EFFECTS OF EVAPOTRANSPIRATION BASED IRRIGATION, DOUBLE MOWING, AND WETTING
AGENT ON AN
Agrostis stolonifera var. palustris PUTTING GREEN
By
Rodney V. Tocco, Jr.

A DISSERTATION
Submitted to
Michigan State University
in partial fulfillment of the requirements
for the degree of
Crop and Soil Sciences - Doctor of Philosophy
2014

ABSTRACT
EFFECTS OF EVAPOTRANSPIRATION BASED IRRIGATION, DOUBLE MOWING, AND WETTING
AGENT ON AN
Agrostis stolonifera var. palustris PUTTING GREEN
By
Rodney V. Tocco, Jr.
State of Michigan legislators recommend the amount of irrigation water should be equal
to total evapotranspiration (ET) since the last irrigation. To the common citizen this
recommendation makes sense and is good policy, however, the legislation makes no
differentiation between turfgrass species, mowing height, and soil type. The demand for
optimum Agrostis stolonifera var. palustris (creeping bentgrass) putting greens requires golf
courses’ to manage inputs closely. Challenges include low mowing heights, summer heat stress,
traffic, along with limitations in viable irrigation sources in order to manage creeping bentgrass.
A factorial field experiment was designed on a Crenshaw putting green during the summers of
2010-2012 in East Lansing, MI comparing irrigation and mowing frequencies with and without a
wetting agent. Daily irrigation replenishment of 30, 60, and 90% evapotranspiration (ET)
measurements were compared for irrigation use efficacy while maintaining quality playing
conditions and turfgrass health. Daily single and double mowing frequencies were compared
for long-term aesthetics, pest populations, and playability when mowed at 0.3175 cm (0.125
in). Monthly applications of a wetting agent (Revolution®) were compared to untreated plots.
Playability and overall aesthetics were characterized by weekly measurements of ball roll
distance, percent volumetric water content (%VWC), and visual quality ratings (1-9). Annual soil
measurements included water drop penetration (WDP) test and total microbial biomass (TMB).

Cumulative effects were averaged at the conclusion of the study, and data presented no
significant differences among irrigation or wetting agent treatments for ball roll distance. Three
year ball roll distance averages were significantly increased from 284.5 to 317.5 cm (112 to 125
inches) for single versus double mowed plots, respectively. Values for percent volumetric water
content (%VWC) averaged 23.3, 33.1, and 35.6 for 30, 60, and 90% ET levels, respectively. Data
of 60 and 90% were statistically similar, and were significantly greater than 30% ET in %VWC.
Overall, double mowing and wetting agent application data presented no significant differences
among treatments for %VWC. Visual quality averaged 5.6, 7.9, and 8.1 for 30, 60, and 90% ET
levels, respectively. 60 and 90% were statistically similar in visual quality, and were significantly
greater than 30% ET. Visual quality increased significantly from 6.7 to 7.9 with use of a wetting
agent. Double mowing data presented no significant difference among treatments for visual
quality. No significant differences in TMB were observed in soils treated with 30, 60 , or 90% ET
daily irrigation from 2010 to 2012, with levels ranging from 29.9 to 60.1 μg g dry soil

-1

(Table

26). Daily double mowing and wetting agent application did not significantly affect TMB.
However, during the driest season of 2012, TMB was significantly increased with the use of
wetting agent at 30% ET replenishment. Data obtained from water drop penetration (WDP)
tests resulted in significantly lower hydrophobicity in soil at the 0-1 cm depth below plant
and/or thatch with wetting agent applications in all years (8-18 seconds). No differences were
observed at sampling depths below 1 cm, and in response to irrigation or mowing treatments.
Soil hydrophobicity reductions were more responsive to wetting agent applications than
irrigation or mowing treatment effects.

Copyright by
RODNEY V. TOCCO, JR.
2014

To the one percent… Here I come!
&
To my loving family… “¡Ci Siamo!”

v

ACKNOWLEDGMENTS

I would like to thank my family first and foremost. Mom and Dad – you are constant
pillars of what is right and teachers of how to treat people as you want to be treated. Your love,
encouragement, and patience have made me who I am today. Dominic and Gino – you have
been the best siblings and are always there for me. Kari Louise – your support and love brought
completing this dissertation to fruition.
My tenure at Michigan State University under Dr. Thom A. Nikolai has been nothing
short of exceptional. I am forever indebted for the opportunity to work on this degree with
such a great person of core values. Thank you for the opportunity to succeed.
A special thanks is owed to each of my remaining committee member’s for the
leadership to complete this dissertation. Dr. Joe Vargas – for your incredible wealth of
knowledge of pathology and guidance through building a sound curriculum. Dr. Kevin Frank –
for your patience with my questions and willingness to help, especially through the written
comprehensive exams. Dr. Kurt Steinke – for your advice on everything from salinity projects
outside my dissertation to my future career. I thank each of you.
A special thanks must go to Frank Roggenbuck – if I may ever know half of the wisdom
you have forgotten, I will be a lucky man. Thanks for being such a great friend.
Thanks to the many people at the Hancock Turfgrass Research Center for help in
maintaining the field study: Mark Collins, Tom MacDonald, Randy, and Paul Rieke Jr.
Dr. Stan Kostka from Aquatrols, Inc. in Paulsboro, NJ is owed many thanks for the sheer
luck that I was given wetting agent product through your generosity. Without the gift, we may

vi

never have met nor come to find such awesome results. I now consider you a friend and hope
to rub elbows many times more as my career progresses.
Dr. Bernard Zandstra and Dr. Mathieu Ngouajio from the Department of Horticulture at
Michigan State University. I learned a great deal about a field I would have never known
because you both were willing to teach and allow me use of your facilities for the microbial
analysis. Bernie – I wish you well in your future and/or retirement, if you decide to finally quit
working! Mathieu – you have the greatest patience and understanding of anyone I have ever
known. Good luck feeding the world!
Thanks to the many people who contributed to the success of my academic career and
this degree. Fellow graduate students Jeff Dunne and Paul Giordano – your help and constant
support were pillars of my time here. Thanks are also due to the many graduate and
undergraduate students I now call friends: Nick Binder, Anthony Hayes, Kevin Laskowski, Megan
Nakkula, Brendan Taylor, and Ashley Wildeman. From start to finish each of you contributed to
the completion of this project and its success.
Last but not least, I would like to give special thanks to the staff which are the true
building blocks of both departments that I have been a part of at Michigan State University:
Darlene, Linda, Sandie, Therese, Rita, and Jodi in Plant, Soil, and Microbial Sciences & Lori,
Sherry, and Joyce in Horticulture. Without these women, both departments would not function
and nothing would ever get done.
This work was supported by: the Michigan Turfgrass Foundation, Michigan Agriculture
Experiment Station, Michigan State University Extension, the Michigan Nursery and Landscape
Association, Aquatrols, Inc. and other grants and gifts.

vii

PREFACE

This dissertation is submitted for the degree of Doctor of Philosophy at Michigan State
University in East Lansing, MI. The research described herein was conducted under the
supervision of Dr. T.A. Nikolai in the Department of Plant, Soil, and Microbial Sciences, Michigan
State University, between September 2009 and December 2014.
This work is to the best of my knowledge original, except where acknowledgements and
references are made to previous work. Neither this nor any substantially similar dissertation
has been submitted for any degree, diploma or qualification at any university.

Rodney V. Tocco Jr.
December 2014

viii

TABLE OF CONTENTS

LIST OF TABLES ........................................................................................................................ x
LIST OF FIGURES .................................................................................................................... xiv
INTRODUCTION ....................................................................................................................... 1
CHAPTER ONE: EFFECTS OF ‘ET’ BASED IRRIGATION, DOUBLE MOWING, AND A WETTING
AGENT ON A ‘CRENSHAW’ Agrostis stolonifera var. palustris (CREEPING BENTGRASS)
PUTTING GREEN PLAYABILITY & QUALITY................................................................................ 7
ABSTRACT .................................................................................................................................................. 7
INTRODUCTION ......................................................................................................................................... 9
MATERIALS & METHODS ......................................................................................................................... 13
RESULTS & DISCUSSION .......................................................................................................................... 16
CONCLUSIONS ......................................................................................................................................... 66

CHAPTER TWO: EFFECTS OF WATERING REGIME, MOWING, AND A WETTING AGENT ON A
‘CRENSHAW’ Agrostis stolonifera var. palustris (CREEPING BENTGRASS) PUTTING GREEN
TOTAL MICROBIAL POPULATION & HYDROPHOBICITY........................................................... 68
ABSTRACT ................................................................................................................................................ 68
INTRODUCTION ....................................................................................................................................... 70
MATERIALS & METHODS ......................................................................................................................... 74
RESULTS & DISCUSSION .......................................................................................................................... 79
CONCLUSIONS ......................................................................................................................................... 91

APPENDICES .......................................................................................................................... 93
APPENDIX A ............................................................................................................................................. 94
APPENDIX B ........................................................................................................................................... 101

LITERATURE CITED ............................................................................................................... 105

ix

LIST OF TABLES

Table 1.1. 2010 main effects and mean squares for treatment effects of irrigation, mowing, and
wetting agent on average ball roll distance in meters at the Hancock Turfgrass Research
Center in East Lansing, MI. .................................................................................................... 19
Table 1.2. 2010 main effects and mean squares for treatment effects of irrigation, mowing, and
wetting agent on average ball roll distance in meters at the Hancock Turfgrass Research
Center in East Lansing, MI. .................................................................................................... 20
Table 2.1. 2011 main effects and mean squares for treatment effects of irrigation, mowing, and
wetting agent on ball roll distance in meters at the Hancock Turfgrass Research Center in
East Lansing, MI. .................................................................................................................... 21
Table 2.2. 2011 main effects and mean squares for treatment effects of irrigation, mowing, and
wetting agent on ball roll distance in meters at the Hancock Turfgrass Research Center in
East Lansing, MI. .................................................................................................................... 22
Table 2.3. 2011 main effects and mean squares for treatment effects of irrigation, mowing, and
wetting agent on ball roll distance in meters at the Hancock Turfgrass Research Center in
East Lansing, MI. .................................................................................................................... 23
Table 3.1. 2012 main effects and mean squares for treatment effects of irrigation, mowing, and
wetting agent on ball roll distance in meters at the Hancock Turfgrass Research Center in
East Lansing, MI. .................................................................................................................... 24
Table 3.2. 2012 main effects and mean squares for treatment effects of irrigation, mowing, and
wetting agent on ball roll distance in meters at the Hancock Turfgrass Research Center in
East Lansing, MI. .................................................................................................................... 25
Table 3.3. 2012 main effects and mean squares for treatment effects of irrigation, mowing, and
wetting agent on ball roll distance in meters at the Hancock Turfgrass Research Center in
East Lansing, MI. .................................................................................................................... 26
Table 4.1. 2011-2012 green speeds (meters) as affected by irrigation and mowing† (MOW) at
the Hancock Turfgrass Research Center in East Lansing, MI. ............................................... 27
Table 4.2. 2011-2012 green speeds (meters) as affected by irrigation and wetting agent† (WA)
at the Hancock Turfgrass Research Center in East Lansing, MI. ........................................... 27

x

Table 5.1. 2010 main effects and mean squares for treatment effects of irrigation, mowing, and
wetting agent on percent volumetric water content (%VWC) at the Hancock Turfgrass
Research Center in East Lansing, MI. .................................................................................... 32
Table 5.2. 2010 main effects and mean squares for treatment effects of irrigation, mowing, and
wetting agent on volumetric water content (%VWC) at the Hancock Turfgrass Research
Center in East Lansing, MI. .................................................................................................... 33
Table 6.1. 2011 main effects and mean squares for treatment effects of irrigation, mowing, and
wetting agent on volumetric water content (%VWC) at the Hancock Turfgrass Research
Center in East Lansing, MI. .................................................................................................... 34
Table 6.2. 2011 main effects and mean squares for treatment effects of irrigation, mowing, and
wetting agent on volumetric water content (%VWC) at the Hancock Turfgrass Research
Center in East Lansing, MI. .................................................................................................... 35
Table 6.3. 2011 main effects and mean squares for treatment effects of irrigation, mowing, and
wetting agent on volumetric water content (%VWC) at the Hancock Turfgrass Research
Center in East Lansing, MI. .................................................................................................... 36
Table 7.1. 2012 main effects and mean squares for treatment effects of irrigation, mowing, and
wetting agent on volumetric water content (%VWC) at the Hancock Turfgrass Research
Center in East Lansing, MI. .................................................................................................... 37
Table 7.2. 2012 main effects and mean squares for treatment effects of irrigation, mowing, and
wetting agent on volumetric water content (%VWC) at the Hancock Turfgrass Research
Center in East Lansing, MI. .................................................................................................... 38
Table 7.3. 2012 main effects and mean squares for treatment effects of irrigation, mowing, and
wetting agent on volumetric water content (%VWC) at the Hancock Turfgrass Research
Center in East Lansing, MI. .................................................................................................... 39
Table 8.1. 2010-2012 percent volumetric water content (%VWC) as affected by irrigation and
wetting agent† (WA) at the Hancock Turfgrass Research Center in East Lansing, MI. ......... 40
Table 8.2. 2012 percent volumetric water content (%VWC) as affected by irrigation and
mowing† (MOW) at the Hancock Turfgrass Research Center in East Lansing, MI. ............... 40
Table 9.1. 2010 main effects and mean squares for treatment effects of irrigation, mowing, and
wetting agent on visual quality (1-9) at the Hancock Turfgrass Research Center in East
Lansing, MI............................................................................................................................. 45
Table 9.2. 2010 main effects and mean squares for treatment effects of irrigation, mowing, and
wetting agent on visual quality (1-9) at the Hancock Turfgrass Research Center in East

xi

Lansing, MI............................................................................................................................. 46
Table 10.1. 2011 main effects and mean squares for treatment effects of irrigation, mowing,
and wetting agent on visual quality (1-9) at the Hancock Turfgrass Research Center in East
Lansing, MI............................................................................................................................. 47
Table 10.2. 2011 main effects and mean squares for treatment effects of irrigation, mowing,
and wetting agent on visual quality (1-9) at the Hancock Turfgrass Research Center in East
Lansing, MI............................................................................................................................. 48
Table 10.3. 2011 main effects and mean squares for treatment effects of irrigation, mowing,
and wetting agent on visual quality (1-9) at the Hancock Turfgrass Research Center in East
Lansing, MI............................................................................................................................. 49
Table 11.1. 2012 main effects and mean squares for treatment effects of irrigation, mowing,
and wetting agent on visual quality (1-9) at the Hancock Turfgrass Research Center in East
Lansing, MI............................................................................................................................. 50
Table 11.2. 2012 main effects and mean squares for treatment effects of irrigation, mowing,
and wetting agent on visual quality (1-9) at the Hancock Turfgrass Research Center in East
Lansing, MI............................................................................................................................. 51
Table 11.3. 2012 main effects and mean squares for treatment effects of irrigation, mowing,
and wetting agent on visual quality (1-9) at the Hancock Turfgrass Research Center in East
Lansing, MI............................................................................................................................. 52
Table 12.1. 2010-2012 visual quality as affected by irrigation and wetting agent† (WA) at the
Hancock Turfgrass Research Center in East Lansing, MI. ...................................................... 53
Table 12.2. 2010-2012 visual quality as affected by irrigation and mowing† (MOW) at the
Hancock Turfgrass Research Center in East Lansing, MI. ...................................................... 54
Table 13. 2010-2011 main effects and mean squares for treatment effects of irrigation, mowing,
and wetting agent on localized dry spot (LDS) observed at the Hancock Turfgrass Research
Center in East Lansing, MI. .................................................................................................... 59
Table 14.1. 2012 main effects and mean squares for treatment effects of irrigation, mowing,
and wetting agent on localized dry spot (LDS) observed at the Hancock Turfgrass Research
Center in East Lansing, MI. .................................................................................................... 60
Table 14.2. 2012 main effects and mean squares for treatment effects of irrigation, mowing,
and wetting agent on localized dry spot (LDS) observed at the Hancock Turfgrass Research
Center in East Lansing, MI. .................................................................................................... 61

xii

Table 15. 2012 localized dry spot (LDS) counts as affected by irrigation and wetting agent† (WA)
at the Hancock Turfgrass Research Center in East Lansing, MI. ........................................... 62
Table 16. 2010-2012 main effects and mean squares for treatment effects of irrigation, mowing,
and wetting agent on total microbial biomass (TMB) in micrograms per gram of soil
obtained by chloroform fumigation incubation method at the Hancock Turfgrass Research
Center in East Lansing, MI. .................................................................................................... 82
Table 17. 2012 average total microbial biomass† (TMB) as affected by irrigation and wetting
agent‡ (WA) at the Hancock Turfgrass Research Center in East Lansing, MI. ...................... 83
Table 18. 2010 main effects and mean squares for treatment effects of irrigation, mowing, and
wetting agent on soil hydrophobicity measured by water drop penetration (WDP) tests at
the Hancock Turfgrass Research Center in East Lansing, MI. ............................................... 86
Table 19. 2011 main effects and mean squares for treatment effects of irrigation, mowing, and
wetting agent on soil hydrophobicity measured by water drop penetration (WDP) tests at
the Hancock Turfgrass Research Center in East Lansing, MI. ............................................... 87
Table 20. 2012 main effects and mean squares for treatment effects of irrigation, mowing, and
wetting agent on soil hydrophobicity measured by water drop penetration (WDP) tests at
the Hancock Turfgrass Research Center in East Lansing, MI. ............................................... 88
Table 21. 2012 hydrophobicity determined by water drop penetration† (WDP) tests as affected
by irrigation and wetting agent‡ (WA) at the Hancock Turfgrass Research Center in East
Lansing, MI............................................................................................................................. 89
Table 22. Seasonal weather data (May-October) summary for ‘Crenshaw’ native soil putting
green at the Hancock Turfgrass Research Center in East Lansing, MI, in 2010-2012. .......... 94

xiii

LIST OF FIGURES

Figure 1. Irrigation effects on ball roll distance in 2010-12. Values are averages of mowing and
wetting agent for each irrigation treatment. Error bars represent least significant difference
(LSD) using Fisher’s Protected Method. Overlapping error bars represent statistically similar
treatments at α=0.05. N=18. ................................................................................................. 28
Figure 2. Mowing effects on ball roll distance from 2010-12. Values are averages of irrigation
and wetting agent for each mowing treatment. Error bars represent least significant
difference (LSD) using Fisher’s Protected Method. Overlapping error bars represent
statistically similar treatments at α=0.05. N=18. .................................................................. 29
Figure 3. Irrigation Effects on percent volumetric water content (%VWC) in 2010-12. Values are
averages of mowing and wetting agent for each irrigation treatment. Error bars represent
least significant difference (LSD) using Fisher’s Protected Method. Overlapping error bars
represent statistically similar treatments at α=0.05. N=15. ................................................. 41
Figure 4. Irrigation Effects on Visual Quality in 2010-12. Values are averages of mowing and
wetting agent for each irrigation treatment. Error bars represent least significant difference
(LSD) using Fisher’s Protected Method. Overlapping error bars represent statistically similar
treatments at α=0.05. N=3. ................................................................................................... 55
Figure 5. Mowing effects on visual quality 2010-12. Values are averaged over irrigation and
wetting agent for each mowing treatment. Error bars represent least significant difference
(LSD) using Fisher’s Protected Method. Overlapping error bars represent statistically similar
treatments at α=0.05. N=3. ................................................................................................... 56
Figure 6. Irrigation (A) and Revolution® (B) effects on Localized Dry Spot (LDS) occurrence in
2010-12. (A) graph values are averaged over mowing and wetting agent for each irrigation
treatment. (B) graph values are averaged over irrigation and mowing for each wetting
agent treatment. Error bars represent least significant difference (LSD) using Fisher’s
Protected Method. Overlapping error bars represent statistically similar treatments at
α=0.05. N=12. (NS = not significant)...................................................................................... 63
Figure 7. Irrigation and Revolution® interaction and effects on localized dry spot (LDS) in 2012.
Values are averaged over treatments. Error bars represent least significant difference (LSD)
using Fisher’s Protected Method. Overlapping error bars represent statistically similar
treatments at α=0.05. N=3. ................................................................................................... 64
Figure 8. Irrigation effects on total microbial biomass (TMB) in 2010-2012. Values are averaged
over treatments. Error bars represent least significant difference (LSD) using Fisher’s

xiv

Protected Method. Overlapping error bars represent statistically similar treatments at
α=0.05. N=9 ........................................................................................................................... 84
Figure 9. Revolution® effects on water drop penetration (WDP) tests in 2010-2012. Values are
averaged over treatments. Error bars represent least significant difference (LSD) using
Fisher’s Protected Method. Overlapping error bars represent statistically similar
treatments at α=0.05. N=9 .................................................................................................... 90
Figure 10. Sixty-five foot above plot overhead image portraying turfgrass quality between
treatments at the lowest irrigation regime in NE block of daily 30% evapotranspiration (ET)
replenishment. 29 June 2012 (first week of summer dry-down)....................................... 101
Figure 11. Sixty-five foot above plot overhead image portraying turfgrass quality between
treatments at the lowest irrigation regime in NE block of daily 30% evapotranspiration (ET)
replenishment. 11 July 2012 (second week of summer dry-down). .................................. 102
Figure 12. Sixty-five foot above plot overhead image portraying turfgrass quality between
treatments at the lowest irrigation regime in NE block of daily 30% evapotranspiration (ET)
replenishment. 20 July 2012 (third week of summer dry-down)....................................... 103
Figure 13. Sixty-five foot above plot overhead image portraying turfgrass quality between
treatments at the lowest irrigation regime in NE block of daily 30% evapotranspiration (ET)
replenishment. 1 August 2012 (fourth week of summer dry-down). ................................ 104

xv

INTRODUCTION
Public concerns of water use led to ‘Michigan’s Water Use Reporting Program’, initially
mandated by Public Act (P.A.) 148 of 2003. This act is now Part 327, Great Lakes Preservation,
of the Natural Resources and Environmental Protection Act, 1994 P.A. 451, as amended.
Industries with the capacity to withdraw over 100,000 gallons per day (70 gallons per minute)
are required to report to the state the water withdrawals and water conservation practices of
their pumps, which applies to most Michigan golf courses. Irrigation is defined as water
withdrawn and artificially applied on lands to assist in the growing of crops, pastures or in the
maintenance of recreational lands such as golf courses and parks. Irrigation is responsible for
3% of total water use in Michigan (Water Use Report, 2006), and irrigation on golf courses is
often viewed negatively even though it is a small portion of total irrigation. In 2006, 619
registered Michigan golf courses were involved with the ‘Water Use Reporting Program’. Due to
varying soils, turfgrass species, management practices, and micro-environments, this program
did not establish baseline irrigation levels for golf courses in Michigan.
Proper watering of golf course putting greens has been debated since their inception.
The amount of water and frequency of application depend on weather and on the physical
properties of the soil including drainage (USGA Green Section Staff, 1922). Each green has
unique requirements that are dictated by grass species, soils and microclimates. Putting this all
together makes proper turfgrass irrigation the most difficult day-to-day agronomic decision a
golf course superintendent makes (Beard, 2001). Deciding when and how much water to use is
a delicate problem, especially on bentgrass, which suffers frequently from being too wet or too
dry (Engel, 1982).

1

To ensure sustainability, people must have conservation awareness, and continue to be
efficient and wise when using water resources (Norman, 2009). Stewardship of water quantity
means using water as efficiently as possible while providing for the crop/landscape water needs
(MDA GAAMP’s, 2010). Ideally, irrigation regimes should be based on scientific principles and
research; however, in most instances, intuition and experience are used to replenish water
through irrigation. Technological advances such as potential evapotranspiration and time
domain reflectometry measuring devices are available, but their effective application requires
research.
Summer decline of creeping bentgrass (Agrostis stolonifera L.) putting greens is a
common problem attributed to environmental and mechanical stresses (Dernoeden, 2002; Fry
and Huang, 2004). Excessive watering is thought to not only increase costs associated with
water consumption, but also to reduce environmental stress tolerance, predisposing turf to
injury from mechanical stresses, cyanobacteria, moss, and disease (Beard, 1973; Dernoeden,
2002; Turgeon, 2008). Superintendents often use daily irrigation combined with hand watering
and syringing practices when managing creeping bentgrass in the summer (Fu and Dernoeden,
2009). Optimal water supply is crucial to growing turfgrass, but has for a long time been
determined by experience and “feel” due to a lack of soil science fundamentals combined with
simple and reliable soil moisture measurement devices.
Public acts in the state of Michigan recommend evapotranspiration (ET) technology,
stating that the amount of irrigation water to apply generally should be equal to the total ET
since the last irrigation, minus any precipitation that occurred during the period (MDA
GAAMP’s, 2010). ET is the loss of water from the soil by evaporation and from the plants by

2

transpiration (Beard, 1973). As much as 80 to 85% of the soil moisture depletion can be
attributed to ET (Anonymous, 1933). Remaining plant-available soil moisture is dependent on
retention and transmittance properties of the soil. To create putting green watering schedules
based on ET, data are required to validate irrigation amounts at individual sites.
Water replenishment on turfgrass is most often estimated by an individual’s experience
at a site. Two contrasting irrigation methodologies known as deep and infrequent (DI) or light
and frequent (LF) are practiced with the merits of both debated for decades. It is accepted that
optimum irrigation frequency varies with plant species, climatic conditions, and soil types
(Pessarakli, 2008). In general, DI irrigation is applied at leaf wilting point, whereas LF involves
maintaining soil at field capacity (Fry and Huang, 2004). DI irrigation of creeping bentgrass at 4day intervals showed significantly increased turf quality compared with irrigation every 1 or 2
days on a USGA-type root zone mixture (Jordan et al., 2003). However, studies involving fairway
height creeping, colonial, and velvet bentgrass varieties reported significant decreases in
turfgrass quality when maintained in deficit irrigation 60% ET versus 100% ET replenishment
three times per week in North Brunswick, NJ, however, 100%ET was found not necessary to
sustain plant growth (DaCosta and Huang, 2006). Some research across multiple root zones has
shown that moderate drought stress, incurred by ET based irrigation, does not significantly
affect summer performance of turfgrasses (Gibeault et al., 1985; Jordan et al., 2003; Fu et al.,
2004; DaCosta and Huang, 2006). Gibeault et al. (1985) showed that the quality of turf irrigated
at 80% ET was not significantly reduced compared to that irrigated at 100% ET. Fu et al. (2004)
on silt loam soil reported achieving the same turf quality at 60 or 80% ET compared to wellwatered turfgrass. DaCosta and Huang (2006) also showed an increase in irrigation to 80% of ET

3

in three bentgrass cultivars on sandy loam soil had similar or higher quality than turf replaced
with 100% ET. Minor differences in results may be attributable to soil types, mowing heights,
micro-environments, and cultivar differences. Results from these studies indicate that water
replenishment up to 100% ET is not necessary, and may also be detrimental to the health of a
putting green.
Conversely, it is believed that minimizing irrigation on putting surfaces creates
significantly longer ball roll distance or green speed (Rist and Gaussoin, 1997). Considering
public concerns over water use, conflicting results from past irrigation studies, and the methods
turfgrass managers use to estimate irrigation, there is a need for research on light and frequent
ET-based irrigation on Michigan putting greens over subsequent seasons.
Double mowing influences turfgrass physiology and disease. Double mowing has
negative physiological effects on turfgrass water use rate (Beard, 1973). A reduction in the leaf
area causes a decrease in total transpiration rate per plant, but the water loss rate per unit of
leaf area actually increases (Beard, 1973). Research on double mowing effects on creeping
bentgrass diseases, has brought contradicting results. Double mowing can increase severity of
diseases such as basal rot anthracnose by creating greater mechanical abrasion wounds
allowing the pathogen to enter the plant more readily, especially with mowing heights below
0.4 cm (0.156 inch) (Rimelspach and Boehm, 2006). However, double mowing at 0.36 cm
(0.140 in) and rolling, to duplicate green speeds achieved by a lower mowing height at 0.28 cm
(0.110 in), has led to less severe incidences of anthracnose (Rossi, 2008). Despite negative
physiological and disease effects, double mowing is the primary mechanical practice for
increased ball roll distance.

4

Playability is often determined by visual quality (aesthetics) and ball roll distance
(Moeller, 2013). Both are ways to assess leaf growth habit and smoothness (playability). No
consistently accurate quantitative method measuring turfgrass visual quality has been
perfected. However, ball roll distance can be quantitatively measured using a Stimpmeter
(Thomas, 2001), developed by Edward Stimpson, Sr., 1935 or a Pelz Meter (Pelz et al., 2002).
Either tool creates a repeatable incline plane, on which gravity acts to force a golf ball to roll
down and then across the turfgrass surface for a measure of speed. “Putting green speed” or
“speed” is a term commonly used to describe playability as a condition of the putting surface
related to ball roll distance (Throssel, 1981). The distance a ball travels on the putting surface
after rolling down the incline is measured and reported in feet (USGA, 2004). A 3-day study
showed that double mowing significantly increased ball roll distance (Throssel, 1981).
However, a 5-week study showed that reducing mowing frequency to 3 times per week
combined with rolling on alternate days of mowing significantly increased putting green speed
(Nikolai, 2005). Double mowing alone, or in combination with a groomer, also significantly
increased ball roll distance (Danneberger et al., 1988), but Stahnke and Beard (1981) found that
double mowing resulted in a slight decrease in ball roll distance in three of five tests.
Considering that most previous studies were short-term and resulted in mixed results it is
apparent that a long-term double mowing study may contribute to our understanding the
mechanical practice has on turfgrass disease, localized dry spot, irrigation use, and playability.
Double mowing stress and reduced irrigation quantity may lead to localized dry spots
(LDS) (Beard, 1973; Karnok, 2003). LDS are irregularly shaped areas of wilted or dead turfgrass
(Tucker, et. al., 1990). Soil surfactant or wetting agent, which refers to a canopy-applied

5

nonionic chemical surfactant designed to wet the soil profile are often used to alleviate LDS
(Zontek and Kostka, 2012). Wetting agents are a common and effective management tool for
conserving water, combating LDS, and reducing sodium build up in putting greens (Mitra, S., et
al., 2004; Danneberger, 2008.; Gelernter & Stowell, 1997; Throssel, 2006.). Wetting agents are
used to avoid or alleviate soil water repellency and/or reduce the surface tension of water to
uniformly wet the soil rootzone, increasing infiltration rate (Anonymous, 2011). Even with these
considerations, few publications exist evaluating the efficacy of wetting agents on LDS in
temperate climates (Lyons, et. al., 2009). Non-ionic wetting agents are the most widely used
because of their efficacy and general safety on turfgrass. The products attach to hydrophobic
soil particle coatings with a non-polar end, and provide a polar site for water to re-coat areas
improving water distribution (Karnok, K. et. al., 2004). It is hypothesized that with proper
irrigation and application of a wetting agent, daily double mowing to increase playability is
plausible without detrimental effects to turfgrass physiology.
Specific objectives of this research were to evaluate combinations of ET-based irrigation,
daily double mowing, and a wetting agent applied at label rate and frequency. It was
hypothesized that turfgrass quality would be maintained with the correct combination of
irrigation level, mowing, and wetting agent. It was hypothesized that percent organic matter
and microbial biomass would significantly increase in irrigated plots as water inputs increased.
WDPT were hypothesized to show no differences in soil hydrophobicity with application of the
wetting agent.

6

CHAPTER ONE:
EFFECTS OF ‘ET’ BASED IRRIGATION, DOUBLE MOWING, AND A WETTING AGENT ON A
‘CRENSHAW’ Agrostis stolonifera var. palustris (CREEPING BENTGRASS)
PUTTING GREEN PLAYABILITY & QUALITY
ABSTRACT
Proper watering of creeping bentgrass (Agrostis stolonifera var. palustris) golf course
putting greens has been debated since their inception. The amount of water and frequency of
application depend upon the weather and in a large part upon the soil type and drainage (USGA
Green Section Staff, 1922). Increased public concern of water use has led to “Michigan’s Water
Use Reporting Program”. Irrigation on golf courses is only a portion of total state water use, but
often has a negative connotation in the public eye. State of Michigan legislation is embracing
evapotranspiration (ET) technology, and recommends the amount of irrigation water needed
generally is equal to the total ET since the last irrigation minus any precipitation that occurred
during the period. ET is the loss of water from the soil by evaporation and by transpiration from
the plants. This research follows state-suggested daily ET regimes, but addresses the Michigan
Water Use reports not establishing baseline irrigation levels for golf course putting greens in
Michigan. ET-based irrigation is hypothesized to be an effective water conservation solution.
Double mowing influences turfgrass physiology and disease. Double mowing has negative
physiological effects on turfgrass water use rate. Research results on double mowing effects on
creeping bentgrass over long periods of time are contradictory.

7

Double mowing is practiced solely because it enhances playability through increased
speed. Putting green speed is a term commonly used to describe playability in terms of ball roll
distance. The distance a ball travels on the putting surface after rolling down an incline is
measured and reported in terms of feet. Previous research results are mixed and have not
evaluated the impact of long-term daily double mowing on the plant and soil. This research
analyzes the effects of season-long daily double mowing over three-years. With proper
irrigation and application of a wetting agent, daily double mowing was hypothesized to increase
playability without detrimental effects to turfgrass physiology.
Wetting agent refers to a canopy-applied nonionic chemical surfactant intended to
increase the amount of plant available water in a soil profile. Wetting agents are widely used to
help re-wet or prevent an area known to be hydrophobic. Hydrophobicity occurs when soil
particles are coated in microbial-produced ‘humic’ acid films, which prevent water adsorption.
Wetting agents reduce the hydrophobicity of soil particles and restore soil structure by reestablishing a healthy water and air continuum. Repeated use produces good soil structure by
creation of a surface on the hydrophobic soil particle for water to reattach. Often organic
matter and clays can slow infiltration of previously open pores between larger soil particles.
Water is proposed to be distributed more evenly throughout the soil profile by wetting agents,
in essence becoming more plant available (Kostka, 2000). Research is limited on the
interactions between wetting agents, irrigation regimes, and double mowing over multiple
years. The effects of long term usage on potential water conservation, while retaining turfgrass
quality and playability at acceptable levels were evaluated.

8

INTRODUCTION
Proper watering for golf course putting greens has been debated since their inception,
and for turfgrass managers, irrigation is the most important daily decision (Beard, 1973).
Deciding when and how much water to use is a delicate problem, especially on bentgrass that
suffers frequently from being too wet or too dry (Engel, 1982). The amount of water and
frequency of application depend upon the weather and in a large part upon the character of
the soil and drainage. Increased public awareness of water use has led to “Michigan’s Water
Use Reporting Program” (Water Withdrawal Reports, 2006). Irrigation on golf courses is only a
portion of total state water use, but often has a negative connotation in the public eye.
The Michigan Department of Environmental Quality (MI DEQ) Water Reports estimates
that 3% of Michigan total water usage is attributed to irrigation, some of which is attributed to
the previously mentioned registered Michigan golf courses (Water Reports, 2006). In 2003, the
Michigan Department of Agriculture (MDA) passed the irrigation water-use reporting program
into law via Public Act 148, which contains Generally Accepted Agricultural and Management
Practices (GAAMPs). The 2010 update of the GAAMPs states that stewardship of water quantity
means using water as efficiently as possible while providing for the crop or landscape water
needs (MDA GAAMPs, 2010). The current Michigan recommendation states “The amount of
irrigation water to apply is generally equal to the total evapotranspiration (ET) since the last
irrigation minus any precipitation that occurred during that period” (MDA GAAMPs, 2010).
While well intentioned by not being overly restricted, this level of replenishment has not been
evaluated for creeping bentgrass, and in some instances may lead to over-irrigated turfgrass.
Over-irrigation can lead to numerous turfgrass problems, including infestations of weeds,

9

diseases and algae, ball marks, and foot-printing (Moeller, 2013). Evaluation of the varying
levels of irrigation used in this study will be beneficial for Michigan golf courses by providing
insights into the impact irrigation has on the putting surface and underlying root zone.
State of Michigan legislation (Public Act 148 of 2003, now Part 327 of P.A. 451 of 1994)
is embracing evapotranspiration (ET) technology, and suggests the amount of irrigation water
needed generally is equal to the total ET since the last irrigation minus any precipitation that
occurred during the period. ET is the loss of water from the soil by evaporation and by
transpiration from the plants (Beard, 1973). ET-based irrigation is hypothesized to be an
effective water conservation solution, however, this only holds true with an understanding of
the factors used to determine ET. In turfgrass cropping systems ET is at best an “estimate” in
regard to water replenishment via irrigation. An objective of this research is to demonstrate
that using 100% ET may be wasteful in terms of sustainability, and may also have a negative
impact on plant physiology and the playing surface. In contrast, it is believed that withholding
irrigation to lower ET increases ball roll distance, however, we hypothesize this premise is only
true if irrigation is withheld to the point of wilt or localized dry spot (LDS) formation. If LDS is
allowed to form, the putting surface is put into jeopardy and turfgrass manager’s employment
is in jeopardy.
Double mowing putting greens are common practice during tournament play for
increasing ball roll distance, but long-term application is often relinquished due to known
negative physiological plant stresses and mower wear (Beard, 2005; Blais, 2002; Sweeney et.
al., 2000). The term putting green speed is commonly used to describe the distance a ball
travels on the putting surface after rolling down an incline, and is measured and reported in

10

terms of feet (USGA, 2004). Previous studies, the longest five weeks in duration, show mixed
results and have not looked at long-term daily double mowing regimes (Danneberger et al.,
1988; Nikolai, 2005; Stahnke and Beard, 1981; Throssel, 1981). Double mowing cultural
practices are hypothesized to influence turfgrass physiology and disease, and are believed to
have negative physiological effects on turfgrass water use rate (Beard, 1973 and Karnok, 2003).
However, research results of double mowing effects on creeping bentgrass are contradictory.
This research analyzes the effects of season-long daily double mowing over a three-year
duration. With proper irrigation and/or application of a wetting agent, daily double mowing is
hypothesized to increase ball roll distance without detrimental effects to turfgrass physiology.
Wetting agent refers to a canopy-applied nonionic chemical surfactant intended to
retain moisture in the soil profile. Wetting agents are widely used to help wet an area known to
be hydrophobic. Hydrophobicity occurs when soil particles are coated in microbial-produced
humic acid films, which prevent water adsorption (Bond, 1968; Bond and Harris, 1964; Savage,
1969). Wetting agents reduce the hydrophobicity of soil particles and restore soil structure by
re-establishing a water and air continuum. Repeated use produces good soil structure by
creation of a surface on the hydrophobic soil particle for water to reattach. Organic matter and
clays may slow infiltration of previously open pores between larger soil particles. Companies
propose water is distributed more evenly throughout the soil profile by wetting agents, in
essence becoming more plant available (Kostka, 2000). Research is limited on the interactions
among wetting agents, irrigation regimes, and mowing frequencies for potential in conserving
water over multiple years.

11

An objective of this study was to determine if irrigation volume could be decreased and
turfgrass aesthetics and playability retained with the use of daily ET replenishment combined
with a soil surfactant under two mowing regimes. Combining management practices of daily ET
irrigation, double mowing, and use of a wetting agent may reduce irrigation inputs while
maintaining turfgrass quality and ball roll distance.

12

MATERIALS & METHODS
Research was conducted at the Hancock Turfgrass Research Center (HTRC) at Michigan
State University in East Lansing, Michigan, on a 1296-m2 (36 x 36 m) owosso-marlette sandy
loam native soil experimental putting green, seeded with creeping bentgrass (Agrostis
stolonifera var. palustris) ‘Crenshaw’ in 2003. The area comprises nine 148-m2 (12 x 12 m) plots.
In each plot Hunter PGP™ (Hunter Industries Inc., San Marcos, CA USA) irrigation heads were
installed on each corner. The nine plots were arranged in a randomized complete block design
with three replications of main plot evapotranspiration (ET) replenishment levels (30,60, and
90% daily ET). Daily ET data were determined by the onsite Enviro-weather station (East Lansing
/ MSUHTRC) of the Michigan Agricultural Weather Network (MAWN). Each irrigation plot
contained four 2.1 m by 9.8 m (20.6-m2) sub-plots. Sub-plot treatments consisted of daily single
mowing double mowing treatments with and without a wetting agent treatment.
From May to October daily irrigation replenishment at 30%, 60%, and 90%
evapotranspiration (ET) were applied. The system utilized the Penman-Monteith equation to
estimate potential ET (Penman, 1948; Monteith, 1965). Applicable rainfall was subtracted from
ET to determine the overall daily replenishment for each treatment per current Michigan
Department of Agriculture (MDA) recommendations (MDA GAAMP’s, 2010). Project technology
provided by Spartan Distributors (Sparta, MI) included a TORO Site Pro ‘Central’ computer
control center running software v. 2.2 (1996-2006 TORO Irrigation Division, Bloomington, MN
USA) and TORO NSN Connect© (The Toro Company, Bloomington, MN USA) computer software
controls daily irrigation levels from an onsite computer and remotely via an iPhone 4© (Apple,
Inc., Cupertino, CA USA) application. Irrigation audits were conducted throughout each of the

13

growing seasons to ensure distribution of uniformity of 0.7 or greater and obtain data for
scheduling accurate run-times (Leinauer and Smeal, 2012). Audits were conducted by placing
six AcuRite™ Magnifying Rain Gauge 00850 (Chaney Instrument Company, Lake Geneva, WI
USA) within each plot for three separate full-turns of the irrigation heads. Water amounts were
averaged, and run-times adjusted accordingly.
The area was mowed six days per week with a Toro 1000 (The Toro Company,
Bloomington, MN USA) greens mower at a bench setting height of 0.125 in (0.3175 cm).
Mowing treatment sub-plots within each plot were double-mowed daily. The second cut
immediately followed the initial cut always in a different direction. The entire area was lightly
topdressed with sand weekly throughout the growing season and was rolled three days per
week with a DMI Speed Roller (DMI/IPAC Group, Amherst, NY) throughout the growing season
to simulate golf course putting green management practices. With the exception of
preventative Sclerotinia homeocarpa (Dollar spot) treatments, pesticides were applied on a
curative basis to allow disease, insect, and weed observations. To prevent total loss of the
highly susceptible ‘Crenshaw’ creeping bentgrass putting green, the fungicides chlorothalonil
(Bravo Weather Stik, Syngenta) and propiconazole (Banner MAXX, Syngenta) were applied to
preventatively control Sclerotinia homeocarpa throughout 2011 and 2012. Treatments that
warranted a monthly application of a wetting agent (Revolution®, Aquatrols, Paulsboro, NJ USA)
were applied at the labeled rate of 168 mL/ 90 m2 (6 oz/ 1000 ft2) from May-October.
Qualitative visual ratings were taken as described by the National Turfgrass Evaluation
Program (NTEP) based on a 1 to 9 scale (Morris and Shearman, 2005). At the same time soil
moisture measurements were obtained with time domain reflectometry (TDR) with a

14

FieldScout TDR 300 Soil Moisture Meter (Spectrum Technologies, Plainfield, IL) at the 3.8 cm
tine depth. On the same day, ball roll distance was measured with a Pelz-meter (Pelz Golf,
Spicewood, TX). The same investigator took all visual ratings for the duration of the study. In
the fall of each year, soil samples were obtained with a 2.54 cm diameter probe to monitor
percent organic matter content (OM). OM content was determined by loss on ignition
(Hummel, 1993). Additional data collected from these plots included pest and localized dry spot
counts.
All statistical analysis was performed in SAS v. 9.3 (SAS institute, Inc., Cary, NC) using
Proc Gli-Mix Procedure. The model statement for each response variable analyzed all main
factors evaluated and all possible interactions with the main treatment factors. All data analysis
utilized mean separation conducted at alpha = 0.05. All data were analyzed separately within
years, because the number of ratings/sampling dates varied each year in addition to time frame
between dates. All parameters included the random term Replication*Irrigation Level*Mowing
Frequency*Wetting Agent. Evaluations for the entire study area on a single day were pooled if
there was not a significant interaction. All parameters in this study were analyzed in this
manner. Variables were additionally analyzed/imported into ARM v. 8.3.4© (Gylling Data
Management 1982-2011, Brookings, SD) and/or GraphPad Prism (GraphPad Software, Inc., La
Jolla, CA) for visual figure development.

15

RESULTS & DISCUSSION
Data for ball roll distance, %VWC, and visual quality were collected 43 times between
May 2010 and August 2012. Plots were rated 12 times from 19 July to 6 Oct., 2010; 16 times
from 9 May to 29 Aug., 2011; 15 times from 8 May to 22 Aug., 2012. Time between collections
were weekly with an average of seven +/- two days. Consideration for correlation in data was
made by all collections occurring on the same day within a two-hour time frame.
Total irrigation amounts applied each day were calculated based on weather data
(Appendix A) from approximately May to October each season. In 2010, total daily irrigation
applied for 30, 60, and 90% ET were 11.25, 22.63, and 33.91 cm, respectively. In 2011, total
daily irrigation applied for 30, 60, and 90% ET were 15.44, 30.63, and 46.05 cm, respectively. In
2012, total daily irrigation applied for 30, 60, and 90% ET were 17.27, 34.29, and 51.56 cm,
respectively.
Karcher et. al. (2001) found there was no significant difference in golfer green speed
perception within six inches of one another. Irrigation level is often scrutinized for potential
effects on ball roll distance. Analysis of variance means for each date of ball roll distance as
affected by irrigation are shown in Tables 1.1 through 3.3. Interactions, if observed, are shown
in Tables 4.1 and 4.2.
On one date in 2010, one date in 2011, and two dates in 2012, irrigation had a
significant effect on ball roll distance (Tables 1.1 to 3.3). However, on all other dates from 2010
to 2012, the response to irrigation effects on ball roll distance were not significant. This
suggests no significant differences in irrigation replenishment to 30, 60, and 90% ET effects on
ball roll distance. Overall, average ball roll distance showed no significant differences between

16

30, 60, and 90% ET irrigation treatments (P=0.0756). Year significantly affected average ball roll
distance (P<0.0001). The year difference is attributed to progression in application of
treatments over time. 2010 was the year of experiment inception, whereas 2012 presented the
culmination of three successive years of treatments. 2011 was average for results in
comparison to 2010 and 2012, which is represented in observed ball roll distances.
Daily values shown in Figure 1 are averages of mowing and wetting agent for each
irrigation treatment, and show the trend effects of irrigation on ball roll distance over each
season.
Double mowing significantly increased ball roll distance for nearly all dates for the
duration of the study. Analysis of variance means for each date of ball roll distance as affected
by mowing are shown in Tables 1.1 through 3.3. Interactions, if observed, are shown in Table
4.1.
In 2010-2012, average ball roll distance showed significant increases when daily double
(2X) mowing versus traditional single daily (1X) mowing (P<0.0001). Year significantly affected
average ball roll distance (P<0.0001), with a steady increase in speeds as the study progressed.
The year difference is most likely attributed to the management of the plots over time. An
interaction between mowing and year was observed to be significant (P<0.0001), suggesting
that mowing may not be the sole factor attributing to ball roll distance increases (Table 4.1).
Daily values shown in Figure 2 are averages of irrigation and wetting agent for each
mowing treatment, and show the trend effects of mowing on ball roll distance over each
season. Figure 2 emphasizes playability as determined by ball roll distance was effected
frequently with daily double mowing, and suggests significant increases would continue.

17

Wetting agent had effect on ball roll distance on one, two, and one date(s) in 2010-12,
respectively. Analysis of variance means for each date of ball roll distance as affected by
wetting agent are shown in Tables 1.1 through 3.3. Interactions, if observed, are shown in Table
4.2.
In 2010-2012, average ball roll distance showed no significant differences between
untreated and wetting agent treatments (P=0.9460). Year significantly affected average ball roll
distance (P<0.0001). The year difference is most likely attributed to management over time.
Daily or overall seasonal averages of ball roll distance did not differ with application of wetting
agent. Ball roll distances are maintained in creeping bentgrass putting greens with long-term
use of wetting agent.

18

Table 1.1. 2010 main effects and mean squares for treatment effects of irrigation, mowing, and wetting agent on average ball roll
distance in meters at the Hancock Turfgrass Research Center in East Lansing, MI.

Irrigation (IRR)
30% ET
60% ET
90% ET
Significance
LSD (0.05)
Mowing (MOW)
1X daily
2X daily
Significance
LSD (0.05)
Wet-Agent (WA)
Untreated
1X monthly
Significance
LSD (0.05)

19 July
2.06
2.08
2.05
NS
NS

27 July
1.94
1.94
1.93
NS
NS

2.00b
2.12a
***
0.05

2.02a
1.85b
***
0.06

2.07
2.06
NS
NS

1.96
1.91
NS
NS

Average Ball Roll Distance in Meters
2010
3 Aug
10 Aug
2.39
2.45
2.39
2.43
2.71
2.37
NS
NS
NS
NS
2.31
2.68
NS
NS
2.61
2.39
NS
NS
Mean Square and Pr>F

16 Aug
2.50
2.42
2.42
NS
NS

23 Aug
2.42
2.46
2.41
NS
NS

2.35b
2.49a
***
0.05

2.39b
2.51a
*
0.11

2.34b
2.52a
***
0.08

2.45a
2.39b
*
0.05

2.45
2.44
NS
NS

2.44
2.42
NS
NS

Source
df
Replication
2
0.34
0.1678
2.18
0.0029
15.46
0.4503
0.73
0.0407
IRR
2
0.12
0.2611
0.04
0.7570
16.21
0.4640
0.80
0.3170
Error for IRR
4
0.06
0.8384
0.12
0.7595
17.31
0.4666
0.52
0.0630
MOW
1
5.89
<.0001
10.26
<.0001
45.94
0.1329
6.37
<.0001
WA
1
0.02
0.7105
0.67
0.1300
15.77
0.3686
1.40
0.0144
IRRxMOW
2
0.08
0.6263
0.09
0.7107
17.83
0.4011
0.03
0.8665
IRRxWA
2
0.05
0.7663
0.55
0.1541
19.52
0.3694
0.39
0.1598
MOWxWA
1
0.02
0.7653
0.12
0.5021
18.97
0.3251
0.04
0.6644
IRRxMOWxWA
2
0.16
0.4196
0.13
0.6143
21.63
0.3338
0.54
0.0841
Error
18
0.17
0.27
18.54
0.19
*, **, *** Significant at the 0.05, 0.01, and 0.001 probability levels, respectively.
† NS, non-significant at the 0.05 level.
‡ Within columns, means followed by the same letter are not significantly different according to LSD (0.05).

19

0.28
0.93
0.70
5.33
0.06
0.54
0.03
0.10
0.46
1.00

0.7554
0.3610
0.6036
0.0335
0.8158
0.5920
0.9736
0.7530
0.6423

0.07
0.35
0.06
10.57
0.29
0.00
0.36
0.00
0.45
0.49

0.8699
0.0731
0.9689
0.0002
0.4497
0.9987
0.4945
0.9039
0.4150

Table 1.2. 2010 main effects and mean squares for treatment effects of irrigation, mowing, and wetting agent on average ball roll
distance in meters at the Hancock Turfgrass Research Center in East Lansing, MI.

Irrigation (IRR)
30% ET
60% ET
90% ET
Significance
LSD (0.05)
Mowing (MOW)
1X daily
2X daily
Significance
LSD (0.05)
Wet-Agent (WA)
Untreated
1X monthly
Significance
LSD (0.05)

31 August
2.44
2.38
2.35
NS
NS

7 Sept
2.27a
2.18b
2.11c
*
0.11

2.27b
2.50a
***
0.04

2.09b
2.28a
***
0.06

2.39
2.38
NS
NS

2.19
2.19
NS
NS

Average Ball Roll Distance in Meters
2010
14 Sept
20 Sept
2.21
2.17
2.12
2.13
2.14
2.09
NS
NS
NS
NS
2.08b
2.24a
***
0.05
2.19a
2.13b
*
0.05
Mean Square and Pr>F

29 Sept
2.32
2.25
2.27
NS
NS

6 Oct
2.16
2.14
2.11
NS
NS

2.06b
2.21a
***
0.06

2.14a
2.42b
***
0.05

2.09b
2.17a
**
0.05

2.15
2.12
NS
NS

2.28
2.28
NS
NS

2.16a
2.11b
*
0.05

Source
df
Replication
2
0.43
0.0923
2.48
0.0023
0.05
0.7602
0.20
0.5224
IRR
2
1.01
0.1477
2.80
0.0483
0.98
0.2860
0.65
0.2100
Error for IRR
4
0.31
0.1392
0.39
0.2786
0.57
0.0439
0.27
0.4689
MOW
1
18.54
<.0001
12.03
<.0001
8.51
<.0001
7.77
<.0001
WA
1
0.08
0.4810
0.00
0.9644
1.15
0.0230
0.36
0.2861
IRRxMOW
2
0.15
0.4111
0.18
0.5346
0.56
0.0743
0.02
0.9202
IRRxWA
2
0.04
0.7611
0.35
0.3123
0.01
0.9269
0.13
0.6442
MOWxWA
1
0.16
0.3261
0.03
0.7408
0.00
0.9048
0.03
0.7575
IRRxMOWxWA
2
0.04
0.7930
0.19
0.5303
0.35
0.1802
0.42
0.2658
Error
18
0.16
0.28
0.18
0.29
*, **, *** Significant at the 0.05, 0.01, and 0.001 probability levels, respectively.
† NS, non-significant at the 0.05 level.
‡ Within columns, means followed by the same letter are not significantly different according to LSD (0.05).

20

0.34
0.71
0.65
26.78
0.00
0.17
0.40
0.03
0.24
0.19

0.2048
0.4171
0.0335
<.0001
0.9683
0.4296
0.1597
0.7233
0.3174

0.11
0.31
0.32
2.34
1.03
0.08
0.11
0.39
0.07
0.22

0.6094
0.4504
0.2702
0.0047
0.0457
0.7114
0.6173
0.2055
0.7237

Table 2.1. 2011 main effects and mean squares for treatment effects of irrigation, mowing, and wetting agent on ball roll distance in
meters at the Hancock Turfgrass Research Center in East Lansing, MI.

Irrigation (IRR)
30% ET
60% ET
90% ET
Significance
LSD (0.05)
Mowing (MOW)
1X daily
2X daily
Significance
LSD (0.05)
Wet-Agent (WA)
Untreated
1X monthly
Significance
LSD (0.05)

9 May
2.70
2.56
2.72
NS
NS

Average Ball Roll Distance in Meters
2011
23 May
1 June
6 June
2.34
2.72
2.94
2.27
2.69
2.98
2.33
2.65
3.00
NS
NS
NS
NS
NS
NS

14 June
2.62
2.67
2.68
NS
NS

21 June
2.45
2.46
2.55
NS
NS

2.61
2.71
NS
NS

2.19b
2.43a
***
0.10

2.50b
2.81a
***
0.09

2.35b
2.62a
***
0.04

2.65
2.67
NS
NS

2.33
2.29
NS
NS

2.68
2.64
NS
NS

2.47
2.50
NS
NS

2.56b
2.81a
***
0.13

2.84b
3.10a
***
0.06

2.75
3.03a
2.63
2.91b
NS
**
NS
0.06
Mean Square and Pr>F

Source
df
Replication
2 0.31 0.7286
0.32 0.6570
1.56 0.3148
1.80
0.0140
0.32
IRR
2 3.60 0.4949
0.65 0.4944
0.66 0.3595
0.50
0.3795
0.47
Error for IRR
4 4.28 0.0113
0.76 0.4146
0.49 0.8128
0.40
0.3409
0.11
MOW
1 3.02 0.0931 21.41 <.0001 21.98 0.0006 22.81
<.0001 35.47
WA
1 0.09 0.7672
0.40 0.4706
4.94 0.0634
4.65
0.0014
0.37
IRRxMOW
2 5.20 0.0145
1.38 0.1814
0.97 0.4776
0.31
0.4090
0.17
IRRxWA
2 1.28 0.2895
1.50 0.1585
0.56 0.6489
0.21
0.5472
0.34
MOWxWA
1 0.70 0.4050
1.20 0.2161
0.00 0.9907
0.56
0.2086
1.34
IRRxMOWxWA
2 0.05 0.9517
1.80 0.1152
2.23 0.1991
1.12
0.0562
0.98
Error
18 0.96
0.74
1.26
0.33
0.70
*, **, *** Significant at the 0.05, 0.01, and 0.001 probability levels, respectively.
† NS, non-significant at the 0.05 level.
‡ Within columns, means followed by the same letter are not significantly different according to LSD (0.05).

21

0.6407
0.1046
0.9551
<.0001
0.4790
0.7858
0.6284
0.1838
0.2722

0.19
1.26
0.64
25.69
0.29
0.26
0.11
0.17
0.56
0.10

0.1903
0.2525
0.0025
<.0001
0.1101
0.1029
0.3535
0.2107
0.0137

Table 2.2. 2011 main effects and mean squares for treatment effects of irrigation, mowing, and wetting agent on ball roll distance in
meters at the Hancock Turfgrass Research Center in East Lansing, MI.

Irrigation (IRR)
30% ET
60% ET
90% ET
Significance
LSD (0.05)
Mowing (MOW)
1X daily
2X daily
Significance
LSD (0.05)
Wet-Agent (WA)
Untreated
1X monthly
Significance
LSD (0.05)

27 June
2.09
2.17
2.15
NS
NS

5 July
2.46a
2.41b
2.37b
*
0.04

2.02b
2.25a
***
0.04

2.29b
2.54a
***
0.06

2.14
2.13
NS
NS

2.39
2.44
NS
NS

Average Ball Roll Distance in Meters
2011
12 July
19 July
2.36
2.33
2.30
2.28
2.35
2.28
NS
NS
NS
NS
2.26b
2.42a
***
0.08

2.24b
2.36a
**
0.08

2.34
2.31
2.33
2.29
NS
NS
NS
NS
Mean Square and Pr>F

25 July
1.92
1.87
1.87
NS
NS

4 August
2.59
2.55
2.54
NS
NS

1.82b
1.96a
***
0.04

2.45b
2.68a
***
0.05

1.89
1.89
NS
NS

2.57
2.56
NS
NS

Source
df
Replication
2
0.04 0.7796
0.20
0.5586 0.49 0.3962 1.50 0.0793 0.14
IRR
2
0.73 0.4731
0.92
0.0170 0.47 0.3989 0.32 0.4908 0.39
Error for IRR
4
0.81 0.0069
0.07
0.9301 0.40 0.5348 0.38 0.5786 0.11
MOW
1
18.86 <.0001 22.28 <.0001 8.68 0.0006 5.37 0.0046 7.66
WA
1
0.03 0.6629
0.82
0.1326 0.03 0.8266 0.06 0.7316 0.00
IRRxMOW
2
0.32 0.1668
0.00
0.9954 0.40 0.4622 0.00 0.9967 0.16
IRRxWA
2
0.09 0.5865
0.08
0.7989 0.06 0.8954 0.01 0.9804 0.06
MOWxWA
1
0.03 0.6818
0.05
0.6992 0.17 0.5664 2.03 0.0625 0.17
IRRxMOWxWA
2
0.00 0.9827
0.07
0.8205 0.04 0.9330 0.12 0.7880 0.15
Error
18
0.16
0.33
0.50
0.51
0.10
*, **, *** Significant at the 0.05, 0.01, and 0.001 probability levels, respectively.
† NS, non-significant at the 0.05 level.
‡ Within columns, means followed by the same letter are not significantly different according to LSD (0.05).

22

0.2775
0.1285
0.3938
<.0001
0.9474
0.2243
0.5740
0.2143
0.2466

0.20
0.36
0.59
17.77
0.04
0.01
0.59
0.02
0.05
0.20

0.3804
0.5886
0.0488
<.0001
0.6430
0.9440
0.0773
0.7555
0.7657

Table 2.3. 2011 main effects and mean squares for treatment effects of irrigation, mowing, and wetting agent on ball roll distance in
meters at the Hancock Turfgrass Research Center in East Lansing, MI.

Irrigation (IRR)
30% ET
60% ET
90% ET
Significance
LSD (0.05)
Mowing (MOW)
1X daily
2X daily
Significance
LSD (0.05)
Wet-Agent (WA)
Untreated
1X monthly
Significance
LSD (0.05)

10 August
2.48
2.40
2.45
NS
NS

Average Ball Roll Distance in Meters
2011
15 August
22 August
2.67
2.70
2.68
2.72
2.67
2.73
NS
NS
NS
NS

2.34b
2.55a
***
0.10

2.59b
2.76a
***
0.07

2.61b
2.82a
***
0.07

2.47
2.42
NS
NS

2.69
2.70
2.66
2.73
NS
NS
NS
NS
Mean Square and Pr>F

29 August
2.45
2.45
2.49
NS
NS
2.35b
2.58a
***
0.06
2.47
2.46
NS
NS

Source
df
Replication
2
2.01
0.0911
2.74
0.0033
2.17
0.0115
0.01
0.9582
IRR
2
0.87
0.7416
0.05
0.9630
0.09
0.8607
0.26
0.3375
Error for IRR
4
2.70
0.0232
1.18
0.0291
0.58
0.2324
0.18
0.6875
MOW
1
15.58
0.0002 10.55
<.0001 15.94
<.0001
19.72
<.0001
WA
1
0.94
0.2734
0.21
0.4478
0.21
0.4629
0.12
0.5488
IRRxMOW
2
0.51
0.5086
0.96
0.0879
0.09
0.7804
0.24
0.4905
IRRxWA
2
0.75
0.3809
0.13
0.6834
0.44
0.3292
1.28
0.0364
MOWxWA
1
0.04
0.8257
0.13
0.5477
1.23
0.0874
0.01
0.8602
IRRxMOWxWA
2
0.80
0.3575
0.45
0.2963
0.24
0.5338
0.05
0.8704
Error
18
0.73
0.34
0.38
0.32
*, **, *** Significant at the 0.05, 0.01, and 0.001 probability levels, respectively.
† NS, non-significant at the 0.05 level.
‡ Within columns, means followed by the same letter are not significantly different according to LSD (0.05).

23

Table 3.1. 2012 main effects and mean squares for treatment effects of irrigation, mowing, and wetting agent on ball roll distance in
meters at the Hancock Turfgrass Research Center in East Lansing, MI.

Irrigation (IRR)
30% ET
60% ET
90% ET
Significance
LSD (0.05)
Mowing (MOW)
1X daily
2X daily
Significance
LSD (0.05)
Wet-Agent (WA)
Untreated
1X monthly
Significance
LSD (0.05)

8 May
2.84
2.87
2.90
NS
NS

17 May
2.78b
2.90a
2.85ab
*
0.08

2.70b
3.03a
***
0.07

2.65b
3.04a
***
0.10

2.90
2.84
NS
NS

2.84
2.84
NS
NS

Average Ball Roll Distance in Meters
2012
24 May
30 May
2.71
2.74
2.69
2.80
2.74
2.84
NS
NS
NS
NS
2.59b
2.84a
***
0.11
2.75
2.69
NS
NS
Mean Square and Pr>F

6 June
2.91
2.96
2.97
NS
NS

13 June
2.96
3.04
3.07
NS
NS

2.65b
2.94a
***
0.09

2.78b
3.12a
***
0.07

2.85b
3.20a
***
0.08

2.80
2.79
NS
NS

2.97
2.93
NS
NS

3.04
3.01
NS
NS

Source
df
Replication
2
0.53 0.2587
1.63
0.1393
0.13
0.8736
1.22
0.2116
IRR
2
0.37 0.2858
1.99
0.0242
0.24
0.7176
1.23
0.4214
Error for IRR
4
0.21 0.6807
0.18
0.9073
0.67
0.5889
1.14
0.2230
MOW
1
39.13 <.0001
55.84
<.0001
21.53
0.0001
28.98
<.0001
WA
1
1.06 0.1044
0.02
0.8710
1.26
0.2600
0.01
0.9017
IRRxMOW
2
0.20 0.5896
1.09
0.2569
1.48
0.2312
0.13
0.8422
IRRxWA
2
0.06 0.8407
1.04
0.2696
0.64
0.5170
0.67
0.4137
MOWxWA
1
0.41 0.3013
3.79
0.0361
0.31
0.5711
1.63
0.1501
IRRxMOWxWA
2
0.27 0.4938
0.71
0.4044
0.74
0.4694
1.87
0.1014
Error
18
0.36
0.74
0.94
0.72
*, **, *** Significant at the 0.05, 0.01, and 0.001 probability levels, respectively.
† NS, non-significant at the 0.05 level.
‡ Within columns, means followed by the same letter are not significantly different according to LSD (0.05).

24

0.08
0.50
0.92
40.70
0.50
1.23
0.05
0.10
0.05
0.39

0.8249
0.6182
0.0898
<.0001
0.2715
0.0652
0.8915
0.6088
0.8724

0.15
1.53
1.81
41.66
0.35
0.38
0.25
0.09
0.13
0.48

0.7331
0.4930
0.0220
<.0001
0.4044
0.4687
0.6039
0.6699
0.7640

Table 3.2. 2012 main effects and mean squares for treatment effects of irrigation, mowing, and wetting agent on ball roll distance in
meters at the Hancock Turfgrass Research Center in East Lansing, MI.

Irrigation (IRR)
30% ET
60% ET
90% ET
Significance
LSD (0.05)
Mowing (MOW)
1X daily
2X daily
Significance
LSD (0.05)
Wet-Agent (WA)
Untreated
1X monthly
Significance
LSD (0.05)

21 June
3.10
3.25
3.17
NS
NS

Average Ball Roll Distance in Meters
2012
27 June
2 July
11 July
3.23
3.05
3.48
3.26
3.10
3.11
3.29
3.08
3.13
NS
NS
NS
NS
NS
NS

19 July
2.84
2.87
2.91
NS
NS

31 July
2.93a
2.70b
2.64b
**
0.14

3.00b
3.35a
***
0.10

3.04b
3.48a
***
0.08

3.08b
3.41a
***
0.14

2.73b
3.02a
***
0.05

2.62b
2.89a
***
0.07

3.17
3.18
NS
NS

3.27
3.26
NS
NS

3.26
3.23
NS
NS

2.87
2.88
NS
NS

2.78
2.73
NS
NS

2.93b
3.23a
***
0.07
3.11a
3.04b
*
0.07
Mean Square and Pr>F

Source
df
Replication
2
0.44 0.5845
0.20
0.6997
0.15
0.6501
5.95
0.0487
0.82
IRR
2
2.49 0.6238
0.43
0.2892
0.37
0.3359 21.08
0.1897
0.58
Error for IRR
4
4.67 0.0032
0.25
0.7675
0.26
0.5697
8.14
0.0074
0.54
MOW
1
42.76 <.0001 68.98
<.0001 31.21
<.0001 38.91
0.0001 29.10
WA
1
0.03 0.8480
0.09
0.6968
1.76
0.0357
0.35
0.6527
0.02
IRRxMOW
2
0.13 0.8473
0.30
0.5816
0.27
0.4669
1.59
0.4027
0.01
IRRxWA
2
0.19 0.7854
0.45
0.4521
0.25
0.4977
2.50
0.2477
0.84
MOWxWA
1
0.27 0.5669
0.14
0.6204
0.00
0.8931
3.18
0.1825
0.16
IRRxMOWxWA
2
0.56 0.5035
0.66
0.3209
0.17
0.6110
0.16
0.9084
0.07
Error
18
0.79
0.55
0.34
1.66
0.19
*, **, *** Significant at the 0.05, 0.01, and 0.001 probability levels, respectively.
† NS, non-significant at the 0.05 level.
‡ Within columns, means followed by the same letter are not significantly different according to LSD (0.05).

25

0.0284
0.4225
0.0532
<.0001
0.7587
0.9368
0.0260
0.3722
0.6979

0.51
11.49
0.58
27.15
1.12
0.29
0.81
0.38
0.23
0.38

0.2923
0.0084
0.2395
<.0001
0.1044
0.4797
0.1496
0.3331
0.5591

Table 3.3. 2012 main effects and mean squares for treatment effects of irrigation, mowing, and wetting agent on ball roll distance in
meters at the Hancock Turfgrass Research Center in East Lansing, MI.

Irrigation (IRR)
30% ET
60% ET
90% ET
Significance
LSD (0.05)
Mowing (MOW)
1X daily
2X daily
Significance
LSD (0.05)
Wet-Agent (WA)
Untreated
1X monthly
Significance
LSD (0.05)

Average Ball Roll Distance in Meters
2012
8 August
14 August
3.54
2.90
3.10
2.85
3.16
2.83
NS
NS
NS
NS

22 August
3.52
3.39
3.45
NS
NS

3.06b
3.47a
***
0.17

3.31b
3.59a
***
0.09

3.36a
3.17b
*
0.17

2.75b
2.98a
***
0.05
2.87
2.86
NS
NS
Mean Square and Pr>F

3.43
3.47
NS
NS

Source
df
Replication
2
2.39
0.3719
0.06
0.7697
1.56
0.1199
IRR
2 27.88
0.3890
0.62
0.1212
1.86
0.3057
Error for IRR
4 23.11
0.0002
0.17
0.5375
1.15
0.1803
MOW
1 57.51
<.0001 17.76
<.0001
28.51
<.0001
WA
1 13.15
0.0275
0.00
0.9082
0.28
0.5193
IRRxMOW
2
7.39
0.0630
0.89
0.0298
0.45
0.5184
IRRxWA
2
6.64
0.0805
0.50
0.1181
0.82
0.3102
MOWxWA
1
0.00
0.9654
0.00
0.9847
0.01
0.8883
IRRxMOWxWA
2
0.64
0.7589
0.36
0.1998
0.15
0.7987
Error
18
2.28
0.21
0.65
*, **, *** Significant at the 0.05, 0.01, and 0.001 probability levels, respectively.
† NS, non-significant at the 0.05 level.
‡ Within columns, means followed by the same letter are not significantly different according to LSD (0.05).

26

Table 4.1. 2011-2012 green speeds (meters) as affected by irrigation and mowing† (MOW) at the Hancock Turfgrass Research
Center in East Lansing, MI.
9 May 2011
14 August 2012
Irrigation
1X MOW
2X MOW
1X MOW
2X MOW
30% ET
2.59c
2.81ab
2.79c
3.02a
60% ET
2.63bc
2.48c
2.70c
3.00a
90% ET
2.62c
2.83a
2.77c
2.90b
LSD (0.05)‡
0.19
0.09
LSD (0.05)§
0.27
0.12
† Mowing was applied six days per week from May till September at 0.3175-cm
‡ Between mowing means at same irrigation level on the single date listed above.
§ Among irrigation level at the same or different mowing on the single date listed above.

Table 4.2. 2011-2012 green speeds (meters) as affected by irrigation and wetting agent† (WA) at the Hancock Turfgrass Research
Center in East Lansing, MI.
29 August 2011
17 May 2012
19 July 2012
Irrigation
WA
No WA
WA
No WA
WA
No WA
30% ET
2.42b
2.48ab
2.80ab
2.75b
2.89a
2.79b
60% ET
2.40b
2.50ab
2.85ab
2.95a
2.84ab
2.90a
90% ET
2.54a
2.44ab
2.89ab
2.82ab
2.90a
2.92a
LSD (0.05) ‡
0.11
0.17
0.08
LSD (0.05) §
0.15
0.24
0.12
† Wetting agent was applied monthly from May till September with Revolution® from Aquatrols, Inc. (Paulsboro, N.J) at 1.87-ml/m2.
‡ Between wetting agent means at same irrigation level on the single date listed above.
§ Among irrigation level at the same or different wetting agent on the single date listed above.

27

Figure 1. Irrigation effects on ball roll distance in 2010-12. Values are averages of mowing and wetting agent for each irrigation
treatment. Error bars represent least significant difference (LSD) using Fisher’s Protected Method. Overlapping error bars
represent statistically similar treatments at α=0.05. N=18.

28

Figure 2. Mowing effects on ball roll distance from 2010-12. Values are averages of irrigation and wetting agent for each mowing
treatment. Error bars represent least significant difference (LSD) using Fisher’s Protected Method. Overlapping error bars
represent statistically similar treatments at α=0.05. N=18.

29

Technological advancements in time domain reflectometry (TDR) devices have given
way to affordable means of measuring percent volumetric water content (%VWC). Analysis of
variance means for each date of percent volumetric water (%VWC) as affected by irrigation are
shown in Tables 5.1 through 7.3. On every date significance was observed, 60 and 90% ET were
statistically similar, and greater in %VWC than 30% ET. Interactions, if observed, are shown in
Tables 8.1 and 8.2.
In 2010-2012, %VWC showed significant differences between 30, 60, and 90% ET
irrigation treatments (P<0.0001). 60 and 90% ET were statistically similar, and were greater
than 30% ET each year.
Daily %VWC (Figure 3) numbers are averages of mowing and wetting agent values for
each irrigation treatment. Irrigation had significant effects on %VWC over each season for all
but one date in the three-year study. In 2012, 30% ET consistently showed significant reduction
in overall %VWC; however, there was no significant difference between 60% ET and 90% ET in
regards to %VWC. The use of time domain reflectometry to determine %VWC is an important
technology to utilize for gauging water replenishment levels on putting greens each day (Kieffer
and O’Connor, 2007).
For 2010-2012, mowing and wetting agent treatments had no significant effect on
%VWC. Analysis of variance means for each date of percent volumetric water (%VWC) as
affected by mowing or wetting agent are shown in Tables 5.1 through 7.3. %VWC values were
statistically reduced with application of a wetting agent on two dates in 2010 and five dates in
2011, but then significantly increased on two dates in 2012 (Tables 5.1 to 7.3). Interactions, if
observed, are shown in Tables 8.1 and 8.2. Interactions between irrigation and wetting agent in

30

Table 8.1 suggest the wetting agent helped the soil drain better at 90% ET, while holding more
moisture at the 30% ET with no significant difference at 60% ET replenishment regimes.

31

Table 5.1. 2010 main effects and mean squares for treatment effects of irrigation, mowing, and wetting agent on percent volumetric
water content (%VWC) at the Hancock Turfgrass Research Center in East Lansing, MI.

Irrigation (IRR)
30% ET
60% ET
90% ET
Significance
LSD (0.05)
Mowing (MOW)
1X daily
2X daily
Significance
LSD (0.05)
Wet-Agent (WA)
Untreated
1X monthly
Significance
LSD (0.05)

19 July
28.81b
34.15a
34.88a
**
2.98

Average Volumetric Water Content (%VWC)
2010
27 July
3 Aug
10 Aug
29.05
15.23b
18.08
31.49
18.33a
22.02
31.44
20.09a
22.18
NS
*
NS
NS
2.39
NS

16 Aug
13.42b
16.62ab
17.98a
*
3.38

23 Aug
14.62b
19.58a
21.05a
**
2.95

33.05
32.18
NS
NS

30.80
30.52
NS
NS

21.22
20.30
NS
NS

16.38
15.63
NS
NS

18.71
18.12
NS
NS

32.63
32.60
NS
NS

30.61
30.71
NS
NS

20.76
20.76
NS
NS

16.07
15.94
NS
NS

18.75
18.07
NS
NS

18.02
17.74
NS
NS
18.20
17.56
NS
NS
Mean Square and Pr>F

Source
df
Replication
2
21.46
0.0105
9.84
0.0104 19.50
0.0082 6.22
0.1107
IRR
2 131.64
0.0090
23.19
0.2186 72.80
0.0119 64.60
0.1117
Error for IRR
4
6.92
0.1523
10.18
0.0027
4.45
0.2588 16.21
0.0020
MOW
1
6.86
0.1854
0.67
0.5319
0.73
0.6310 7.51
0.0998
WA
1
0.01
0.9587
0.08
0.8262
3.67
0.2887 0.00
0.9967
IRRxMOW
2
0.95
0.7730
0.42
0.7808
0.58
0.8306 0.55
0.8043
IRRxWA
2
4.90
0.2834
6.63
0.0364
2.62
0.4425 3.68
0.2553
MOWxWA
1
6.62
0.1930
1.60
0.3379
0.02
0.9298 1.39
0.4646
IRRxMOWxWA
2
0.76
0.8131
3.09
0.1833
1.00
0.7269 1.32
0.5984
Error
18
3.62
1.65
3.07
2.49
*, **, *** Significant at the 0.05, 0.01, and 0.001 probability levels, respectively.
† NS, non-significant at the 0.05 level.
‡ Within columns, means followed by the same letter are not significantly different according to LSD (0.05).

32

14.54
65.77
8.89
4.96
0.14
2.31
1.61
0.05
1.43
2.98

0.0204
0.0453
0.0475
0.2139
0.8284
0.4757
0.5930
0.8971
0.6273

20.35
136.26
6.79
3.18
4.18
2.40
5.01
3.25
2.51
3.07

0.0070
0.0082
0.1088
0.3225
0.2590
0.4735
0.2238
0.3173
0.4580

Table 5.2. 2010 main effects and mean squares for treatment effects of irrigation, mowing, and wetting agent on volumetric water
content (%VWC) at the Hancock Turfgrass Research Center in East Lansing, MI.

Irrigation (IRR)
30% ET
60% ET
90% ET
Significance
LSD (0.05)
Mowing (MOW)
1X daily
2X daily
Significance
LSD (0.05)
Wet-Agent (WA)
Untreated
1X monthly
Significance
LSD (0.05)

31 August
10.40b
16.00a
19.01a
*
4.91

Average Volumetric Water Content (%VWC)
2010
7 Sept
14 Sept
14.72b
12.75b
18.10a
16.17a
19.68a
16.75a
*
*
2.51
2.85

15.19
15.09
NS
NS

17.48
17.51
NS
NS

15.69
14.59
NS
NS

18.18
16.81
*
1.04

15.17
15.27
NS
NS
15.46
14.98
NS
NS
Mean Square and Pr>F

20 Sept
17.27
19.37
24.34
NS
NS

29 Sept
15.19
20.94
18.91
NS
NS

6 Oct
14.54b
18.08a
18.86a
**
1.33

18.78
21.88
NS
NS

19.04
17.65
NS
NS

17.02
17.31
NS
NS

22.12
18.54
NS
NS

17.72
18.97
NS
NS

17.56a
16.76b
*
0.76

Source
df
Replication
2
27.76
0.0077
15.01
0.0063 11.90
0.0288
85.40 0.3333
IRR
2 229.29
0.0198
76.96
0.0127 56.13
0.0338 158.25 0.1875
Error for IRR
4
18.75
0.0123
4.89
0.1083
6.33
0.0972
60.42 0.5253
MOW
1
0.09
0.8866
0.01
0.9594
0.09
0.8613
86.43 0.2912
WA
1
10.93
0.1284
16.78
0.0130
2.13
0.3892 115.56 0.2246
IRRxMOW
2
9.67
0.1348
0.52
0.7923
0.60
0.8046
80.32 0.3545
IRRxWA
2
4.77
0.3518
0.79
0.7044
0.02
0.9910 103.98 0.2669
MOWxWA
1
0.01
0.9545
0.02
0.9313
2.29
0.3725
74.25 0.3268
IRRxMOWxWA
2
3.17
0.4924
2.02
0.4181
0.45
0.8497
84.75 0.3359
Error
18
4.31
2.21
2.74
73.07
*, **, *** Significant at the 0.05, 0.01, and 0.001 probability levels, respectively.
† NS, non-significant at the 0.05 level.
‡ Within columns, means followed by the same letter are not significantly different according to LSD (0.05).

33

79.19
102.03
29.89
17.33
14.16
20.35
40.30
20.28
45.86
27.91

0.0849
0.1365
0.3997
0.4409
0.4854
0.4961
0.2620
0.4052
0.2211

8.02
63.57
1.37
0.75
5.71
0.83
2.46
0.00
2.42
1.16

0.0060
0.0017
0.3519
0.4338
0.0398
0.5037
0.1492
0.9732
0.1536

Table 6.1. 2011 main effects and mean squares for treatment effects of irrigation, mowing, and wetting agent on volumetric water
content (%VWC) at the Hancock Turfgrass Research Center in East Lansing, MI.

Irrigation (IRR)
30% ET
60% ET
90% ET
Significance
LSD (0.05)
Mowing (MOW)
1X daily
2X daily
Significance
LSD (0.05)
Wet-Agent (WA)
Untreated
1X monthly
Significance
LSD (0.05)

9 May
14.54b
16.33a
16.85a
*
1.43

23 May
20.97b
22.33a
22.34a
*
0.80

15.63
16.17
NS
NS

21.46
22.30
NS
NS

16.36a
15.46b
*
0.90

22.36
21.39
NS
NS

Average Volumetric Water Content (%VWC)
2011
1 June
6 June
18.10b
17.02b
20.03a
20.26a
20.17a
20.28a
*
*
1.60
2.67
18.73b
20.12a
**
0.94
19.97a
18.89b
*
0.94
Mean Square and Pr>F

14 June
14.33b
17.80a
17.89a
*
3.00

21 June
18.48b
21.83a
22.57a
*
2.22

18.56b
19.81a
*
0.95

16.47
16.87
NS
NS

20.51
21.41
NS
NS

19.61
18.77
NS
NS

17.04a
16.30b
*
0.73

21.86a
20.06b
**
1.17

Source
df
Replication
2 15.20
0.0017
18.19
0.0038
43.64
<.0001
25.81
0.0002
IRR
2 17.57
0.0237
7.47
0.0137
15.99
0.0401
42.36
0.0432
Error for IRR
4
1.60
0.4456
0.50
0.9292
2.00
0.3840
5.56
0.0448
MOW
1
2.67
0.2182
6.42
0.1163
17.50
0.0060
14.06
0.0126
WA
1
7.29
0.0492
8.41
0.0751
10.35
0.0279
6.33
0.0795
IRRxMOW
2
0.53
0.7299
0.08
0.9652
4.59
0.1070
1.06
0.5722
IRRxWA
2
2.73
0.2174
1.13
0.6279
1.20
0.5287
5.82
0.0659
MOWxWA
1
4.13
0.1296
1.21
0.4829
0.01
0.9513
2.01
0.3092
IRRxMOWxWA
2
0.35
0.8112
1.83
0.4748
1.38
0.4817
1.02
0.5822
Error
18
1.64
2.36
1.81
1.83
*, **, *** Significant at the 0.05, 0.01, and 0.001 probability levels, respectively.
† NS, non-significant at the 0.05 level.
‡ Within columns, means followed by the same letter are not significantly different according to LSD (0.05).

34

19.05
49.61
7.04
1.44
4.99
2.48
6.42
0.75
2.39
1.08

<.0001
0.0488
0.0020
0.2641
0.0458
0.1301
0.0105
0.4160
0.1394

13.12
56.78
3.84
7.20
29.34
1.35
6.66
1.03
2.48
2.79

0.0227
0.0142
0.2808
0.1255
0.0045
0.6247
0.1202
0.5503
0.4289

Table 6.2. 2011 main effects and mean squares for treatment effects of irrigation, mowing, and wetting agent on volumetric water
content (%VWC) at the Hancock Turfgrass Research Center in East Lansing, MI.

Irrigation (IRR)
30% ET
60% ET
90% ET
Significance
LSD (0.05)
Mowing (MOW)
1X daily
2X daily
Significance
LSD (0.05)
Wet-Agent (WA)
Untreated
1X monthly
Significance
LSD (0.05)

27 June
17.98b
20.92a
21.69a
*
2.37

Average Volumetric Water Content (%VWC)
2011
5 July
12 July
19 July
13.29
13.33
10.54b
19.01
19.06
16.68a
18.98
19.11
16.30a
NS
NS
*
NS
NS
4.40

25 July
10.03b
17.27a
19.46a
*
4.81

4 Aug
27.73b
31.76a
32.14a
**
1.29

17.94
20.59
NS
NS

16.76
17.43
NS
NS

14.58
14.43
NS
NS

15.87
15.31
NS
NS

30.40
30.68
NS
NS

20.83
19.56
NS
NS

17.94a
16.25b
*
1.32

14.53
14.48
NS
NS

15.43
15.74
NS
NS

31.03
30.05
NS
NS

17.21
17.13
NS
NS
17.08
17.26
NS
NS
Mean Square and Pr>F

Source
df
Replication
2
7.19 0.2121
20.87 0.0108
18.85 0.0396
14.41 0.0149
22.93
IRR
2 46.14 0.0255 130.16 0.0597 132.45 0.0797
141.83 0.0308 291.91
Error for IRR
4
4.38 0.4181
21.03 0.0032
26.05 0.0050
15.09 0.0041
17.98
MOW
1
5.76 0.2594
4.13 0.2945
0.06
0.9109
0.22 0.7791
2.83
WA
1 14.44 0.0817
25.67 0.0150
0.30
0.8056
0.03 0.9201
0.90
IRRxMOW
2
1.77 0.6660
3.76 0.3672
13.56 0.0877
2.22 0.4534
12.15
IRRxWA
2
6.18 0.2595
1.92 0.5906
20.67 0.0306
1.74 0.5360
11.93
MOWxWA
1
0.09 0.8859
0.02 0.9443
1.40
0.5976
0.87 0.5762
2.95
IRRxMOWxWA
2
1.76 0.6675
1.36 0.6862
7.48
0.2409
2.08 0.4753
0.19
Error
18
4.24
3.54
4.85
2.69
5.75
*, **, *** Significant at the 0.05, 0.01, and 0.001 probability levels, respectively.
† NS, non-significant at the 0.05 level.
‡ Within columns, means followed by the same letter are not significantly different according to LSD (0.05).

35

0.0368
0.0120
0.0406
0.4916
0.6966
0.1498
0.1545
0.4831
0.9678

52.10
71.84
1.29
0.72
8.70
4.21
3.72
0.72
10.22
1.97

<.0001
0.0012
0.6317
0.5526
0.0500
0.1471
0.1802
0.5526
0.0167

Table 6.3. 2011 main effects and mean squares for treatment effects of irrigation, mowing, and wetting agent on volumetric water
content (%VWC) at the Hancock Turfgrass Research Center in East Lansing, MI.

Irrigation (IRR)
30% ET
60% ET
90% ET
Significance
LSD (0.05)
Mowing (MOW)
1X daily
2X daily
Significance
LSD (0.05)
Wet-Agent (WA)
Untreated
1X monthly
Significance
LSD (0.05)

10 August
27.58b
31.60a
31.23a
*
2.22

Average Volumetric Water Content (%VWC)
2011
15 August
22 August
29 August
35.89
26.09b
20.05b
33.84
30.40a
29.52a
33.09
30.07a
30.53a
NS
**
**
NS
2.07
2.59

8 Sept
31.13b
34.98a
36.12a
**
2.26

12 Sept
27.83b
31.15a
31.60a
**
1.45

30.11
30.17
NS
NS

32.27
36.28
NS
NS

33.95
34.19
NS
NS

30.02
30.37
NS
NS

30.60
29.68
NS
NS

33.13
35.42
NS
NS

34.19
33.96
NS
NS

30.36
30.03
NS
NS

28.50
29.21
NS
NS

28.20
28.53
NS
NS

29.03
8.55
28.67
8.44
NS
NS
NS
NS
Mean Square and Pr>F

Source
df
Replication
2 12.43
0.0152
69.50 0.5429
7.20
0.0215
13.50
0.0171
7.84
IRR
2 59.18
0.0131
25.21 0.7955 68.95
0.0078
101.89
0.0086
82.09
Error for IRR
4
3.82
0.2081 104.00 0.4603
3.33
0.1078
5.22
0.1396
3.97
MOW
1
0.03
0.9143 145.20 0.2655
4.48
0.1014
0.97
0.5516
0.54
WA
1
7.65
0.0868
47.38 0.5198
1.17
0.3885
0.27
0.7535
0.49
IRRxMOW
2
6.00
0.1039
74.71 0.5194
3.76
0.1101
4.47
0.2106
2.66
IRRxWA
2
1.69
0.4973 148.07 0.2851
4.75
0.0665
2.74
0.3732
1.89
MOWxWA
1
0.13
0.8130 117.00 0.3159
0.20
0.7179
1.32
0.4870
1.28
IRRxMOWxWA
2
8.33
0.0493 149.25 0.2824
4.51
0.0750
6.38
0.1164
2.08
Error
18
2.33
109.95
1.50
2.63
1.87
*, **, *** Significant at the 0.05, 0.01, and 0.001 probability levels, respectively.
† NS, non-significant at the 0.05 level.
‡ Within columns, means followed by the same letter are not significantly different according to LSD (0.05).

36

0.0318
0.0078
0.1195
0.5979
0.6145
0.2667
0.3836
0.4175
0.3495

4.59
50.78
1.63
1.14
0.93
0.07
4.45
0.16
0.21
1.52

0.0737
0.0036
0.3975
0.3978
0.4427
0.9564
0.0787
0.7491
0.8716

Table 7.1. 2012 main effects and mean squares for treatment effects of irrigation, mowing, and wetting agent on volumetric water
content (%VWC) at the Hancock Turfgrass Research Center in East Lansing, MI.

Irrigation (IRR)
30% ET
60% ET
90% ET
Significance
LSD (0.05)
Mowing (MOW)
1X daily
2X daily
Significance
LSD (0.05)
Wet-Agent (WA)
Untreated
1X monthly
Significance
LSD (0.05)

8 May
37.53
37.68
37.07
NS
NS

Average Volumetric Water Content (%VWC)
2012
17 May
24 May
30 May
33.27
25.90b
27.68
34.36
30.98a
28.79
35.35
32.79a
32.37
NS
**
NS
NS
2.92
NS

6 June
29.00b
34.63a
37.08a
**
3.10

13 June
23.13b
32.09a
35.09a
**
4.48

37.23
37.62
NS
NS

34.14
34.51
NS
NS

28.41
30.81
NS
NS

33.74
33.39
NS
NS

30.28
29.93
NS
NS

37.66
37.19
NS
NS

34.19
34.46
NS
NS

31.71
27.51
NS
NS

33.51
33.63
NS
NS

29.81
30.40
NS
NS

29.96
29.82
NS
NS
30.04
29.74
NS
NS
Mean Square and Pr>F

Source
df
Replication
2 10.13
0.0097
7.58
0.0276
13.14 0.0196
71.21
0.5062
26.67
IRR
2 1.22
0.7254
13.03
0.0697
153.21 0.0063
72.08
0.6781 206.05
Error for IRR
4 3.49
0.1242
2.34
0.2867
6.62
0.0807
168.09
0.2007
7.50
MOW
1 1.32
0.3851
1.25
0.4055
0.17
0.8015
51.84
0.4822
1.10
WA
1 2.01
0.2873
0.67
0.5411
0.78
0.5952
158.76
0.2253
0.12
IRRxMOW
2 0.60
0.7019
0.50
0.7530
0.83
0.7364
100.74
0.3872
2.40
IRRxWA
2 1.12
0.5235
0.02
0.9902
1.33
0.6158
78.77
0.4723
6.98
MOWxWA
1 0.06
0.8487
0.42
0.6260
1.48
0.4659
49.00
0.4943
0.12
IRRxMOWxWA
2 4.02
0.1182
3.63
0.1503
3.26
0.3182
64.49
0.5386
4.05
Error
18 1.67
1.72
2.67
100.68
3.17
*, **, *** Significant at the 0.05, 0.01, and 0.001 probability levels, respectively.
† NS, non-significant at the 0.05 level.
‡ Within columns, means followed by the same letter are not significantly different according to LSD (0.05).

37

0.0026
0.0046
0.0913
0.5625
0.8463
0.4826
0.1392
0.8463
0.3022

34.19
464.51
15.65
1.14
3.12
2.14
2.48
0.64
4.07
6.43

0.0153
0.0040
0.0849
0.6790
0.4949
0.7216
0.6860
0.7560
0.5427

Table 7.2. 2012 main effects and mean squares for treatment effects of irrigation, mowing, and wetting agent on volumetric water
content (%VWC) at the Hancock Turfgrass Research Center in East Lansing, MI.

Irrigation (IRR)
30% ET
60% ET
90% ET
Significance
LSD (0.05)
Mowing (MOW)
1X daily
2X daily
Significance
LSD (0.05)
Wet-Agent (WA)
Untreated
1X monthly
Significance
LSD (0.05)

21 June
22.93b
34.12a
37.03a
**
5.37

Average Volumetric Water Content (%VWC)
2012
27 June
2 July
3 July
21.48b
21.15b
20.65b
33.26a
34.25a
33.23a
37.52a
37.85a
38.13a
**
*
*
7.38
10.10
10.70

5 July
23.03b
34.82a
38.67a
*
9.17

6 July
21.65b
34.50a
38.19a
*
10.18

31.54
31.17
NS
NS

31.22
30.28
NS
NS

30.86
30.48
NS
NS

32.71
31.63
NS
NS

31.58
31.32
NS
NS

31.49
31.23
NS
NS

30.85
30.65
NS
NS

30.67
30.67
NS
NS

32.24
32.09
NS
NS

31.58
31.32
NS
NS

31.33
30.84
NS
NS
31.08
31.08
NS
NS
Mean Square and Pr>F

Source
df
Replication
2
26.17 0.0606
43.10 0.0012
41.71 0.0152
50.61 0.0063
70.31
IRR
2 664.20 0.0040 828.63 0.0086 926.92 0.0214 975.29 0.0239 797.06
Error for IRR
4
22.47 0.0557
42.41 0.0002
79.36 0.0002
89.10 <.0001
65.46
MOW
1
1.25
0.6968
8.03 0.1891
2.15 0.6063
1.25 0.6872
10.35
WA
1
0.61
0.7844
0.36 0.7759
0.00 1.0000
0.00 0.9952
0.20
IRRxMOW
2
11.60 0.2590
5.44 0.3069
12.77 0.2229
10.36 0.2742
5.22
IRRxWA
2
16.00 0.1628
5.44 0.3068
1.70 0.8064
2.13 0.7547
0.21
MOWxWA
1
1.40
0.6798
1.78 0.5288
1.52 0.6644
0.10 0.9089
6.17
IRRxMOWxWA
2
9.16
0.3384
6.04 0.2717
5.00 0.5391
4.48 0.5589
7.13
Error
18
7.96
4.31
7.82
7.45
6.33
*, **, *** Significant at the 0.05, 0.01, and 0.001 probability levels, respectively.
† NS, non-significant at the 0.05 level.
‡ Within columns, means followed by the same letter are not significantly different according to LSD (0.05).

38

0.0007
0.0199
0.0002
0.2172
0.8600
0.4544
0.9680
0.3366
0.3460

100.17
904.76
80.64
0.61
0.61
18.96
2.13
0.27
3.13
8.56

0.0006
0.0229
0.0003
0.7920
0.7920
0.1381
0.7827
0.8618
0.6990

Table 7.3. 2012 main effects and mean squares for treatment effects of irrigation, mowing, and wetting agent on volumetric water
content (%VWC) at the Hancock Turfgrass Research Center in East Lansing, MI.

Irrigation (IRR)
30% ET
60% ET
90% ET
Significance
LSD (0.05)
Mowing (MOW)
1X daily
2X daily
Significance
LSD (0.05)
Wet-Agent (WA)
Untreated
1X monthly
Significance
LSD (0.05)

11 July
13.70b
26.92a
32.87a
*
12.16

19 July
27.60b
37.14a
38.78a
*
8.75

24.57
24.42
NS
NS

34.61
34.40
NS
NS

23.58b
25.41a
*
1.71

34.62
34.39
NS
NS

Average Volumetric Water Content (%VWC)
2012
31 July
8 Aug
19.48b
12.18b
32.47a
28.84a
34.82a
30.41a
*
*
8.22
9.65

14 Aug
24.42b
33.34a
34.08a
*
6.03

22 Aug
19.73b
31.65a
33.93a
**
6.42

23.63
23.99
NS
NS

30.90
30.32
NS
NS

28.63
28.24
NS
NS

27.82
22.98
30.02
24.64
NS
NS
NS
NS
Mean Square and Pr>F

29.80
31.42
NS
NS

27.64b
29.23a
*
1.44

28.48
29.36
NS
NS

Source
df
Replication
2
73.40
0.0004
52.93
0.0040
28.25
0.0833
156.71
0.0008
IRR
2 1154.89 0.0276
437.18
0.0459
818.40
0.0130 1224.21
0.0112
Error for IRR
4
115.04
<.0001
59.58
0.0005
52.56
0.0052
72.54
0.0067
MOW
1
0.22
0.8504
0.40
0.8129
6.93
0.4129
1.21
0.7753
WA
1
29.88
0.0378
0.44
0.8033
43.56
0.0500
24.67
0.2072
IRRxMOW
2
27.04
0.0252
4.63
0.5260
2.03
0.8159
8.55
0.5629
IRRxWA
2
1.10
0.8330
0.14
0.9808
9.05
0.4175
6.50
0.6441
MOWxWA
1
0.09
0.9035
0.28
0.8420
4.99
0.4863
8.22
0.4599
IRRxMOWxWA
2
0.19
0.9686
6.81
0.3947
4.05
0.6696
10.01
0.5121
Error
18
5.95
6.95
9.87
14.41
*, **, *** Significant at the 0.05, 0.01, and 0.001 probability levels, respectively.
† NS, non-significant at the 0.05 level.
‡ Within columns, means followed by the same letter are not significantly different according to LSD (0.05).

39

19.79
346.95
28.30
3.00
23.68
2.60
13.63
2.15
1.99
5.65

0.0519
0.0197
0.0068
0.4752
0.0555
0.6379
0.1179
0.5449
0.7080

50.53
697.72
32.05
1.36
22.72
3.30
0.80
0.59
1.67
4.25

0.0005
0.0071
0.0009
0.5783
0.0327
0.4744
0.8290
0.7142
0.6808

Table 8.1. 2010-2012 percent volumetric water content (%VWC) as affected by irrigation and wetting agent† (WA) at the
Hancock Turfgrass Research Center in East Lansing, MI.
27 July 2010
14 June 2011
12 July 2011
Irrigation
WA
No WA
WA
No WA
WA
No WA
30% ET
29.96b
28.15c
14.3d
14.4d
14.5c
12.1c
60% ET
31.14ab
31.83a
17.9ab
17.7bc
19.5ab
18.7ab
90% ET
31.03ab
31.85a
16.7c
19.1a
17.8b
20.5a
LSD (0.05)‡
1.56
1.26
2.67
LSD (0.05)§
2.21
1.79
3.77
† Wetting agent was applied monthly from May till September with Revolution® from Aquatrols, Inc. (Paulsboro, N.J) at 1.87-ml/m2.
‡ Between wetting agent means at same irrigation level on the single date listed above.
§ Between irrigation level at the same or different wetting agent on the single date listed above.

Table 8.2. 2012 percent volumetric water content (%VWC) as affected by irrigation and mowing† (MOW) at the Hancock Turfgrass
Research Center in East Lansing, MI.
11 July 2012
Irrigation
1X MOW
2X MOW
30% ET
15.4c
12.0d
60% ET
26.8b
27.0b
90% ET
31.6a
34.2a
LSD (0.05) ‡
2.96
LSD (0.05) §
4.18
† Mowing was applied six days per week from May till September at 0.3175-cm.
‡ Between mowing means at same irrigation level on the single date listed above.
§ Among irrigation level at the same or different mowing on the single date listed above.

40

Figure 3. Irrigation Effects on percent volumetric water content (%VWC) in 2010-12. Values are averages of mowing and wetting
agent for each irrigation treatment. Error bars represent least significant difference (LSD) using Fisher’s Protected Method.
Overlapping error bars represent statistically similar treatments at α=0.05. N=15.

41

Analysis of variance means for each date of visual quality as affected by irrigation are
shown in Tables 9.1 through 11.3. Irrigation had significant effects on visual quality (Figure 4
and Tables 9.1 to 11.3) on four dates in 2010 and nine dates in 2012. On each of these thirteen
dates, 60 and 90% were statistically similar and significantly greater than 30% ET
replenishment. Interactions, if observed, are shown in Tables 12.1 and 12.2. Table 12.1 shows
wetting agent significantly improved visual quality at 30% ET irrigation replenishment in 2012.
Table 12.2 shows a trend of increased turfgrass quality most often at the 90% ET irrigation
replenishment.
In 2010-2012, average visual quality showed significant differences between 30, 60, and
90% ET irrigation treatments (P<0.0001). Year significantly affected average ball roll distance
(P<0.0001). The year difference is most likely attributed to management over time. The
irrigation x year interaction was significant (P<0.0001), suggesting irrigation alone is not entirely
responsible for acceptable visual quality. Daily values shown in Figure 4 are averages of mowing
and wetting agent for each irrigation treatment, and show the effects of irrigation on visual
quality over each season. 2010-11 seasons visual quality separations based on irrigation were
not observed. 60 and 90% ET replenishment were significantly higher in visual quality in 2012
compared to the 30% ET treatment. Effectively, the data shows no difference between 60 and
90% ET.
Long-term double mowing is rarely used as a mechanical practice because of the
perceived negative physiological plant stress it puts on putting greens as well as it being labor
intensive. Overall in our study, double mowing did not result in conclusive significant effects on
visual quality. Visual quality was significantly reduced with double mowing on two dates in

42

2010, six dates in 2011, and eight dates in 2012 (Tables 9.1 to 11.3). In contrast, visual quality
was significantly increased with double mowing on three dates in 2010 and four dates in 2011
(Tables 9.1 to 10.3). On eighteen dates from 2010-2012, double mowing has no significant
effect on visual quality. Analysis of variance means for each date of visual quality as affected by
mowing are shown in Tables 9.1 through 11.3. Interactions, if observed, are shown in Tables
12.1 and 12.2.
In 2010-2012, average visual quality showed no significant differences when daily
double (2X) mowing versus single daily (1X) mowing (P=0.3150). Year significantly affected
average visual quality (P<0.0001), and is most likely attributed to the same seasonal variations
in weather mentioned previously. No interaction between mowing and year was observed to
be significant (P=0.3026), suggesting that year may be the sole factor attributing to visual
quality x mowing differences observed.
Daily values shown in Figure 5 are averages of irrigation and wetting agent for each
mowing treatment, and show the effects of mowing on visual quality over each season. Figure 5
emphasizes visual quality was effected frequently with daily double mowing, but suggests
significant decreases were temporary. The data shows daily 2X mowing for increased ball roll
distance may be obtained without loss of turfgrass quality.
Wetting agent applications on golf course putting greens are scrutinized for efficacy and
costs of applications. Analysis of variance means for each date of visual quality as affected by
wetting agent are shown in Tables 9.1 through 11.3. Interactions, if observed, are shown in
Tables 12.1 and 12.2. Table 12.2 shows wetting agent significantly improved visual quality at

43

30% ET replenishment on nine dates in 2012. Wetting agent effects on visual quality at 60 and
90% ET were statistically similar for these nine dates where interactions occurred (Table 12.2).
In 2010 and 2011 there was adequate precipitation to sustain visual quality without a
wetting agent on the research site even at the 30% ET treatment, however, during the summer
of 2012 there was statistical separation among ET treatments.
In 2010-2011, average visual quality showed statistically similar values between
untreated and wetting agent treatments (P=0.0496). During the driest year, 2012, wetting
agent resulted in significant increases in visual quality, especially on the 30% ET treatment. Year
significantly affected average visual quality (P<0.0001), and is most likely attributed to
management over time. A significant mowing x year interaction was observed (P=0.0003), and
is hypothesized to be due directly to the weather of 2012. Daily averages of visual quality did
not differ with wetting agent treatment in 2010 or 2011. Data shows visual quality is
maintained in creeping bentgrass putting greens with long-term use of wetting agent, especially
during periods of heat and drought stress.

44

Table 9.1. 2010 main effects and mean squares for treatment effects of irrigation, mowing, and wetting agent on visual quality (1-9)
at the Hancock Turfgrass Research Center in East Lansing, MI.

Irrigation (IRR)
30% ET
60% ET
90% ET
Significance
LSD (0.05)
Mowing (MOW)
1X daily
2X daily
Significance
LSD (0.05)
Wet-Agent (WA)
Untreated
1X monthly
Significance
LSD (0.05)

19 July
5.25
5.92
6.08
NS
NS

27 July
4.50
5.58
5.92
NS
NS

6.39a
5.11b
***
0.61

5.61a
5.06b
*
0.48

6.06a
5.44b
*
0.61

5.44
5.22
NS
NS

Average Visual Quality (1-9)
2010
3 Aug
4.25b
5.50a
6.08a
*
1.19
5.39
5.17
NS
NS
5.50
5.06
NS
NS
Mean Square and Pr>F

10 Aug
4.25b
5.83a
6.17a
*
1.01

16 Aug
5.58
6.42
6.83
NS
NS

23 Aug
3.92
5.17
5.67
NS
NS

5.28
5.56
NS
NS

6.22
6.33
NS
NS

4.61
5.22
NS
NS

5.61
5.22
NS
NS

6.39
6.17
NS
NS

4.94
4.89
NS
NS

Source
df
Replication
2
9.33
0.0004
6.08
0.0003
15.86
<.0001
9.33
0.0001
IRR
2
2.33
0.1634
6.58
0.2404
10.53
0.0304 12.58
0.0125
Error for IRR
4
0.79
0.4068
3.16
0.0017
1.11
0.1325
0.79
0.3020
MOW
1
14.69
0.0003
2.77
0.0260
0.44
0.3790
0.69
0.2969
WA
1
3.36
0.0485
0.44
0.3448
1.78
0.0880
1.36
0.1500
IRRxMOW
2
0.77
0.3747
0.53
0.3487
4.53
0.0028
1.19
0.1664
IRRxWA
2
3.11
0.0330
0.36
0.4800
0.19
0.7053
1.02
0.2094
MOWxWA
1
0.03
0.8495
0.11
0.6335
0.11
0.6574
0.03
0.8323
IRRxMOWxWA
2
0.44
0.5633
0.19
0.6686
0.19
0.7053
0.19
0.7280
Error
18
0.75
0.47
0.55
0.60
*, **, *** Significant at the 0.05, 0.01, and 0.001 probability levels, respectively.
† NS, non-significant at the 0.05 level.
‡ Within columns, means followed by the same letter are not significantly different according to LSD (0.05).

45

9.53
4.86
1.11
0.11
0.44
0.86
1.02
0.00
0.25
0.40

<.0001
0.0984
0.0578
0.6038
0.3047
0.1440
0.1034
1.0000
0.5450

2.08
9.75
3.21
3.36
0.03
0.36
0.19
0.03
0.36
0.50

0.0326
0.1575
0.0022
0.0184
0.8163
0.4992
0.6834
0.8163
0.4992

Table 9.2. 2010 main effects and mean squares for treatment effects of irrigation, mowing, and wetting agent on visual quality (1-9)
at the Hancock Turfgrass Research Center in East Lansing, MI.

Irrigation (IRR)
30% ET
60% ET
90% ET
Significance
LSD (0.05)
Mowing (MOW)
1X daily
2X daily
Significance
LSD (0.05)
Wet-Agent (WA)
Untreated
1X monthly
Significance
LSD (0.05)

31 August
5.33
7.17
7.50
NS
NS

Average Visual Quality (1-9)
2010
7 Sept
14 Sept
6.50
6.08
7.25
7.00
7.50
7.67
NS
NS
NS
NS

20 Sept
5.33b
6.50a
6.75a
**
0.60

29 Sept
5.75b
6.42a
6.83
**
0.46

6.67
6.67
NS
NS

6.67b
7.50a
***
0.40

5.89b
6.50a
***
0.29

6.00b
6.67a
**
0.40

6.72
6.61
NS
NS

7.11
7.06
NS
NS

6.11
6.28
NS
NS

6.28
6.39
NS
NS

6.83
7.00
NS
NS
7.00
6.83
NS
NS
Mean Square and Pr>F

Source
df
Replication
2
2.08
0.0292
3.00
0.0017
6.58
<.0001
0.53
0.0751
IRR
2
16.33
0.0649
3.25
0.2870
7.58
0.0554
6.86
0.0056
Error for IRR
4
2.79
0.0035
1.88
0.0036
1.17
0.0430
0.28
0.2228
MOW
1
0.00
1.0000
6.25
0.0004
0.25
0.4277
3.36
0.0004
WA
1
0.11
0.6367
0.03
0.7730
0.25
0.4277
0.25
0.2487
IRRxMOW
2
0.33
0.5133
0.08
0.7761
1.75
0.0242
0.36
0.1574
IRRxWA
2
2.11
0.0281
0.03
0.9182
0.08
0.8050
0.08
0.6302
MOWxWA
1
0.11
0.6367
0.25
0.3913
0.03
0.7899
0.03
0.6958
IRRxMOWxWA
2
0.11
0.7962
0.08
0.7761
0.36
0.4049
0.03
0.8551
Error
18
0.48
0.32
0.38
0.18
*, **, *** Significant at the 0.05, 0.01, and 0.001 probability levels, respectively.
† NS, non-significant at the 0.05 level.
‡ Within columns, means followed by the same letter are not significantly different according to LSD (0.05).

46

0.08
3.58
0.16
4.00
0.11
0.25
0.36
0.11
0.36
0.32

0.7761
0.0072
0.7262
0.0025
0.5655
0.4770
0.3498
0.5655
0.3498

Table 10.1. 2011 main effects and mean squares for treatment effects of irrigation, mowing, and wetting agent on visual quality (1-9)
at the Hancock Turfgrass Research Center in East Lansing, MI.

Irrigation (IRR)
30% ET
60% ET
90% ET
Significance
LSD (0.05)
Mowing (MOW)
1X daily
2X daily
Significance
LSD (0.05)
Wet-Agent (WA)
Untreated
1X monthly
Significance
LSD (0.05)

Average Visual Quality (1-9)
2011
1 June
6 June
6.92
7.50
7.33
6.92
7.17
7.25
NS
NS
NS
NS

14 June
8.25
8.08
8.25
NS
NS

21 June
8.67
8.75
8.83
NS
NS

8.61a
7.33b
***
0.30

7.11
7.17
NS
NS

8.61a
7.78b
**
0.52

9.00a
8.50b
**
0.29

7.72b
8.22a
**
0.30

7.78
8.00a
6.50
6.44b
***
***
0.42
0.39
Mean Square and Pr>F

8.33
8.06
NS
NS

8.78
8.72
NS
NS

23 May
7.83
8.08
8.00
NS
NS

7.56a
6.89b
**
0.39

Source
df
Replication
2
0.19 0.3704
1.19 0.0561
0.03
0.9135 0.86
0.2393
0.08
IRR
2
0.19 0.5017
0.53 0.5071
1.03
0.1231 0.11
0.8646
0.08
Error for IRR
4
0.24 0.3164
0.65 0.1623
0.28
0.4796 0.74
0.2986
0.17
MOW
1 14.69 <.0001
0.03 0.7819
4.00
0.0020 6.25
0.0035
2.25
WA
1
2.25 0.0026 14.69 <.0001 21.77
<.0001 0.69
0.2783
0.03
IRRxMOW
2
0.03 0.8618
0.03 0.9244
0.08
0.7644 2.33
0.0318
0.08
IRRxWA
2
0.25 0.2843
0.03 0.9244
0.53
0.2060 0.11
0.8205
0.03
MOWxWA
1
0.25 0.2605
0.03 0.7819
0.44
0.2434 0.25
0.5109
0.03
IRRxMOWxWA
2
0.08 0.6446
0.53 0.2497
0.03
0.9135 0.33
0.5594
0.03
Error
18
0.19
0.35
0.31
0.56
0.18
*, **, *** Significant at the 0.05, 0.01, and 0.001 probability levels, respectively.
† NS, non-significant at the 0.05 level.
‡ Within columns, means followed by the same letter are not significantly different according to LSD (0.05).

47

0.6302
0.6400
0.4596
0.0022
0.6958
0.6302
0.8551
0.6958
0.8551

Table 10.2. 2011 main effects and mean squares for treatment effects of irrigation, mowing, and wetting agent on visual quality (1-9)
at the Hancock Turfgrass Research Center in East Lansing, MI.

Irrigation (IRR)
30% ET
60% ET
90% ET
Significance
LSD (0.05)
Mowing (MOW)
1X daily
2X daily
Significance
LSD (0.05)
Wet-Agent (WA)
Untreated
1X monthly
Significance
LSD (0.05)

27 June
8.42
8.25
8.58
NS
NS

5 July
7.50
8.58
8.50
NS
NS

8.78a
8.06b
***
0.31

8.11
8.28
NS
NS

8.44
8.39
NS
NS

8.22
8.17
NS
NS

Average Visual Quality (1-9)
2011
12 July
19 July
8.17
6.83
8.83
8.42
8.75
8.33
NS
NS
NS
NS
8.83a
8.33b
**
0.29

7.94
7.78
NS
NS

8.50
7.61b
8.67
8.11a
NS
*
NS
0.49
Mean Square and Pr>F

25 July
7.33
7.92
8.08
NS
NS

4 August
7.17
6.92
6.50
NS
NS

7.78
7.78
NS
NS

6.61
7.11
NS
NS

7.50b
8.06a
*
0.47

6.94
6.78
NS
NS

Source
df
Replication
2 1.00
0.0171 0.36
0.3294 0.58 0.0594 1.03 0.1473 2.53
IRR
2 0.33
0.7257 4.36
0.1139 1.58 0.1189 9.53 0.0565 1.86
Error for IRR
4 0.96
0.0073 1.11
0.0243 0.42 0.0913 1.49 0.0424 1.36
MOW
1 4.69
0.0001 0.25
0.3777 2.25 0.0022 0.25 0.4804 0.00
WA
1 0.03
0.7099 0.03
0.7665 0.25 0.2487 2.25 0.0444 2.78
IRRxMOW
2 0.11
0.5746 0.08
0.7644 0.08 0.6302 0.58 0.3209 0.58
IRRxWA
2 0.78
0.0365 0.53
0.2060 0.08 0.6302 0.25 0.6036 0.19
MOWxWA
1 0.03
0.7099 0.25
0.3777 0.03 0.6958 0.03 0.8129 0.11
IRRxMOWxWA
2 0.11
0.5746 0.25
0.4570 0.36 0.1574 2.19 0.0250 0.69
Error
18 0.19
0.31
0.18
0.48
0.45
*, **, *** Significant at the 0.05, 0.01, and 0.001 probability levels, respectively.
† NS, non-significant at the 0.05 level.
‡ Within columns, means followed by the same letter are not significantly different according to LSD (0.05).

48

0.0131
0.3528
0.0464
1.0000
0.0235
0.3007
0.6579
0.6267
0.2433

6.19
1.36
2.36
2.25
0.25
0.58
0.08
0.69
0.86
0.53

0.0005
0.6026
0.0110
0.0537
0.5001
0.3526
0.8551
0.2664
0.2233

Table 10.3. 2011 main effects and mean squares for treatment effects of irrigation, mowing, and wetting agent on visual quality (1-9)
at the Hancock Turfgrass Research Center in East Lansing, MI.

Irrigation (IRR)
30% ET
60% ET
90% ET
Significance
LSD (0.05)
Mowing (MOW)
1X daily
2X daily
Significance
LSD (0.05)
Wet-Agent (WA)
Untreated
1X monthly
Significance
LSD (0.05)

10 August
7.33
6.75
6.75
NS
NS

Average Visual Quality (1-9)
2011
15 August
22 August
7.08
7.42
6.25
6.33
6.00
6.33
NS
NS
NS
NS

6.39b
7.50a
***
0.49

5.55b
7.33a
***
0.48

5.61b
7.78a
***
0.68

7.17
6.72
NS
NS

6.78a
7.06a
6.11
6.33b
**
*
0.48
0.68
Mean Square and Pr>F

29 August
8.67
8.58
8.25
NS
NS
8.00b
9.00a
***
0.22
8.55
8.44
NS
NS

Source
df
Replication
2
0.78
0.2323
4.19
0.0021
0.19
0.8142
0.00
1.0000
IRR
2
1.36
0.1382
3.86
0.3648
4.69
0.2184
0.58
0.1736
Error for IRR
4
0.40
0.5287
2.94
0.0025
2.03
0.1140
0.21
0.1308
MOW
1 11.11
0.0002 28.44
<.0001 42.25
<.0001
9.00
<.0001
WA
1
1.78
0.0731
4.00
0.0093
4.69
0.0379
0.11
0.3101
IRRxMOW
2
0.36
0.4930
1.86
0.0381
1.58
0.2120
0.58
0.0119
IRRxWA
2
0.19
0.6786
0.08
0.8397
0.03
0.9708
0.19
0.1770
MOWxWA
1
1.00
0.1706
1.78
0.0682
0.25
0.6114
0.11
0.3101
IRRxMOWxWA
2
0.08
0.8452
0.19
0.6686
0.25
0.7684
0.19
0.1770
Error
18
0.73
0.47
0.94
0.10
*, **, *** Significant at the 0.05, 0.01, and 0.001 probability levels, respectively.
† NS, non-significant at the 0.05 level.
‡ Within columns, means followed by the same letter are not significantly different according to LSD (0.05).

49

Table 11.1. 2012 main effects and mean squares for treatment effects of irrigation, mowing, and wetting agent on visual quality (1-9)
at the Hancock Turfgrass Research Center in East Lansing, MI.

Irrigation (IRR)
30% ET
60% ET
90% ET
Significance
LSD (0.05)
Mowing (MOW)
1X daily
2X daily
Significance
LSD (0.05)
Wet-Agent (WA)
Untreated
1X monthly
Significance
LSD (0.05)

8 May
7.83
7.67
7.42
NS
NS

17 May
7.42
7.33
7.33
NS
NS

8.00a
7.28b
**
0.51

7.56
7.17
NS
NS

7.56
7.72
NS
NS

7.22
7.50
NS
NS

Average Visual Quality (1-9)
2012
24 May
30 May
7.83
7.33
8.33
7.92
8.33
7.92
NS
NS
NS
NS
8.39
7.94
NS
NS
7.83b
8.50a
**
0.48
Mean Square and Pr>F

6 June
7.17
7.83
7.67
NS
NS

13 June
6.42
7.92
7.33
NS
NS

7.89
7.56
NS
NS

8.06a
7.06b
***
0.39

7.83a
6.61b
***
0.52

7.50
7.94
NS
NS

7.50
7.61
NS
NS

6.83b
7.61a
*
0.52

Source
df
Replication
2 0.11
0.8150
0.86
0.2445
0.08
0.8397
0.78
0.3242
IRR
2 0.53
0.1800
0.03
0.9512
1.00
0.3906
1.36
0.3120
Error for IRR
4 0.19
0.8323
0.69
0.3334
0.83
0.1800
0.86
0.2974
MOW
1 4.69
0.0084
1.36
0.1380
1.78
0.0682
1.00
0.2301
WA
1 0.25
0.5037
0.69
0.2821
4.00
0.0093
1.78
0.1150
IRRxMOW
2 0.19
0.7012
0.03
0.9521
0.11
0.7927
0.08
0.8802
IRRxWA
2 0.25
0.6352
0.53
0.4111
0.33
0.5068
0.36
0.5824
MOWxWA
1 0.03
0.8227
0.25
0.5143
0.11
0.6335
0.00
1.0000
IRRxMOWxWA
2 0.36
0.5228
0.08
0.8639
0.11
0.7927
0.08
0.8802
Error
18 0.54
0.56
0.47
0.65
*, **, *** Significant at the 0.05, 0.01, and 0.001 probability levels, respectively.
† NS, non-significant at the 0.05 level.
‡ Within columns, means followed by the same letter are not significantly different according to LSD (0.05).

50

2.03
1.44
0.61
9.00
0.11
0.33
0.11
0.00
1.00
0.31

0.0069
0.2101
0.1377
<.0001
0.5540
0.3571
0.7001
1.0000
0.0613

0.36
6.86
1.19
13.44
5.44
1.03
2.53
0.00
0.58
0.55

0.5284
0.0667
0.1117
0.0001
0.0055
0.1811
0.0239
1.0000
0.3646

Table 11.2. 2012 main effects and mean squares for treatment effects of irrigation, mowing, and wetting agent on visual quality (1-9)
at the Hancock Turfgrass Research Center in East Lansing, MI.

Irrigation (IRR)
30% ET
60% ET
90% ET
Significance
LSD (0.05)
Mowing (MOW)
1X daily
2X daily
Significance
LSD (0.05)
Wet-Agent (WA)
Untreated
1X monthly
Significance
LSD (0.05)

21 June
5.50b
8.00a
7.83a
*
1.36

27 June
5.17b
8.33a
8.67a
**
1.70

7.56a
6.67b
**
0.62

7.72a
7.06b
*
0.52

6.33b
7.89a
***
0.62

6.67b
8.11
***
0.52

Average Visual Quality (1-9)
2012
2 July
11 July
5.00b
2.50b
7.92a
7.67a
8.42a
8.75a
**
***
1.40
1.302
7.44a
6.78b
*
0.55
6.22b
8.00a
***
0.55
Mean Square and Pr>F

19 July
3.58b
7.67a
8.25a
***
1.16

31 July
3.83b
7.75a
8.25a
***
1.10

6.78a
5.83b
**
0.61

6.50
6.50
NS
NS

6.72
6.50
NS
NS

5.72b
6.89a
***
0.61

5.56b
7.44a
***
0.57

5.44b
7.78a
***
0.53

Source
df
Replication
2
1.69
0.1451
0.53
0.4053
0.11
0.8353
0.19
0.7768
0.33
IRR
2 23.44
0.0120 44.78
0.0082 40.86
0.0048 133.86 0.0004 77.58
Error for IRR
4
1.44
0.1660
2.24
0.0167
1.53
0.0790
1.32
0.1856
1.04
MOW
1
7.11
0.0076
4.00
0.0152
4.00
0.0197
8.03
0.0044
0.00
WA
1 21.78
<.0001 18.78
<.0001 28.44
<.0001
12.25
0.0008 32.11
IRRxMOW
2
0.44
0.5783
0.33
0.5594
0.08
0.8734
1.69
0.1362
3.25
IRRxWA
2
8.44
0.0009
8.11
0.0002 11.19
<.0001
1.08
0.2660
4.19
MOWxWA
1
0.00
1.0000
1.78
0.0905
4.00
0.0197
0.03
0.8505
0.00
IRRxMOWxWA
2
0.33
0.6611
0.78
0.2722
1.75
0.0832
0.36
0.6291
0.08
Error
18
0.79
0.55
0.61
0.76
0.66
*, **, *** Significant at the 0.05, 0.01, and 0.001 probability levels, respectively.
† NS, non-significant at the 0.05 level.
‡ Within columns, means followed by the same letter are not significantly different according to LSD (0.05).

51

0.6106
0.0007
0.2214
1.0000
<.0001
0.0194
0.0080
1.0000
0.8817

1.19
70.19
0.94
0.44
49.00
0.19
4.75
1.78
0.19
0.58

0.1580
0.0007
0.2127
0.3942
<.0001
0.7209
0.0030
0.0979
0.7209

Table 11.3. 2012 main effects and mean squares for treatment effects of irrigation, mowing, and wetting agent on visual quality (1-9)
at the Hancock Turfgrass Research Center in East Lansing, MI.

Irrigation (IRR)
30% ET
60% ET
90% ET
Significance
LSD (0.05)
Mowing (MOW)
1X daily
2X daily
Significance
LSD (0.05)
Wet-Agent (WA)
Untreated
1X monthly
Significance
LSD (0.05)

Average Visual Quality (1-9)
2012
8 August
14 August
2.92b
5.00b
7.08a
7.08a
8.08a
8.25a
**
**
1.71
1.22

22 August
5.75b
7.75a
8.50a
*
1.91

6.22
5.83
NS
NS

7.39
7.28
NS
NS

4.72b
7.33a
***
0.62

7.06a
6.50b
*
0.50
5.61b
7.94a
***
0.50
Mean Square and Pr>F

6.50b
8.17a
***
0.74

Source
df
Replication
2
3.44
0.0273
0.03
0.9480
1.58
0.2691
IRR
2 90.11
0.0023 32.53
0.0044
24.25
0.0359
Error for IRR
4
2.28
0.0500
1.15
0.1072
2.83
0.0766
MOW
1
1.36
0.2024
2.78
0.0327
0.11
0.7564
WA
1 61.36
<.0001 49.00
<.0001
25.00
0.0002
IRRxMOW
2
0.78
0.3874
0.53
0.3812
0.53
0.6318
IRRxWA
2
2.78
0.0494
7.58
0.0002
6.08
0.0143
MOWxWA
1
0.25
0.5778
0.44
0.3668
0.00
1.0000
IRRxMOWxWA
2
0.33
0.6579
0.36
0.5113
0.25
0.8022
Error
18
0.78
0.52
1.12
*, **, *** Significant at the 0.05, 0.01, and 0.001 probability levels, respectively.
† NS, non-significant at the 0.05 level.
‡ Within columns, means followed by the same letter are not significantly different according to LSD (0.05).

52

Table 12.1. 2010-2012 visual quality as affected by irrigation and wetting agent† (WA) at the Hancock Turfgrass Research
Center in East Lansing, MI.
19 July 2010
31 Aug 2010
27 June 2011
13 June 2012
No WA
WA
No WA
WA
No WA
WA
No WA
5.0c
5.7c
5.0c
8.7a
8.2ab
7.3a
5.5b
6.3ab
6.7b
7.7a
8.0b
8.5ab
8.0a
7.8a
6.8a
7.5ab
7.5ab
8.5ab
8.7a
7.5a
7.2a
1.05
0.84
0.53
0.90
1.49
1.19
0.76
1.27
21 June 2012
27 June 2012
2 July 2012
19 July 2012
Irrigation
WA
No WA
WA
No WA
WA
No WA
WA
No WA
30% ET
7.2b
3.8c
6.8b
3.5c
7.0c
3.0d
5.2c
2.0d
60% ET
8.7a
7.3b
8.7a
8.0a
8.3ab
7.5bc
8.5a
6.8b
90% ET
7.8ab
7.8ab
8.8a
8.5a
8.7a
8.2ab
8.7a
7.8a
LSD (0.05)‡
1.08
0.90
0.95
0.98
LSD (0.05)§
1.52
1.28
1.34
1.39
31 July 2012
8 Aug 2012
14 Aug 2012
22 Aug 2012
Irrigation
WA
No WA
WA
No WA
WA
No WA
WA
No WA
30% ET
5.7d
2.0e
4.5c
1.3d
7.0b
3.0d
7.3bc
4.2d
60% ET
8.8a
6.7c
8.7a
5.5c
8.2a
6.0c
8.5ab
7.0c
90% ET
8.8a
7.7b
8.8a
7.3b
8.7a
7.8ab
8.7a
8.3ab
LSD (0.05)‡
0.93
1.07
0.87
1.28
LSD (0.05)§
1.31
1.51
1.24
1.82
† Wetting agent was applied monthly from May till September with Revolution® from Aquatrols, Inc. (Paulsboro, N.J) at 1.87-ml/m2.
‡ Between wetting agent means at same irrigation level on the single date listed above.
§ Among irrigation level at the same or different wetting agent on the single date listed above.
Irrigation
30% ET
60% ET
90% ET
LSD (0.05)‡
LSD (0.05)§

WA
5.5bc
5.5bc
5.3bc

53

Table 12.2. 2010-2012 visual quality as affected by irrigation and mowing† (MOW) at the Hancock Turfgrass Research Center
in East Lansing, MI.
3 Aug 2010
14 Sep 2010
1X MOW
2X MOW
1X MOW
2X MOW
4.8c
3.7d
4.8d
5.8c
5.8ab
5.2bc
6.3bc
6.7ab
5.5bc
6.7a
6.5ab
7.0a
0.90
0.75
1.27
1.06
14 June 2011
15 Aug 2011
29 Aug 2011
Irrigation
1X MOW
2X MOW
1X MOW
2X MOW
1X MOW
2X MOW
30% ET
9.0a
7.5b
6.5b
7.7a
8.3b
9.0a
60% ET
8.7a
7.5b
5.5c
7.0ab
8.2b
9.0a
90% ET
8.2ab
8.3ab
4.7c
7.3ab
7.5c
9.0a
LSD (0.05)‡
0.90
0.83
0.39
LSD (0.05)§
1.28
1.18
0.55
19 July 2012
Irrigation
1X MOW
2X MOW
30% ET
4.2c
3.0d
60% ET
7.5b
7.8ab
90% ET
7.8ab
8.7a
LSD (0.05)‡
0.98
LSD (0.05)§
1.39
† Mowing was applied six days per week from May till September at 0.3175-cm.
‡ Between mowing means at same irrigation level on the single date listed above.
§ Among irrigation level at the same or different mowing on the single date listed above.
Irrigation
30% ET
60% ET
90% ET
LSD (0.05)‡
LSD (0.05)§

54

Figure 4. Irrigation Effects on Visual Quality in 2010-12. Values are averages of mowing and wetting agent for each irrigation
treatment. Error bars represent least significant difference (LSD) using Fisher’s Protected Method. Overlapping error bars
represent statistically similar treatments at α=0.05. N=3.

55

Figure 5. Mowing effects on visual quality 2010-12. Values are averaged over irrigation and wetting agent for each mowing
treatment. Error bars represent least significant difference (LSD) using Fisher’s Protected Method. Overlapping error bars
represent statistically similar treatments at α=0.05. N=3.

56

Reduction in irrigation amounts combined with physiological stresses of daily double
mowing is believed to cause increased occurrence of localized dry spots (LDS). Analysis of
variance means for each date of localized dry spot (LDS) as affected by irrigation, mowing, and
wetting agent are shown in Tables 13 through 14.2. Interactions, if observed, are shown in
Table 15.
From 2010-12, LDS was observed on one, three, and 10 days in each year, respectively.
In 2010 and 2012, LDS was significantly higher in 30% ET treatments when compared to 60 and
90% ET (P=0.0111). Average LDS observations for daily occurrences due to irrigation in 2010-12
are presented in Figure 6 A, and shows irrigation regime significantly effected LDS counts in
2010 and 2012. 2011 was a wet year in terms of rainfall (See Appendix A), and mean separation
did not occur on any date. For the one date in 2010, LDS showed statistically different (P≤0.05)
average occurrences of 12, 9, and 7 in 30, 60, and 90% ET plots, respectively. Averaged across
all dates in 2012, LDS showed statistically different (P≤0.05) average occurrences of 12, 3, and 2
in 30, 60, and 90% ET plots, respectively. In 2010 and 2012, watering to 60 or 90% ET were
statistically similar, and significantly decreased LDS occurrence compared to the 30% regime.
Average LDS count for daily occurrences due to wetting agent in 2010-12 are presented
in Figure 6(B), and show application of a wetting agent to significantly reduce LDS occurrence in
2012 (P≤0.05). 2012 was the hottest and driest of the three years (See Appendix A), and shows
that wetting agent application may go unnoticed on flat topography in fine textured soils even
when maintained at 0.3175 cm in terms occurrence until conditions favoring LDS are present. In
2010 or 2011, mild seasons with more precipitation did not allow for mean separation.

57

With proper irrigation and application of a wetting agent in 2010-11, daily double
mowing maintained playability without detrimental effects to the turfgrass physiology. In 2012,
LDS occurrence averages significantly (P≤0.05) increased from 4.8 to 6.1 counts per plot for
single versus double mowing, respectively (Tables 24.1 and 24.2).

58

Table 13. 2010-2011 main effects and mean squares for treatment effects of irrigation, mowing, and wetting agent on localized dry
spot (LDS) observed at the Hancock Turfgrass Research Center in East Lansing, MI.

Irrigation (IRR)
30% ET
60% ET
90% ET
Significance
LSD (0.05)
Mowing (MOW)
1X daily
2X daily
Significance
LSD (0.05)
Wet-Agent (WA)
Untreated
1X monthly
Significance
LSD (0.05)

27 July 10
11.92
9.25
7.08
NS
NS

Average LDS (count per plot)
2010 & 2011
22 June 11
5 July 11
0.17
3.58
0.25
1.92
0.33
2.67
NS
NS
NS
NS

19 Aug 11
1.83
1.33
1.25
NS
NS

25 Aug 11
1.33
1.25
1.33
NS
NS

9.22
9.61
NS
NS

0.28
0.22
NS
NS

1.39
1.56
NS
NS

1.28
1.33
NS
NS

9.22
9.61
NS
NS

0.39
0.11
NS
NS

1.78b
1.17a
*
0.58

1.50
1.11
NS
NS

3.05
2.39
NS
NS
2.61
2.83
NS
NS
Mean Square and Pr>F

Source
df
Replication
2 206.08
0.0002
0.58
0.1770
1.36
0.3898 0.03
0.9598
IRR
2
70.33
0.1780
0.08
0.8858
8.36
0.2582 1.19
0.7961
Error for IRR
4
25.67
0.1782
0.67
0.1123
4.32
0.0396 4.94
0.0011
MOW
1
1.36
0.7626
0.03
0.7665
4.00
0.1047 0.25
0.5507
WA
1
1.36
0.7626
0.69
0.1490
0.44
0.5761 3.36
0.0387
IRRxMOW
2
24.78
0.2086
0.19
0.5407
1.58
0.3372 2.08
0.0706
IRRxWA
2
6.78
0.6335
0.19
0.5407
2.69
0.1689 0.53
0.4729
MOWxWA
1
8.03
0.4660
0.03
0.7665
5.44
0.0616 0.03
0.8416
IRRxMOWxWA
2
3.44
0.7906
0.86
0.0861
1.69
0.3139 0.86
0.3038
Error
18
14.47
0.31
1.37
0.68
*, **, *** Significant at the 0.05, 0.01, and 0.001 probability levels, respectively.
† NS, non-significant at the 0.05 level.
‡ Within columns, means followed by the same letter are not significantly different according to LSD (0.05).

59

1.69
0.03
0.49
0.03
1.36
0.86
1.36
0.03
0.19
0.67

0.1066
0.9452
0.5837
0.8405
0.1702
0.2991
0.1588
0.8405
0.7505

Table 14.1. 2012 main effects and mean squares for treatment effects of irrigation, mowing, and wetting agent on localized dry spot
(LDS) observed at the Hancock Turfgrass Research Center in East Lansing, MI.

Irrigation (IRR)
30% ET
60% ET
90% ET
Significance
LSD (0.05)
Mowing (MOW)
1X daily
2X daily
Significance
LSD (0.05)
Wet-Agent (WA)
Untreated
1X monthly
Significance
LSD (0.05)

13 June
2.17
0.75
0.33
NS
NS

Average LDS (count per plot)
2012
21 June
27 June
3.50
6.25b
1.25
0.92a
0.75
0.67a
NS
*
NS
4.47

2 July
7.83b
1.75a
0.42a
*
4.34

11 July
17.33b
2.25a
1.08a
*
12.50

0.61
1.56
NS
NS

1.44
2.22
NS
NS

2.67
4.00
NS
NS

5.72
8.06
NS
NS

2.00b
0.17a
**
1.17

3.61b
0.06a
***
1.53

6.22b
0.44a
***
1.40

10.56b
3.22a
***
2.45

2.39
2.83
NS
NS
5.00b
0.22a
***
1.52
Mean Square and Pr>F

Source
df
Replication
2
4.00
0.2651
6.75
0.2692
9.03
0.1767
6.33 0.2326
IRR
2 11.08
0.2289
25.75
0.2251 119.36
0.0428 187.58 0.0183
Error for IRR
4
5.08
0.1694
11.63
0.0850
15.57
0.0341
14.67 0.0236
MOW
1
8.03
0.1074
5.44
0.2999
1.78
0.5472
16.00 0.0608
WA
1 30.25
0.0041
113.78
0.0001 205.44
<.0001 300.44 <.0001
IRRxMOW
2
1.19
0.6588
3.36
0.5080
0.19
0.9597
6.58 0.2206
IRRxWA
2 12.25
0.0282
22.53
0.0226
92.03
<.0001 122.69 <.0001
MOWxWA
1
6.25
0.1522
7.11
0.2382
7.11
0.2356
21.78 0.0314
IRRxMOWxWA
2
3.25
0.3352
4.69
0.3936
0.86
0.8348
10.36 0.1026
Error
18
2.80
4.78
4.72
4.00
*, **, *** Significant at the 0.05, 0.01, and 0.001 probability levels, respectively.
† NS, non-significant at the 0.05 level.
‡ Within columns, means followed by the same letter are not significantly different according to LSD (0.05).

60

45.03
985.86
121.57
49.00
484.00
31.58
148.08
1.00
1.58
12.28

0.0461
0.0391
0.0002
0.0611
<.0001
0.1041
0.0005
0.7786
0.8798

Table 14.2. 2012 main effects and mean squares for treatment effects of irrigation, mowing, and wetting agent on localized dry spot
(LDS) observed at the Hancock Turfgrass Research Center in East Lansing, MI.

Irrigation (IRR)
30% ET
60% ET
90% ET
Significance
LSD (0.05)
Mowing (MOW)
1X daily
2X daily
Significance
LSD (0.05)
Wet-Agent (WA)
Untreated
1X monthly
Significance
LSD (0.05)

19 July
18.67b
4.17a
2.75a
*
13.05
7.44
9.61
NS
NS
14.44b
2.61a
***
3.12

Average LDS (count per plot)
2012
31 July
8 Aug
23.33b
30.42b
2.50a
6.25a
3.08a
2.67a
*
*
14.53
15.59
9.56
9.72
NS
NS

12.56
13.67
NS
NS

17.06b
21.61b
2.22a
4.61a
***
***
3.54
4.66
Mean Square and Pr>F

14 Aug
9.58b
2.00a
0.67a
*
7.15

22 Aug
4.33
2.42
0.42
NS
NS

3.44
4.72
NS
NS

2.11
2.67
NS
NS

7.17b
1.00a
***
2.80

4.50b
0.28a
***
1.39

Source
df
Replication
2
16.03 0.4623
16.44
0.5363
65.53 0.2547
19.08 0.3255
5.44
IRR
2
931.19 0.0490 1688.86 0.0265 2733.86 0.0148 277.58 0.0496
46.03
Error for IRR
4
132.44 0.0018
164.24
0.0021
189.07 0.0134
39.79 0.0797
18.15
MOW
1
42.25 0.1623
0.25
0.9222
11.11 0.6228
14.69 0.3500
2.78
WA
1 1260.25 <.0001 1980.25 <.0001 2601.00 <.0001 342.25 0.0002 160.44
IRRxMOW
2
33.08 0.2175
18.08
0.5052
28.03 0.5431
8.03 0.6130
2.86
IRRxWA
2
237.25 0.0005
771.08
<.0001
683.58 0.0001 173.08 0.0008
29.36
MOWxWA
1
12.25 0.4429
1.36
0.8199
0.11 0.9606
4.69 0.5943
0.00
IRRxMOWxWA 2
10.58 0.5965
22.86
0.4253
12.19 0.7628
0.53 0.9675
0.08
Error
18
19.90
25.49
44.37
15.96
3.95
*, **, *** Significant at the 0.05, 0.01, and 0.001 probability levels, respectively.
† NS, non-significant at the 0.05 level.
‡ Within columns, means followed by the same letter are not significantly different according to LSD (0.05).

61

0.2777
0.1944
0.0099
0.4129
<.0001
0.4986
0.0044
1.0000
0.9792

Table 15. 2012 localized dry spot (LDS) counts as affected by irrigation and wetting agent† (WA) at the Hancock Turfgrass
Research Center in East Lansing, MI.
2012
13 June
Irrigation
30% ET
60% ET
90% ET
LSD (0.05)‡
LSD (0.05)§

WA
0.2a
0.0a
0.3a

Irrigation
30% ET
60% ET
90% ET
LSD (0.05)‡
LSD (0.05)§

WA
9.7c
0.0a
0.0a

21 June
No WA
4.2b
1.5a
0.3a

WA
0.2a
0.0a
0.0a

2.03
2.87
11 July

27 June
No WA
6.8b
2.5a
1.5a

WA
0.7a
0.0a
0.0a

2.65
3.75
19 July
No WA
25.0d
4.5b
2.2ba

WA
7.7c
0.2ab
0.0a

2 July
No WA
11.8b
1.8a
1.3a

WA
1.3ab
0.0a
0.0a

2.64
3.73
31 July
No WA
29.7d
8.2c
5.5bc

WA
6.7b
0.0a
0.0a

4.25
6.01
14 August

No WA
14.3c
3.5b
0.8a
2.43
3.43
8 August

No WA
40.0c
5.0ab
6.2b

WA
13.5c
0.0a
0.3a

5.41
6.12
8.08
7.65
8.66
11.43
22 August
Irrigation
WA
No WA
WA
No WA
30% ET
2.2a
17.0b
0.8a
7.8c
60% ET
0.5a
3.5a
0.0a
4.8b
90% ET
0.3a
1.0a
0.0a
0.8a
LSD (0.05)‡
4.85
2.41
LSD (0.05)§
6.85
3.41
† Wetting agent was applied monthly from May till September with Revolution® from Aquatrols, Inc. (Paulsboro, N.J) at 1.87-ml/m2.
‡ Between wetting agent means at same irrigation level on the single date listed above.
§ Among irrigation level at the same or different wetting agent on the single date listed above.

62

No WA
47.3d
12.5bc
5.0ab

Figure 6. Irrigation (A) and Revolution® (B) effects on Localized Dry Spot (LDS) occurrence in
2010-12. (A) graph values are averaged over mowing and wetting agent for each irrigation
treatment. (B) graph values are averaged over irrigation and mowing for each wetting
agent treatment. Error bars represent least significant difference (LSD) using Fisher’s
Protected Method. Overlapping error bars represent statistically similar treatments at
α=0.05. N=12. (NS = not significant).

63

ET irrigation treatment level and wetting agent treatment are presented in Figure 7,
resulting in statistically significant reduction of LDS in 2012 (P<0.0001). Data shows with
addition of a wetting agent, LDS was significantly reduced for all levels of irrigation in 2012,
especially 60 and 90% ET replenishment (P≤0.05). Cumulative effects of wetting agent
applications over three years are shown with the results observed in 2012 averages.

Figure 7. Irrigation and Revolution® interaction and effects on localized dry spot (LDS) in 2012.
Values are averaged over treatments. Error bars represent least significant difference (LSD)
using Fisher’s Protected Method. Overlapping error bars represent statistically similar
treatments at α=0.05. N=3.

64

Percent organic matter (%OM) from soil samples averaged approximately 3% +/- 0.5 for
the duration of the study. Crenshaw is highly susceptible to Sclerotinia homeocarpa (dollar
spot), and counts were taken in the fall of each year after cessation of preventative fungicide
maintenance. This was performed to assure the putting green would be present for analysis of
all other factors, and did not show significant differences. Tissue tests were taken in the fall of
2011 for nutrient analysis. %OM, dollar spot counts, and tissue test analysis were performed at
P≤0.05 and no significant differences were observed (Data not shown).

65

CONCLUSIONS
Daily irrigation replenishment to 90% ET on native soil flat putting green in Michigan led
to no observed benefits to the turfgrass plant. It seems apparent that 90% ET may lead to
overwatering the putting surface and a waste of water. This is based upon data during the
driest season in history showing no measureable benefit to irrigating to 90% versus 60% ET
daily even at a height of cut (HOC) of 0.3175-cm.
30% ET irrigation replenishment was enough during early spring or late fall. In 2 of 3
successive years, irrigation to 30% ET provided acceptable turfgrass quality on a native soil nonpocketed flat putting green maintained at an HOC of 0.3175-cm. However, with proper
application of a wetting agent, plots irrigated to 30% ET provided aesthetic quality and
performance equal to those irrigated with twice the amount of water. Overall, the data
indicates ET irrigation replenishment can be a useful tool depending upon putting green slope,
topography, etc., but 100% ET is most likely not necessary for most locations.
Double mowing on a daily basis for three consecutive years yielded few of the
numerous negative consequences on turfgrass often prescribed to the practice while yielding
positive response to ball roll. This is based upon visual color, quality, disease, and %VWC via
TDR measurements. However, 2X mowing required use of a wetting agent to sustain acceptable
turfgrass quality levels at the 30% ET water replenishment in one of three years, and that was
during the driest season of the three.
The wetting agent Revolution® improved turfgrass quality during the driest season of
the three on plots irrigated with as little as 30% ET water replenishment. Additionally,
Revolution® had no observed negative impact on ball roll distance or playability. Combining

66

these two findings indicate that use of this product, and possibly other wetting agents, may
lead to improved putting conditions with minimal irrigation.
30% ET irrigation replenishment consistently showed less %VWC measured with a TDR
than 60 and 90% ET. 60 and 90% ET were often, if not always statistically the same. 90% ET
replenishment did not provide significantly better visual quality or performance to 60% ET,
which indicates water was most likely wasted and undue burden was placed upon the irrigation
system. Making widely generalized irrigation recommendations based upon ET measurements
is a poor idea. Additionally, TDR technology has improved immediate methods to measure
%VWC, but the user is advised that a great deal of variation exists, and individual comfort in the
instrumentation of the device will vary on a site by site basis mainly due to soil texture
differences.
This research warrants further investigations in creeping bentgrass or other species on
putting greens managed under United States Golf Association sand specifications.

67

CHAPTER TWO:
EFFECTS OF WATERING REGIME, MOWING, AND A WETTING AGENT
ON A ‘CRENSHAW’ AGROSTIS STOLONIFERA VAR. PALUSTRIS (CREEPING BENTGRASS)
PUTTING GREEN TOTAL MICROBIAL POPULATION & HYDROPHOBICITY
ABSTRACT
Microbial abundance is an indicator of good soil health as microorganisms are critical,
and may affect soil particles covered in hydrophobic substances. Microbial populations are
influenced by thatch, roots, and water levels in the soil. This study investigated treatment
effects of daily evapotranspiration (ET) irrigation regimes, daily mowing frequencies, and
monthly application of a wetting agent under golf course putting green management
conditions. Treatments were compared in a split-plot experimental design on the same plots
over three years. Total microbial biomass (TMB) data were determined by chloroform
fumigation incubation method (Jenkinson and Powlson, 1976). Soil hydrophobicity data were
determined by water drop penetration test (WDPT). Data on TMB and WDPT were measured
with cores taken at the end of each year.
No significant differences in TMB were observed in soils treated with 30, 60 , or 90% ET
daily irrigation from 2010 to 2012, with levels ranging from 29.9 to 60.1 μg g dry soil

-1

(Table

26). Daily double mowing and wetting agent application did not significantly affect TMB.
However, during the driest season of 2012, TMB was significantly increased with the use of
wetting agent at 30% ET replenishment (Table 27). Data obtained from water drop penetration
(WDP) tests resulted in significantly lower hydrophobicity in soil at the 0-1 cm depth below
plant and/or thatch with wetting agent applications in all years (8-18 seconds). No differences

68

were observed at sampling depths below 1 cm, and in response to irrigation or mowing
treatments. Soil hydrophobicity reductions were more responsive to wetting agent applications
than irrigation or mowing treatment effects.

69

INTRODUCTION
In production agriculture, healthy soils are defined as those with high levels of biological
activity where total microbial biomass (TMB) can directly affect nutrient availability from soil
organic matter (SOM), thus TMB is an effective indication of fertility and productivity in the
cropping system (Bending et al., 2004; Friedel et al., 2001; Nair and Ngouajio, 2012; Smith and
Paul, 1990). In soil, TMB is representative of the active pool of SOM present. Microbes in the
soil are often carbon (C) limited (Smith and Paul, 1990) and lower microbial biomass is generally
attributed to low organic C presence (Flie”bach and Mäder, 2000). The ideal microbe soil
environment mirrors plant needs including nutrients, moisture, organic matter, and pores filled
with air (Zuberer, 2012).
Microbes in USGA or native soil turfgrass putting green systems are abundant, are
affected by the environmental conditions, and possibly cultural and mechanical practices
created by managers (Zuberer, 2012). However, microbial putting green research is limited, and
no research has evaluated the cumulative effects over multiple years of irrigation, mowing, and
surfactant applications on a native soil putting green in relation to total microbial biomass
(TMB). This research investigated total microbial biomass (TMB) levels in response to irrigation
level, mowing frequency, wetting agent, turfgrass quality, and disease activity.
In regard to irrigation on turfgrass it appears inevitable that limitations and restrictions
on irrigation use will increase for years to come (Water Reports, 2006). Obviously, native soil
putting greens are more prone to anaerobic soil conditions compared to predominantly sand
root zones. Ideally, irrigation regimes should be based on scientific principles and research;

70

however, in most instances, intuition and experience are used to replenish water through
irrigation.
Managing water application rates by evapotranspiration (ET) through the onsite Enviroweather station (East Lansing / MSUHTRC) of the Michigan Agricultural Weather Network
(MAWN) provided a repeatable quantitative measurement of potential evapotranspiration
(PET), or daily water loss. Use of this technology may reduce risk of over-watering. Replenishing
irrigation water to 30, 60, and 90% of daily ET was studied for potential water conservation, and
effects on total soil microbial populations. ET based watering may allow managers to establish
acceptable baselines, which will reduce the potential for improper watering. It is hypothesized
ET based irrigation regimes effect on total microbial biomass (TMB) may promote or
compromise a healthy soil environment.
Double mowing compared to single mowing has be reported to have a negative
physiological effect on turfgrass plants (Beard, 1973), however, it is not known if this negative
impact is due to mechanical stress and if the degradation has an impact on TMB. Clippings
returned to the soil may provide a nutrient source for microbes through decomposition. While
clipping removal is normal on putting greens, an inevitable amount of clippings are not thrown
in the mower bucket. Daily double mowing may enhance clipping collection by picking up
missed clippings from the first pass. If this were true, it is possible that this reduction could be
reflected in disease incidence and/or TMB.
Past wetting agent research has focused upon localized dry spot (LDS), enhanced
infiltration, and its contribution to a more homogeneous wetting of the root zone (Oostindie,
et. al., 2010). Wetting agents also allow soil water and solutes to move less rapidly to the

71

subsoil and remain more accessible to the turf (Oostindie, et. al., 2010). However, wetting
agents have never been evaluated for their impact on soil microbial populations. A soil with
greater TMB indicates more potential from microbial biochemical activities. It seems possible
that wetting agent application could provide greater TMB under dry soil conditions and possible
decreased TMB under wet soil conditions.
Hydrophobic conditions due to soil texture, watering regimes, thatch, and organic
matter development reduce aesthetics and playing conditions on golf course putting greens
(DeBels and Soldat, 2010., McMillan et. al., 2012). While the origin of soil water repellency is
not well understood, it is generally accepted to be caused by organic compounds from roots or
microbes coating soil particles, whereas critical soil water content is dependent on soil
properties plus wetting and drying history of the area (Doerr et al., 2000, Larsbo et al., 2008).
Previous water drop penetration tests (WDPT) studies have shown water repellent soil is
prevalently found in the thatch and mat area (0 to 1 cm depth) of a turfgrass profile (McMillan
et. al., 2012). Localized dry spots (LDS) are one consequence of soil hydrophobic conditions on
turfgrass putting greens, but wetting agents have been shown to reduce repellency and
improve turfgrass quality (Cisar et al., 2000; Kostka, 2000; Larsbo et al., 2008). Research of the
effects wetting agents have on hydrophobic conditions in predominantly sand USGA
specification root zones are extensive (Cisar et al., 2000, DeBels and Soldat, 2010., Doerr et al.,
2000, Kostka, 2000, Larsbo et al., 2008, McMillan et. al., 2012), but native soil putting green
research is limited. An objective of this study was to evaluate LDS causing hydrophobic
conditions in response to three watering regimes, daily single and double mowing, and a
wetting agent on a native soil putting green.

72

The ability to provide water to a creeping bentgrass putting surface most efficiently
could be characterized by microbial abundance, visual quality, ball roll distance, and time
domain reflectometry (TDR) measurements. Presumption of soil health will be made based on
TMB and/or WDP tests, along with statistical significance regarding irrigation, mowing, and
wetting agent treatments.
Long-term research on the cumulative effects of daily ET irrigation, double mowing, and
use of a wetting agent are lacking. These management practices in varying combinations were
evaluated for efficacy by considering soil microbial populations, soil hydrophobicity, and
turfgrass quality.
Expected results from this study include watering levels will have a significant impact on
microbial populations. The aim of this research is to quantify the impact that different watering
regimes, mowing frequencies, and a wetting agent has on soil health and putting green quality.

73

MATERIALS & METHODS
Data for TMB and WDPT provide cumulative treatment effects on long-term soil health
and water repellency, respectively. Time of collections was annual, and is admittedly only a
snapshot into the total picture of seasonal fluctuations.
Research was conducted at the Hancock Turfgrass Research Center (HTRC) at Michigan
State University in East Lansing, Michigan, on a 1296-m2 (36 x 36 m) owosso-marlette sandy
loam native soil experimental putting green, seeded with creeping bentgrass (Agrostis
stolonifera var. palustris) ‘Crenshaw’ in 2003. The area comprises nine 148-m2 (12 x 12 m) plots.
In each plot Hunter PGP™ (Hunter Industries Inc., San Marcos, CA USA) irrigation heads were
installed on each corner. The nine plots were arranged in a randomized complete block design
with three replications of main plot evapotranspiration (ET) replenishment levels (30,60, and
90% daily ET). Daily ET data were determined by the onsite Enviro-weather station (East Lansing
/ MSUHTRC) of the Michigan Agricultural Weather Network (MAWN). Each irrigation plot
contained four 2.1 m by 9.8 m (20.6-m2) sub-plots. Sub-plot treatments consisted of daily single
mowing double mowing treatments with and without a wetting agent treatment.
From May to October daily irrigation replenishment at 30%, 60%, and 90%
evapotranspiration (ET) were applied. Irrigation replenishment was determined with the
Penman-Monteith equation to estimate potential ET (Penman, 1948; Monteith, 1965).
Applicable rainfall was subtracted from ET to determine the overall daily replenishment for
each ET treatment per current recommendations (MDA GAAMP’s, 2010). Project technology
provided by Spartan Distributors (Sparta, MI) included a TORO Site Pro ‘Central’ computer
control center running software v. 2.2 (1996-2006 TORO Irrigation Division, Bloomington, MN

74

USA) and TORO NSN Connect© (The Toro Company, Bloomington, MN USA) computer software
controls daily irrigation levels from an onsite computer and remotely via an iPhone 4© (Apple,
Inc., Cupertino, CA USA) application. Irrigation audits were conducted throughout each of the
growing seasons to ensure distribution of uniformity of 0.7 or greater and obtain data for
scheduling accurate run-times (Leinauer and Smeal, 2012). Audits were conducted by placing
six AcuRite™ Magnifying Rain Gauge 00850 (Chaney Instrument Company, Lake Geneva, WI
USA) within each plot for three separate full-turns of the irrigation heads. Water amounts were
averaged and run-times adjusted if needed until the system was corrected.
The area was mowed six times per week with a Toro 1000 (The Toro Company,
Bloomington, MN USA) greens mower at a bench setting height of 0.125 in (0.3175 cm).
Mowing treatment sub-plots within each plot were double-mowed daily. The second cut
immediately followed the initial cut in a different pattern direction. The entire area was lightly
topdressed with sand weekly throughout the growing season and the entire area was rolled
three days per week with a DMI Speed Roller (DMI/IPAC Group, Amherst, NY). With the
exception of preventative Sclerotinia homeocarpa (Dollar spot) treatments, pesticides were
applied on a curative basis to allow disease, insect, and weed observations. To prevent total
loss of the highly susceptible ‘Crenshaw’ creeping bentgrass putting green, the fungicides
chlorothalonil (Bravo Weather Stik, Syngenta) and propiconazole (Banner MAXX, Syngenta)
were applied to preventatively control Dollar spot throughout 2011 and 2012. Treatments that
warranted a monthly application of a wetting agent (Revolution®, Aquatrols, Paulsboro, NJ USA)
were applied at the labeled rate of 168 mL/ 90 m2 (6 oz/ 1000 ft2) from May-October.

75

Total microbial biomass (TMB) was determined by chloroform fumigation incubation
method (Jenkinson and Powlson, 1976; Parkinson and Paul, 1982). In October of each year (1
Oct. 2010, 18 Oct. 2011, and 10 Oct. 2012) samples were obtained with a 2.54-cm diameter soil
probe to a depth of 10.16 cm to evaluate treatment effects on TMB populations in soil.
Approximately 1000 g of soil (twenty cores) were taken from each plot. Cores were placed in
1020.6 g Whirl-Pak (Aristotle Corporation, Stamford, CT) bags, and were immediately
transferred to a refrigerator maintained at the temperature of 4 °C. Samples were removed
from refrigerator and maintained at room temperature for 24 h. Individual samples were sieved
through a 2 mm screen with visible organic residue and stones removed (Jenkinson and
Powlson, 1976). Six 50 g soil samples from each treatment replication were weighed into
beakers. Three of these samples were fumigated with alcohol-free CHCl3 and incubated for 24
h, while the remaining three served as non-fumigated controls. After incubation, each
fumigated sample was inoculated with approximately 1 g of its corresponding non-fumigated
soil, thoroughly mixed and brought to 55% water holding capacity. Fumigated and nonfumigated samples were then incubated at 22 °C for 5 d in a 1 L airtight mason jar with rubber
septum on the lid. After incubation, a CO2 sample was drawn through the septum using 1 mL
syringe and injected into an infrared gas analyzer (Qubit S151 CO2 analyzer, Qubit Systems Inc.,
-1

Kingston, Ontario, Canada). Total microbial biomass (μg g soil) in soil was calculated using the
equation: 1.73FC-0.56NFC, where FC and NFC are mineralized carbon from fumigated and nonfumigated soil samples, respectively (Horwath et al., 1996).

76

Soil hydrophobicity determined by water repellency was measured with the water drop
penetration (WDP) test (Dekker and Jungerius, 1990; Larsbo et al., 2008). On 1 Oct. 2010, 18
Oct. 2011, and 10 Oct. 2012, three soil samples per plot were obtained with a 1.27 cm inside
diameter soil probe to a depth of 10.16 cm. After 96 h of air-drying in the laboratory at
approximately 20°C and 60% relative humidity, a 0.05 ml drop of water was placed by eye
dropper (Walter Stern, Inc., Port Washington, NY) on each soil core surface at depths of 0-1, 12, and 2-3 cm just below visible plant and thatch layer. Times until the water drops infiltrated
the soil were measured in seconds (s). Each WDPT was treated as an individual measurement,
resulting in three sub-samples per treatment for statistical analysis. The WDPT test performed
on air-dry samples is an acceptable standard of potential soil water repellency versus actual
repellency due to removal of soil moisture variability present at time of sampling (Dekker and
Ritsema, 1994; Larsbo, 2008). Dekker and Jungeris (1990) proposed a soil water repellency
classification of: a soil is considered wettable if drop infiltration is immediate, non-repellent if
WDPT < 5 s, slightly water repellent if 5 s < WDPT < 60 s, and strongly water repellent if 60 s <
WDPT < 600 s (Larsbo, 2008).
Statistical analysis was performed in SAS v. 9.3 (SAS institute, Inc., Cary, NC) using Proc
Gli-Mix Procedure. The model statement for each response variable analyzed all main factors
evaluated and all possible interactions with the main treatment factors. All data analysis utilized
mean separation conducted at alpha = 0.05. Microbial biomass and water drop penetration
(WDP) test times include all data and over year analysis because sampling number and time
were consistent for all three years. All parameters included the random term
replication*irrigation level*mowing frequency*wetting agent. All parameters in this study were

77

analyzed in this manner. Regression analyses were performed between TMB and WDPT to
compare response variables of ball roll distance, percent volumetric water content (%VWC),
and visual quality. Variables were additionally analyzed/imported into ARM v. 8.3.4© (Gylling
Data Management 1982-2011, Brookings, SD) and/or GraphPad Prism (GraphPad Software, Inc.,
La Jolla, CA) for visual figure development.

78

RESULTS & DISCUSSION
Total irrigation amounts applied each day were calculated based on weather data
(Appendix A) from approximately May to October each season. In 2010, total daily irrigation
applied for 30, 60, and 90% ET were 11.25, 22.63, and 33.91 cm, respectively. In 2011, total
daily irrigation applied for 30, 60, and 90% ET were 15.44, 30.63, and 46.05 cm, respectively. In
2012, total daily irrigation applied for 30, 60, and 90% ET were 17.27, 34.29, and 51.56 cm,
respectively.
Analysis of variance means for total microbial biomass (TMB) as affected by irrigation
are shown in Table 16. Irrigation, mowing, and wetting agent treatments had no significant
effects on TMB on 2010-2012. However, an interaction was observed in 2012 between
irrigation and wetting agent (Table 17). Table 17 indicates a significant increase in TMB at 30%
ET replenishment with use of a wetting agent. Conversely, table 17 indicates a significant
reduction in TMB at 90% ET replenishment. Soil microbes require a sufficient amount of water
for growth and reproduction. Insufficient amounts of water may slow life processes, but too
much water leads to anaerobic soil conditions which has a negative impact on most soil
microbes and plant health. End of season TMB measurements (Figure 8) are average of mowing
and wetting agent over each irrigation treatment. Year significantly affected average TMB
(P<0.0001). The year difference is most likely attributed to management over time. 2010 was
the wettest and coolest of the three years; 2012 was the hottest and driest season (Appendix
A). Average TMB did not significantly differ in 2010, and measured 33.33, 32.08, and 29.89 μg g
dry soil

-1

for 30, 60, and 90% ET, respectively (P<0.05). This result may be attributed to greater

seasonal rainfall, and initiation of treatments on an established putting green not yet

79

overcoming previous management practices. In 2011, average TMB did not significantly differ,
and measured 60.08, 55.53, and 52.66 μg g dry soil

-1

for 30, 60 and 90% ET, respectively

(P<0.05). In 2012, average TMB did not significantly differ, and measured 40.07, 45.58, and
42.13 μg g dry soil

-1

for 30, 60 and 90% ET, respectively (P<0.05).

Fluctuation of TMB over a season or from season to season may occur due to many
factors, in particular due to porosity and moisture content. These fluctuations are reflected in
the data as presented in Figure 8. No significant differences in TMB were observed due solely to
irrigation replenishment regime in any one year from 2010 to 2012.
Mowing frequencies and wetting agent treatments were evaluated for effects on total
microbial biomass (TMB). Analysis of variance for total microbial biomass (TMB) as affected by
mowing and wetting agent are shown in Table 16. Interactions, if observed, are shown in Table
17.
In 2010, double mowing and wetting agent treatments did not result in statistically
different TMB. TMB measured 31.19 and 32.34 μg g dry soil

-1

in daily single mowed compared

to double mowed plots, respectively (P=0.1399). TMB measured 31.69 and 31.84 μg g dry soil

-1

in untreated compared to wetting agent treatments, respectively (P=0.8491). Both 2011 and
2012 supported no biological significance when neither treatment separated TMB levels
statistically (See Table 16). The data shows that the hypothesis of a second mowing pass
providing more carbon for microbial degradation as disproved. An interaction in 2012 (Table
17), showed application of wetting agent significantly increased TMB at 30% ET replenishment.

80

Chemical use on turfgrass remains under scrutiny for the possible negative effects they
may have on the environment. TMB data from all three years indicate that the wetting agent
had no negative impact on soil microbial activity, and in fact enhances TMB under low irrigation
regimes. Additionally, the fact that the wetting agent at 30% ET replenishment also maintained
adequate playing conditions indicates the surfactant could save water. Further investigation is
warranted on other soil types and/or with even lower ET irrigation levels.

81

Table 16. 2010-2012 main effects and mean squares for treatment effects of irrigation, mowing, and wetting agent on total
microbial biomass (TMB) in micrograms per gram of soil obtained by chloroform fumigation incubation method at the Hancock
Turfgrass Research Center in East Lansing, MI.
Irrigation (IRR)
30% ET
60% ET
90% ET
Significance
LSD (0.05)
Mowing (MOW)
1X daily
2X daily
Significance
LSD (0.05)
Wet-Agent (WA)
Untreated
1X monthly
Significance
LSD (0.05)

2010
33.33
32.08
29.89
NS
NS
31.19
32.34
NS
NS
31.69
31.84
NS
NS

Average TMB (µg/g-1)
2011
60.08
55.53
52.66
NS
NS
55.02
57.16
NS
NS
55.79
56.39
NS
NS
Mean Square and Pr>F

2012
40.07
45.58
42.13
NS
NS
42.54
42.64
NS
NS
41.86
43.33
NS
NS

Source
df
Replication
2 20.70
0.0339
1316.47
<.0001 462.29
<.0001
IRR
2 36.39
0.4224
168.25
0.2328
92.92
0.2076
Error for IRR
4 33.79
0.0017
78.45
0.0041
38.89
0.0167
MOW
1 12.02
0.1399
40.96
0.1044
0.08
0.9284
WA
1
0.19
0.8491
3.24
0.6363
19.51
0.1725
IRRxMOW
2
0.85
0.8460
1.17
0.9205
6.66
0.5150
IRRxWA
2
0.13
0.9739
13.15
0.4094 238.70
<.0001
MOWxWA
1
8.41
0.2127
25.00
0.1982
0.78
0.7795
IRRxMOWxWA
2
4.79
0.4050
11.27
0.4626
5.54
0.5737
Error
18
5.04
14.00
9.66
*, **, *** Significant at the 0.05, 0.01, and 0.001 probability levels, respectively.
† NS, non-significant at the 0.05 level.
‡ Within columns, means followed by the same letter are not significantly different according to LSD (0.05).

82

Table 17. 2012 average total microbial biomass† (TMB) as affected by irrigation and wetting agent‡ (WA) at the Hancock
Turfgrass Research Center in East Lansing, MI.
2012
Irrigation
WA
No WA
30% ET
45.95a
34.18c
60% ET
43.88ab
47.27a
90% ET
40.15b
44.12a
LSD (0.05)§
3.77
LSD (0.05)#
5.33
† Micrograms per gram of soil obtained by chloroform fumigation incubation method.
‡ Wetting agent was applied monthly from May till September with Revolution® from Aquatrols, Inc. (Paulsboro, N.J) at 1.87-ml/m2.
§ Between wetting agent means at same irrigation level on the single date listed above.
# Among irrigation level at the same or different wetting agent on the single date listed above.

83

Figure 8. Irrigation effects on total microbial biomass (TMB) in 2010-2012. Values are averaged
over treatments. Error bars represent least significant difference (LSD) using Fisher’s
Protected Method. Overlapping error bars represent statistically similar treatments at
α=0.05. N=9

Frequent wet to dry cycles along with several other factors contribute to soil
hydrophobicity in golf course putting greens (McMillan et al., 2012). Analysis of variance means
for water drop penetration (WDP) tests as affected by irrigation and mowing are in Table 18
through 20. Interactions, if observed, are in Table 21.
For all years of the study no significant differences in WDP tests were observed across
averages for different treatments of irrigation or mowing at P<0.05. As stated in chapter one,
irrigation reduction showed significant increase on LDS from counts and visual quality. Mowing
followed the same trend as irrigation, and WDP test results contradict hydrophobicity
observations that double mowing increases LDS.
WETTING AGENT AND HYDROPHOBICITY

84

Analyses of variance for water drop penetration (WDP) tests as affected by wetting
agent are in Table 18 through 20. Interactions, if observed, are shown in Table 21.
Applications of wetting agent (Revolution®) significantly reduced soil water repellency at
the 0 to 1 cm depth (Figure 9 and Tables 18, 19, and 20). No significant differences were
observed below 1 cm in all years. Measurements in Figure 9 are averaged across irrigation and
mowing treatments. In 2010, WDP test averages were 56 and 18 s for untreated versus wetting
agent plots, respectively (P=0.0043 and LSD 25). In 2011, WDP test averages were 25 and 9 s for
untreated versus wetting agent plots, respectively (P=0.0115 and LSD 13). The overall reduction
to both untreated and wetting agent treatments support the combined management regime
contributed positively to combating soil water repellency. In 2012, the driest year, WDP test
averages were 28 and 8 s for untreated versus wetting agent plots, respectively (P=0.0276 and
LSD 17). In each year a reduction in hydrophobicity from the previous was observed regardless
of wetting agent treatment However, wetting agent plots were significantly less hydrophobic
than untreated in every year. This WDP test data strongly supports data on wetting agent
effects to playability, and suggests reduced hydrophobicity benefits are attained with long-term
and repeated application.

85

Table 18. 2010 main effects and mean squares for treatment effects of irrigation, mowing, and wetting agent on soil hydrophobicity
measured by water drop penetration (WDP) tests at the Hancock Turfgrass Research Center in East Lansing, MI.

Irrigation (IRR)
30% ET
60% ET
90% ET
Significance
LSD (0.05)
Mowing (MOW)
1X daily
2X daily
Significance
LSD (0.05)
Wet-Agent (WA)
Untreated
1X monthly
Significance
LSD (0.05)

Average WDP (seconds)
2010
0-1 cm
1-2 cm
47.50
8.00
49.58
3.83
18.08
5.25
NS
NS
NS
NS

2-3 cm
3.75
0.67
0.75
NS
NS

30.28
46.50
NS
NS

0.61
2.83
NS
NS

4.17
7.22
NS
NS

61.78b
8.83
15.00a
2.25
**
NS
26.78
NS
Mean Square and Pr>F

2.83
0.61
NS
NS

Source
df
Replication
2
121.53 0.9206
21.19
0.8029
35.36
0.4370
IRR
2
3723.86 0.2640
53.86
0.7260
37.03
0.4147
Error for IRR
4
1967.44 0.2916
155.07
0.2110
33.49
0.5285
MOW
1
2368.44 0.2193
84.03
0.3603
44.44
0.3103
WA
1 19693.44 0.0018
354.69
0.0697
44.44
0.3103
IRRxMOW
2
1111.19 0.4821
16.36
0.8437
43.69
0.3633
IRRxWA
2
1601.36 0.3557
53.86
0.5783
29.86
0.4946
MOWxWA
1
5675.11 0.0644
140.03
0.2413
40.11
0.3344
IRRxMOWxWA
2
1253.36 0.4409
34.69
0.7000
51.19
0.3087
Error
18
1462.06
95.37
40.78
*, **, *** Significant at the 0.05, 0.01, and 0.001 probability levels, respectively.
† NS, non-significant at the 0.05 level.
‡ Within columns, means followed by the same letter are not significantly different according to LSD (0.05).

86

Table 19. 2011 main effects and mean squares for treatment effects of irrigation, mowing, and wetting agent on soil hydrophobicity
measured by water drop penetration (WDP) tests at the Hancock Turfgrass Research Center in East Lansing, MI.

Irrigation (IRR)
30% ET
60% ET
90% ET
Significance
LSD (0.05)
Mowing (MOW)
1X daily
2X daily
Significance
LSD (0.05)
Wet-Agent (WA)
Untreated
1X monthly
Significance
LSD (0.05)

Average WDP (seconds)
2011
0-1 cm
1-2 cm
18.79
5.19
15.04
3.96
17.61
7.68
NS
NS
NS
NS

2-3 cm
1.83
1.40
2.59
NS
NS

17.73
15.57
NS
NS

1.71
2.17
NS
NS

25.46b
8.83a
**
11.40

5.11
6.11
NS
NS
7.04
4.18
NS
NS
Mean Square and Pr>F

2.12
1.76
NS
NS

Source
df
Replication
2
368.85 0.2739
79.89
0.1236
12.17
0.0360
IRR
2
44.14 0.9312
43.06
0.5695
4.36
0.4924
Error for IRR
4
608.56 0.0987
66.21
0.1457
5.13
0.1950
MOW
1
12.08 0.8333
9.11
0.6108
1.96
0.4321
WA
1 2489.84 0.0067
73.65
0.1581
1.17
0.5420
IRRxMOW
2
134.69 0.6098
33.25
0.3947
5.18
0.2090
IRRxWA
2
253.90 0.4022
1.62
0.9536
0.44
0.8659
MOWxWA
1
181.67 0.4184
2.91
0.7732
2.30
0.3954
IRRxMOWxWA
2
92.24 0.7106
22.07
0.5338
0.83
0.7641
Error
18
264.87
33.95
3.02
*, **, *** Significant at the 0.05, 0.01, and 0.001 probability levels, respectively.
† NS, non-significant at the 0.05 level.
‡ Within columns, means followed by the same letter are not significantly different according to LSD (0.05).

87

Table 20. 2012 main effects and mean squares for treatment effects of irrigation, mowing, and wetting agent on soil hydrophobicity
measured by water drop penetration (WDP) tests at the Hancock Turfgrass Research Center in East Lansing, MI.

Irrigation (IRR)
30% ET
60% ET
90% ET
Significance
LSD (0.05)
Mowing (MOW)
1X daily
2X daily
Significance
LSD (0.05)
Wet-Agent (WA)
Untreated
1X monthly
Significance
LSD (0.05)

Average WDP (seconds)
2012
0-1 cm
1-2 cm
30.22
7.33
13.03
4.83
11.08
3.06
NS
NS
NS
NS

2-3 cm
2.97
1.95
1.53
NS
NS

20.55
15.67
NS
NS

1.69
2.61
NS
NS

27.83b
8.39a
**
14.14

5.33
4.81
NS
NS
6.31b
3.83a
*
2.27
Mean Square and Pr>F

2.67
1.63
NS
NS

Source
df
Replication
2
552.44 0.2832
47.99
0.0246
5.77
0.2486
IRR
2 1331.51 0.4853
55.37
0.1595
6.64
0.5762
Error for IRR
4 1528.69 0.0218
18.41
0.1812
10.45
0.0619
MOW
1
214.96 0.4772
2.43
0.6359
7.69
0.1738
WA
1 3402.58 0.0098
55.43
0.0336
9.69
0.1293
IRRxMOW
2
43.16 0.9002
1.54
0.8642
2.10
0.5870
IRRxWA
2 1653.99 0.0352
44.18
0.0314
0.21
0.9479
MOWxWA
1
15.09 0.8496
0.61
0.8126
0.99
0.6170
IRRxMOWxWA
2
143.57 0.7080
13.43
0.3014
0.84
0.8052
Error
18
407.92
10.47
3.83
*, **, *** Significant at the 0.05, 0.01, and 0.001 probability levels, respectively.
† NS, non-significant at the 0.05 level.
‡ Within columns, means followed by the same letter are not significantly different according to LSD (0.05).

88

Table 21. 2012 hydrophobicity determined by water drop penetration† (WDP) tests as affected by irrigation and wetting
agent‡ (WA) at the Hancock Turfgrass Research Center in East Lansing, MI.
2012
0-1 cm

1-2 cm
Irrigation
WA
No WA
WA
No WA
30% ET
6.94a
53.50b
3.89a
10.78b
60% ET
10.11a
15.94a
4.89a
4.78a
90% ET
8.11a
14.05a
2.72a
3.39a
LSD (0.05)§
24.50
3.92
LSD (0.05)#
34.65
5.55
† Time in seconds for absorption.
‡ Wetting agent was applied monthly from May till September with Revolution® from Aquatrols, Inc. (Paulsboro, N.J) at 1.87-ml/m2.
§ Between wetting agent means at same irrigation level on the single date listed above.
# Among irrigation level at the same or different wetting agent on the single date listed above.

89

Figure 9. Revolution® effects on water drop penetration (WDP) tests in 2010-2012. Values are
averaged over treatments. Error bars represent least significant difference (LSD) using
Fisher’s Protected Method. Overlapping error bars represent statistically similar
treatments at α=0.05. N=9

Regression analyses were performed between TMB and WDPT to compare response
variables of ball roll distance, percent volumetric water content (%VWC), and visual quality.
Investigation of correlations was proposed to develop a prediction model development based
on response variables, however, no significant correlations between variables were observed
across years.

90

CONCLUSIONS
Daily irrigation replenishment to 90% ET on the research plots led to no observed
benefits to the total microbial biomass (TMB) populations. Daily irrigation replenishment to
60% ET provided acceptable TMB on plots for the three-year study duration. TMB levels in plots
receiving 60% ET were equal to or greater than the 90% ET, even in the driest of years (2012),
indicating a potential thirty percent savings in water applied while maintaining aesthetics and
soil health. 30% ET may be enough for TMB levels in temperate climates during early spring or
late fall. However, consideration is warranted for dry years such as 2012.
TMB data from all three years indicate that the wetting agent had no negative impact on
soil microbial activity, and in fact enhances TMB under low irrigation regimes. Additionally, the
fact that the wetting agent at 30% ET replenishment also maintained adequate playing
conditions indicates the surfactant could save water. Also, wetting agent appeared to improve
plant uptake of volumetric water content (%VWC) present in plots, as represented in WDP
tests. Combining these two findings indicate that use of wetting agents may lead to improved
TMB levels with better water uptake potential in plots receiving 30% ET replenishment.
Double mowing on a daily basis for three consecutive years yielded few negative
impacts to plots above ground (as represented in chapter one), and laboratory TMB plus WDP
test measurements indicate no negatives in the root zone. Combining these two findings
suggest double mowing daily over the long-term is possible.
Again, this research warrants further investigations in creeping bentgrass or other
species on putting greens managed under United States Golf Association sand specifications. At

91

the conclusion of the study and as expected, daily ET replenishment regime did not show an
effect on TMB at P<0.05, but more sampling throughout the year is warranted in the future.

92

APPENDICES

93

APPENDIX A
Table 22. Seasonal weather data (May-October) summary for ‘Crenshaw’ native soil putting green at the Hancock Turfgrass Research
Center in East Lansing, MI, in 2010-2012.

2010
5/1
5/2
5/3
5/4
5/5
5/6
5/7
5/8
5/9
5/10
5/11
5/12
5/13
5/14
5/15
5/16
5/17
5/18
5/19
5/20
5/21
5/22

°F
Max
72.4
71.5
72.6
72.9
66.5
64.3
58.6
49
55.6
57.6
46.6
51.1
65.5
63.9
64.9
65.5
66.8
65.4
76.7
81.2
69.3
75.6

°F
Min
61.9
54.7
52.9
44.3
55
47.4
46.3
38.1
32.1
29.2
41.2
41.3
44.3
48.1
45.4
40.6
46
47.9
42.2
48
58
57.7

Rainfall
(In)
PET
0.05
0.109
0.4
0.074
0.16
0.189
0.01
0.153
0.156
1.1
0.037
0.02
0.075
0.145
0.158
0.7
0.036
0.043
0.7
0.036
0.165
0.136
0.152
0.144
0.05
0.089
0.187
0.191
0.97
0.06
0.02
0.105

2011
5/1
5/2
5/3
5/4
5/5
5/6
5/7
5/8
5/9
5/10
5/11
5/12
5/13
5/14
5/15
5/16
5/17
5/18
5/19
5/20
5/21
5/22

°F
Max
71.6
55.9
49
60.4
64.3
63.3
68.7
68.4
69.2
72.3
78
86
85.6
63
49.8
55.2
56.3
62
72.8
75.3
76.7
83.2

°F
Min
51.1
46
38.3
36.9
34.1
48.7
39.1
43.6
39.4
52.1
54.2
54.7
58.2
48.5
39.7
39.1
44.2
48
54.8
56.3
53.3
58.3

94

Rainfall
(In)

0.03

0.04
0.25
2.26
0.2
0.39
0.07
0.43
0.1
0.03
0.07

PET
0.167
0.13
0.068
0.147
0.178
0.154
0.161
0.179
0.195
0.175
0.194
0.163
0.156
0.035
0.047
0.14
0.09
0.042
0.099
0.132
0.159
0.207

2012
5/1
5/2
5/3
5/4
5/5
5/6
5/7
5/8
5/9
5/10
5/11
5/12
5/13
5/14
5/15
5/16
5/17
5/18
5/19
5/20
5/21
5/22

°F
Max
59.2
81.3
84.7
78.4
66.6
67.3
69.1
67.7
62.5
65.9
73.3
62.4
72.9
75.1
79.6
64.9
69.7
77.1
84.3
87.4
74.2
71

°F
Min
46.8
50.3
57.8
55.4
49.1
50.1
50.4
48.1
45.9
39.9
38.3
55.2
49.6
41.3
44.4
48.6
35.3
43.8
49.3
58
56.6
49.6

Rainfall
(In)
PET
0.01
0.062
0.147
0.85
0.177
0.35
0.098
0.074
0.28
0.115
0.12
0.068
0.156
0.02
0.114
0.181
0.198
0.32
0.055
0.14
0.144
0.196
0.03
0.217
0.05
0.184
0.176
0.206
0.228
0.253
0.083
0.16

Table 22 (cont’d)

5/23
5/24
5/25
5/26
5/27
5/28
5/29
5/30
5/31
6/1
6/2
6/3
6/4
6/5
6/6
6/7
6/8
6/9
6/10
6/11
6/12
6/13
6/14
6/15
6/16
6/17
6/18
6/19
6/20
6/21

83
85
82.7
90.4
85.6
85.5
84.8
86.9
81.7
80.6
72.9
75.2
78.7
78.4
67.7
70.5
69
77.2
75.9
78.9
84.9
74.4
75.3
74.8
73.5
77.9
87.8
80.7
80
81.5

52.7
61.9
60.1
60
66.8
60.4
58.2
56.6
65.1
63.5
61.2
60.5
53.5
60.2
55.4
48.6
47.7
56.2
56.8
59.9
69.4
62.1
65
61.4
64.7
60
58.1
64.9
61.3
57.5

0.07
0.61
0.1
0.55
0.98
0.12
0.01
0.1

0.04
0.04
0.24

0.205
0.209
0.195
0.218
0.25
0.237
0.224
0.224
0.099
0.205
0.073
0.105
0.12
0.138
0.116
0.191
0.106
0.182
0.191
0.126
0.141
0.094
0.083
0.114
0.133
0.192
0.203
0.198
0.174
0.168

5/23
5/24
5/25
5/26
5/27
5/28
5/29
5/30
5/31
6/1
6/2
6/3
6/4
6/5
6/6
6/7
6/8
6/9
6/10
6/11
6/12
6/13
6/14
6/15
6/16
6/17
6/18
6/19
6/20
6/21

77.5
74.6
60.6
56.6
54.4
66
74.5
88
88.2
74.8
71
75.6
89.4
85.4
84.7
92.9
91.4
82.4
60
75.2
66.2
78.4
76.5
67.3
73
77.8
82.6
80.2
76
86.8

61.8
57.7
50.5
44.2
45.4
52.3
55.9
58.5
67.8
61.4
50.5
51.6
60.7
56.8
55.6
73.8
74.9
57.4
52.9
58.1
50.3
52.2
50.1
47.5
57.7
53.2
56
56.6
59.8
66.8
95

0.04
0.77
0.35
0.01
0.69
0.03

0.01
0.44

0.05
0.51

0.24

0.185
0.175
0.035
0.034
0.051
0.076
0.09
0.216
0.226
0.27
0.201
0.193
0.215
0.221
0.214
0.242
0.271
0.129
0.049
0.108
0.112
0.216
0.219
0.096
0.14
0.122
0.213
0.198
0.107
0.158

5/23
5/24
5/25
5/26
5/27
5/28
5/29
5/30
5/31
6/1
6/2
6/3
6/4
6/5
6/6
6/7
6/8
6/9
6/10
6/11
6/12
6/13
6/14
6/15
6/16
6/17
6/18
6/19
6/20
6/21

77.7
84.9
80.1
74.7
81.1
90.2
81.9
68.5
56.8
53
70.2
75.7
71.2
68.5
77.5
78.7
80.5
84.5
88.2
80.3
74.5
72.7
79
85.7
86.9
80
79.6
91.5
90
84.8

41.1
56.3
63.7
59.4
59.4
61.4
63.8
49.9
44.1
46.1
46.1
56.8
52.2
49.1
43.8
51.1
49.3
62.7
58.7
64.8
57.7
47.5
47.8
53.3
62.6
59.6
57.6
73.4
71.3
62.9

0.08
0.01

0.18
0.58

0.01

0.02
0.02

0.37

0.05

0.207
0.229
0.24
0.129
0.184
0.243
0.269
0.152
0.067
0.03
0.168
0.226
0.168
0.145
0.209
0.214
0.221
0.25
0.235
0.147
0.231
0.19
0.222
0.245
0.21
0.152
0.143
0.259
0.259
0.176

Table 22 (cont’d)

6/22
6/23
6/24
6/25
6/26
6/27
6/28
6/29
6/30
7/1
7/2
7/3
7/4
7/5
7/6
7/7
7/8
7/9
7/10
7/11
7/12
7/13
7/14
7/15
7/16
7/17
7/18
7/19
7/20
7/21

82.6
86
79.5
79.5
83
82.1
80.1
70.3
72
76
79.6
83.7
90
89.2
90
91.3
84.7
85.4
84.8
85.1
81.5
80.7
85
89.3
85.8
86.2
84.7
80.7
82.2
85.1

63.9
65.6
68
52.8
64.9
64.4
64.8
54.5
45.2
49.1
49.7
52.1
59.8
73.1
68.5
69.9
70.8
68.8
59.6
61.3
65.4
66
59.7
70.3
61.4
67.5
63.2
68.6
63.9
65.9

0.74
0.26

0.13

0.16

0.01
0.06

0.7

0.04
0.03

0.193
0.154
0.205
0.212
0.181
0.106
0.215
0.195
0.202
0.2
0.213
0.235
0.227
0.238
0.226
0.204
0.1
0.184
0.185
0.164
0.153
0.117
0.196
0.154
0.238
0.241
0.107
0.156
0.118
0.227

6/22
6/23
6/24
6/25
6/26
6/27
6/28
6/29
6/30
7/1
7/2
7/3
7/4
7/5
7/6
7/7
7/8
7/9
7/10
7/11
7/12
7/13
7/14
7/15
7/16
7/17
7/18
7/19
7/20
7/21

79.9
70.1
64.5
77.7
81
78.3
70.9
78.7
83
85.6
91.6
86.7
85.4
87.6
86.1
79.6
86.1
89.4
89
80.1
86.1
78.1
80
84.5
90.9
91.2
90.4
93
92.9
93.9

63.9
62.1
58.3
57.4
52.2
58.1
61.3
53.3
51.4
58.4
68.9
66.1
62.7
57.7
67.5
56.5
56.8
60.2
66.2
66.8
66.2
59.4
51.5
61.8
57.4
64.8
74.6
72.6
70.3
72
96

0.26
0.02
0.05

0.34

0.2

0.142
0.082
0.074
0.209
0.207
0.116
0.171
0.217
0.177
0.188
0.229
0.224
0.236
0.238
0.225
0.166
0.215
0.207
0.213
0.092
0.234
0.21
0.187
0.182
0.215
0.226
0.159
0.203
0.199
0.263

6/22
6/23
6/24
6/25
6/26
6/27
6/28
6/29
6/30
7/1
7/2
7/3
7/4
7/5
7/6
7/7
7/8
7/9
7/10
7/11
7/12
7/13
7/14
7/15
7/16
7/17
7/18
7/19
7/20
7/21

80.5
82.7
84.2
73.8
80.7
86.7
94.5
87
87.5
90.8
94.7
92.4
96.9
95.7
100.9
92.3
83.2
86.2
82.6
85.2
88
90.4
90.3
88.4
92.6
95.9
84.7
74.8
80.5
85.1

58.2
52.8
64.7
54.7
46.6
52.7
66.2
64.5
65
61
61
70.1
72.4
68.4
68.9
73.2
63.9
57.5
61.1
54.7
53.9
59.4
63.8
68
65.9
75.2
68
65.9
60
53.9

0.03

0.2

0.4
0.26
0.01

0.194
0.196
0.193
0.208
0.212
0.236
0.248
0.201
0.232
0.206
0.201
0.21
0.231
0.18
0.231
0.232
0.216
0.177
0.211
0.206
0.22
0.209
0.217
0.221
0.227
0.294
0.144
0.081
0.193
0.204

Table 22 (cont’d)

7/22
7/23
7/24
7/25
7/26
7/27
7/28
7/29
7/30
7/31
8/1
8/2
8/3
8/4
8/5
8/6
8/7
8/8
8/9
8/10
8/11
8/12
8/13
8/14
8/15
8/16
8/17
8/18
8/19
8/20

79.5
87.3
81
81.5
84.7
84
84.7
82.3
82.3
76
82.4
83
85.5
85.4
83.9
78.7
80.5
84.8
81.8
87.9
79.8
87.8
86.8
81.7
86.3
76.5
78.7
78.9
83.9
86.7

58.6
73
70.9
63.3
57.5
58.3
70.3
59.8
55.4
64.3
59.9
61.5
71.6
67.2
67.3
60
52.2
66.6
71.1
64.4
64.2
70.5
67.2
70.5
67.1
60.7
55.4
59.2
58.6
63.5

0.52
0.12
0.1

0.26
0.26

0.01

0.096
0.154
0.088
0.194
0.16
0.194
0.141
0.188
0.163
0.082
0.144
0.153
0.178
0.144
0.222
0.191
0.166
0.162
0.087
0.153
0.083
0.103
0.177
0.101
0.186
0.204
0.16
0.167
0.184
0.171

7/22
7/23
7/24
7/25
7/26
7/27
7/28
7/29
7/30
7/31
8/1
8/2
8/3
8/4
8/5
8/6
8/7
8/8
8/9
8/10
8/11
8/12
8/13
8/14
8/15
8/16
8/17
8/18
8/19
8/20

82
86.8
86.3
86.9
82.5
77.4
86.1
87.2
88.2
88
88.8
85.7
84
80.8
84.5
80.8
81
81.2
79.6
73.9
77.8
78.7
79.5
72.9
79.2
83.3
80.6
82.8
83.4
80.7

65.7
67.7
67.2
71.4
65
56.5
69.2
70.4
62.4
64.2
71.6
68.3
70.2
64.9
61.9
69.9
66.3
-40
63.2
60.4
53.3
55.2
60.6
58.4
56.5
53.5
55.4
62.7
53.3
59.8
97

0.03
0.02

1.28
1.62
1.61

0.06
0.77

0.09
0.02
0.28

0.31
0.17

0.01
0.49

0.093
0.136
0.145
0.217
0.234
0.092
0.135
0.192
0.22
0.232
0.208
0.105
0.132
0.091
0.168
0.071
0.133
0.121
0.166
0.176
0.188
0.158
0.077
0.06
0.178
0.181
0.165
0.182
0.18
0.075

7/22
7/23
7/24
7/25
7/26
7/27
7/28
7/29
7/30
7/31
8/1
8/2
8/3
8/4
8/5
8/6
8/7
8/8
8/9
8/10
8/11
8/12
8/13
8/14
8/15
8/16
8/17
8/18
8/19
8/20

89.2
93.4
83.2
88.4
84.5
79.3
80.9
85.5
87.6
85.4
83.8
89
94.2
89.4
81.8
83.1
86.5
83.7
71.4
62.5
72.2
76.5
70.9
78
82.6
75.9
73.4
75.1
77.6
75.6

65.1
71.7
65.6
55.8
69.3
65.7
59.9
53.8
59.6
62.7
60.6
61.7
66
68.1
66.1
50.7
54.5
65.1
58.6
57.7
57.2
55.9
60
60.6
56.9
60.9
57.1
44.9
51
49.2

0.04
0.02
0.19

0.31

0.11

0.43
0.7
0.38
0.03
0.05
0.06

0.189
0.252
0.22
0.206
0.107
0.119
0.2
0.186
0.206
0.187
0.204
0.156
0.206
0.194
0.23
0.205
0.203
0.185
0.033
0.035
0.071
0.157
0.052
0.147
0.147
0.098
0.151
0.158
0.162
0.152

Table 22 (cont’d)

8/21
8/22
8/23
8/24
8/25
8/26
8/27
8/28
8/29
8/30
8/31
9/1
9/2
9/3
9/4
9/5
9/6
9/7
9/8
9/9
9/10
9/11
9/12
9/13
9/14
9/15
9/16
9/17
9/18
9/19

79.2
84
73.5
77.2
76.9
75.1
78.3
83.2
91.1
89.3
88.2
83.9
74
73.3
60.9
70.4
71.6
79.1
63.5
66.8
67.6
60.9
74
76.6
70.6
71.8
66.8
66.3
66.6
71.1

69.2
65.1
63.6
58
58.8
50.4
45.9
55.4
58.8
65.9
70.6
69.6
66.1
55.4
49.9
42.6
56.2
61.1
54.2
50.3
42.2
51
54.7
52.1
48
41.8
54.2
51.5
53.7
51.1

0.04

0.22
0.22
0.41

0.13

0.45

1.34
0.38

0.086
0.164
0.082
0.093
0.179
0.171
0.167
0.189
0.181
0.169
0.193
0.112
0.044
0.131
0.117
0.141
0.072
0.245
0.118
0.118
0.122
0.03
0.142
0.18
0.147
0.131
0.043
0.09
0.044
0.081

8/21
8/22
8/23
8/24
8/25
8/26
8/27
8/28
8/29
8/30
8/31
9/1
9/2
9/3
9/4
9/5
9/6
9/7
9/8
9/9
9/10
9/11
9/12
9/13
9/14
9/15
9/16
9/17
9/18
9/19

76.7
76.2
80.3
87.8
76.9
79.5
81.9
75.1
76.4
77.2
79.9
89.1
90.5
88.7
73.4
59.5
66.6
67.2
64.4
76.7
78.8
77.6
81.8
76.4
65.4
59.8
58.9
64.8
69.3
66.7

56.5
49.3
53.2
65.5
58.9
51.5
55.9
54.8
47.9
53.7
61.2
64.1
71.1
68.5
58.9
48.1
46.2
48.9
55.6
59.1
60.1
57.5
58.9
54.2
43.8
38.9
36.3
45.9
43.8
55.9
98

0.02
0.45
0.41

0.01
0.11

0.06
0.33
0.04

0.16

0.73

0.169
0.168
0.162
0.182
0.136
0.164
0.17
0.165
0.155
0.132
0.108
0.169
0.185
0.161
0.114
0.077
0.11
0.076
0.042
0.075
0.111
0.114
0.149
0.133
0.064
0.105
0.073
0.098
0.122
0.036

8/21
8/22
8/23
8/24
8/25
8/26
8/27
8/28
8/29
8/30
8/31
9/1
9/2
9/3
9/4
9/5
9/6
9/7
9/8
9/9
9/10
9/11
9/12
9/13
9/14
9/15
9/16
9/17
9/18
9/19

78.1
80.3
86.9
88.2
89.7
88.7
84.4
78.9
81.2
84.2
90.9
80.8
83.2
89.9
83.9
79
83.7
76.4
68
71.2
74
79.1
82.4
78.4
70.4
73.6
76.3
75.7
64.4
65

49.2
49.1
50.4
58.6
58.6
63.8
67.9
58.6
50.7
51.6
68.1
61.2
64.2
60.2
66.1
63.9
63.7
57.8
52.9
47.9
41.8
51
55.4
55.7
51.5
41.6
47.9
50.7
43.5
38.8

0.12
0.2

0.05
0.64

0.28
0.06

0.2
0.36

0.01
0.19
0.01

0.169
0.171
0.172
0.175
0.192
0.175
0.14
0.155
0.152
0.174
0.213
0.123
0.126
0.149
0.086
0.102
0.135
0.07
0.117
0.126
0.133
0.158
0.158
0.096
0.125
0.125
0.126
0.113
0.091
0.129

Table 22 (cont’d)

9/20
9/21
9/22
9/23
9/24
9/25
9/26
9/27
9/28
9/29
9/30
10/1
10/2
10/3
10/4
10/5
10/6
10/7
10/8
10/9
10/10
10/11
10/12
10/13
10/14
10/15
10/16
10/17
10/18
10/19

65.6
85.8
76.6
86.5
80.6
58.7
56.8
60.8
62.4
71.7
72.1
67.3
53.6
55.2
59.3
66.9
70.4
69.9
76.3
77
79.4
79.1
68.8
59.8
61.8
61.4
63.2
60.1
56.8
57

55.4
58.4
60.1
60.2
57
49
42.5
43.1
49.3
39.4
48.1
45.4
43.6
37.6
35.1
32
39.9
44.3
41.7
45.7
49.5
46.5
43.7
46.3
42
43
34.1
41.2
43.7
31.8

0.15

0.01

0.03
0.14
0.01
0.28

0.49
0.03

0.091
0.164
0.071
0.128
0.159
0.092
0.071
0.054
0.042
0.112
0.136
0.104
0.032
0.071
0.089
0.107
0.127
0.125
0.133
0.104
0.115
0.106
0.08
0.025
0.094
0.087
0.089
0.101
0.062
0.076

9/20
9/21
9/22
9/23
9/24
9/25
9/26
9/27
9/28
9/29
9/30
10/1
10/2
10/3
10/4
10/5
10/6
10/7
10/8
10/9
10/10
10/11
10/12
10/13
10/14
10/15
10/16
10/17
10/18
10/19

71
74.7
67.4
63.9
64.8
70.1
69.3
65.7
61.7
62.4
52.3
53.8
62
68.5
73.8
77.1
82
79
80.7
82
77.1
78.1
68.6
64.5
58.1
55.4
59.1
56.6
53.3
47.5

46.5
51.9
49.8
50.9
43.9
49.5
49.1
43.8
52
49.3
39.9
38.1
35.3
43.1
37.2
41.2
43.5
45.2
49.8
49.7
48.6
45
49.1
52.1
47.8
44.3
45.6
43.1
36.9
43
99

0.01

0.02
0.61
0.09
0.35
0.13

0.13
0.01

0.1
0.32
0.03
0.05
0.01
0.06
0.85

0.107
0.11
0.087
0.056
0.086
0.05
0.06
0.064
0.043
0.039
0.045
0.076
0.109
0.115
0.106
0.102
0.101
0.123
0.116
0.104
0.1
0.12
0.077
0.052
0.053
0.096
0.084
0.108
0.039
0.015

9/20
9/21
9/22
9/23
9/24
9/25
9/26
9/27
9/28
9/29
9/30
10/1
10/2
10/3
10/4
10/5
10/6
10/7
10/8
10/9
10/10
10/11
10/12
10/13
10/14
10/15
10/16
10/17
10/18
10/19

68.3
67.1
58.7
55.8
61.9
67.7
71.3
65
69.2
71.7
64.4
66.6
69.9
65.1
75.2
59.6
46.5
46.8
53.6
61.4
54.6
61.1
52
62.2
69.1
50.9
60.6
73
58.7
52.1

47.7
43.4
44.2
40.6
37.5
49.5
49.6
47.2
45.7
40.3
44.8
35.6
51.4
55.6
53.9
44.9
38.9
35.3
30.3
36.5
34.5
29.9
30.1
31.6
50.9
44.5
31.4
52.8
43.4
41.2

0.06
0.16
0.06
0.06
0.01
0.02
0.01

0.09
0.01

0.17
0.03
0.04
0.84
0.37
0.01
0.27
0.37
0.12

0.132
0.093
0.065
0.076
0.123
0.103
0.089
0.09
0.101
0.108
0.088
0.076
0.081
0.038
0.112
0.05
0.04
0.034
0.08
0.102
0.045
0.105
0.067
0.016
0.06
0.036
0.072
0.123
0.069
0.032

Table 22 (cont’d)

10/20
10/21
10/22
10/23
10/24
10/25
10/26
10/27
10/28
10/29
10/30
10/31

63.8
50.7
56.9
62.4
71.3
71.8
66.6
65
51.4
50.8
59.2
49.8

39.4
34.8
29.1
46.8
51
56.9
54.4
51.4
41.1
38.5
38.7
31.6

0.27
0.01

0.01
0.17
0.15

0.099
0.056
0.074
0.054
0.101
0.062
0.088
0.185
0.057
0.079
0.095
0.054

10/20
10/21
10/22
10/23
10/24
10/25
10/26
10/27
10/28
10/29
10/30
10/31

45.9
46.5
58.7
64.1
59.5
66.6
58
48.7
49.8
51.4
50.4
49.5

41.7
35.3
29.8
36.8
38.5
37
42.9
37.4
26.7
32.6
25.6
34.4

100

0.96

0.28
0.01

0.14

0.021 10/20
10/21
0.064 10/22
0.076 10/23
0.091 10/24
0.049 10/25
0.018 10/26
0.037 10/27
0.042 10/28
0.032 10/29
0.053 10/30
0.035 10/31

55.8
61.7
70
65
77.8
75.9
70.3
52.4
45.9
43.5
38.9
41.2

42.9
32.9
40
59.2
57.7
57.6
41.8
33.5
32.9
34.4
32.2
34.5

0.06
0.58
0.22

0.06

0.35
0.02

0.047
0.07
0.046
0.022
0.071
0.123
0.049
0.055
0.042
0.072
0.025
0.017

APPENDIX B

Figure 10. Sixty-five foot above plot overhead image portraying turfgrass quality between
treatments at the lowest irrigation regime in NE block of daily 30% evapotranspiration (ET)
replenishment. 29 June 2012 (first week of summer dry-down).

101

Figure 11. Sixty-five foot above plot overhead image portraying turfgrass quality between
treatments at the lowest irrigation regime in NE block of daily 30% evapotranspiration (ET)
replenishment. 11 July 2012 (second week of summer dry-down).

102

Figure 12. Sixty-five foot above plot overhead image portraying turfgrass quality between
treatments at the lowest irrigation regime in NE block of daily 30% evapotranspiration (ET)
replenishment. 20 July 2012 (third week of summer dry-down).

103

Figure 13. Sixty-five foot above plot overhead image portraying turfgrass quality between
treatments at the lowest irrigation regime in NE block of daily 30% evapotranspiration (ET)
replenishment. 1 August 2012 (fourth week of summer dry-down).

104

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111