and leachate evacuation from

ground lysimeters. Treatment application one was 5.0 g N m-2 and the following three

were 2.5 g N m-2. Treatments were AN, KN, AS, and CN. A total of 12.5 g N m-2 was

applied to each plot. An ANOVA table was used for the determination of statistical

differences in the analysis of effects of fertilizer source (Table 3-7).

Table 3-7. Analysis of variance (ANOVA) table used for the determination of statistical
differences in the analysis for effect fertilizer source for the turfgrass field overseed
2002 study.
Source DF
Fertilizer 3
Replication 3
Error 9
Total 15


Citrus Glasshouse 2001

A SN fertilizer study was started on citrus rootstock trees July 12, 2001 and ended

January 28, 2002. Objectives of this study were to (1) to detenninthe the N leachir_

potential and utilization of "N labeled sources AN, KN, urea, and CN on soils t) pical to

those that citrus trees are grown on in Florida; (2) to differentiate retention, leaching and

plant utilization of 'N from CS vs. UCS through a mass balance study; (3) to identify

components responsible for any differential leaching and utilization of applied "N; (4) to

determine the influence of Ca 2 on NO3- retention, leaching, and plant uptake of applied

' N; and (5) to evaluate TropicoateTM prill coating affect on 5Ca(NO-)2 NH4NO31I OH20

retention, leaching, and utilization.









Fertilization and leachate collection methods were similar to the previously

described turfgrass studies. The sands used and were CS and uncoated fine sand (UCFS)

(Table 3-1) were randomized into three RCBD blocks. An ANOVA table was used for

the determination of statistical differences in the analysis of effects of sand type, and

fertilizer source (Table 3-8). Treatment means were separated by single degree of

freedom contrast procedure. In addition to the direct comparisons of AN, KN, Urea, and

CN, regression analysis was conducted on 0, 0.5x, 1.0x, 2.0x rates of CN. These

additional 4 treatments were included in each block for the purpose of quantifying Ca-2

and N03- in the leachate and through the use of regression analysis identifying the

mechanism of any differential nitrate leaching. Additionally, there was a direct

comparison performed using 2x rate CN on CS included in each block. One CN

treatment had the TropicoateTM coating intact while the other CN treatment had the

TropicoateTM coating removed by washing with carbon tetrachloride.

A total of 12 leachates were collected from the lysimeters. Leaves, stems, and

roots were harvested at termination. Soil, plant matter, and leachates were analyzed for

concentration of 'N. A total of 0.382 g N lysimeter'' was applied over 12 fertilization

events and corresponds to 450 kg ha -. Treatments were all in the ratio of 4-1-2 N-P-K.

Table 3-8. Analysis of variance (ANOVA) table used for the determination of statistical
differences in the analysis for effects of sand type and N fertilizer source on citrus
2001 study.
Source DF
Replication 2
Treatment 7
Fertilizer (3)
Sand (1)
Fertilizer X sand (3)
Error 14
Total 23










Mass Balance Calculations

Nitrogen mass balance calculations were performed on all studies to determine the

fate of applied N. Three studies (Turfgrass glasshouse 2000, Turfgrass Field Growin

2001, and Citrus 2001) were conducted with 15N enriched fertilizer sources as a tracer.

Applied 15N was traced and quantified from soil retention, leachate, and plant uptake.

Varying amounts of N have been shown in the literature to be lost through mechanisms

of volatilization and dentitrification and it is common to estimate these losses in the N

balance sheet by calculating recovery from soil retention, leachate, and plant uptake and

subtracting from N applied (Allison, 1955).

The '5N enrichment of N in a sample from a tracer experiment represents a mixture

of labeled N from the tracer, applied at a known enrichment (5% for turfgrass and citrus

studies), and unlabeled N containing 15N at the background value characteristic of the

material and environment. The amount of N derived from the tracer was calculated from

the following equation given by Hauck and Bremner (1976):

F = T(A.=-A)
AF

where F is weight of N derived from labeled fertilizer in crop or soil sample, T is total

weight of N in sample [T and F are expressed in the same units], As is atom % excess N

in labeled sample of crop or soil, AB is atom % excess 5N in control sample of crop or

soil at natural abundance (i.e., the background enrichment), and AF is atom % excess N

in labeled fertilizer as added. Atom % excess is defined as the atom % 15N in the

material minus 0.3663 (Powlson and Barraclough, 1993).

Advancement in N isotope analysis has led to the interfacing of a N/C analyzer to a

mass spectormeter (ANCA-MS) (Mulvaney, 1992). All N compounds (organic and










inorganic of solid samples containing 20-150 pg N are converted in one step to N2 gas by

dry combustion. The N2 gas is then admitted to the mass spectometer for measurement of

the m/e 28, 29, and 30. Since solid material is used and the reaction takes place is a

closed system, dilution and cross contamination risks for '5N are much smaller that in the

traditional Kjeldahl-Rittenberg method (D.A. Graetz, personal communication, 2000).

A diffusion procedure for automated isotope ratio analysis of inorganic N in soil

extracts (including KCI extracts or natural water samples such as leachate) was developed

by Brooks et al. (1989) and modified by Khan et al. (1997) as used for '5N recovery from

soil and leachate. Wide mouth mason jars were used to hold the liquid sample and

acidified filter paper disks (acidified with KHSO4) on a stainless steel wire was used as

an acid trap for NH3. Mild alkali (MgO) and reducing agent (Devarda's alloy) are used

to convert (NH4 and NO3)-N to NH3-N. The method used by Khan does not result in

quantitative N determinations, thus the inorganic N concentration of samples must be

measured prior to diffusion.















CHAPTER 4
GLASSHOUSE 2000 TURFGRASS STUDY

Influence of Sand Type and Fertilizer Source on Dry Matter Tissue (Clippings)

An analysis of variance revealed that the dry matter tissue (harvest 1-7 clip!in -.)

was influenced by sand type and fertilizer. Thirty-four percent more dry matter clippings

were produced on the CS than on the UCS (Table 4-1). Sand coatings apparently

enhanced tissue production. Brown and Sartain (2000) found that CS retained more

Mehlich I extractable P, which resulted in more P uptake, less P leaching, and an

improved cover rating than UCS. Dry matter clippings produced using AN or KN were

not different than that produced using CN. Urea produced 6.6% more clippings tissue

than CN. The tissue grown with AN produced a higher gram total in magnitude than CN,

but was not significantly different at the 0.05 probability level. The CN treatment

produced a higher clippings gram total in magnitude than KN, but was not significantly

different at the 0.05. probability level.

Table 4-1. Tissue dry matter clippings weight for all harvests for glasshouse 2000
turfgrass study as influenced by sand type and fertilizer.
Dry Matter Tissue
Sand type -- g Fertilizer -- g --
CS(1) 16.82 AN (1) 15.08
UCS (2) 12.52 KN (2) 13.68
------------ Urea (3) 15.44
Contrast: 1 vs. 2 *** CN (4) 14.48

Contrast: 1 vs. 4 NS
Contrast: 2 vs. 4 NS
CV = 6.9 Contrast: 3 vs. 4 *
*, ***, Significant at the 0.05, 0.001 probability levels, respectively.










Nitrogen Uptake (Clippings) and Total Dry Matter Accumulation as Influenced by Sand
Type

Total dry matter and N taken up by the tissue were both affected by the presence of

a sand coating (Table 4-2). Growth media comprised of sand with grain coatings resulted

in more N being taken up by the turfgrass as well as an increase in total dry matter verses

sand with no grain coatings. Although Brown and Sartain (2000) did not find increased

dry matter production on CS when comparing P sources, they did find that more P was

taken up by the turfgrass when grown on sands with grain coatings. The sand coatings

have the ability to retain nutrients through ion exchange mechanisms where as the UCS

has less ability to do so. The CS media produced 13% more total dry matter than the UCS

even though the UCS media contained the USGA prescribed 15% peat by volume and the

uncoated media did not. Nitrogen uptake into tissue was 29% higher on bermudagrass

grown on CS than on UCS.

Table 4-2. Nitrogen uptake in clippings and total dry matter accumulation for the
glasshouse 2000 turfgrass study as influenced by sand type.
N Uptake Tissue Total Dry Matter
Sand type -- mg -- Sand type g -
CS(1) 319 CS(1) 32.99
UCS (2) 247 UCS (2) 29.12

Contrast: 1 vs. 2 *** Contrast: 1 vs. 2 ***
CV = 9.1
***, Significant at the 0.001 probability level.

Total N Uptake as Influenced by Sand Type and Fertilizer

The effects of sand coating and fertilizer type on N uptake were very similar to

those of total dry matter tissue discussed in Table 4-1. Analysis of variance of total N

uptake for the glasshouse 2000 turfgrass study revealed that sand type and fertilizer type

both influenced total N uptake (Table 4-3). Coated sand produced turfgrass growth with










a total N uptake 21% greater than that ofturfgrass grown on UCS. Sand with grain

coatings improved nutrient efficiency over sand with little or no grain coatings.

Total turfgrass N uptake was not different using AN verses CN. Although AN has

a slightly larger value in magnitude, it was not enough to satisfy significance at the 0.05

probability level. Turfgrass N uptake resulting from KN fertilizer was very close in

magnitude to that of CN and was not significantly different. As in the result for dry

matter tissue, the urea treatment produced a significantly higher value for total N uptake

than the CN.

Table 4-3. Total N uptake for glasshouse 2000 turfgrass study as influenced by sand type
and fertilizer.
Total N Uptake
Sand type -- mg -- Fertilizer -- mg --
CS(1) 445 AN (1) 418
UCS (2) 366 KN (2) 392
------------------ Urea (3) 429
Contrast: 1 vs. 2 *** CN (4) 384

Contrast: 1 vs. 4 NS
Contrast: 2 vs. 4 NS
CV = 6.9 Contrast: 3 vs. 4 *
*, ***, Significant at the 0.05, 0.001 probability levels, respectively.

Nitrogen Retained in the Soil as Influenced by Sand Type and Fertilizer

An analysis of variance for N retained in the soil revealed a fertilizer by sand type

interaction. Differences in N retention, as measured by KCI extraction, were found on

the CS but not the UCS (Table 4-4). The ability of ions to be electrostatically retained on

the surfaces of the sands via cation exchange allowed NH4 forming fertilizer sources AN

and urea to be retained in larger magnitudes on the CS media than fertilizer sources KN

and CN, dominated by negatively charged N03-. Coated sand treated with AN had higher

retention of N than those treated with CN. The UCS retained N in similar amounts for all










fertilizer treatments. The UCS treated with CN retained N in amounts similar for UCS

treated with AN, KN, and urea.

Table 4-4. Nitrogen retained in the soil for glasshouse 2000 turfgrass study as influenced
by sand type by fertilizer.
Total KCl Exchangeable Soil N
------------- mg --------------
CS UCS
AN (1) 29.58 18.62
KN (2) 12.18 18.44
Urea (3) 20.88 21.75
CN (4) 12.18 18.79

Contrast: 1 vs. 4 NS
Contrast: 2 vs. 4 NS NS
Contrast: 3 vs. 4 NS NS
CV 37.9
*, Significant at the 0.05 probability level.

Leachate pH as Influenced by Sand Type by Fertilizer Interaction

Leachate pH was affected by treatment through a sand type by fertilizer interaction

(Table 4-5). The UCS media mix contained 15% peat by volume and had lower (more

acidic) leachate pH values by magnitude than the CS which did not have any organic

amendment. Peat decreases soil solution pH due to the release of organic acids during

mineralization and acted as a buffer that kept leachate pH values acidic. Trends for CS

and UCS mixes were similar for relative pH levels. Both mixes had leachate pH values

from highest to lowest that followed the order KN > CN > urea > AN. Note that leachate

pH values were similar for urea and AN treated lysimeters and could be considered to be

about the same, or in the same range, for CS and UCS. Ammonium content of the

fertilizer source resulted in lower leachate pH values and should be monitored when

soluble sources of N are used for extended periods of time (Malhi et al., 2000; Snyder et

al., 1979).











Table 4-5. Leachate pH taken 98 DASt for glasshouse 2000 turfgrass study as influenced
by sand type by fertilizer interaction.
pH
CS UCS
AN (1) 5.2 3.5
KN (2) 9.2 5.2
Urea (3) 5.3 3.7
CN (4) 8.9 4.1

Contrast: 1 vs. 4 *** NS
Contrast: 2 vs. 4 NS *
Contrast: 3 vs. 4 *** NS
CV = 15.3
*, ***, Significant at the 0.05, 0.001 probability levels, respectively.
t Days after sprigging

The KN treated CS lysimeters had leachate pH means that were higher in

magnitude than the CN, however they were not different statistically. Values for these

NO3 sources were well above the neutral value of 7, suggesting that as N03O was taken

up by the turfgrass, an equivalent amount of OH- was released into the soil solution.

Ammonium sources used on CS lysimeters created additional H+ through nitrification

and release of H" in conjunction with root uptake of NH4-, thus lowering leachate pHi

values. The CN treated CS lysimeters were higher in pH than for AN and urea but were

not different than KN. Leachate pH values from CS media were similar to those from

UCS media regarding the ranking order of most acidic leachate to least acidic for each

fertilizer treatment (AN > urea > CN > KN). The CN treated leachate pH values were

not different for AN and urea, while resulting in a lower leachate pH than those treated

with KN.

Leachate EC as Influenced by Sand Type and Fertilizer

Evaluation of leachate EC revealed that sand type and fertilizer influenced leachate

EC (Table 4-6). Electrical conductivity of leachate from CS media was higher than those










from the UCS mix. Volumes of leachates taken from the UCS media were larger than

from the CS, thus diluting dissolved salts in solution resulting in lower EC values.

Saturated conductivity for the CS was 47.1 cm hr-' and 120.1 cm hr' for the UCS (85:15

sand to peat ratio) which caused some difficulty in leaching the same volumes through

the different sand mixes (Table 3-2). It is also possible that the 15% peat fraction by

volume increased sorption of soluble salts in the soil reducing EC values in the UCS

leachate.

Table 4-6. Leachate electrical conductivity taken 98 DASt for glasshouse 2000 turfgrass
study as influenced by sand type and fertilizer.
Electrical Conductivity
Sand type -- uS cm- -- Fertilizer -- uS cm --
CS (1) 264 AN (1) 219
UCS (2) 179 KN (2) 258
---------------Urea (3) 171
Contrast: 1 vs. 2 *** CN (4) 238

Contrast: 1 vs. 4 NS
Contrast: 2 vs. 4 NS
CV = 20.8 Contrast: 3 vs. 4 *
*, ***, Significant at the 0.05, 0.001 probability levels, respectively.
t Days after sprigging

Fertilizer source CN resulted in leachate EC values that were not different than

those of AN and KN. Leachate EC values of urea were, however, lower than those from

the CN treated lysimeters. Urea is a non-ionic molecule in solution which resulted in

lower leachate EC values. It is also possible for NH3 volatilization from urea to have

contributed to a reduction in soluble salts in the soil solution, even though volatilization

from urea was kept to a minimum by cultural practices such as applying treatments in

liquid form and maintaining a low pH.










Total N leached as Influenced by Sand Type and Fertilizer

An analysis of variance for total N leached for the glasshouse 2000 turfgrass study

revealed treatment effects due to sand type and fertilizer. The UCS media mixes leached

50% more N through the profile than the CS mix. This finding is in agreement with

-"rown and Sartain (2000) who found CS leached less P than UCS. It is possible that the

large difference in saturated conductivity of the two sand mixes was responsible for more

total N being leached by the UCS (Table 3-2). It may have been the case that N applied

moved faster past the depth of the plant roots in the UCS (85:15 mix) to leach more N,

especially early in the experiment before the roots in either sand had a chance to colonize

deep in the profile.

Table 4-7. Total N Leached for glasshouse 2000 turfgrass study as influenced by sand
type and fertilizer.
Total N Leached
Sand type -- mg -- Fertilizer -- mg --
CS (1) 154.9 AN (1) 186.8
UCS (2) 232.1 KN (2) 264.7
----------- Urea (3) 91.2
Contrast: 1 vs. 2 *** CN (4) 231.2

Contrast: 1 vs. 4 *
Contrast: 2 vs. 4 NS
CV =19.5 Contrast: 3 vs. 4 ***
***, Significant at the 0.05, 0.001 probability levels, respectively.

The postulated CaNO3' ion pair did not reduce NO3 leaching from CN compared

to the other sources. The two-predominately N03- fertilizer sources, CN and KN, did not

differ in total N leached, although CN leached slightly less N in magnitude than KN. The

small amount of NH4 present in the CN material may have contributed to some

electrostatic N retention. It is possible that formation of the ion pair CaNO3+ contributed

to some electrostatic N retention, however, these two retention mechanisms together










failed to reduce N leaching from CN treatments to levels less than those of KN at the 0.05

probability level. Therefore these mechanisms did not result in lower N leaching when

comparing these two fertilizer sources against one another in this turfgrass glasshouse

evaluation.

Fertilizer source urea leached less total N than CN. It is possible that through the

mechanism of N volatilization, some urea-N was lost to the atmosphere as NH3 resulting

in less N in the leachate. This finding is in agreement with previous research concluding

that volatilization can contribute to N loss from urea with a possible reduction of N in the

leachate (Snyder et al., 1980; Volk, 1959; Boch, 1984; Petrovic, 1990; and Tisdale et al.,

1999). After urease converts urea to the NH4 form, N retention is possible through

cation exchange (CE) of the soil media, reducing N leaching. Fertilizer source AN

leached less total N than CN. Only half of the N from AN being in the NIH4 form allows

for some soil N retention through CE of the soil media and to a lesser degree, some of the

NH4C could have possibly hydrolized water allowing for the formation of NH3, which

could then volatilize.

Regression analysis was conducted on 0, 0.5x, 1.0x, 2.0x rates of CN for the

purpose of quantifying Ca2 and NO3- in the leachate to determine if there was any

relationship that would show the mechanism of differential nitrate leaching. Regression

analysis for CS and UCS material for the turfgrass glasshouse 2001 experiment are

shown in Figure 4-1. Regressions for Ca+2 and NO3- behaved similarly for the CS and

UCS. These sands behaved similar regarding CE. Both sands had r2 values for Ca-2 that

showed extremely good linear fit and both had a slope of0.085x. Nitrate leaching also

behaved similar in both sands. If a significant amount of retention was occurring by












elecrostatic retention of the CaNO3+ ion pair, the NO3" in the leachate would tend to curve


down as more NO3- in held in the soil from leaching. Evidence was not seen for the


retention effect of the CaNO3+ ion pair in this study, however, it is possible that due to


the low CEC of the sands, the CE sites were saturated resulting in a masking of the ion


pair effect.


Mass Balance Calculations

Turfgrass glasshouse 2000 was conducted with '5N enriched fertilizer sources as a


tracer. Recovery data shows where applied '5N ended up whether in plant tissue, retained


in the soil, leached, or lost to the atmosphere. All 15N enriched samples were analyzed


for enrichment content and total recovery recorded. Enriched fertilizer materials were


3 .5 -.-. ...............-- --.. .... ...... .. .......................
An y=0.364x- 1.019 3.23
3.0
aly R = 0.976
te 2.5 CV=11
lea
ch 2.0 nitrate-N
ed 1.5 a calcium
(g)
1.0 y 0.0855x 0.1378 0
; 0.77 r 2= 0.9
0.5 0.21 = 10.4
0.34
0.0
2.8 5.7 8.6 11.5
Calcium nitrate applied (g)


(a)

3.5 ..........
An y =0.337x- 0.705 3 13
aly 2= 0.999
te 2.5 CV= 14.2
lea
ch 2.0 nitrate-N
d1.5 a calcium
(g) .25
1.0 y 0.085x-0.23 075
r2 0
0.5 0. 2=.
00 .0 0.24
2.8 5.7 8.6 11.5
Calcium nitrate applied (g)


(b)
Figure 4-1. Total N03 -N and Ca leached from (a) coated sand, (b) uncoated sand
turfgrass glasshouse 2000 study.









minimum 5% 'N which means that analysis data from the mass spectrometer at 5% 'N

enrichment indicates very close to 100% of the N in the sample was from the labeled

source. There was little extraneous N introduced in this glasshouse study, therefore most

samples were found to contain at or near 100% labeled N. Nitrogen found to be from

applied 15N sources was calculated so that N balance results could be reported.

A total of 0.91 g 15N enriched N was applied to each lysimeter over the duration of

the study. Values reported are averages of N recovered from CS and UCS materials

from all 4 fertilizer sources over the entire study. Total labeled '5N recovered in dry

matter was found to be 406 mg N which represents 44.6% of applied N. Nitrogen

recovered by KCI extraction was found to be 18.7 mg N or 2.1% of applied N and

leachate N was found to be 193.4 mg N or 21.3% of applied N. Average '5N labeled N

recovery for the study was 68% of applied N, which means that 32% of applied N was

unaccounted for and presumed to be lost to the atmosphere through volatilization and

denitrification. Urea had the lowest percent recovery which corroborates Snyder et

al.(1980) when it was concluded that lower NO3- leached from urea because of urea

volatilization.

Table 4-8. Mass balance and percent 15N recovered for the turfgrass glasshouse 2000
study.
Fertilizer source
ANI KN urea CN#
------- % of N applied-------
N in plant 45.9 43.1 47.2 42.2
N in soil 2.6 1.7 2.3 1.7
N in leachate 20.5 29.1 10.0 25.4
Total N recovered 69.0 73.9 59.5 69.3
t 0.91 g N applied lysimeter-1
t NH4NO3
1 KNO3
CO(NH2)2
# 5Ca(N03)2NH4N0310H20















CHAPTER 5
GLASSHOUSE 2001 TURFGRASS STUDY

Tissue Dry Matter as Influenced by Sand Type and Fertilizer

An analysis of variance of the dry matter for all tissue harvested revealed that dry

matter tissue was influenced by sand type and fertilizer (Table 5-1). Unlike the previous

year's study, the UCS used in the glasshouse 2001 turfgrass study was not amended v ith

peat. It is not uncommon in the construction of USGA greens to occasionally omit ith

addition of the recommended organic amendment. The omission of the peat can have

dramatic effects on turfgrass production such as decreased nutrient and water holding

capacities resulting in poor turfgrass establishment and management (Snow, 1992). The

tissue dry matter production was 2.84 times greater on CS media than on UCS media.

The UCS was not effective in nutrient or water retention. The omission of peat severely

reduced the early rooting of the turfgrass due to the inability of the UCS to retain

adequate water at the surface where sprigs were applied. The UCS media was observed

drying out shortly after irrigation to a depth of> 2.5cm.

All fertilizer treatments produced the same amount of tissue dry matter as CN

except for AS, which produced only 75% of the CN treatment. The AS fertilizer

treatment did not produce as much tissue as the CN due to difficulty establishing

turfgrass treated with AS on the UCS media. This finding was similar to the results by

Shaddox and Sartain (2001) when they reported that lower coverage and higher leaching

rates were observed using AS instead of AN. They recommended that AN be used as the

soluble N source rather than AS during turfgrass establishment due to an unusually long









establishment period brought on by a possible toxic result of NH4+ or NH3 after

fertilization with AS. The tissue dry matter production on the CS material treated with

AS (data not shown), was similar in magnitude to the other fertilizer sources, suggesting

that the UCS material did not have the buffering ability of the CS material. It is possible

that the turfgrass grown on the UCS media with AS developed injury due to NH4

toxicity, NH3 toxicity, or both.

Table 5-1. Total tissue dry matter weight for all harvests for glasshouse 2001 turfgrass
study as influenced by sand type and fertilizer.
Dry Matter Tissue
Sand type -- g -- Fertilizer -- g --
CS (1) 16.84 AN (1) 12.37
UCS (2) 5.93 KN (2) 12.36
-- -- ---- --- AS (3) 8.46
Contrast: 1 vs. 2 *** CN (4) 11.28

Contrast: 1 vs. 4 NS
Contrast: 2 vs. 4 NS
CV= 19.4 Contrast: 3 vs. 4 *
*, ***, Significant at the 0.05, 0.001 probability levels, respectively.

Total Soil N as Influenced by Sand Type and Fertilizer

An analysis of variance of total N retained in the soil for the glasshouse 2001

turfgrass study revealed that N retained in the soil was influenced by sand type and

fertilizer source. The CS media retained 2.28 times more N in the soil profile than the

UCS media (Table 5-2). Increased ion retention due to clay coatings resulted in the CS

having the ability to retain N in the soil, where it could be held from leaching and remain

available for plant uptake.

Nitrogen retention in the soil resulting from treatments AN and AS did not differ

from that of CN. Fertilizing with CN resulted in N retention that was 1.76 times greater

than that of KN. Due to the magnitude of this difference, it is possible that the NH4









portion of the CN treatment was not solely responsible for the entire difference, but :I.nl

the retention of the CaNO3 ion pair contributed to the increased retention of N as well.

Table 5-2. Total N retained in the soil for glasshouse 2001 turfgrass study as influenced
by sand type and fertilizer.
Total N Retained in the Soil
Sand type -- mg -- Fertilizer -- mg --
CS (1) 78.52 AN (1) 59.05
UCS (2) 34.36 KN (2) 34.69
-------------- AS (3) 71.01
Contrast: 1 vs. 2 *** CN (4) 61.01

Contrast: 1 vs. 4 NS
Contrast: 2 vs. 4 *
CV = 38.4 Contrast: 3 vs. 4 NS
*, ***, Significant at the 0.05, 0.001 probability levels, respectively.

N Tissue Uptake as Influenced by Sand Type and Fertilizer

An analysis of variance on N uptake by the turfgrass tissue revealed that sand type

and fertilizer influenced N tissue uptake but no interaction between them was found.

Turfgrass grown on CS media produced 2.78 times more tissue than turfgrass on the LCS

media (Table 5-3). The inability of the UCS media to retain nutrients and water

compared to the CS media resulted in dramatically reduced N uptake by the tissue.

Fertilizer source influenced N uptake by the tissue. The turfgrass treated \w ith the

CN fertilizer took up 52% more N than that treated with AS. The AS treated lurlgra,

did not perform as well as the other sources because the AS treatment on the UCS

suffered a slower establishment, increased susceptibility to dehydration injury, and some

limited plant death. The UCS lack of ability to retain water at the surface of the ;r.iti '.

coupled with possible injury due to NH4' toxicity, NH3 toxicity, or both contributed to

lower dry matter production from AS. Tissue uptake of N from CN treated lysimeters

was not different from that of AN and KN treated lysimeters.











Table 5-3. Nitrogen uptake by the harvested tissue for glasshouse 2001 turfgrass study as
influenced by sand type and fertilizer.
N Uptake Tissue
Sand type -- mg -- Fertilizer -- mg --
CS(1) 434.0 AN (1) 319.7
UCS (2) 156.0 KN (2) 330.1
------------------------------ AS (3) 210.1
Contrast: 1 vs. 2 *** CN (4) 320.1

Contrast: 1 vs. 4 NS
Contrast: 2 vs. 4 NS
CV =21.0 Contrast: 3 vs. 4 **
**, ***, Significant at the 0.01, 0.001 probability levels, respectively.

Total Dry Matter Production as Influenced by Sand Type and Fertilizer

An analysis of variance of total dry matter production revealed an interaction of

sand type by fertilizer. The magnitude of total dry matter accumulated was larger for the

CS media than the UCS media for all fertilizers (Table 5-4). The CS was a more

hospitable growing media than the UCS due to increased nutrient and water retaining

properties. Total dry matter accumulation for CN treated lysimeters was not different

than that of AN, KN, or AS on CS media. All fertilizer treatments were equally effective

in total dry matter production on the CS media.

The CN treated lysimeters produced 2.89 times more total dry matter than the AS

treated lysimeters on the UCS media. Total dry matter accumulation was reduced

dramatically for AS treatment on the UCS media as previously discussed. Total dry

matter accumulation from CN treated lysimeters was not different from that of AN and

KN treated lysimeters on the UCS media.












Table 5-4. Total dry matter for glasshouse 2001 turfgrass study as influenced by sand
type and fertilizer.
Total Dry Matter
Coated sand Uncoated sand
-------- ------- g -----------------------
AN (1) 37.3 25.9
KN (2) 35.8 26.4
AS (3) 33.9 9.1
CN (4) 36.4 26.2

Contrast: 1 vs. 4 NS NS
Contrast: 2 vs. 4 NS NS
Contrast: 3 vs. 4 NS **
CV 13.6
**, Significant at the 0.01, probability level.

Total N Uptake as Influenced by Sand Type by Fertilizer

Nitrogen uptake is generally positively correlated to dry matter production unless

another factor such as water or a nutrient is in short supply. In this study total N uptake

was characterized by the same trends as total dry matter. Analysis of variance of total N

uptake revealed an interaction of sand type by fertilizer. The magnitude of total N uptake

was larger for the CS media than the UCS media for all fertilizers (Table 5-5). The CS

was a more hospitable growing media than the UCS which allowed for a larger

magnitude of N to be taken up by the turfgrass. Total N uptake for CN treated lysimeters

was not different than that of AN, KN, or AS on CS media. All fertilizer treatments were

equally effective regarding total N uptake on the CS media.

The CN treated lysimeters allowed for 2.87 times more total N uptake than the AS

treated lysimeters on the UCS media. Total N uptake was reduced dramatically from AS

treatment on the UCS media as previously discussed. Total N uptake from CN treated










lysimeters was not different from that of AN and KN treated lysimeters on the UCS

media.


Table 5-5. Total N uptake for glasshouse 2001 turfgrass study as influenced by sand type
by fertilizer.
Total N Uptake
Coated sand Uncoated sand
------------------- mg ------------------
AN (1) 638.4 418.4
KN (2) 657.9 476.4
AS (3) 610.9 136.4
CN (4) 701.2 391.9

Contrast: 1 vs. 4 NS NS
Contrast: 2 vs. 4 NS NS
Contrast: 3 vs. 4 NS **
CV 18.2
**, Significant at the 0.01 probability level.

Total N Leached as Influenced by Sand Type and Fertilizer

An analysis of variance of total N leached revealed an interaction of sand type by

fertilizer. The CS media leached less N in magnitude than the UCS (Table 5-6). The

CaNO3" ion pair did not reduce N03 leaching from CN compared to the other sources.

The lysimeters treated with the CN fertilizer leached amounts of N that were not different

from lysimeters treated with AN, KN, or AS on the CS media. Although not significantly

different at the 0.05% probability level, it is notable that the magnitude differences of N

leached remain similar to that of the previous year study (Turfgrass Glasshouse 2000), in

that the order of magnitude for N leached on the CS was KN > CN > AN.

The UCS did not include an organic amendment or have significant amount of clay

coatings for water or nutrient retention. The USGA specification for sand particle size

results in the UCS having a greater saturated conductivity than the CS. These factors

created more variability for nutrient leaching through the UCS media resulting in









quantities of N leached that did not follow expected trends. Growth on the UCS was

characterized by soil drying shortly after irrigation and somewhat inconsistent initial

growth patterns and difficulty in turfgrass establishment. The CN treated lysimeters

leached more total N than both AN and KN treatments on the UCS media. There was no

difference in total N leached between the CN and AS treatments on the UCS media.


Table 5-6. Total N leached for glasshouse 2001 turfgrass study as influenced by sand
type by fertilizer.
Total N Leached
Coated sand Uncoated sand
------------------- mg ------------------
AN (1) 20 153
KN (2) 49 153
AS (3) 57 235
CN (4) 39 238

Contrast: 1 vs. 4 NS *
Contrast: 2 vs. 4 NS *
Contrast: 3 vs. 4 NS NS
CV = 29.0
*, Significant at the 0.05 probability level.

Regression analysis was conducted on 0, 0.5x, 1.0x, 2.0x rates of CN for the

purpose of quantifying Ca2 and N03" in the leachate to determine if there was any

relationship that would show the mechanism of differential nitrate leaching (Figure 5-1).

The Ca+2 and NO3- regressions on the UCS are both highly linear. The Ca+2 and NO3

linearity are not as good for the CS where more growth was occurring resulting in less

leaching of both Ca2 and NO3-. There is not a decrease in slope of N03- at the 2x rate

for either sand material, which might have indicated an effect of CaNO3+ ion pair.















1.5
An y 0.157x-0.517 135
aly r2 = 0.933
te CV = 36.1
lea 1.0
lea
ch nitrate-N
9ed 0 6 a calcium
(g) 0.5
y= 0.069x 0.161
007 .18 2 = 0.979
0.0 7 7 0.17 CV =11.2
2.8 5.7 8.6 11.5
Calcium nitrate applied (g)

(a)

3.0
An y= 0.293x -0.647 2.70
aly 2.5 = 0.999
te CV 15.1
lea 2.0
ch 1 5 nitrate-N
1.5
ed calcium
(9) 1.0 y=0.095x-0.137 04

0.5 2
0.0
o.o -I' 3--------

2.8 5.7 8.6 11.5
Calcium nitrate applied (g)


Figure 5-1. Total NO3--N and Ca leached from (a) coated sand and (b) uncoated sand for
the turfgrass glasshouse 2001 study.

Leachate pH as Influenced by Sand Type and Fertilizer

An analysis of variance ofpH for the leachate taken 98 DAS revealed an


interaction of sand type by fertilizer. The NH4 fertilizer sources (AN and AS) tended to


lower leachate pH while the NO3" fertilizer sources (KN and CN) generally increased


leachate pH (Table 5-7). The CS media, having more buffering capacity than the UCS


media, kept the leachate pH values for each fertilizer treatment closer to that of neutral


compared to more acidic and alkaline pH values from UCS media leachate. The UCS


media resulted in larger extremes of leachate pH due to fertilizer treatment than did the


CS media.










The CS media treated with CN had leachate pH values that were found to not differ

from leachate pH values of AN and KN. Although not statistically different, the pH

values are sequentially inversely proportional to the fertilizers NH4+ content. The

leachate pH value for lysimeters treated with AS were significantly lower than CN. More

H+ was produced from AS because 100% of the N in AS was in the NH4' form versus

only 8.3 % of the N in CN. For every mole of NH4+ nitrified, two moles of H+ are

produced and released into the soil solution.

The UCS media did not buffer leachate pH as well as the CS media and thus wider

ranges of leachate pH values were observed. The pH values for leachate from CN treated

lysimeters were different than the other three sources on the UCS. Trends for pH values

of leachates for UCS media remained consistent with the glasshouse 2000 turfgrass study

and the CS media from the glasshouse 2001 turfgrass study because more NH4 content

in the fertilizer source resulted in lower leachate pH values. Leachate pH values for

lysimeters treated with CN were lower than those for KN and higher for leachate values

of both AS and AN treated lysimeters.

Table 5-7. Leachate pH taken 98 DASt for glasshouse 2001 turfgrass study as influenced
by sand type by fertilizer.
pH
Coated sand Uncoated sand
AN (1) 6.0 4.2
KN (2) 7.3 7.8
AS (3) 3.7 3.1
CN (4) 6.3 7.0

Contrast: 1 vs. 4 NS ***
Contrast: 2 vs. 4 NS **
Contrast: 3 vs. 4 ** ***
CV= 11.9
**, *** Significant at the 0.05, 0.001 probability levels, respectively.
t Days after sprigging










Leachate Electrical Conductivity as Influenced by Sand Type and Fertilizer

An analysis of variance of the EC for the leachate taken 98 DAS revealed an

interaction of sand type by fertilizer. Electrical conductivity for leachates from KN and

CN treated lysimeters were approximately twice the magnitude on the UCS media than

on the CS media. The EC values of leachates for AN and CN from the CS are similar in

magnitude to those of the UCS media (Table 5-8).

The EC of the leachate taken 98 DAS from the CS media for fertilizer CN was not

different from treatments AN or KN. Coated sand leachate EC from lysimeters treated

with AS were 2.2 times higher than from CN indicating that the soluble salts leached

from fertilization with AS were greater than those resulting from fertilization with CN.

The UCS media leachate EC from lysimeters treated with CN did not differ from

lysimeters treated with AN but were lower than those from KN and AS. The KN

fertilizer treatment resulted in a higher rate of K applied to the KN lysimeters to allow the

N to be applied in equivalent amounts for each fertilizer. The UCS media apparently

could not buffer this extra K in solution resulting in a soluble salts measurement that was

Table 5-8. Leachate electrical conductivity taken 98 DASt for glasshouse 2001 turfgrass
study as influenced by sand type by fertilizer.
EC
Coated sand Uncoated sand
----------------- uS cm ------------
AN (1) 127 128
KN (2) 192 301
AS (3) 416 709
CN (4) 189 120

Contrast: 1 vs. 4 NS NS
Contrast: 2 vs. 4 NS **
Contrast: 3 vs. 4 *** ***
CV= 15.7
** ***, Significant at the 0.01, 0.001 probability levels, respectively.
t Days after sprigging










2.5 times greater than that of CN. The leachate EC from lysimeters treated with AS were

5.91 greater than those treated with CN.

Mass Balance Calculations

Turfgrass glasshouse 2001 was not conducted with 15N enriched fertilizer sources

as a tracer because unlabeled AS was introduced as a nutrient source in place of urea and

because the previous year study (Turfgrass Glasshouse 2000) revealed that samples

contained high content of labeled material. Very little extraneous N was able to enter the

turfgrass glasshouse system, reasonably assuring recovery of N to be to be from the

treatment applications.

A total of 0.91 g N was applied to each lysimeter over the duration of the study.

Values reported are averages of N recovered from CS and UCS materials from all 4

fertilizer sources over the entire study. Total N recovered in dry matter was found to be

504 mg N which represents 55.4% of applied N. Nitrogen recovered by KCI extraction

was found to be 56.4 mg N or 6.2% of applied N and leachate N was found to be

approximately 118.5 mg N or 13% of applied N. Average N recovery for the study was

74.6% of applied N, which means that 25.4% of applied N was unaccounted for and

presumed to be lost to the atmosphere through volatilization and denitrification. The

N03-N sources CN and KN had the highest magnitude of recovery followed by NH4-N

sources AN and AS.







65


Table 5-9. Mass balance and percent N recovered for the turfgrass glasshouse 2001 study.
Fertilizer source
ANT KN AS CN#
------- % of N applied -------
N in plant 58.1 62.3 41.1 60.1
N in soil 6.5 3.8 7.8 6.7
N in leachate 9.6 11.1 16.1 15.3
Total N recovered 74.2 77.2 65.0 82.1


0.91 g N applied lysimeter-
NH4NO3
KNO3
(NH4)2S04
5Ca(N03)2NH4N0310H20














CHAPTER 6
FIELD TURF GROW-IN STUDY

Total N Leached as Influenced by Fertilizer Source

An analysis of variance for total N leached for the field grow-in turfgrass study did

not detect a difference in N leached due to fertilizer source. The CaNO3 ion pair did not

reduce NO3 leaching from CN compared to the other sources. The two NO3-N sources,

KN and CN, leached N in similar magnitudes while the NH4-N sources, AN and urea,

leached less N in magnitude than the N03-N sources (Table 6-1). There appears to be a

correlation between the amount of N in the NH4F form and reduction of N leached even

though the analysis of variance was not significant at the 0.05% probability level. The

NH4-N in the fertilizer treatments was capable of being held by the soil through an

electrostatic retention known as cation exchange (CE), thereby reducing the N leached.

Ammonium-N sources also have the ability to lower the pH of the system through the

release of H ions during the nitrification process (Tisdale et al., 1999). The resulting

lower soil pH is in a range more suitable to optimum plant growth, thereby inducing

increased N uptake by the plants and reducing N leached as bermudagrass has been found

to tolerate acidic conditions (Lundberg et al., 1977; Sartain, 1985; and Snyder et al.,

1979).










Table 6-1. Total N leached for field grow-in 2001 turfgrass study as influenced by
fertilizer source.
Total N Leachedt
Fertilizer -- g --
AN (1) 9.76
KN (2) 12.78
Urea (3) 8.25
CN (4) 12.54

Contrast: 1 vs. 4 NS
Contrast: 2 vs. 4 NS
Contrast: 3 vs. 4 NS
CV 32.9
t Average of 19% for all sources of total N applied (57.5 g N m2).

Soil N as Influenced by Fertilizer Source

Nitrogen source did not influence the quantity of KCl extractable N retained by the

soil (Table 6-2). Although the N retained in the soil was not affected by N source at the

0.05% probability level, a positive correlation was found between the amount of N in the

fertilizer source that is in the NH4+ form and the magnitude of N retained in the soil. The

NH4-N can be held by the soil via an electrostatic retention where as N03-N readily

moves with the wetting front following irrigation or rain event (Bauder and Montgomery,

1980).

Soil N retention represented 1.3% of the total N applied. Low nutrient retention is

one of the major drawbacks of the USGA specification golf greens (Snow, 1992). Snyder

et al. (2001) reported results that indicate sand grain coatings and peat improve

characteristics of sand based putting greens without adversely affecting putting green

water relations.









Table 6-2. Soil N (KCI Extractable) for field grow-in 2001 turfgrass study as influenced
by fertilizer source.
Total N in Soilt
Fertilizer g -
AN (1) 0.847
KN (2) 0.520
Urea (3) 1.015
CN (4) 0.657

Contrast: 1 vs. 4 NS
Contrast: 2 vs. 4 NS
Contrast: 3 vs. 4 NS
CV = 32.2
t Average of 1.3% for all sources of total N applied (57.5 g N m ).

Leachate pH as Influenced by Fertilizer Source

An analysis of variance for the pH of the leachate taken 52 days after sprigging,

representative of all the leachates, revealed an influence due to fertilizer source (Table 6-

3). The pH values obtained in the leachate taken 52 DAS reveal a trend that serves as a

microcosm for understanding the results of the entire study. Soil solution pH is possibly

the most important indicator regarding the status of soil-plant relationships. Soil

chemical and biological properties are greatly influenced by pH. Nutrient availability to

plants can be greatly modified by changes in pH. Leachate pH is an indication of the

amount of acidity or alkalinity that is present in a solution. These values are also an

indication of the average amount of H' ions in solution, so it is possible that pH values of

the rhizosphere (the soil zone that surrounds and is influenced by the roots of plants) may

be even more acidic or alkaline than the measured leachate pH, depending on the

predominant N form supplied to the plant. This is because H+ and OH" efflux from the

roots will cause pH microenvironments around the roots (Lucena, 2000). Plants that take

up NH4 from the soil solution release an equivalent amount of H+ into the solution,

which lowers the pH of the rhizosphere. When plants take up NO3- from the soil solution









an equivalent amount of OH' is released into the soil solution, which raises the pH of the

rhizosphere.

Fertilizer source AN resulted in pH values from the leachate taken 52 DAS that

were lower than those resulting from fertilizer source CN (Table 6-3). Half of the N in

AN is in the NH4 form, thus the ability of AN fertilizer to reduce soil pH is substantial,

while fertilizer source CN contains only 8.3% of its N in the NH4 form. Fertilizer source

urea resulted in a leachate pH that was more acidic than CN as well. Upon hydrolysis of

urea by the urease enzyme, two NH4+ molecules are produced and can be nitrified,

reducing solution pH values.

Leachate values from CN treated plots were lower than leachate values from KN

treated plots. Fertilizer source CN contains 8.3% of its N in the NH4+ form, which was

enough to keep leachate pH values lower than KN, which has all of its N in the NO3-

form. It is the belief of the researcher that N03-N sources, KN and CN, increased

rhizosphere pH values more than the leachate pH values as described by Riley and Barber

(1969) when they reported pH increases at the root surface and in the rhizoplane soil

from N3O supply and uptake by the roots. The release of an equivalent amount of OH-

into the soil solution by the roots for all N03" taken up by the plant raised the pH of i e

rhizosphere and rhizocylinder (roots plus strongly adhereing soil) above that of neutral

(7.0).









Table 6-3. Leachate pH taken 52 days after sprigging for field grow-in 2001 turfgrass
study as influenced by fertilizer source.
Fertilizer -- pH --
AN (1) 6.4
KN (2) 7.4
Urea (3) 6.6
CN (4) 7.1

Contrast: 1 vs. 4 ***
Contrast: 2 vs. 4 *
Contrast: 3 vs. 4 **
CV = 2.7
*, **, ***, Significant at the 0.05, 0.01, 0.001 probability levels, respectively.

Dry Matter Tissue and N Uptake by Tissue as Influenced by Fertilizer Source

Dry matter tissue and N uptake are highly correlated to each other and have similar

trends based on statistical analysis, so they are discussed together (Table 6-4). Dry

matter tissue and tissue N uptake were similar in magnitude for the NH4-N fertilizer

sources AN and urea. Both NH4-N sources produced higher tissue dry matter

accumulation and tissue N uptake than N03-N source CN. Nitrate fertilizer sources KN

and CN resulted in similar values in magnitude for dry matter tissue accumulation and

tissue N uptake. It is possible that the magnitude difference of dry matter tissue and N

uptake between the NH4-N fertilizer sources (AN and urea) and the N03-N sources (KN

Table 6-4. Dry matter tissue and N uptake by tissue for field grow-in 2001 turfgrass study
as influenced by fertilizer source.
Dry Matter Tissue N Uptake Tissue
Fertilizer -- g -- Fertilizer -- g --
AN (1) 87.77 AN (1) 1.89
KN (2) 40.17 KN (2) 0.79
Urea (3) 74.63 Urea (3) 1.62
CN (4) 39.89 CN (4) 0.78

Contrast: 1 vs. 4 *** Contrast: 1 vs. 4 ***
Contrast: 2 vs. 4 NS Contrast: 2 vs. 4 NS
Contrast: 3 vs. 4 *** Contrast: 3 vs. 4 ***
CV = 12.3 CV 12.7
***, Significant at the, 0.001 probability level.








and CN) were probably due to a pH induced micronutrient deficiency induced by the

NO3-N sources which was the same finding as reported by Snyder et. al. (1979).

Total Dry Matter as Influenced by Fertilizer Source

An analysis of variance for total dry matter accumulation reveals an influence by

fertilizer source. Total dry matter includes all tissue, roots and verdure harvested over a

16 week period. The trends for total dry matter and roots plus verdure were similar and

thus only total dry matter in discussed (Table 6-5).

Total dry matter followed similar statistical trends as the previously discussed

results for tissue dry matter and N uptake by the tissue (Table 6-4). Ammonium-N

fertilizer sources AN and urea resulted in dry matter totals that were similar in magnitude

to each other and that were larger in magnitude than totals for the N03-N sources KN and

CN. Ammonium-N fertilizer sources AN and urea had higher total dry matter

accumulation than that produced from fertilizer source CN. Nitrate-N fertilizer source

KN resulted in total dry matter accumulation that was not different from that treated with

CN. As discussed previously, a positive correlation between the presence of N of each

treatment in the NH4 form and the magnitude of total dry matter accumulation is present.

Ammonium fertilization and its acidifying consequences will show increased

micronutrient (Mn and Fe in particular) availability in soils with neutral or alkaline pH

values resulting in increased plant vigor as reported by Snyder et. al. (1979). These

results concur with the findings of Snyder and Burt (1985) when they reported that

bermudagrass clipping weights were negatively correlated to soil pH when comparing

soluble N sources.









Table 6-5. Total dry matter for field grow-in 2001 turfgrass study as influenced by
fertilizer source.
Total Dry Matter
Fertilizer -- g --
AN (1) 942
KN (2) 540
Urea (3) 804
CN (4) 623

Contrast: 1 vs. 4 ***
Contrast: 2 vs. 4 NS
Contrast: 3 vs. 4 **
CV = 8.7
**, ***, Significant at the 0.01, 0.001 probability levels, respectively.

Total N Uptake as Influenced by Fertilizer Source

An analysis of variance of total N uptake (tissue N + roots and verdure N) revealed

an influence of fertilizer source (Table 6-6). Fertilization with AN resulted in 41.5%

more total N uptake by the turfgrass than with CN. Fertilization with urea resulted in

32.1% more total N uptake by the turfgrass than with CN. The amount of turfgrass N

uptake from fertilizer source KN did not differ from that of CN. Fertilizer sources AN

and urea contain appreciable amounts of NH4-N, and had higher magnitudes of N uptake

Table 6-6. Total N uptake for field grow-in 2001 turfgrass study as influenced by
fertilizer source.
Total N Uptake
Fertilizer -- g --
AN (1) 7.5
KN (2) 5.2
Urea (3) 7.0
CN (4) 5.3

Contrast: 1 vs. 4 **
Contrast: 2 vs. 4 NS
Contrast: 3 vs. 4 *
CV = 12.0
*, **, Significant at the 0.05, 0.01 probability levels, respectively.








than the N03-N sources KN and CN. Release of H lowered the pH of the turfgrass soil

system, via the nitrification process of the NH4+ forming fertilizers, allowed the turfgrass

to accumulate more total N than that from N03-N sources.

Percent Cover as Influenced by Fertilizer Source

An analysis of variance of percent (%) cover for the grow-in of bermudagrass

revealed an influence of fertilizer source. The trend for all three cover rating dates

extending over a 10 week establishment period was similar from the start and remained

through the last cover rating score. The % cover ranking from highest to lowest was AN

> urea > CN > KN (Table 6-7). The cover rating score taken 38 DAS showed that the

AN treatment resulted in plots that had 64% more cover than plots treated with CN. Plots

treated with urea had 49% more cover than plots treated with CN. The plots treated with

KN were not different than those treated with CN for % cover.

Cover rating taken 47 DAS was similar to cover rating 38 DAS in order of

treatment producing highest % cover to lowest % cover. Ammonium nitrate treatment

resulted in plots that had 38% more cover than plots treated with CN. Plots treated with

urea had 34% more cover than plots treated with CN. The plots treated with KN were not

different than those treated with CN for % cover.

Cover rating taken 69 DAS showed that fertilizer sources AN, urea, and CN were

generally at complete cover. Plots treated with CN had 9% more cover than plots treated

with KN. The plots treated with KN lagged behind all others for the entire grow-in study

and reached full cover after all other treatments. Turfgrass rhizosphere pH of the plots

treated with the N03-N sources KN and CN were above the optimum pH values for Mn

availability to turfgrass due to the OH efflux from the plant upon NO3- uptake.









Table 6-7. Percent cover for field grow-in 2001 turfgrass study as influenced by fertilizer
source.
Cover 38 DASt Cover 47 DAS Cover 69 DAS
Fertilizer -- % -- Fertilizer -- % -- Fertilizer -- %--
AN (1) 64 AN (1) 80 AN (1) 100
KN (2) 36 KN (2) 53 KN (2) 89
Urea (3) 58 Urea (3) 78 Urea (3) 100
CN (4) 39 CN (4) 58 CN (4) 97

Contrast: 1 vs. 4 *** *** NS
Contrast: 2 vs. 4 NS NS *
Contrast: 3 vs. 4 ** ** NS
CV = 12.0 CV = 8.8 CV = 4.8
*, **, ***, Significant at the 0.05, 0.01, 0.001 probability levels, respectively.
t Days after sprigging.

Leachate EC as Influenced by Fertilizer Source

An analysis of variance of EC for leachates collected 52 DAS and 91 DAS revealed

an influence of fertilizer source. Leachates from these two sampling events showed a

trend that was consistent with all leachate events, thus they are discussed here. Both

sampling events had leachate EC values that were, from largest to smallest in magnitude,

KN > CN > urea > AN (Table 6-8). Contrast separations are different between the two

leaching events, but show that the N03-N sources KN and CN generally had a higher

magnitude of soluble salts than the NH4-N sources AN and urea.

Leachate EC values from plots treated with CN were higher than values from plots

treated with AN and urea for leachate collected 52 DAS. Fertilizer sources AN and urea

generally produced more plant growth and nutrient uptake than CN which resulted in less

soluble salts in the soil solution and less soluble salts leached. Leachate EC values from

plots treated with CN were not different than values from plots treated with KN from

leachate collected 52 DAS. The N03-N sources KN and CN behaved similarly in many

soil-plant parameters and leachate EC for leachate collected 52 DAS was also similar.









Table 6-8. Leachate EC for field grow-in 2001 turfgrass study as influenced by fertilizer
source.
Leachate 52 DASt Leachate 91 DAS
Fertilizer --uS cm'-- Fertilizer --uS cm'--
AN (1) 191 AN (1) 148
KN (2) 276 KN (2) 283
Urea (3) 199 Urea (3) 187
CN (4) 249 CN (4) 201

Contrast: 1 vs. 4 ** Contrast: I vs. 4 NS
Contrast: 2 vs. 4 NS Contrast: 2 vs. 4 *
Contrast: 3 vs. 4 Contrast: 3 vs. 4 NS
CV 10.8 CV 18.0
*, **, Significant at the 0.05 and 0.01 probability levels, respectively.
t Days after sprigging.

Leachate EC values from plots treated with CN were not higher than plots treated

with AN and urea for leachate collected 91 DAS. Although the NH4-N sources AN and

urea had EC values that were higher in magnitude than CN for leachate collected 91

DAS, the values were not different from CN treated plots at the 0.05% probability level.

Leachate EC values from plots treated with CN were lower than from plots treated with

KN from leachate collected 91 DAS. Fertilizer source KN had a higher equivalence of K

applied than the other sources to keep the N applied equivalent for all sources, which may

have contributed to the increase in leachate EC values from KN treated plots.

It appears that the contribution of H+ from the nitrification of NH4 improved

growing conditions for the turfgrass, which in turn resulted in increased nutrient uptake.

Fertilizer sources KN and CN, having N predominately in the N03-N form, developed a

micronutrient deficiency due to increased pH of the soil solution. The rhizosphere pH of

the turfgrass fertilized with KN and CN was increased due to expulsion of OH- upon

uptake of N3- to the point that micronutrient availability was reduced around the plant









roots. The result was reduced tissue production along with a general detriment to

turfgrass quality and performance for plots treated with fertilizer sources KN and CN.

Mass Balance Calculations

Turfgrass 2000 field grow-in study was conducted with "N enriched fertilizer

sources as a tracer. Recovery data shows where applied '5N ended up whether in plant

tissue, retained in the soil, leached, or lost to the atmosphere. A total of 57.5 g '"N

enriched N was applied to each m2 plot over the duration of the study 16 week study.

Total labeled '5N recovered in dry matter was found to be 6.25 g N which represents

10.9% of applied N (Table 6-9). Nitrogen recovered by KCI extraction was found to be

0.75 g N or 1.3% of applied N and leachate N was found to be 10.82 g N or 18.8% of

applied N. Average 15N labeled N recovery for the study was 31% of applied N, which

means that approximately 69% of applied N was unaccounted for and presumed to be lost

to the atmosphere through volatilization and denitrification.

Low levels of applied 15N was recovered from the turfgrass field grow-in system

indicating that low efficiency of applied N can occur as also found by Bock (1984).

Horgan et al. (2002) concurs reporting that recovery of applied N is typically low in

turfgrass systems and cites denitrification as the reason. Denitrification can be a large

contributor to lost N in USGA greens due to increased retention by soil underlain by

gravel. Miller and Bunger (1963) reported that the moisture content of soil underlain by

gravel changed very little after the first few days following irrigation and the moisture

content of the soil above the textural discontinuity increased as the layer was approached.







77


Table 6-9. Mass balance and percent 1N recovered for the turfgrass field grow-in 2000
study.


N in plant
N in soil
N in leachate
Total N recovered


Fertilizer source
ANt KN ureal CN#
------- % of N applied------
13.0 9.1 12.1 9.3
1.5 0.9 1.8 1.1
17.0 22.2 14.3 21.8
31.5 32.2 28.2 32.2


57.5 g N applied m2
NH4NO3
KNO3
CO(NH2)2
5Ca(N03)2NH4N0310H20















CHAPTER 7
FIELD TURF OVERSEED STUDY

Total N Leached as Influenced by Fertilizer Source

An analysis of variance for total N leached for the field turfgrass overseed study did

not detect a difference in N leached due to fertilizer source (Table 7-1). The CaNO3- ion

pair did not reduce N03- leaching from CN compared to the other sources. Leaching

values were low (< 0.1% of 12.5g m-2 applied N) because the ryegrass was established

and ready for nutrient uptake at the first treatment application (Table 7-1). This concurs

with the findings by Miltner et al. (1996) that recovery of 15N labeled urea applied to

Kentucky bluegrass to be 0.23% in leachate and total 15N recovery to be up to 81%.

Rapid uptake and immobilization of '5N labeled N was observed over the 2 year

experiment leading to the conclusion that a well-maintained turf intercepts and

immobilizes N quickly making leaching an unlikely avenue of N loss from a turf system.

This is also in agreement with Blue (1974) when he concluded that N leaching is not a

major loss route when N is applied to perennial grass pastures at biologically useable

rates and Lee et al. (2003) in a report that N fertilization of turfgrass systems poses no

inherent risks to water quality and the environment.









Table 7-1. Total N leached for field overseed 2002 turfgrass study as influenced by
fertilizer source.
Total N Leachedt
Fertilizer -- mg --
AN (1) 10.25
KN (2) 16.93
AS (3) 6.03
CN (4) 7.52

Contrast: 1 vs. 4 NS
Contrast: 2 vs. 4 NS
Contrast: 3 vs. 4 NS
CV = 104.5
t Represents < 0.1% of total applied N (12.5g m2).

Soil N as Influenced by Fertilizer Source

Soil N as measured by 2M KC1 extraction shows a positive correlation between the

amount of N in the fertilizer source that is in the NH4I form and the magnitude of N

retained in the soil (Figure 7-1). This study took place over the winter when nitrification

is slow due to decreased temperatures and thus NH4' in the treatments were retained in

the soil by CE rather than being oxidized to NO3-. The most N was retained by AS with

100% N in the NH4- form, followed by AN with 50% N in the NH4' form, followed by

CN with 8.3% N in the NH4+ form, followed by KN with no N in the NH4' form (Table

7-2). Fertilizer source CN had 18% more N retained in the soil than KN. Fertilizer

source AS had 58% more N retained in the soil than CN, and AN had 22% more N

retained in the soil than CN. These findings agree with Bauder and Montgomery (1 i0)

that NO3- leaching can be minimized by application and soil retention of NH4 based

fertilizers and careful irrigation management.





























Figure 7-1. Soil N (KCI extractable) retained vs. % NH4+ content of fertilizer source.



Table 7-2. Soil N (KC1 extractable) for field overseed 2002 turfgrass study as influenced
by fertilizer source.
Total N in Soilt
Fertilizer -- mg --
AN (1) 407
KN (2) 284
AS (3) 529
CN (4) 334

Contrast: 1 vs. 4 **
Contrast: 2 vs. 4 *
Contrast: 3 vs. 4 ***
CV = 7.0
*, **, ***, Significant at the 0.05, 0.01, 0.001 probability levels, respectively.

t Represents 3.1% of total applied N (12.5g m2).

Dry Matter Tissue (Clippings) as Influenced by Fertilizer Source

Dry matter tissue (clippings) was not affected by fertilizer source for the field

overseed study. All N sources produced the same amount of tissue (Table 7-3). The

quality of the tissue was affected as will be discussed further regarding Mn concentration

in the tissue and tissue color.


550 .. ........ ...

500 m m ium
> sulfate
E 450
e .A Ammonium
. 400 nitrate
0 350
Z Calcium y = 2.304x + 297.33
nitrate r2 = 0.985
300
4 Potassium CV = 7 0
250 nitrate
250
0 20 40 60 80 100
Percent ammonium of N source










Table 7-3. Dry matter tissue for field overseed 2002 turfgrass study as influenced by
fertilizer source.
Dry Matter Tissue
Fertilizer -- g --
AN (1) 117
KN (2) 123
AS (3) 123
CN (4) 105

Contrast: 1 vs. 4 NS
Contrast: 2 vs. 4 NS
Contrast: 3 vs. 4 NS
CV 13.1

Total N Uptake as Influenced by Fertilizer Source

The NH4' forming fertilizer sources AS and AN resulted in more total N uptake

than the N03" sources KN and CN (Table 7-4). Sources KN and CN did not differ in

total N uptake while AN resulted in 35% more total N uptake than CN and AS resulted in

27% more total N uptake than CN. Snyder and Burt (1985) found clipping weights to be

negatively correlated to soil pH which is similar to data in Table 7-4 which indicates that

NI-4 content of fertilizer sources were positively correlated to total N uptake.


Table 7-4. Total N uptake for field overseed 2002 turfgrass study as influenced by
fertilizer source.
Total N Uptake
Fertilizer g -
AN (1) 10.5
KN (2) 7.7
AS (3) 9.9
CN (4) 7.8

Contrast: 1 vs. 4 **
Contrast: 2 vs. 4 NS
Contrast: 3 vs. 4 **
CV= 9.7
**, Significant at the 0.01, probability level.










Total Dry Matter as Influenced by Fertilizer Source

Total dry matter was influenced by fertilizer source (Table 7-5). Fertilizer AN had

35% more total dry matter than CN. Total dry matter values for KN and AS were not

different than CN. Ammonium nitrate with its 1:1 balance of N forms produced the

highest accumulation of dry matter which agrees with findings by Baily (1999) who

reported that the process of N absorption, storage, and assimilation were actually best

synchronized when the two forms of N were supplied in equal proportions and both

forms of N were absorbed at almost equal rates until the supply of the minor N

component in each treatment was almost exhausted.

Table 7-5. Total dry matter for field overseed 2002 turfgrass study as influenced by
fertilizer source.
Total Dry Matter
Fertilizer -- g --
AN (1) 1132
KN (2) 786
AS (3) 1019
CN (4) 836

Contrast: I vs. 4 **
Contrast: 2 vs. 4 NS
Contrast: 3 vs. 4 NS
CV= 11.8
**, Significant at the 0.01 probability level.

Color Rating as Influenced by Fertilizer Source

Turfgrass color is a very important characteristic in determining turfgrass quality.

Dark green color is preferred and lighter shades of green or yellowing are not desirable.

Color rating scores (1-9 with 9 being the best and 5 the minimum acceptable) for the

ryegrass overseed study consistently showed that NO3- sources KN and CN did not differ

through the study (Table 7-6) and that NH4+ sources AN and AS were superior to CN for

all rating dates. This finding is similar to that reported by Volk and Dudeck (1976) and










Sartain (personal communication, 2003) when chartreuse yellow turf color was found to

be a result of isobutylidene diurea (IBDU) rates that increased soil pH levels.

Table 7-6. Color rating for field overseed 2002 turfgrass study as influenced by fertilizer
source.
Color rating 7 DAIt Color rating 14 DAI Color rating 28 DAI
Fertilizer
AN (1) 6.9 7.7 6.7
KN (2) 6.0 5.7 6.2
AS (3) 7.0 8.2 7.0
CN (4) 6.1 6.0 6.1

Contrast: 1 vs. 4 ** *** **
Contrast: 2 vs. 4 NS NS NS
Contrast: 3 vs. 4 ** *** ***
CV = 4.0 CV = 4.9 CV = 3.6
**, ***, Significant at the 0.01 and 0.001 probability levels, respectively.
t Days after initiation.

Leachate pH as Influenced by Fertilizer Source

Leachate pH from lowest to highest was in the order AS = AN < CN < KN for

samples collected 14 DAI (Table 7-7). Alkaline irrigation water increased soil and

leachate pH values over time and NH4+ forming fertilizers can neutralize some of the

alkalinity. Nitrate sources KN and CN did not differ and were above neutral, which has

been shown to cause Mn deficiency (Snyder et al., 1979). Ammonium sources AS and

AN had lower pH values than CN. These pH values are negatively correlated to NH4I

content of N sources. Similar results were found by Snyder and Burt (1985) and Malhi et

al. (2000).











Table 7-7. Leachate pH for field overseed 2002 turfgrass study as influenced by fertilizer
source.
Leachate pH 14 DAIt
Fertilizer -- pH --
AN (1) 6.8
KN (2) 7.3
AS (3) 6.8
CN (4) 7.2

Contrast: 1 vs. 4 **
Contrast: 2 vs. 4 NS
Contrast: 3 vs. 4 *
CV = 2.4
*, **, Significant at the 0.05, 0.01, probability levels, respectively.
t Days after initiation.

Leachate EC as Influenced by Fertilizer Source

Leachate EC taken 14 DAS increased for fertilizer sources in the order AN = CN <

KN and AS (Table 7-8). Leachate EC from CN treated lysimeters was not different that

that of AN treated lysimeters. Leachate EC from CN treated lysimeters was lower than

EC from lysimeters treated with KN and AS.

Table 7-8. Leachate EC for field overseed 2002 turfgrass study as influenced by fertilizer
source.
Leachate EC (14 DAIt)
Fertilizer --dS cm'--
AN (1) 228
KN (2) 286
AS (3) 293
CN (4) 239

Contrast: 1 vs. 4 NS
Contrast: 2 vs. 4 *
Contrast: 3 vs. 4 *
CV = 10.9
*, Significant at the 0.05, probability level.
t Days after initiation.









Tissue Mn Concentration as Influenced by Fertilizer Source

Tissue Mn concentration for ryegrass was influenced by fertilizer source (Table 7-

9). Nitrate sources KN and CN produced tissue that was deficient in Mn (Jones, 194% ,1.

Manganese deficient turf causes a yellow appearance of turfgrass (Snyder et al., 1979.

Volk and Dudeck 1976, and J.B. Sartain, personal communication, 2003). Fertilizer

source CN had more Mn than KN due to the 8.3% NH4' in its composition. Fertilizer

sources AN and AS produced turfgrass tissue that had more Mn than tissue produced

from CN. Long term (3 year) application of CN on Bahiagrass resulted in an increase in

soil pH and a response to added Fe and Mn (J.B. Sartain, personal communication, 2L 03).

Similar results to this study were found by Snyder et al. (1979). Manganese

deficiencies were pH-induced rather than attributable to insufficient total Mn in the soil

and were responsible for severely limited turf appearance and growth. Snyder et al.

concluded that the best method of alleviating the Mn deficiency was through reducing

soil pH through the potential acidity of N sources.

Table 7-9. Tissue Mn concentration for field overseed 2002 turfgrass study as u .,lucni ed
by fertilizer source.
Mn Tissue Concentration (Harvested 28 DAIt)
Fertilizer -- ppm --
AN (1) 203
KN (2) 17
AS (3) 121
CN (4) 40

Contrast: 1 vs. 4 ***
Contrast: 2 vs. 4 *
Contrast: 3 vs. 4 ***
CV = 14.4
*, ***, Significant at the 0.05, 0.001, probability levels, respectively.
t Days after initiation.










Tissue Fe Concentration as Influenced by Fertilizer Source

Iron and Mn behave similarly in soils and are often grouped together when

considering micronutrient deficiencies. Fertilizer source CN did not produce tissue that

differed in Fe concentration from sources AN, KN, or AS (Table 7-10). Iron

concentration in the ryegrass tissue was not found to be deficient as a result of

fertilization from any source (Jones, 1980).

Table 7-10. Tissue Fe concentration for field overseed 2002 turfgrass study as influenced
by fertilizer source.
Fe Tissue Concentration (Harvested 28 DAIt)
Fertilizer -- ppm --
AN (1) 102
KN (2) 132
AS (3) 119
CN (4) 118

Contrast: 1 vs. 4 NS
Contrast: 2 vs. 4 NS
Contrast: 3 vs. 4 NS
CV = 22.2
t Days after initiation.


Mass Balance Calculations

The turfgrass field overseed 2002 study was not conduced with 15N enriched

fertilizer sources as a tracer because this study was an addendum to the proposed research

and enriched materials were used to completion. This study was added after the original

turfgrass field grow-in study produced results that warranted further investigation. It was

not known at the time why the N03" fertilizer sources KN and CN performed so poorly

during the field grow-in study. This study was performed to start with a full coverage of

perennial ryegrass at initiation because the grow-in plots fertilized with N03" fertilizer

sources KN and CN never produced quality harvests for reliable tissue analysis.









A total of 12.5 g N was applied to each m2 plot over the duration of the study.

Total N recovered in dry matter was found to be 9.0 g N which represents 72% of applied

N. Nitrogen recovered by KC1 extraction was found to be 388 mg N or 3.1% of applied

N and leachate N was found to be approximately 10 mg N or 0.083% of applied N.

Average N recovery for the study was 75% of applied N, which means that 25% of

applied N was unaccounted for and presumed to be lost to the atmosphere through

volatilization and denitrification. The NI-H4-N sources had higher recovery magnitudes

that the N3O sources probably due to higher plant uptake and retention levels. Little N

was leached under established turf conditions and ordinary maintenance of turfgrass

systems.

Table 7-11. Mass balance and percent N recovered for the turfgrass field overseed 2002
study.
Fertilizer source
ANI KN AST CN#
------- % of N applied -------
N in plant 83.76 62.00 78.96 62.32
N in soil 3.26 2.28 4.23 2.67
N in leachate 0.08 0.14 0.05 0.06
Total N recovered 87.10 64.42 83.24 65.05
t 12.5 g N applied m2
+ NH4NO3
1 KNO3
(NH4)2S04
# 5Ca(N03)2NH4N0310H20




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