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1 COMPARATIVE MAINTENANCE OF PASPALUM AND BERMUDA GRASSES By IVAN M. VARGAS ALTAMIRANO A THESIS PRESENTED TO THE GRADUATE SCHOOL OF THE UNIVERSITY OF FLORIDA IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MAS TER OF SCIENCE UNIVERSITY OF FLORIDA 20 10
2 20 10 Ivan M. Vargas Altamirano
3 To my parents who taught me the i mportance of intense dedication
4 ACKNOWLEDGMENTS First, I must thank GOD for his love, guidance and help. Next, I wish to express my ap preciation to Dr. Jerry B. Sartain, chairman of my supervisory committee, for his support, strong ethic, and encouragement throughout my degree program. I would also like to thank my committee members Dr. Obreza and Dr. Kruse for their support. I want to give a sincere thank you to the lab and field people Nahid Varshovi, Martin Sandquest, Dawn Lucas, Ronald Gonzalez, Carolina Medina, and Mark Kann for their assistance. Also, I would like to thank Florida Turfgrass Association (FTGA) for generously supporti ng my research and to Soil and Water Science Department and the College of Agricultural and Life Sciences for providing my research assistantship. Finally, I want to thank my family and friends. I thank my father Rosendo Vargas and my mother Sandra Altamir ano who provide me with the best examples of honesty, love, and hard work. Thank go out to my brothers and sisters. I want to thank La Familia of Gainesville for their support during the period of my degree; moreover, I want to give special recognition t o Jena Chojnowski for her invaluable help, patience, and love.
5 TABLE OF CONTENTS page ACKNOWLEDGMENTS ...................................................................................................... 4 LIST OF TABLES ................................................................................................................ 6 LIST OF FIGURES .............................................................................................................. 7 ABSTRACT .......................................................................................................................... 9 CHAPTER 1 INTRODUCTION ........................................................................................................ 11 Golf Course Economical Impact ................................................................................. 11 Bermudagrass ............................................................................................................. 12 Seashore Paspalum ................................................................................................... 14 Maintenance Practices ............................................................................................... 18 Hypothesis and Research Objectives ........................................................................ 20 2 MATERIAL AND METHODS ...................................................................................... 21 Field Study Design ...................................................................................................... 21 Data Collection ............................................................................................................ 22 Data Analysis .............................................................................................................. 23 3 RESULTS AND DISCUSSION COMPARATIVE MAINTENANCE OF PASPALUM AND BERMUDA GRASSES ................................................................. 25 Study Description ........................................................................................................ 25 Introduction and Material and Methods ............................................................... 25 2008 and 2009 Results and Discussion .................................................................... 26 Turf Visual Quality ................................................................................................ 26 Ball Roll ................................................................................................................ 32 Growth Rate ......................................................................................................... 36 Nitrogen Uptake ................................................................................................... 38 Thatch Depth ........................................................................................................ 40 Root Dry Matter .................................................................................................... 42 Loss on Ignition .................................................................................................... 44 Economic Analysis ............................................................................................... 45 4 SUMMARY AND CONCLUSSIONS .......................................................................... 47 REFERENCES .................................................................................................................. 74 BIOGRAPHICAL SKETCH ................................................................................................ 78
6 LIST OF TABLES Table page 3 -1 Ball roll distance of paspalum cultivars in response to man agement practices and N rate 2008 and 2009. .................................................................................... 57 3 -2 Growth rate of bermuda cultivars in response to management practices and N rate in 2009. ........................................................................................................ 60 3 -3 Nitrogen uptake of paspalum cultivars and bermuda cultivars in respond to management practices and N rate in 2008. .......................................................... 63 3 -4 Percent weight loss on ignition of bermuda cultivar s in respond to management practices and N rate in 2008. .......................................................... 71 3 -5 Cultural practices and total maintenance cost of two paspalum cultivars (Sea Dwarf and Sea Isle Supreme) grown in putting greens of 125.4 m2. ................... 72 3 -6 Cultural practices and total maintenance cost of two bermuda cultivars (Mini Verde and Jones Dwarf) grown in putting greens of 125.4 m2. ............................ 73
7 LIST OF FIGURES Figure page 2 -1 Individual plot plan split -block design with three nitrogen rates and three replications arranged in a randomized complete block design (RCBD) with two topdressing as the sub -plot factor. .................................................................. 49 3 -1 Effect of nitrogen rate on the overall mean visual quality in 2008 for A) Paspalum cultivars, B) Bermuda cultivars, and in 2009 for C) Paspalum cultivars, D) Bermuda cultivars. ............................................................................ 50 3 -2 Effect of nitrogen rate on visual quality in the 2nd evaluation period for paspalum grasses in 2008. .................................................................................... 52 3 -3 Effect of nitrogen rate on Mini Verde bermuda grass visual quality 2nd evaluation period in 2008. ...................................................................................... 52 3 -4 Effect of nitrogen rate on Jones Dwarf bermuda grass visual quality 4th evaluation period in 2008. ...................................................................................... 53 3 -5 Effect of nitrogen rate on the overall mean Mini Verde bermuda grass visual quality in 2009. ....................................................................................................... 53 3 -6 Effect of nitrogen rate on the overall mean Jones Dwarf Bermuda grass visual quality evaluation period in 2009. ................................................................ 54 3 -7 Effect of nitrogen rate on the overall mean ball roll distance in 2008 for A) Paspalum cultivars, B) Bermuda cultivars, and in 2009 for C) Paspalum cultivars, D) Bermuda cultivars. ............................................................................ 55 3 -8 Effect of nitrogen rate on the overall mean growth rate in 2008 for A) Paspalum cultivars, B) Bermuda cultivars, and in 2009 for C) Paspalum cultivars, D) Bermuda cultivar s Paspalum cultivars. ............................................ 58 3 -9 Effect of nitrogen rate on Mini Verde overall mean growth rate in 2008. ............. 60 3 -10 Effect of nitrogen rate on the overall nitrogen uptake in 2008 for A) Paspalum cultivars, B) Bermuda cultivars, and in 2009 for C) Paspalum cultivars, D) Bermuda cultivars .................................................................................................. 61 3 -11 Effect of nitrogen rate on Mini Verde bermudagrass nitrogen uptake 2nd evaluation period in 2008. ...................................................................................... 64 3 -12 Effect of nitrogen rate on the overall nitrogen uptake for Mini Verde in 2009 ...... 64
8 3 -13 Effect of nitrogen rate on the overall thatch depth in 2008 for A) Paspalum cultivars, B) Bermuda cultivars, and in 2009 for C) Paspalum cultivars, D) Bermuda cultivars ................................................................................................... 65 3 -14 Effect of nitrogen rate on the overall roots dry matter in 2008 for A) Paspalum cultivars, B) Bermuda cultivars, and in 2009 for C) Paspalum cultivars, D) Bermuda cultivars Paspalum cultivars. ................................................................ 67 3 -15 Effect of nitrogen rate on the overall loss on ignition in 2008 for A) Paspalum cultivars, B) Bermuda cultivars, and in 2009 for C) Paspalum cultivars, D) Bermuda cultivars. .................................................................................................. 69
9 Abstract of Thesis Present ed to the Graduate School of the University of Florida in Partial Fulfillment of the Requirements for the Degree of Master of Science COMPARATIVE MAINTENANCE OF PASPALUM AND BERMUDA GRASSES By Ivan M. Vargas Altamirano May 2010 Chair: Jerry B Sartain Major: Soil and Water Science Paspalum grasses have been adopted by golf courses in the southeast U S. because they appear to have a low nitrogen (N) requirement and a high tolerance to high salinity irrigation water. However, adequate management practi ces and their economical implications that permit acceptable playability for paspalum grasses are mostly unknown and undocumented compared with the commonly used bermuda grasses. This study (run in 2008 and 2009) evaluated two Paspalum cultivars Paspalum v aginatum Swarz (Sea Dwarf and Sea Isle Supreme) and two bermuda cultivars C. dactylon (L). Pers. X C. transvaalensis Burtt Davy (Jones Dwarf and Mini Verde) grown on putting greens relative to their playability, N nutrition, and maintenance costs. In 2008, two factors such as: three N rates (49, 98 and 196 kg N ha1 yr1) and two topdressing frequencies ( twice and every month) were studied. In 2009, the N rates were reduced for paspalum grasses (12, 24, and 49 kg N ha1 yr1) and increased for bermuda grass es (122, 244, and 488 kg N ha1 yr1). Also in 2009, the topdressing frequency was changed to a verticutting frequency factor (every 2 weeks and every 4 weeks). The effect of the treatments was determined for multiple parameters including visual quality, golf ball roll, growth rate, nitrogen uptake, thatch depth, root dry matter, and thatch accumulation (weight loss on ignition). The principal results from (i) turfgrass
10 cultivar, (ii) N nutrition requirements, and (iii) total maintenance cost are as follow. (i) Jones Dwarf produced the highest growth rate. Paspalum grasses produced more root dry matter than Bermuda grasses, which was reflected in higher N uptake and greater thatch depth. Different topdressing applications did not influence visual quality. Ho wever, Jones Dwarf beneficed from monthly topdressing with 1.6 mm of sand. Verticutting every 2 weeks should be included as a management practice for the Paspalum cultivar (Sea Isle Supreme) in order to achieve acceptable golf playability conditions. Maint enance requirements for both bermuda cultivars and one Paspalum cultivar (Sea Dwarf) when grown on push -up native soil greens should include verticutting once a month in order to obtain acceptable ball roll distance. (ii) Paspalum cultivars should be ferti lized four times (from May to August) with an N application rate of 49 kg N ha1 yr1 in order to obtain an acceptable visual quality. In comparison bermuda cultivars should be fertilized throughout all the active growth period (from May to September) at t he rate of 488 kg N ha1 yr1 to maintain acceptable quality. (iii) Paspalum grass fertilization cost ($138) was lower than bermuda grasses ($806) per year basis growing in putting greens of 125.4 m2. Paspalum grasses had a higher verticutting cost ($560) than bermuda grasses ($280). Paspalum grasses total maintenance cost was lower ($4811) than bermuda grasses total maintenance ($5199). Therefore, this study found that Paspalum cultivars differed with bermuda grasses in terms of turfgrass cultivar, N nutri tion requirements, and total maintenance cost.
11 CHAPTER 1 INTRODUCTION Golf Course Economical Impact In the United States, golf is a popular recreational activity. In 2007, there were 29.5 million golfers in the United States aged 6 and above (National G olf Foundation, 2008). Moreover, in the same year there was an estimated total of 15,970 facilities. Of those, 11,555 were open to the public. A facility is defined as a complex that contains at least one 18 holes golf course. Popular Golfers travel desti nations for golf include: Florida South Carolina, North Carolina, California, and Arizona (National Golf Foundation, 2008). In 2007, Florida reported the most golf facilities with around 1,060 followed by California, Michigan, Texas, and New York containi ng 927, 836, 832, and 818, respectively (National Golf Foundation, 2008). In 2000, the economic impact of the Florida golf industry was estimated to have total annual revenue of $4.44 billion. At the same time the golf industry in Florida represented direc t employment for 73,000 people. According to Haydu and Hodges (2002), the area owned by Florida golf courses was 82,961 hectares with 56,656 hectares irrigated and 59,489 hectares in maintained turf. Golf courses represent an important economic component o f Florida. For example, the estimated travel expense in Florida is $22.9 billion by golf player visitors These expenditures had an impact of 226,000 jobs and $9.2 billion in personal and business net income on the Florida economy (Haydu and Hodges, 2002). The predominant type of turfgrass on typical putting greens and fairways in Florida is some cultivar of bermudagrass representing 93% of maintained turf areas. Accounting for the water used, it was estimated that 173 billion gallons were used for
12 irrigati on, of which 49% came for recycled water, with lesser amounts of 29% and 21% from surface waters and wells, respectively (Haydu and Hodges, 2002). Bermudagrass Bermudagrass originated in Africa and was introduced into the United States in the mid1700s (Hanson et al., 1969). It is the primary warm -season turfgrass for golf and is tolerant of low mowing heights; therefore, some cultivars are used on golf course greens. Taliaferro (1995) suggested that there are nine species in the genus Cynodon, with Cynodon dactylon [l.] Pers. most widely used. This species is known in the United States as common bermudagrass and in other parts of the world by a variety of names including Couch, Doob, and Kweek (Taliaferro, 1995). In most cases, some variant of hybrid bermud agrass [C. dactylon (L). Pers. X C. transvaalensis Burtt Davy] has been used in the southern parts of USA for putting greens. Some of the best known of these C. dactylon x C. transvaalensis hybrid cultivars are Champion, FloraDwarf, Midiron, Midlawn, Midfield, Tiffine, Tifgreen, Tifdwarf, TifEagle (TW -72), Tiflawn, Tifway, and Tifsport (Beard and Sifers, 1996; Taliaferro and McMaugh, 1993).The prefix Tif comes from Tifton, GA, home of the Coastal Plain Experiment Station, where the se cultivars were developed in the breeding program of Dr. G.W. Burton. The Mid cultivars were jointly released from the Kansas and Oklahoma Agriculture Experiment Stations. These hybrids are sterile, and thus no seed is available, so they must be establ ished vegetatively. Produced from a C transvaalensis and C dactylon cross, Tifgreen was the first vegetative cultivar to be sprigged on putting greens (Hein, 1961). In 1966, Tifdwarf (a vegetative off -type of Tifgreen) was released because of its smaller leaves, reduced seed head production, and darker green color (Burton, 1966). Since its release for
13 southern putting greens, Tifdwarf has become the standard bermudagrass cultivar. However, selected off -types have been released as cultivars and are commonl y grouped together under the term ultradwarfs (Hollingsworth et al., 2005). Ultradwarfs in the past decade have emerged as a favorite for renovated or newly constructed bermudagrass putting greens. The term ultradwarf has come into common usage in recent years to describe bermudagrass that can be maintained at very low mowing height on golf course greens. Some examples of the ultradwarfs are: Champion, FloraDwarf, Mini Verde, Mississippi (MS) Supreme, and TifEagle. Those grasses can be maintained at 3.04 to 3.56 mm if properly managed (Cowan, 2001, Hollingsworth et al., 2005). from Tifgreen, Tifdwarf, and the previous ultradwarfs (Hanna and Elsner, 1999). Champion is a vegetative selection from Tifdwarf, with genetically different DNA (Beard an d Sifers, 1996). MS Supreme is an ecotype selection from Tifgreen and is genetically different from both Tifgreen and Tifdwarf (Krans et al., 1999). FloraDwarf is a vegetative selection from Tifdwarf and it also differs genetically from Tifdwarf (Dudeck an d Murdoch, 1998). In general, ultradwarf bermudagrass have better turf quality, shorter internodes, higher shoot densities, and the ability to withstand lower mowing heights than Tifdwarf; thus, those cultivars have become popular on putting greens. Althou gh they may offer improved turf quality, they present new issues in terms of management (Hollingsworth et al., 2005).
14 Seashore Paspalum New Paspalum type grasses such as Seashore Paspalum have been adopted by golf courses in the state as a way to avoid man agement problems associated with the use of high salinity water. Seashore paspalum is relatively intolerant of cold temperatures and is generally limited to the southern part of the transition zone and south into the tropics (Christians, 2007). This grass usage has increased rapidly in the United States in recent years on areas where salt levels are too high for bermudagrass and other warm -season turf grass species (Christians, 2007). Seashore Paspalum ( Paspalum vaginatum Swarz. ) is a warm -season native to subtropical and tropical regions around the world. This species has stolons and rhizomes, and its texture varies from coarse to very fine. It has pointed leaves and its blades are narrower than those of bahiagrass. The ligule is a membrane with fine hairs protruding from its upper edge (Christians, 2007). This grass is often found in brackish marsh water or in close proximity to ocean water; it grows naturally in coastal environments. It has been observed that it can grow in areas that receive extended peri ods of heavy rain and low light intensity. However, the best growth occurs in response to warm temperatures and long day lengths (Trenholm, 2000). Duncan and Carrow (2000) suggested that Seashore Paspalum ( Paspalum vaginatum Swarz. ) is known by a number of common names other than Seashore Paspalum such as siltgrass, saltwater couch, and sand knotgrass. Some cultivars can be maintained with seawater containing 34,486 mg L1 salt, so that it is known for its high salinity tolerance (Duncan et al. 2000). The U niversity of Georgia turfgrass breeding program has the largest testing program and collection of paspalum, and has assembled more than 300 ecotypes of
15 this species. The selection of cultivars for sports turf has been limited to the mid and late 1990s, even though the species has been in existence for hundreds of years. Seashore paspalum must be planted as plugs, sods, or springs because it does not produce viable seeds. However once establishment it produce a high -quality, prostrategrowing, dense turf (Tr enholm, 2000). It has been suggested that Seashore Paspalum produces a high-quality turfgrass with minimal fertility requirements. Despite the fact that it will exhibit its best quality and growth under optimal environmental conditions, it can exist under less than optimal conditions for extended periods of time. Some of the advantages of this turfgrass refer to the fact that it can tolerate a wide range of stress. For example, Trenholm (2000) reports that seashore paspalum has excellent tolerance for salin e or recycled water, good drought tolerance under proper management, tolerance of low soil fertility, tolerance to a wide range of soil pH (from 49), minimal pesticide requirements, excellent wear tolerance, tolerance to extended periods of low light inte nsity (such as prolonged cloudy or rainy periods), good insect and disease resistance, and tolerance to flooding or extended wet periods. However, there are some disadvantages, such as it produces moderate amounts of thatch during periods of active growth and does not perform well under tree shade (Trenholm, 2000). Some of the cultivars are Sea Isle 1, Sea Isle 2000, Sea Isle Supreme Salam, Seaway, Sea Dwarf, and Sea Spray (Christians, 2007). Sea Isle 2000 was developed by plant geneticist Dr. R.R. Duncan at the University of Georgia's Griffin Experiment Station from a sample collected at Alden Pines Country Club in Bokeelia, FL, which is owned and operated by Stewart Bennett. It
16 was suggested that Sea Isle 2000 is ideal for golf greens and t ees, especially in salt challenged environments. It is similar to the dwarf bermudas in texture and playability when maintained at 3.175 mm mowing height (Phillip Jennings Turf Farms, 2009). Stimpmeter readings of 3.05 m or more can be seen if regular vert i -cutting, light topdressing and periodic rolling are applied. Sea Isle Supreme is a grass that thrives on salt water, using a seawater blend, or even straight ocean water with the right management practices. It also grows well when watered with recycled o r effluent sources. The principal characteristics of Sea Isle Supreme 2000 are that it is a very aggressive creeping type of grass (Phillip Jennings Turf Farms, 2009). The soil reaction range for Sea Isle Supreme 2000 has been suggested at a pH above 6.0. Moreover, it has been observed to perform best on a low level of applied nitrogen, approximately 146 kg N ha1 per year given a balanced N:P:K program according to soil tests (Phillip Jennings Turf Farms, 2009). Another Seashore Paspalum cultivar that has become popular is Sea Dwarf TM Seashore Paspalum. It was developed and marketed internationally by Environmental Turf. They market this grass as the Premium Seashore Paspalum turf grass, suggesting that Sea Dwarf is suited for use on golf courses tee-to gr een and on sports fields such as soccer, baseball, softball and football (Environmental Turf, 2009). Some of the general characteristics are fine texture, a bright green color, tolerates a wide range of mowing heights, about 2.54 mm to about 10.16 cm, can be irrigated with varied water quality and alternative water sources such as effluent, reclaimed or brackish. Moreover, it also grows well in flow way applications where the turf will remain wet or even submerged for periods of time and it is fairly shade tolerant,
17 fairly cold tolerant, and can withstand prolonged wet conditions (Environmental Turf, 2009). In terms of maintenance characteristics it has been suggested that Sea Dwarf has different maintenance requirements than other turfgrasses such as bermudagrass. For instance, it has been suggested that it takes up to 50% less water and requires up to 75% less nitrogen fertilizer than bermudagrass. Besides that salt can be used as an herbicide (Environmental Turf, 2009). This variety (Sea Dwarf) has become very popular for golf courses; for example, in the United States it is utilized in Hammock Bay Golf & Country Club, Naples, Florida, Crown Colony Golf & Country Club, Fort Myers, Florida, Olde Palm Golf & Country Club, Palm Beach Gardens, Florida, Galvest on Country Club, Galveston, Texas, and Coco Beach Golf & Country Club, Rio Grande, Puerto Rico. In addition, Sea Dwarf is the grass used in Palma de Mallorca, Mallorca, Spain (Environmental Turf, 2009). There are several studies referring to Seashore Paspalum that can be found in the literature. For example, in 1979 Henry et al. showed N fertilization response for Paspalum, using increasing rates from 8.1 to 33.3 kg ha1. On a monthly basis, visual quality was improved on Adalayd and Futurf paspalum. However, scalping injury was noticed on both cultivars. Another study Beard et al. (1991) noted that cutting height has a greater effect on visual quality, fall color retention, and spring green up than did N application. There was a linear response to mowing h eight, and they noticed a superior visual quality with shorter cut turf, spring greenup, and shoot density (Beard et al., 1991).
18 In 2001, a study was conducted in Georgia using N application of 196 or 392 kg ha1 in Paspalum vaginatum mowed at 4 mm during a 4month period with two ecotypes (AP10 and AP14). This study showed that application of the higher rate of N did not affect shoot growth, but improved visual quality, color, density and wear tolerance (Trenholm et al., 2001). Kopec et al. (2007) reported a study with Sea Isle Supreme 2000 Seashore Paspalum ( Paspalum vaginatum Sw .) that was maintained as a putting green surface. They evaluated turf grass response attributes, nutrient content, and ball roll distance (BRD) as affected by three mowing height s (0.3, 0.4 and 0.5 cm) and four monthly N application rates (12, 18, 24, and 36 kg ha1). They found an acceptable visible turf grass quality of 6.0 (on a scale 1 to 9) or greater for all the treatments. Shoot counts were greatest at the 0.3-cm height and were not significantly influenced by N rates (Kopec et al., 2007). It was suggested that higher levels of applied N with shorter mowing heights generally increased the clipping dry weight. In terms of leaf tissue, N was found to increase in response to increasing levels of N application. Ball roll distance was largely unaffected by N fertilization, but was affected by mowing height and rolling. The maximum BRD observed was 277 cm; where 234 cm and 214 cm were the mean BRD on rolled and unrolled turf surfac es mowed at 0.3-cm height (Kopec et al., 2007). Maintenance Practices Seashore Paspalum has been suggested to have excellent tolerance to the high salt levels found in reclaimed water, effluent, salt spray and seawater after it has been established, and al so requires less fertilizer and less irrigation than many other
19 turfgrasses such as bermudagrasses. However, the maintenance requirements for seashore paspalum compared with bermuda grasses are in most cases unknown. In the case of bermudagrass, McCarty an d Miller (2002) suggested that there are cultural practices that need to be taken into the account such as mowing, irrigation/water management, fertilizing, aerification strategies and techniques, topdressing, and overseeding in order to obtain adequate be rmudagrass golf greens. From those maintenance practices, nutritional requirement is one of the most essential and nitrogen use efficiency a very important component in terms of quality and environmental concern. Power and Schepers (1989) suggested that ni trogen placement, nitrogen timing, and nitrogen source are important factors, but when those factors are compared with optimizing the nitrogen rate they usually produce smaller enhancement in terms of nitrogen use efficiency. Moreover, many other authors h ave shown in several different studies that nitrogen losses increase rapidly when the nitrogen inputs are higher than the crop assimilation capacity, suggesting that the rate of applied nitrogen is the governing factor affecting the nitrogen use efficiency (e.g., Broadbent and Carlton, 1978; Legg and Meisinger, 1982; Vanotti and Bundy, 1994; Schlegel et al., 1996; Doberman et al., 2006; Meisinger et al., 2008). Therefore, the present study evaluated the overall maintenance and nutrition requirements of paspalum and bermuda grasses grown on nature soil push up putting greens in order to determine the best management practices related to their playability and maintenance costs.
20 Hypothesis and Research Objectives Previous studies have determinated some of t he management practices and nutrition requirements of bermudagrasses growing in putting greens; however, Seashore Paspalum grasses nutritional requirements and management practices for Florida golf courses need to be developed. Hypothesis: Paspalum grasses and bermuda grasses growing on putting greens will differ overall in terms of maintenance and nutrition requirements. Principal Objective: To determine overall maintenance and nitrogen nutrition requirements of paspalum and bermuda grasses grown on puttin g greens. Specific Objectives 1: Determine the influence of topdressing and verticutting on paspalum and bermuda grasses grown on putting greens relative to their playability and maintenance costs. Specific Objectives 2: Determine the nitrogen nutrition requirements of paspalum and bermuda grasses grown on putting greens.
21 CHAPTER 2 MATERIAL AND METHODS Field Study Design A field experiment was utilized to evaluate overall maintenance and nitrogen nutrition requirements of paspalum and bermuda grasses grown on push up putting greens. Two cultivars of Seashore Paspalum ( Paspalum vaginatum Swarz ), Sea Dwarf and Sea Isle Supreme, were evaluated and compared with two cultivars of hybrid bermudagrasses [ C. dactylon (L). Pers. X C. transvaalensis Burtt Davy], Min i Verde and Jones Dwarf. The four grasses were established under putting green conditions on native soil push up greens on the UF/IFAS Turfgrass Research Facilities at the Plant Science Research and Education Unit, near Citra, FL. Research was conducted f rom April 17th to September 17th, 2008 and repeated in from April 16th to September 17th 2009. The field plots were established in September 2007. In 2008, three nitrogen rates using urea (46% Nitrogen) were applied at 1.22, 2.44, and 4.88 g m2 every 15 d ays until acceptable visual quality was achieved. In 2008 the nitrogen rates were 49, 98, and 196 kg N ha1 yr1 and 110, 220, and 440 kg N ha1 yr1 for paspalum and bermuda grasses respectively. The plots were mowed at 0.64 cm three times per week. Two l evels of topdressing maintenance were established on all the grasses. Topdressing treatments were applied according to the USGA recommendation (OBrien and Hartwiger, 2003), rates of 3.2 mm twice at 75day intervals and 1.6 mm four times at once per month. The field study was established as a split plot design with three replications. Nitrogen rate treatments were arranged in a randomized complete block design (RCBD), while topdressing was the sub-plot factor.
22 The study was arranged with 72 experimental uni ts total, organized in 18 experimental units per grass within grass as the main plots; topdressing treatment were arranged as sub-plots and N treatments were replicated three times (Figure 21). In 2009 the same four cultivars from 2008 were evaluated, but the nitrogen rates and management practices changed. In 2009 the nitrogen rates were reduced for paspalum grasses (12, 24, and 49 kg N ha1 yr1) and increased for bermudagrasses (122, 244 and 488 kg N ha1 yr1) in order to achieve the nitrogen requirements. In 2009 the management practice topdressing was changed to a verticutting frequency factor (every 2 weeks and every 4 weeks). In addition both bermuda grasses plots were relocated due to the immaturity effect which produced a low visual quality in 2008. In 2009, the mowing height was reduced (0.25 cm) and the mowing frequency was increased (four times per week). Each experimental unit consisted of 6.9 m2 which was 0.91 m wide by 7.62 m long. In 2008 and 2008 clippings were collected every 30 days throughout the 150-day study period. Data Collection Data including all management practices such as aerification, mowing frequency, and pest management (insecticides, fungicides, and herbicides) were recorded with their product name and frequency in order to d etermine the total cost. At termination all maintenance costs were evaluated against the best treatment and compared across turfgrass species. In addition, visual quality, ball roll, clipping yield, N uptake, thatch accumulation, thatch depth, and root dry matter were collected for both years. Visual quality rating was taken weekly and evaluated from 1 to 9, 1 = brown, dead turfgrass, 5.5 = minimal acceptable turfgrass, 9 = ideal green, healthy turfgrass. Golf ball roll distance (BRD) measurement consisted of three releases, in each of two
23 directions from a standard U.S. Golf Association stimpmeter (U.S. Golf Association, 2000). Measurements were taken on a weekly basis immediately after mowing. Clipping yield (g m2) was collected once a month (May, June, J uly, August, and September). Shoot tissue was collected using a Toro walk behind mower following 3 days of growth. Harvested clippings were oven dried at 68 C for 48 hours and weighed to quantify dry matter. All harvested clippings were dried, ground, and analyzed for Total Kjeldahl Nitrogen (TKN). The tissue N concentration was multiplied with the dry matter accumulation to achieve the total nitrogen uptake from each experimental unit. Two root samples were taken from each plot once per month using a rect angular (2 cm by 7 cm) green sampler to a depth of 10 cm in order to measure root dry matter, thatch depth, and thatch organic matter. The top portion of these samples was removed at crown level and thatch depth (cm) was measured using a ruler from three p oints on the soil cores and averaged. Roots were clipped at the base of the thatch layer and the remaining thatch sample was placed in an 80 C oven for 96 h and weighed. Roots were hand washed in a 1-6mm sieve to remove the roots from soil, dried at 70 C for 48 h and weighed to determine the root dry matter (g m2). Thatch samples were placed in a muffle furnace (Benchtop Muffle Furnace LMF -A550, Omega Engineering, Inc., Stamford, CT) at 525 C for 3 h to provide ash free weight (Snyder and Cisar, 2000). D ata Analysis Statistical analysis of data was performed to evaluate the treatment effects using Statistical Analysis System (version 9.1, SAS Institute, Cary, NC). Mean separation was accomplished by using Duncans multiple range test and single degree of freedom
24 contrast based on the general linear model procedure. A standard analysis of variance (ANOVA) was used to determine statistical differences for the effect of turfgrass cultivar, nitrogen rate, management practices (topdressing or verticutting) and their interactions (SAS Institute Inc, 1999).
25 CHAPTER 3 RESULTS AND DISCUSSI ON COMPARATIVE MAINTENANCE OF PASPALUM AND BERMUDA GRASSES Study Description Introduction and Material and Methods Two Seashore Paspalum ( Paspalum vaginatum Sw ) and two Hybrid bermudagrass [ C dactylon (L). Pers. X C transvaalensis Burtt Davy] cultivars w ere evaluated in a field study that ran 150 days yr1 (2008 and 2009). The objective was to evaluate the overall maintenance and nitrogen nutrition requirements of paspalum gra sses and bermuda grasses grown on push up putting greens. In the 2008 study, three factors were evaluated: three nitrogen rates (49, 98 and 196 kg N ha1 yr1), two topdressing levels ( 3.2 mm applied twice and 1.6 mm applied 5 times) and four turfgrasses c ultivars (two Seashore Paspalum cultivars Sea Dwarf and Sea Isle Supreme and two Hybrid bermudagrass cultivars Mini Verde and Jones Dwarf) were studied. In the 2009 study, the same four cultivars from 2008 were evaluated, but the nitrogen rates were reduced for paspalum grasses (12, 24, and 49 kg N ha1 yr1) and increased for bermuda grasses (122, 244, and 488 kg N ha1 yr1). Also in the 2009 study the topdressing factor was changed to a verticutting frequency factor (every 2 weeks and every 4 weeks) and both bermuda grasses were relocated due to the immaturity of the turfgrass. In both years, the effect of the treatments was determined for multiple parameters such as visual quality, ball roll, growth rate, nitrogen uptake, thatch depth, roots dry matter, and thatch accumulation (weight loss on ignition) in order to make a comparison in term of nitrogen requirement and maintenance between paspalum and bermuda grasses.
26 In the 2008 study, topdressing (T) only influenced the overall mean ball roll distance of one cultivar (Jones Dwarf). Other than that topdressing and the interaction between topdressing and nitrogen (N) rate did not influence the evaluated parameters. In the 2009 study, verticutting (V) did not influence any parameters other than: (i) the overall growth rate of Sea Dwarf, (ii) the ball roll distance of Sea Isle Supreme during the 2nd treatment cycle, and (iii) the overall ball roll distance of Jones Dwarf. Moreover, N rate and turfgrass cultivars influenced some of the evaluated parameters in both years. Therefore, the main effects of T, N rate, turfgrass, and the V are presented and discussed below. 2008 and 2009 Results and Discussion Turf Visual Quality Visual quality ratings were taken weekly on a 1 to 9 scale with 9 representing superior qua lity turfgrass and 5.5 representing a minimum acceptable turfgrass. Twenty two (2008) and eighteen (2009) visual quality ratings were averaged and analyzed during the evaluation period. In the 2008 study, visual quality of both paspalum cultivars was impac ted at the highest N (196 kg N ha1 yr1) application rate. Thus, both cultivars were similar in visual quality at the middle (98 kg N ha1 yr1) and lowest (49 kg N ha1 yr1) nitrogen application rates (Fig. 3-1a). Trenholm et al. (2001) suggested that an N rate application from 196 to 392 kg ha1 improved visual quality, color, and density in two cultivars of Paspalum vaginatum. These results coincide with ours and together suggest that a difference between Paspalum grasses cultivars in visual quality oc curs at a high nitrogen rate (above 196 kg N ha1 yr1). The mean visual quality response for both paspalum cultivars in 2008 was above 6 for all three nitrogen rates which was higher than the minimum acceptable level of 5.5
27 (Fig. 3 -1a). In order to establ ish an accurate recommendation of nitrogen application rate it is necessary to obtain values of visual quality below and above the 5.5 acceptable level. The 2008 results suggest that even the lowest nitrogen rate applied (49 kg ha1 yr1) was too high for Paspalum grasses. Therefore, lower rates were applied in 2009 in order to develop a N response curve. On the other hand, in the 2008 study most of the Bermuda grasses cultivars were below the acceptable minimal value of 5.5 (Fig. 3 -1b). Although the N rate applied for bermudagrass (110, 220, and 440 kg N ha 1 yr1) was higher than paspalum grasses only Mini Verde was near acceptable quality at the highest N rate (440 kg N ha1) during the evaluation period of 2008. This suggests that in terms of N requirem ents and maintenance bermuda cultivars required more nitrogen compared with the paspalum cultivars in order to obtain an acceptable visual quality. In the 2008 study, it appeared that preexisting growth characteristics such as immaturity of the grasses on the push up greens used may have been responsible for the poor performance of the hybrid bermuda grasses. Therefore, in the 2009 study both bermuda cultivars were relocated and the N rate increased (122, 244, and 488 kg N ha 1 yr1) in order to achieve th e desirable visual quality level above 5.5. This comparative study was divided into five 30 day evaluation periods per year. All four turfgrasses cultivars responded to nitrogen rate in different periods. Paspalum grasses in 2008 responded in visual qualit y to N rate on Sea Dwarf only during the 2nd 30 day evaluation period and for Sea Isle Supreme a response to N rate was observed during the 2nd, 3rd, 4th, and 5th 30 day evaluation periods. Bermudagrasses showed a visual quality response due to N rate duri ng three evaluation period for both cultivars. Mini Verde and Jones Dwarf responded in visual quality to N rate during the 1st, 2nd, 4th
28 and the 2nd, 3rd, 4th evaluation period in 2008, respectively. In the 2008 study, a fitted model for paspalum grasses a nd Mini Verde comparing visual quality and N rate produced a strong relationship from the 2nd evaluation period for Sea Dwarf (r2 = 0.83), Sea Isle Supreme (r2 = 0.79) (Fig. 32) and Mini Verde (r2 = 0.71) (Fig 3-3). A fitted model for Jones Dwarf was observed during the 4th evaluation period (r2=0.63) (Fig. 34). Although in 2009 the same tendency was found as that in 2008 for paspalum grasses, the relationship between N rate and visual quality of Sea Dwarf (r2 =0.42), and Sea Isle Supreme (r2 =0.37) was m uch weaker. Henry et al. (1979) demonstrated in Adalayd and Futurf Seashore Paspalum that an increase in N rate from 8.1 to 33 kg ha1 on a monthly basis improved visual quality. This suggested that visual quality could be affected by increases in nitrogen rates. Both evaluated paspalum cultivars in 2008 and the 2009 received four N applications. However, they received three of the four nitrogen applications before the 2nd 30 day evaluation period. Therefore, it appears that the response observed of Paspalu m grasses to N rate in 2008 and 2009 was directly due to the actual nitrogen applied. Although the 2008 and the 2009 paspalum cultivars showed a similar tendency in the 2nd evaluation periods where visual quality was affected by N rate, in 2009 the effect of N rate on the overall mean visual quality of paspalum grasses was not different. In 2009 both Bermuda grasses were influenced by N rate in the same three evaluation periods the (1st, 3rd, and 4th). In the 2009 study a fitted linear and quadratic model f or Mini Verde (r2=0.80) (Fig. 35) and Jones Dwarf (r2 =0.71) (Fig. 3-6) illustrated the overall response for bermuda grasses. Increasing N rate resulted in increased quality.
29 Bermuda grasses did not reach a plateau therefore it suggest that the nitrogen r equirement for bermuda grasses could be even higher. Environmental conditions of the study could be another factor contributing to the results. Hybrid bermuda grass growth and development are influenced by environmental conditions such as temperature, nitr ogen, and light (Stanford et al., 2005). In the 2009 study, the overall mean visual quality for the Bermuda grasses was near acceptable at the higher rate (448 kg N ha 1 yr1) (Fig. 31d) and a difference in visual quality response was found between the N rate applied. This complements the 2008 data and together suggested that there is higher nitrogen requirement for Bermuda grasses growing in putting greens compared with Paspalum grasses. In the 2009 study, the paspalum grasses exhibited a reduction in th e overall mean turfgrass visual quality compared to 2008, where it appears that the decreases from 2008 to 2009 in Sea Dwarf and Sea Isle Supreme can be attributed to the reduction in nitrogen rates used in the 2009 study (Fig. 3-1c). Even though the appli cation rates in 2008 (49, 98, and 196 kg ha1 yr1) were reduced in 2009 (12, 24, and 49 kg ha1 yr1) the Paspalum grasses still maintained an acceptable (above 5.5) overall mean visual quality. Rates used in 2009 relate with the results obtained by Kopec et al. (2007) where they reported an acceptable visible turfgrass quality of 6.0 (on a scale 1 to 9) or greater for all treatments at four monthly application rates of 12, 18, 24 and 36 kg ha1 to Seashore Paspalum ( Paspalum vaginatum Sw. ). Also, Environm ental Turf (2009) supports low N rates for Paspalum grasses. They report that the nitrogen requirement for Seashore Paspalum could be up to 75% less than other turfgrasses such as bermuda grasses. According to Phillip Jennings Turf Farms (2009),
30 the N reco mmendation for Seashore Paspalum is low at approximately 14.63 g m2 yr1 or 146 kg ha1 yr1. This comparative study supports those low nitrogen requirements for Seashore Paspalum and high N requirements for bermuda grasses, but according to this study th e actual N recommendation should be even lower (approximately 49 kg ha1 yr1) and bermuda grasses even higher (approximately 488 kg ha1 yr1). An accurate N rate is very important in order to obtain high N use efficiency. Power and Schepers (1989) sugges ted that the effect of N placement, N timing, and N source are important factors, but when those factors are compared with optimizing the N rate they usually produce smaller enhancement in terms of N use efficiency. Moreover, many other authors have shown with several different studies that N losses increase rapidly when the N inputs are higher than the crop assimilation capacity; suggesting that the rate of applied N is the governing factor affecting the N use efficiency (e.g., Broadbent and Carlton, 1978; Legg and Meisinger, 1982; Vanotti and Bundy, 1994; Schlegel et al., 1996; Doberman et al., 2006; Meisinger et al., 2008). Although this study suggested that paspalum requires lower N rates and bermuda requires higher N rates compared with other studies, t he environmental conditions of this study could have influenced turfgrass visual quality. According to Stanford et al. (2005) temperature, nitrogen, and light have an effect on hybrid bermudagrass growth and development. They reported that temperature as w ell as light levels regulated expressions of dwarfness in Tifdwarf bermudagrass. They suggested that in regions that typically have long periods with daytime temperatures less or equal to 27 C and photosynthesis photon flux density (PPFD) less or equal to 600 mol m2 s1 the growth of hybrid bermuda grasses changes considerably producing
31 longer internodes spacing and longer leaves in plants. Also, they reported that an overall trend was seen in which the internodes increased due to an increase in nitrogen. They reported that plants fertilized at the greatest N rate (24.4 kg ha1 wk1) had longest internode length and more total shoot dry weight compared with those at the lowest N rate (8.1 and 16.3 kg ha1 wk1). The previous results support this comparati ve studys results because it was found that bermuda grasses showed a positive response in visual quality to increased N rate applied. Therefore, the recommended N rate for paspalum and bermuda grasses should be adjusted depending on the conditions under w hich the turfgrass will be grown. According to Brosnan and Deputy (2008) paspalum evolution has occurred in coastal, brackish ecosystems, and they report the possibility that paspalum grasses only respond to nitrate nitrogen. In this study in Florida, nitr ogen form was most likely not a problem for paspalum grasses. This is because the high temperatures and soil conditions in Florida during the 150 day evaluation period were appropriate for urea (46% organic soluble nitrogen) to nitrify and NO3-N was the p redominant nitrogen source available. A difference in overall mean visual quality was found between paspalum cultivars in 2009. The overall mean visual quality of Sea Isle Supreme was higher (6.06 to 6.13) than Sea Dwarf (5.51 to 5.64) (Fig. 31c); therefo re, it appears that Sea Dwarf requires a higher nitrogen rate (12 to 24 kg ha1 yr1) than Sea Isle Supreme (12 kg ha1 yr1) in order to obtain an acceptable level. In comparison, both hybrid bermuda (Mini Verde and Jones Dwarf) grasses were similar acros s each N rate and they responded similarly in increasing turf visual quality due to increased N rate applied. Also, a difference in
32 color was noticed between both turfgrasses. The paspalum grasses produced a more persistent green color than the bermuda cul tivars. Finally, this comparative study results demonstrated that there is a clear difference between paspalum cultivars compared with bermuda cultivars in terms of N response and N requirement. Paspalum grasses showed an early response, before the 60 day evaluation period, in visual quality due to N rate; thus, permitting an acceptable visual quality (above 5.5) with only four N applications. Also, it was found that the early response was enough to maintain the paspalum grasses in acceptable visual quality for the entire 150-day evaluation period for both years, which suggests that the N requirement is lower for paspalum cultivars than bermuda cultivars. Contrasting with the low N requirement of paspalum grasses, it was found that bermuda cultivars required higher N rates and a different maintenance plan by applying N throughout the 150day evaluation period for both years in order to obtain acceptable visual quality. These results show that the actual plateau in term of N requirement for paspalum cultivars is lower than the bermuda cultivars. Ball Roll Paspalum grasses have been used in the Caribbean for many reasons such as potential to tolerate high salinity in irrigation water and lower nitrogen requirement. Therefore, in the last few decades some golf courses in United States (US) have adopted new paspalum cultivars for use on golf greens with plans to increase use of salt water while reducing nitrogen application as promising for golf greens that will tolerate saline water and less nitrogen applications. It has been suggested that new paspalum cultivars differ with the hybrid bermuda grasses in terms of golf course playability. Many golfers, primarily in Latin America, the Caribbean, and now in US, have been faced with
33 a problem in terms of golf green playability, principally those golf courses with paspalum cultivars, due to low ball roll speed. However, there is very little information related to the actual management practices in order to alleviate problems produced by paspalum grasses. Therefore, in th is study, a comparison of the effect of maintenance practices and N requirement produced information on maintenance practices required to meet to golfer expectations. In this comparative study ball roll distance was taken weekly using a Stimpmeter to esti mate putting speed, which is considered an accepted measure of golf course playability (Salaiz et al., 1995). As a management practice for paspalum cultivars, Phillip Jennings Turf Farms (2009) suggested that a Stimpmeter reading of 305 cm or more can be obtained if regular verticutting, light topdressing, and periodic rolling are applied. Therefore, in this 2008 study it was expected that topdressing would have an effect on ball roll distance (BRD) in paspalum cultivars; however, topdressing and nitrogen r ate did not influence the overall BRD in the 2008 study for paspalum grasses and Mini Verde. Only one bermuda grass cultivar (Jones Dwarf) was influenced in the overall mean ball roll by topdressing. It was found that a light topdressing produced a higher ball roll distance (198 cm) compared with the heavy topdressing application (183 cm) for Jones Dwarf. Because limited topdressing influence on BRD was observed in the 2008 study, topdressing treatments were replaced by two verticutting frequencies in 2009. An effect due to N rate in mean BRD was found for both paspalum and bermuda cultivars during the first 30day evaluation period (Table 3 -1) in 2008. It appears that lower N rates produced a higher BRD (Fig 37b). Also in the 2008 study, Mini Verde produced a higher ball roll distance than Jones Dwarf. Jones Dwarf tends to produce
34 more growth above ground, which was reflected in low BRD. Also, in 2008 the lowest nitrogen rates produced a higher BRD for both Paspalum cultivars. Likewise, increasing nitrogen rate (98 and 196 kg N ha1 yr1) reduced BRD of both Paspalum cultivars (Fig. 3 -7a). In 2008, Sea Dwarf had higher BRD values (154 cm to 163 cm) compared with Sea Isle Supreme (149 cm to 157 cm). The BRD recorded for paspalum grasses in this study would be considered unacceptable for golf playability, because most of the golf courses in America require from 213 to 366 cm in stimpmeter values to be of acceptable playability (Oatis, 1990). Jones Dwarf BRD was not considered acceptable, but Mini Verde which ranged from 214 to 221 cm, did reach the United States Golf Association (USGA) standards. USGA experience shows that trying to keep the speed above 304 cm on a consistent basis usually causes difficult -to manage turf problems and is not recommended. They rec ommend maintaining a BRD approximately 244 cm on a daily basis. In the 2009 study, the same trend in BRD was observed with Sea Dwarf having a higher BRD; however, no difference between Paspalum cultivars was observed (Fig. 37c). An effect of verticutting was found in Sea Isle Supreme during the 2nd evaluation period, where a higher BRD of 188.7 cm at the high (every 2 week) verticut frequency was obtained compared with a BRD of 174.7 cm at the low (every 4 week) verticut frequency. Moreover, an increase in BRD was observed from 2008 to 2009 in both Paspalum grasses. Sea Dwarf overall BRD changed in 2008 from 153.6 cm / 163.4 cm to 174.7 cm / 183.2 cm in 2009. However, Sea Isle Supreme increased BRD range in 2009 from 149.4 cm / 157.0 cm to 173.7 cm / 175.9 cm, which represents an increase of approximately 15 percent in BRD for both Paspalum grasses. This can be attributed to
35 the increase in mowing frequency from 3 times wk1 (2008) to 4 times wk1 (2009), the reduction in mowing height 6.34 mm (2008) to 2.54 mm (2009) and the reduction in N rate between both years of the study. In the 2009 study, bermuda grass differed between cultivars in the same way as in 2008 where Mini Verde BRD was higher than Jones Dwarf. Unexpectedly in 2009, BRD for Jones Dwarf decli ned (5.2 %) from 190 cm (2008) to 180 cm (2009); This result could be due to the maturity of the Jones Dwarf and the increase in N rate from one year (2008) to the next (2009). On the other hand, Mini Verde BRD increased (2.5 %) from 219 cm to 224 cm (3-7d ). This suggests that the change in location for bermuda grasses in 2009 did not consistently increase BRD compared with 2008. In the 2009 study, N rate only influenced both bermuda grasses in the 4th evaluation period. Results from the 4th period confirmed the reduction in BRD in response to increased N rate applied to bermudagrass. The 2009 study suggested that addition of a higher verticutting frequency could have a positive influence on BRD; therefore, it is suggested that verticutting every 2 weeks should be included as a management practice for seashore paspalum. In the 2009 study, no difference in the BRD due to nitrogen rate was observed for paspalum grasses. This result could be due to the very healthy condition of the turfgrass and it suggests that the nitrogen rate was not a limiting factor. Similarly, Kopec et al. (2007) reported that BRD on Sea Isle Supreme 2000 was not influenced by nitrogen rates. In comparison, this 2009 study found that verticutting influenced only the overall mean BRD of Jon es Dwarf, where high verticutting frequency produced higher BRD values. Therefore, in this comparative study it appears that (i) nitrogen rate did not
36 directly affect BRD at the nitrogen rates applied for paspalum grasses, (ii) verticutting, increased mowi ng frequency, and decreased mowing height can increase BRD around 15% for paspalum grasses, (iii) the BRD of bermuda grasses tends to be higher than paspalum grasses under the same management practices. Growth Rate Crop growth rate (GR) refers to the dry m atter accumulation rate per unit of land area, normally it is expressed as g (m of land)2 day1. Usually crop growth rate is measured by harvesting plants at frequent intervals and calculating the increase in dry weight from one harvest to the next. Norma lly roots are excluded for GR. For a given interval of GR the following equation is used: GR = (W2W1) / SA (t2 t1); where W2 and W1 are crop dry weight at beginning and end of interval, t1 and t2 are the corresponding days, and SA is the soil area occupied by the plants at each sampling. Usually the most accurate GR is obtained when the crop is sampled at frequent intervals. In this comparative study, clippings were collected on a monthly basis in order to obtain growth rate estimates to determine how grow th rate is influenced by the study factors nitrogen rate, topdressing or verticutting, and turfgrass cultivars. In the 2008 study, both paspalum cultivars and Jones Dwarf Bermuda grass showed similar growth rates across the N rates applied. However, it was found that increases in N rate produced an increased in growth rate only for Mini Verde bermuda grass. Mini Verde responded to N rates in three of the four evaluation periods (2nd, 3rd, and 4th) (Table 32). A linear regression model (r2 =0. 87 ) shows a st rong relationship between increases in nitrogen rate and increases in growth rate in Mini Verde for 2008 (Fig. 39). These results are supported by Stanford et al. (2005) was reported at day/night temperatures ranging from 19/11C to 35/27C and increasing N rate from 8.1 to 24.4 kg ha1 wk1
37 resulted in increased dry matter production. Alternatively, an N rate effect on Jones Dwarf was observed only in the 3rd evaluation period in 2008. It was found in 2008 that the Bermuda grass cultivars differed in GR w ith higher growth rate values in Jones Dwarf across all the N rates than Mini Verde (Fig 3 -8b). Each cultivar of paspalum produced a different growth rate, which was demonstrated in the higher growth rate values (3.1 to 3.7 g m2 day1) in Sea Dwarf compar ed with Sea Isle Supreme (2.8 to 3.0 g m2 day1). However, no difference in growth rate by turfgrass was found across the nitrogen rates (Fig. 38a). The usual expectation is that dry matter should increase as the rate of applied N increases; for example, Kopec et al. (2007) suggested that higher levels of applied N with shorter mowing heights generally increased clipping dry weight. However, this study suggests that the growth rate for paspalum grasses was similar for both cultivars at all N rates applied in 2008. Therefore, this implies that nitrogen requirement could be even lower for Paspalum grasses. It appears from this study that Paspalum grasses could produce considerable growth rate at the lowest nitrogen applied for both years. Trenholm (2000) supports this studys results because she reported that paspalum grasses have been observed growing in areas that receive extended periods of heavy rains and low light intensity. Also, she reported that the best growth occurred in response to warm temperatures and long day lengths, conditions very similar to where this study was evaluated. This evidence could explain the similar effect of nitrogen rate on growth rate for paspalum in this study.
38 In this comparative study in 2009, growth rate was not influenced by N rates for paspalum grasses. In this case, growth rate was similar between both Paspalum cultivars (Fig 3-8c) which is ultimately the same result found in 2008. Thus, a shift in overall growth rate relative to cultivars was observed during the 2 years and, it appears that the reduction in the nitrogen rates in 2009 enhanced Sea Isle Supreme Paspalum visual quality more than Sea Dwarf. The same tendency for bermuda grasses was found in 2009 (Fig 3-8d) which suggested that Jones Dwarf tends to have a high er growth rate at all the N rates applied compared with Mini Verde. Also in 2009, an increase in Mini Verde growth rate was due to the change in location and the incorporation of verticutting as a management practice in 2009. Verticutting in 2009 influenced the overall growth rate of Sea Dwarf. Verticutting promoted a lower growth rate (2.69 g m2 day1) at the higher frequency (every 2 weeks) compared with a higher growth rate (3.14 g m2 day1) from the lower frequency (every 4 weeks) in Sea Dwarf Paspalu m. This suggests that verticutting reduced growth rate. One possible explanation could be that the Sea Dwarf did not recuperate from the stresses created by the higher verticutting frequency. Ultimately, this study suggests that both paspalum cultivars and Jones Dwarf grew similarly at the applied nitrogen rates in 2008 and 2009, and Mini Verde tended to have a lower growth rate compared with the rest of the cultivars evaluated. Nitrogen Uptake In the 2008 and the 2009 paspalum study, five and four harvests respectively were collected and analyzed for N concentration. Clippings from each harvest were dried in a forcedair oven at 60C for 48h, weighed, and ground. Then each subsample
39 was prepared for total Kjeldahl N analysis. Yieldweighed tissue N concent rations were calculated using equation 31 to determine the Paspalum grasses mean nitrogen uptake. For any nitrogen rate: Gi= growth rate at ith harvest from each paspalum cultivar (g m2 day1) Ni=tissue N concentration at ith harvest (%) ny= number of harvest. ((G1*N1)+(G2*N2)...(G5*N5))*10 = Mean Nitrogen Uptake (mg m2 day1) ny (3 -1) In the 2008 study, both paspalum and bermuda grass cultivars overall mean N uptake was influenced by N rate. For paspalum grasses as the rate of applied N increased from 49 to 196 kg ha1 yr1 the N uptake also increased from 75 to 93 mg m2 d1and 71 to 83 mg m2 d1 for Sea Dwarf and Sea Isle Supreme, respectively (Fig. 310a). It was found that both paspalum cultivars were similar in terms of overall N u ptake. However, nitrogen uptake for Sea Isle Supreme was influenced in three of the four evaluation periods and for Sea Dwarf was influenced by N rate only during the 2nd 30day evaluation period (Table 3-2) in 2008. Also N uptake was different between ber muda grasses cultivars, as Jones Dwarf had a higher nitrogen uptake than Mini Verde (Fig.310b). In the 2008 study, N rate affected N uptake of Mini Verde which increased as N rate increased. Mini Verde N uptake was influenced by N rate primarily in the 2n d and 3rd evaluation periods (Table 3-4). A fitted model from the 2nd evaluation period of Mini Verde (r2= 0. 86) showed a positive relationship between an increase in
40 nitrogen rate and an increase in nitrogen uptake (Fig. 3 -11). Jones Dwarf showed a respo nse during three of the four evaluation periods: 1st, 2nd, and 3rd (Table 3 3). In the 2009 study, increasing N rate did not increase mean N uptake but the Paspalum cultivars did differ in N uptake. Sea Dwarf N uptake in 2009 was lower than Sea Isle Supreme (Fig. 3-10c). Although in the 2009 study N rate did not influence N uptake, it appears that a trend existed for higher N uptake by both Paspalum cultivars in response to N application rate compared with bermuda cultivars. In the 2009 study, Jones Dwarf accumulated more N than Mini Verde (Fig.310d). Nevertheless, in 2009 there was evidence that an increase in nitrogen application produced an increase in nitrogen uptake. Nitrogen rate did influence the overall mean nitrogen uptake by both Bermuda grasses in 2009. Jones Dwarf was affected by nitrogen rate only in the 4th evaluation period. However, Mini Verde was affected by nitrogen rate in the 1st and the 4th evaluation periods. A linear regression model (r2=0.69) showed increased nitrogen uptake as a res ult of increased nitrogen application in 2009 for Mini Verde (Fig.3-12). A reduction in N rate applied to the paspalum in 2009 resulted in a reduction of N uptake for paspalum grasses from 2008 to 2009. An increase N rate applied to hybrid bermuda grasses produced an increase in N uptake in 2009 compared with 2008. Therefore it is suggested that there is a strong positive relationship between N rate and N uptake for turfgrasses. Thatch Depth Thatch is a layer of partially decomposed organic matter between green shoot tissue and the soil surface (McCarty et al., 2007). Five measurements of thatch depth were made for each year (2008 and 2009). In 2008, paspalum and bermuda grasses thatch depth fluctuated from 2.4 to 2.5 cm (Fig. 3-13a) and from 1.5 to 1.8 cm
41 r espectively. Only Mini Verde was influenced by N rate. During this time period, higher values of thatch depth were found at the highest nitrogen rate in Mini Verde Bermuda grass. However, paspalum grasses did not differ in thatch depth and they were not in fluenced by N rate in 2008. Paspalum grasses showed a higher thatch depth than the hybrid bermuda grasses cultivars. In 2009, the same trend was found as in 2008 where N rate did not influence thatch depth, nor did either paspalum cultivar influence the ov erall thatch depth. The thatch depth in 2009 was higher for both paspalum grasses and bermuda grasses compared with the results in 2008. An increase of around 115% in the thatch depth was noticed from 2008 to 2009 for bermuda grasses. This increased thatch depth is possibly due to turf maturity and relocation. The 2008 evaluation was taken during the first year after establishment and the 2009 evaluation was taken on established grasses. According to Trenholm (2000), one of the disadvantages of Seashore Pas palum is that it produces moderate amounts of thatch during periods of active growth. Therefore, higher thatch depths recorded for paspalum grasses in 2009 were expected. In general, this comparative study suggests for bermuda grasses that Mini Verde tends to produce more thatch compared to Jones Dwarf. These data agree with other studies such as Hollingsworth et al. (2005) where they found that thatch depth can be affected by cultivar. Also, they evaluated the cultural management and nitrogen source effect s on ultradwarf bermuda grass cultivars and reported that other research showed that the ultradwarfs may produce excess thatch (Hollingsworth et al., 2005). In terms of management, it appears that paspalum grasses will require a new set of practices compar ed with bermuda grasses primarily because higher thatch depth
42 produces serious problems for golf course playability in the long term. The chemical components of thatch are cellulose, hemicellullose, and lignin, but the main problem is lignin. Lignin is highly resistant to microbial degradation, so that only 80% of the organic component present in thatch is readily decomposable. According to McCarty (2001) thatch decompositions rely upon the activity of soil microorganisms, whose activity is greatly affected by: pH, aeration, temperature, moisture, and carbonnitrogen ratio. From those factors, mechanical aerification is a commonly used maintenance practice. Some of the available options that can be used by golf course superintendents to reduce thatch accumul ation in paspalum cultivars are practices that focus on aeration. According to Christians (1998), there are available practices that favor aeration such as: core aerification, solid tine aerification, deep -drill aerification, water injection cultivation, a nd vertical mowing. The challenge is to use combination of those maintenance practices to increase microbial activity and reduce the thatch accumulation rate. From this comparative study, the required maintenance for paspalum grasses appears to be different from bermuda grasses because the higher production of thatch depth. Light and frequent topdressing applications, the optimal nitrogen rate and verticutting appeared to produce the best paspalum quality in this study. However, further evaluation of other maintenance practices such as rolling frequency and aerification intervals are highly recommended. Root Dry Matter Root dry matter sampling was taken five times per year. In the 2008 study, N rate did not influence Sea Dwarf root dry matter at any of the evaluated dates, but it did influence the overall root dry matter for Sea Isle Supreme during the 3rd evaluation period. Sea Dwarf root dry matter was higher (1329 to 1059 g m2) compared with Sea
43 Isle Supreme root dry matter (847 to 844 g m2) (Fig. 3 -14a ) in 2008. Root dry matter for bemuda grasses in 2008 was not influenced by N rates. However, a difference was found between cultivars: Jones Dwarf root dry matter was higher (648 to 668 g m2) compared with Mini Verde (446 to 476 g m2 ) (Fig. 3 -14b). In the 2009 study, the same tendency was found where root dry matter was not influenced by N rates for paspalum cultivars. However, a reduction in overall mean root dry matter was found in 2009 for paspalum (Fig 314c). This result suggested that even though the grass was of acceptable quality in 2009, the decrease in N rate produced a reduction in root dry matter between the 2 years. In the 2009 study, paspalum grasses showed the same response to N application as in 2008 for both cultivars in root dry matter, ranging from 857 to 1083 g m2. In 2009, similar results were found compared with bermuda grasses of 2008 because nitrogen rate did not produce a difference in root dry matter (Fig. 3 -14d). In 2009, verticutting did influence the overall mean root dry matter in Jones Dwarf. The high verticutting frequency produced more roots dry matter (692 g m2) compared with the low verticutting frequency (556.6 g m2) for Jones Dwarf in 2009. This result suggests that paspalum cultivars produced similar root dry matte r, and they produce more root dry matter than hybrid bermudagrass. Although paspalum grasses received lower nitrogen application than hybrid bermuda grasses, they produced more root dry matter and it could explain the higher turfgrass visual quality. Also a positive effect in the Jones Dwarf roots dry matter was observed due to the higher verticutting frequency.
44 Loss on Ignition Weight loss on ignition is a measurement of the amount of organic matter or thatch in the sample. Percentage weight loss on igniti on is commonly used to quantify the amount of organic matter accumulated in the thatch layer of turfgrass (Kruse and Sartain 2001, Sartain, 1985; Sartain and Volk, 1984; Smiley and Craven,1978). In 2008, the overall mean percentage loss on ignition of Pasp alum grasses was influenced by nitrogen rate. Unexpectedly it appeared that paspalum grasses percentage loss on ignition values decreased from 13.8% to 12.1% as the nitrogen rate increased from 49 to 196 kg N ha1 yr1 (Fig. 315a). On the other hand, Berm uda grasses loss on ignition was not influenced by N rate in 2008 (Table 3-8). In the 2009 study, an increase in the overall percentage loss on ignition was observed for paspalum and bermuda grasses compared with 2008, with values from 30.35% to 32.58% (315c) and 35.92% to 37.34% (Fig 315d) for paspalum and bermuda grasses, respectively. The increases in amount of oxidizable organic matter were expected in the second year because a higher increase in thatch depth was found. In 2009, paspalum grasses did n ot produce more weight loss on ignition in response to applied N. In 2009 study, all turfgrasses were very similar in weight loss on ignition across the three nitrogen rates. This comparative study differs with other studies because they have shown linear and quadratic effects in percentage loss on ignition with increases in N rate (Guertal and Evans; 2006, and Trenholm et al., 1998). It appears that the percentage loss on ignition results obtained for both years in this study can be attributed to the simil ar growth rate and thatch depth responses of both cultivars to the nitrogen rates applied.
45 Economic Analysis Golf courses represent an important component of the Florida economy. According to Haydu and Hodges (2002) the area owned by Florida golf courses w as 82,961 hectares with 56,656 hectares irrigated and 59,489 hectares in maintained turf. The predominant type of turfgrass on typical putting greens and fairways in Florida is some cultivar of Bermudagrass representing 93% of maintained turf areas. However, paspalum grasses have been adopted by golf courses in the southeast US because they appear to have low N requirements and tolerance to high salinity irrigation water. Accounting for the water used, it was estimated that 173 billion gallons were used for irrigation of golf courses in Florida (Haydu and Hodges, 2002), of which 49% came from recycled water, and with lesser amounts of 29% and 21% from surface waters and wells, respectively (Haydu and Hodges, 2002). Therefore, introduction of new paspalum cul tivars that require less N fertilization can have a positive impact for golf courses in Florida, but at the same time they require a new set of management practices. Golf course superintendents have used many cultural practices in order to produce a health y turf that fulfills golfers expectations. It has been suggested that maintenance costs for paspalum cultivars are lower when compared with bermuda cultivars, but the actual cost of maintaining an acceptable paspalum green is unknown. A comparative maintenance study of paspalum and bermuda grasses was conducted and an economic analysis was accomplished. The cost of each of the cultural practices such as mowing (frequency and height), aerification, irrigation, topdressing (frequency and rate), verticutting (frequency), nitrogen fertilization (rate and frequency), pest management practices (product and
46 doses), labor, and equipment depreciation were recorded for both years (2008 and 2009) to calculate and compare the total cost. Paspalum grasses fertilizatio n cost ($137.5) was lower than bermuda grasses ($805.5) because during this study paspalum grasses required a lower N rate (12.25 kg N ha1yr1) and fewer applications (four) compared with bermuda grasses, which required higher N rate (49kg N ha1yr1) and more applications (nine). However, paspalum grasses had a higher verticutting cost ($560) than bermudagrasses ($280) because paspalum grasses required higher verticutting frequency (twice/month) compared with bermuda grasses (once/month). The other cost c omponent such as: mowing ($2064), Aerification ($92), irrigation ($300), topdressing ($640), and pest management practices ($1017) were similar between cultivars. Finally, paspalum grasses total maintenance cost was lower ($4811) (Table 3-5) than Bermuda grasses total maintenance ($5199) (Table 3-6).
47 CHAPTER 4 SUMMARY AND CONCLUSS IONS In order to maintain an acceptable quality turfgrass throughout the year it is necessary to understand the nitrogen requirement and management practices of the turfgrass c ultivars used. Paspalum grasses have been adopted by golf courses in the southeast US because they appear to have a low N requirement and a high tolerance to high salinity irrigation water. However, necessary management practices that permit acceptable pla yability for paspalum grasses are mostly unknown and undocumented in the US compared with the commonly used bermuda grasses. This study (2008 and 2009) was conducted to determine and compare the overall maintenance and nitrogen nutrition requirements for t wo Paspalum cultivars (Sea Dwarf and Sea Isle Supreme) and two Bermuda cultivars (Jones Dwarf and Mini Verde) grown on native soil pushup putting greens. In both years, the effect of the treatments (three N rates and two management practices) was determin ed for multiple parameters such as visual quality, ball roll, growth rate, nitrogen uptake, thatch depth, roots dry matter, and thatch accumulation (weight loss on ignition). The effects of N rates and management practices (topdressing in 2008 and verticut ting in 2009) were discussed. The following results were obtained: 1 Paspalum cultivars (Sea Dwarf and Sea Isle Supreme) differed compared with bermuda grasses (Mini Verde and Jones Dwarf) in terms of maintenance and nitrogen nutrition requirements. 2 Topdress ing applications did not influence visual quality. However, topdressing at least once a month with 1.6 mm of sand should be applied on bermuda grasses primarily in Jones Dwarf because it increased the ball roll distance. 3 Paspalum cultivars should be fertil ized four times (from May to August) with an N application rate of 49 kg N ha1 yr1 in order to obtain an acceptable visual quality grown in push up greens.
48 4 To obtain acceptable visual quality for bermuda cultivars they should be fertilized throughout th e active growth period (from May to September) at the rate of 488 kg N ha1 yr1. 5 Jones Dwarf produced the highest growth rate. Paspalum grasses produced more root dry matter than Bermuda grasses, which was reflected in higher N uptake and greater thatch d epth. 6 Verticutting every 2 weeks should be included as a management practice for Sea Isle Supreme in order to achieve acceptable golf course playability. 7 Maintenance requirements for both Bermuda cultivars (Mini Verde and Jones dwarf) and Sea Dwarf Seashor e Paspalum should include verticutting once a month to obtain acceptable BRD. 8 Paspalum grasses fertilization cost ($137.5) was lower than bermuda grasses ($805.5) due to a lower N rate (49 kg N ha1yr1) and fewer applications ( four) required compared with bermuda grasses, which required a higher N rate (488 kg N ha1yr1) and more applications (ten). 9 Paspalum grasses had higher verticutting cost ($560) than bermuda grasses ($280) because paspalum grasses required higher verticutting frequency (twice/month ) compared with bermuda grasses (once/month). 10. Paspalum grasses total maintenance cost was lower ($4811) than Bermuda grasses total maintenance ($5199).
49 Figure 21. Individual plot plan split block design with three nitrogen rates and three replications arranged in a randomized complete block design (RCBD) with two topdressing as the sub -plot factor.
50 A) B) Figure 31. Effect of nitrogen rate on the overall mean visual quality in 2008 for A) Paspalum cultivars, B) Bermuda cultivars, and in 2009 for C) Paspalum cultivars, D) Bermuda cultivars. Letters indicate statistical differences across The horizontal line represents a critical 5.5 visual quality minimal acceptable level. 4.0 4.5 5.0 5.5 6.0 6.5 7.0 110 220 440 Nitrogen Rate (kg N ha-1 yr-1) Visual Mean Quality (1-9) Mini Verde Jones Dwarf a a a a a b 4.0 4.5 5.0 5.5 6.0 6.5 7.0 49 98 196 Nitrogen Rate (kg N ha-1 yr-1) Visual Mean Quality (1-9) Sea Dwarf Sea Isle Supreme a a a a a b
51 C) 4.0 4.5 5.0 5.5 6.0 6.5 7.0 122 244 488 Nitrogen Rate (kg N ha-1 yr-1) Visual Mean Quality (1-9) Mini Verde Jones Dwarf a a b b c c D) Figure 31. Continued 4.00 4.50 5.00 5.50 6.00 6.50 7.00 12 24 49 Nitrogen Rate (kg N ha-1 yr-1) Visual Mean Quality (1-9) Sea Dwarf Sea Isle Supreme a a a b b b
52 6.30 6.35 6.40 6.45 6.50 6.55 6.60 6.65 6.70 6.75 6.80 6.85 0 50 100 150 200 250 Nitrogen Rate (kg N ha-1 yr-1) Visual Quality (1-9) Sea Dwarf Raw Data Sea Isle Supreme Raw Data Sea Dwarf Model Sea Isle Supreme Model Sea Isle Supreme y= 0.0022+ 6.30 r2= 0.79 C.V.= 1.10 Sea Dwarf y= 0.0024x + 6.23 r2= 0.83 C.V.= 1.09 Figure 32. Effect of nitrogen rate on visual quality in the 2nd evaluation period for paspalum grasses in 2008. y = 0.0019x + 4.8667 r2 = 0.71 C.V. = 3.32 4 4.5 5 5.5 6 0 100 200 300 400 500 Nitrogen Rate (kg N ha-1 yr-1) Visual Quality (1-9) Fi gure 33. Effect of nitrogen rate on Mini Verde bermuda grass visual quality 2nd evaluation period in 2008.
53 y = 0.00095x + 5.15 r2 = 0.63 C.V. = 1.97 4.5 5 5.5 6 0 100 200 300 400 500 Nitrogen Rate (kg N ha-1 yr-1) Visual Quality (1-9) Figure 34. Effect of nitrogen rate on Jones Dwarf bermuda grass visual quality 4th evaluation period in 2008. 4.0 4.5 5.0 5.5 6.0 0 100 200 300 400 500 600 Nitrogen Rate (kg N ha-1 yr-1) Visual Quality (1-9) y= 0.4809 ln(x) + 2.3356 r2= 0.80 C.V.=2.86 Figure 35. Effect of nitrog en rate on the overall mean Mini Verde bermuda grass visual quality in 2009.
54 y = 0.0017x + 4.6406 r = 0.71 4.0 4.5 5.0 5.5 6.0 0 100 200 300 400 500 600 Nitrogen Rate (kg N ha-1 yr-1) Visual Quality (1-9) C.V.=3.19 Figure 36. Effect of nitrogen rate on the overall mean Jones Dwarf Bermuda grass visual quality evaluation period in 2009.
55 0 50 100 150 200 250 300 110 220 440 Nitrogen Rate (kg N ha-1yr-1) Ball Roll Mean Distances (cm) Mini Verde Jones Dwarf a b c d f e A) B) Figur e 37. Effect of nitrogen rate on the overall mean ball roll distance in 2008 for A) Paspalum cultivars, B) Bermuda cultivars, and in 2009 for C) Paspalum cultivars, D) Bermuda cultivars. Letters indicate statistical differences across nitrogen rates as de 100 120 140 160 180 200 220 49 98 196 Nitrogen Rate (kg N ha-1 yr-1) Ball Roll Mean Distances (cm) Sea Dwarf Sea Isle Supreme a b a a b b
56 C) D) Figure 37. Continued 0 50 100 150 200 250 300 122 244 488 Nitrogen Rate (kg N ha-1 yr-1) Ball Roll Mean Distances (cm) Mini Verde Jones Dwarf a b a b b a 160 165 170 175 180 185 190 195 200 12 24 49 Nitrogen Rate (kg N ha-1 yr-1) Ball Roll Mean Distances (cm) Sea Dwarf Sea Isle Supreme a a a a a a
57 Table 3 1. Ball roll distance of paspalum cultivars in response to management practices and N rate 2008 and 2009 30 Days Evaluation Period 2008 1 st 2 nd 3 rd 4 th 5 th Treatments T N -----------Ball Roll distance (cm) -----------mm Kg ha 1 yr 1 Sea Dwarf 49 148 152 197 177 151 98 145 152 193 173 145 196 135 145 184 173 136 3.2 144 155 195 175 147 1.6 142 145 188 174 141 P Value Top (T) ns ns ns ns ns TxN ns ns ns ns ns Nitrogen rate (N) 0.0291* ns ns ns ns Sea Isle Supreme 49 150 153 179 164 142 98 144 144 175 159 137 196 138 147 169 163 132 3.2 147 154 177 167 142 1.6 141 142 171 157 131 P Value Top (T) ns ns ns ns ns TxN ns ns ns ns ns Nitrogen rate (N) 0.028* ns ns ns ns 30 Days Evaluation Period 2009 1 st 2 nd 3 rd 4 th Treatments V N -----------Ball Roll distance (cm) ----------freq kg ha 1 yr 1 Sea Dwarf 12 152 208 219 173 24 151 204 214 168 49 146 195 210 165 High 154 208 223 171 Low 145 197 206 166 P Value Sea Dwarf Verticutting (V) n.s n.s n.s n.s VxN n.s n.s n.s n.s Nitrogen rate (N) n.s n.s n.s n.s Sea Isle Supreme 12 153 183 208 178 24 154 182 203 179 49 155 179 199 176 High 159 189 213 180 Low 149 175 194 176 P Value Sea Isle Supreme Verticut (V) n.s 0.0442* n.s n.s VxN n.s n.s n.s n.s Nit rogen rate (N) n.s n.s n.s n.s
58 A) 0.0 2.0 4.0 6.0 8.0 10.0 110 220 440 Nitrogen Rate (kg N ha-1yr-1) Growth Rate (gm-2day-1) Mini Verde Jones Dwarf a b a b b a B) Figure 38. Effect of nitrogen rate on the overall mean growth rate in 2008 for A) Paspalum cultivars, B) Bermuda cultivars, and in 2009 for C) Paspalum cultivars, D) Bermuda cultivars P aspalum cultivars. Letters indicate statistical differences across nitrogen rates as determined by Duncan mean square 0.0 2.0 4.0 6.0 8.0 10.0 49 98 196 Nitrogen Rate (kg N ha-1 yr-1) Growth Rate (g m-2day-1) Sea Dwarf Sea Isle Supreme a a a a a a
59 C) D) Figure 38 Continued 0.0 1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0 9.0 10.0 122 244 488 Nitrogen Rate (kg N ha-1 yr-1) Growth Rate (gm-2day-1) Mini Verde Jones Dwarf a b a b b a 0.0 2.0 4.0 6.0 8.0 10.0 12 24 49 Nitrogen Rate (kg N ha-1 yr-1) Growth Rate (g m-2day-1) Sea Dwarf Sea Isle Supreme a a a a a a
60 Table 3 2 Growth rate o f bermuda cultivars in response to management practices and N rate in 2009. Treatments T N 30 Days Evaluation Period 1 st 2 nd 3 rd 4 th Growth Rate mm kg ha 1 yr 1 (g/m2/day) Mini Verde 110 0.28 0.39 1.08 1.42 220 0.29 0.52 1.30 1.55 44 0 0.25 0.91 1.88 2.10 3.2 0.27 0.60 1.29 1.71 1.6 0.27 0.62 1.55 1.67 P Value Top (T) ns ns 0.042 ns TxN ns ns ns ns Nitrogen rate (N) ns 0.0001* 0.0005* 0.0385* Jones Dwarf 110 0.56 1.58 2.07 3.69 220 0.62 1.28 2.27 2.42 440 0.62 1.76 3.42 3.30 3.2 0.70 1.47 2.26 3.91 1.6 0.49 1.61 2.92 2.38 P Value Top (T) ns ns ns ns TxN ns ns ns ns Nitrogen rate (N) ns ns 0.0077* ns y = 0.0015x + 0.6087 R2 = 0.87 C.V. 8.73 0.00 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 0 100 200 300 400 500 Nitrogen Rate (kg N ha-1 yr-1) Growth Rate (gm-2day-1) Figure 39. Effect of nitrogen rate on Mini Verde overall mean growth rate in 2008.
61 A) 0.0 20.0 40.0 60.0 80.0 100.0 120.0 110 220 440 Nitrogen Rate (kg N ha-1 yr-1) Nitrogen Mean Uptake(mg m-2 day-1) Mini Verde Jones Dwarf a b c d d c B) Figure 310. Effect of nitrogen rate on the overall nitrogen uptake in 2008 for A) Paspalum cultivars, B) Bermuda cultivars, and in 2009 for C) Paspalum cultivars, D) Bermuda cultivars. Letters indi cate statistical differences across 0 20 40 60 80 100 120 49 98 196 Nitrogen Rate (kg N ha-1 yr-1) Nitrogen Mean Uptake(mg m-2 day-1) Sea Dwarf Sea Isle Supreme a a b b c c
62 C) D) Figure 310 Continued 0.0 5.0 10.0 15.0 20.0 25.0 122 244 488 Nitrogen Rate (kg N ha-1 yr-1) Nitrogen Mean Uptake (mgm -2day1) Mini Verde Jones Dwarf a a ab ab b b 0 20 40 60 80 100 120 12 24 49 Nitrogen Rate (kg N ha-1 yr-1) Nitrogen Mean Uptake(mg m-2 day-1) Sea Dwarf Sea Isle Supreme a a b a b b
63 Table 3 3 Nitrogen uptake of paspalum cultivars and bermud a cultivars in respond to management practices and N rate in 2008. 30 Days Evaluation Period 1 st 2 nd 3 rd 4 th 5 th Treatments T N Nitrogen Uptake mm kg ha 1 yr 1 (mg m 2 day 1 ) Sea Dwarf 48.8 73.8 63.3 78.4 82.3 76.7 97.6 78.0 6 9.8 80.9 96.5 82.2 196 90.9 82.0 99.7 113.2 81.2 3.2 88.2 72.4 84.6 116.2 84.7 1.6 73.5 71.0 88.1 78.4 75.4 P Value Top (T) ns ns ns ns ns TxN ns ns ns ns ns Nitrogen rate (N) ns 0.0346* ns ns ns Sea Isle Supreme 4 8.8 22.7 77.0 63.6 90.2 103.9 97.6 26.6 81.3 63.1 102.5 93.1 196 36.1 98.4 74.0 126.6 81.6 3.2 28.3 85.6 72.6 97.4 80.1 1.6 28.6 85.5 61.3 115.4 105.6 P Value Top (T) ns ns ns ns ns TxN ns ns ns ns ns Nitrogen rate ( N) 0.0149* 0.0363* ns 0.004* ns 30 Days Evaluation Period 1 st 2 nd 3 rd 4 th Treatments T N Nitrogen Uptake mm kg ha 1 yr 1 (mg m 2 day 1 ) Mini Verde 110 5.7 15.0 41.4 26.1 220 6.3 20.9 49.3 26.7 440 6.6 37.2 76.8 45.9 3.20 6.4 23.1 51.6 28.7 1.60 5.9 25.6 60.1 37.1 P Value Top (T) ns ns ns ns TxN ns ns ns ns Nitrogen rate (N) ns 0.0001* 0.0002** ns Jones Dwarf 110 7.9 40.2 62.8 89.86 220 11.1 40.3 68.0 59.91 440 14.9 55.7 9 4.9 69.93 3.20 12.9 45.0 70.6 90.38 1.60 9.7 45.8 79.9 56.09 P Value Top (T) ns ns ns 0.0493 TxN ns ns ns ns Nitrogen rate (N) 0.0285* 0.0168** 0.0007*** ns
64 y = 0.0683x + 6.8623 r2 = 0.86 C.V.= 16.64 0 5 10 15 20 25 30 35 40 45 0 50 100 150 200 250 300 350 400 450 500 Nitrogen Rate (kg N ha-1 yr-1) Nitrogen Uptake (mg m-2 day-1) Figure 311. Effect of nitrogen rate on Mini Verde bermudagrass nitrogen uptake 2nd evaluation period in 2008. y = 0.0241x + 7.3783 r2 = 0.69 C.V. = 18.44 0.00 5.00 10.00 15.00 20.00 25.00 0 100 200 300 400 500 600 Nitrogen Rate (kg N ha-1 yr-1) Nitrogen Uptake (mg m-2 day -1) Figure 312. Effect of nitrogen rate on the overall nitrogen uptake for Mini Verde in 2009
65 A) B) Figure 313. Effect of nitrogen rate on the overall thatch depth in 2008 for A) Paspalum cultivars, B) Bermuda cultivars, and in 2009 for C) Paspalum cultivars, D) Bermuda cultivars Letters indicate statistical differences across nitrogen rate as determined by Dunca 0.0 0.5 1.0 1.5 2.0 2.5 3.0 110 220 440 Nitrogen Rate (kg N ha-1 yr-1) Thatch depth (cm) Mini Verde Jones Dwarf a a a a a a 0.0 0.5 1.0 1.5 2.0 2.5 3.0 49 98 196 Nitrogen Rate (kg N ha-1 yr-1) Thatch depth (cm) Sea Dwarf Sea Isle Supreme a a a a a a
66 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 12 24 49 Nitrogen Rate (kg N ha-1 yr-1) Thatch depth (cm) Sea Dwarf Sea Isle Supreme a a a a a a C) D) Figure 313. Continued 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 122 244 488 Nitrogen Rate (kg N ha-1 yr-1) Thatch depth (cm) Mini Verde Jones Dwarf a b a b b a
67 A) B) Figure 314. Effect of nitrogen rate on the overall roots dry matter in 2008 for A) Paspalum c ultivars, B) Bermuda cultivars, and in 2009 for C) Paspalum cultivars, D) Bermuda cultivars Paspalum cultivars. Letters indicate statistical differences across nitrogen rate as determined by Duncan mean square 0 250 500 750 1000 1250 1500 1750 2000 110 220 440 Nitrogen Rate (kg N ha-1 yr-1) Root Dry matter (g m-2) Mini Verde Jones Dwarf a a a a a a 0 250 500 750 1000 1250 1500 1750 2000 49 98 196 Nitrogen Rate (kg N ha-1 yr-1) Root Dry matter (g m-2) Sea Dwarf Sea Isle Supreme a a a a a a
68 C) D) Figure 314. Continued 0 250 500 750 1000 1250 1500 1750 2000 122 244 488 Nitrogen Rate (kg N ha-1 yr-1) Root Dry matter (g m-2) Mini Verde Jones Dwarf a a a a a a 0 250 500 750 1000 1250 1500 1750 2000 12 24 49 Nitrogen Rate (kg N ha-1 yr-1) Root Dry matter (g m-2) Sea Dwarf Sea Isle Supreme a a a a a a
69 A) B) Figure 315. Effect of nitrogen rate on the overall loss on ignition in 2008 for A) Paspalum cultivars, B) Bermuda cultivars, and in 2009 for C) Paspalum cultivars, D) Bermuda cultivars. Letters indicate statistical differences across 0.0 5.0 10.0 15.0 20.0 25.0 110 220 440 Nitrogen Rate (kg N ha-1 yr-1) Loss on Ignition (%) Mini Verde Jones Dwarf a a a a a a 0.0 5.0 10.0 15.0 20.0 25.0 49 98 196 Nitrogen Rate (kg N ha-1 yr-1) Loss on Ignition (%) Sea Dwarf Sea Isle Supreme a a b b b b
70 C) D) Figure 31 5. Continued 0.00 10.00 20.00 30.00 40.00 50.00 122 244 488 Nitrogen Rate (kg N ha-1 yr-1) Loss on Ignition (%) Mini Verde Jones Dwarf a a a a a a 0.0 10.0 20.0 30.0 40.0 50.0 12 24 49 Nitrogen Rate (kg N ha-1 yr-1) Loss on Ignition (%) Sea Dwarf Sea Isle Supreme a a a a a a
71 Table 3 4 Percent weight loss on ignition of bermuda cultivars in respond to management practices and N rate in 2008. 30 Days Evaluation Period 1 st 2 nd 3 rd 4 th 5 th Treatments T N -------Loss on ignition (%) --mm kg ha 1 yr 1 Mini Verde 110 3.6 4.3 6.5 26.2 28.2 220 3.6 5.3 6.3 24.1 21.4 440 3.8 4.8 5.8 26.5 28.3 3.2 3.7 4.6 6.4 28.0 24.4 1.6 3.7 5.0 6.1 23.3 27.5 P Value Topdressing (T) ns ns ns ns ns TxN ns ns ns ns ns Nitrogen rate (N) ns ns ns ns 0.045* Jones Dwarf 110 3.7 4.5 5.0 19.3 28.5 220 3.9 4.4 4.8 20.5 27.0 440 4.0 4.9 4.6 19.1 31.0 3.2 3.6 3.9 5.0 21.0 30.0 1.6 4.1 4.6 4.7 18.2 27.8 P Value T op (T) ns ns ns ns ns TxN ns ns ns ns ns Nitrogen rate (N) ns ns ns ns ns
72 Table 3 5. Cultural practices and total maintenance cost of two paspalum cultivars (Sea Dwarf and Sea Isle Supreme) grown in putting greens of 125.4 m2. Cultural Pr actice Amount Units Total Times Frequency Price Units Total Mowing 2064 Equipment 1.5 hr 86 4 times/week 8.0 hour 1032 Labor 1.5 hr 86 4 times/week 8.0 hour 1032 Aerification 92 Equipment 2 hr 2 twice/year 15.0 hour 60 Lab or 2 hr 2 twice/year 8.0 hour 32 Irrigation 300 Equipment 1 days 150 every day 1.0 day 150 Water 1 days 150 every day 1.0 day 150 Topdressing 640 Equipment 2 hr 4 once/month 25.0 hour 200 Sand 1.6 mm 4 once/month 50.0 mm san d 320 Labor 2 hr 4 once/month 15.0 hour 120 Fertilization 137.5 Nitrogen Fertilization 12.25 kgN ha 1 yr 1 4 four/year 1.5 kg N 73.5 Labor 2 hr 4 four/year 8.0 hour 64 Verticutting 560 Equipment 2.5 hr 8 twice/month 20.0 hour 400 Labor 2.5 hr 8 twice/month 8.0 hour 160 Pest Management Practices 1017 Fungicides 2.9 kg ha 1 6 six/year 10.3 lbs 160 Equipment 2.5 hr 6 six/year 20.0 hour 300 Herbicides 910 g ha 1 1 once/year 1.3 oz 17 Equipment 2.5 hr 1 once/y ear 20.0 hour 50 Insectides 3.1 kg ha 1 4 four/year 3.2 lbs 36 Equipment 2.5 hr 4 four/year 20.0 hour 200 Wetting Agent 98.1 g ha 1 5 five/year 0.6 oz 4 Equipment 2.5 hr 5 five/year 20.0 hour 250 Total Cost 4811
73 Table 3 6. Cultural practices and total maintenance cost of two bermuda cultivars (Mini Verde and Jones Dwarf) grown in putting greens of 125.4 m2. Cultural Practice Amount Units Total Times Frequency Price Units Total Mowing 2064 Equipment 1.5 hr 86 4 times/week 8.0 hour 1032 Labor 1.5 hr 86 4 times/week 8.0 hour 1032 Aerification 92 Equipment 2 hr 2 twice/year 15.0 hour 60 Labor 2 hr 2 twice/year 8.0 hour 32 Irrigation 300 Equipment 1 days 150 every day 1.0 day 150 Water 1 days 150 ever y day 1.0 day 150 Topdressing 640 Equipment 2 hr 4 once/month 25.0 hour 200 Sand 1.6 mm 4 once/month 50.0 mm sand 320 Labor 2 hr 4 once/month 15.0 hour 120 Fertilization 805.5 Nitrogen Fertilization 49 kgN ha 1 yr 1 9 nine/ year 1.5 kg N 661.5 Labor 2 hr 9 nine/year 8.0 hour 144 Verticutting 280 Equipment 2.5 hr 4 once/month 20.0 hour 200 Labor 2.5 hr 4 once/month 8.0 hour 80 Pest Management Practices 1017 Fungicides 2.9 kg ha 1 6 six/year 10. 3 lbs 160 Equipment 2.5 hr 6 six/year 20.0 hour 300 Herbicides 910 g ha 1 1 once/year 1.3 oz 17 Equipment 2.5 hr 1 once/year 20.0 hour 50 Insectides 3.1 kg ha 1 4 four/year 3.2 lbs 36 Equipment 2.5 hr 4 four/year 20.0 hour 200 Wetting Agent 98. 1 g ha 1 5 five/year 0.6 oz 4 Equipment 2.5 hr 5 five/year 20.0 hour 250 Total Cost 5199
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78 BIOGRAPHICAL SKETCH Ivan Mauricio Vargas Altamirano was born in Pe rez Zeledon, San Jose Costa Rica, in 1985. He grew up next to his familys animal production farm and coffee operation in the General Valley of the South Pacific of Costa Rica. After graduating from EARTH University with a Licenciatura degree as an Agron omic Engineer in 2006, Ivan soon moved to Gainesville, Florida, where he was admitted to the University of Florida to pursue a Master of Science degree in the Soil and Water Science Department with a specialization in soil fertility and turfgrass science. He received his Master of Science from University of Florida in the spring of 2010. Upon graduation in May 2010, Ivan plans to begin studying towards a Master in Business Administration (MBA) so that he may pursue a business/research career that involves c ollaboration between Latin America and the USA.