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© 2009 Plant Management Network. Late Fall Sod Installation Produces Equivalent or Greater Rooting Strength of Poa pratensis Than Typical Spring Installations During the Subsequent Growing Season Jason Henderson, Nathaniel Miller, and Karl Guillard, Department of Plant Science, and Ofer Harel and Balaji Raman, Department of Statistics, University of Connecticut, Storrs, CT 06269 Corresponding author: Jason J. Henderson. jason.henderson@uconn.edu Henderson, J., Miller, N., Guillard, K., Harel, O., and Raman, B. 2009. Late fall sod installation produces equivalent or greater rooting strength of Poa pratensis than typical spring installations during the subsequent growing season. Online. Applied Turfgrass Science doi:10.1094/ATS-2009-0724-01-RS. Abstract Securing adequate time for proper turfgrass establishment following athletic field construction or renovation is a significant challenge. Spring construction and renovation projects often get delayed thereby diminishing the necessary time for sufficient root development before anticipated athletic field use. An alternative sod installation timing following fall sports may provide adequate root development during a typical period of minimal to no field usage. Five sod installation treatments (December covered, December uncovered, May, June, and July) were evaluated for rooting strength monthly and spring color. The May sod installation timing was used as the control, representing the typical sod installation time with anticipated intense field use in the fall. The objective of this field study was to quantify the effect of sod installation timing on the rooting strength and spring color of Kentucky bluegrass. December covered treatments consistently increased rooting strength over all other treatments in 2006. December covered and uncovered treatments consistently increased rooting strength over all other installation dates in 2007, indicating a considerable advantage to late fall sod installation for more extensive root development throughout the subsequent growing season. Introduction The need for turfgrass establishment can come from intense athletic field use, a playing surface conversion or new construction. For many sports, a high percentage of the traffic is concentrated on a very low percentage of the field. This is particularly evident with the sport of football where 78% of the traffic occurs on only 7% of the field surface area (1). This type of field use results in a very low percentage of turfgrass cover retained in these heavily used areas on a perennial basis. The primary challenge associated with establishing or re-establishing athletic fields in the Northeast is the very short amount of time that is available to prepare a traffic tolerant turfgrass stand prior to field use, as the growing season is also a period of peak field use. Establishment of athletic fields in the northeast United States is further complicated by the slow germination and development of Kentucky bluegrass, the preferred turfgrass species for athletic fields in northern regions (7). Therefore, many fields are established using sod. Sod provides instantaneous turfgrass cover and minimal weed competition, but obtaining sufficient root development prior to field use is a problem which can result in excessive divoting and poor playing surface quality, such as poor traction and an uneven playing surface. Depending on the sport that is played, athletic fields in the northeast United States are typically used until late November/early December, leaving the spring as the primary turfgrass establishment time of year. Unfortunately, this is also a time when many athletic field managers are pressured to open fields for use by those participating in spring sports. Early season field use and non-optimal environmental conditions of the early summer months can make turfgrass establishment difficult during this critical period. Sod is typically installed in the spring or late summer in the northeast United States. However, an alternative installation time for sod may be following athletic field use in early December. This timing may enable proper root development through periods of late fall and early spring prior to field use. Given the previous research conducted on sod establishment or sod rooting strength (2,4,8,9), no potential benefits or hazards were indicated regarding late fall sod establishment in the northern region. The objective of this research was to quantify the effect of sod installation timing on the rooting strength and spring color of Kentucky bluegrass. Measuring Sod Installation Timing Effects on Kentucky Bluegrass Research area. This study was conducted at the University of Connecticut Plant Science Research and Education Facility located in Storrs, CT, in 2005-2006 and 2006-2007. The soil in the research area was a Paxton fine sandy loam (Table 1) with a pH of 5.9. The trial had five treatments arranged in a completely randomized design, with three replications. The plot sizes were 3.1 m by 1.8 m. A sod cutter was used to remove the existing turfgrass in each plot location. A Kentucky bluegrass blend (var. Midnight, Total Eclipse, Northstar, America) was harvested as mineral sod (2 cm thick) from a local sod farm and then installed on the research site (Table 1). The four sodding dates for the first year were: 2 December 2005, 4 May 2006, 6 June 2006, and 6 July 2006. Sod maturity ranged from 16 to 23 months depending on the harvest and installation date of each treatment. The 4 May 2006 date served as the control, which would be considered a typical spring establishment date. The 2 December 2005 sodding date had a covered treatment and an uncovered treatment. Green Evergreen turfgrass covers (Covermaster Inc., Rexdale, ON) were used on the covered treatments. The covered treatment was covered from 2 December 2005 until 6 April 2006. Plots were mowed three times per week at 6.3 cm. Nitrogen (46-0-0) was applied 12 to 14 days after each sod installation to all treatments previously installed at the rate of 24 kg/ha with the first application on 18 May 2006. No fertilizer was applied to the December treatments (covered and uncovered) in 2005. Plots were irrigated as needed to prevent moisture stress. The plots were re-randomized in December 2006 and the study was repeated. A Kentucky bluegrass blend (var. Midnight, Award, Shamrock, Princeton 105) was harvested as a mineral sod (2 cm thick) from a local sod farm and then installed on the research site (Table 2). The four sodding dates for the second year were: 5 December 2006, 4 May 2007, 8 June 2007, and 11 July 2007. Sod maturity ranged from 15 to 22 months depending on the harvest and installation date of each treatment. The covered treatment was covered from 13 December 2006 until 10 April 2007. In the 2006-2007 study, starter fertilizer (18-24-12) was applied according to soil test recommendations at the rate of 48 kg P2O5/ha prior to installing the sod. Additional N was applied at the rate of 24 kg/ha every 21 days starting on 13 June 2007. Table 1. Particle size distribution of soil from plot area and soil from sod installed during the first year of the study. Source of sod 2005-2006, Tuckahoe Turf Farms Inc., Suffield, CT.
Table 2. Particle size distribution of soil from plot area and soil from sod installed during the second year of the study. Source of sod 2006-2007, Winding Brook Turf Farm Inc., Wethersfield, CT.
Turfgrass color. Turfgrass color was assessed qualitatively using a 1 to 9 scale, with 1 = brown turf, 6 = acceptable, and 9 = dark green turf. Turfgrass color was rated from the time the covers were removed in the beginning of April of each year until the color of the December cover treatments and December uncovered treatments equilibrated. Rooting strength. Quantifying the vertical detachment force of sod has been used extensively in turfgrass research to determine the extent of root development (2,3,4,5,6,8,9). Rooting strength was quantified using custom PVC rooting boxes and a digital load cell (Chatillion Model DFE-200, Ametek TCI Division, Largo, FL). The rooting "boxes" were constructed from 15.2-cm diameter schedule 40 PVC pipe cut into 3.8-cm lengths. The opening of each pipe section was encased with a fiberglass mesh screen (17 × 14 strands per linear inch) and secured with a hose clamp. Prior to securing the hose clamp, each section of pipe was wrapped with a 2.5-cm piece of self-adhesive grip tape to help secure the mesh screen. The rooting boxes were installed on the date of sod installation for each treatment. Enough rooting boxes were installed in each plot to enable subsequent monthly root pull data collection. Therefore, the December covered and uncovered plots each received 12 rooting boxes, 9 rooting boxes were installed in the May plots, 6 rooting boxes in the June plots and 3 rooting boxes in the July plots. In 2006-2007, three extra rooting boxes were installed into each plot to allow for potential damage or extra root pulls. Three rooting boxes (subsamples) were pulled from each plot on each root pull date. The peak force required to extract each rooting box was recorded. Root pulls were conducted monthly to assess root development over time; May, June, July, August 2006. During the second year of the study, root pulls were conducted in April, May, June and July 2007. Soil moisture levels have been shown to strongly influence the vertical detachment force when measuring sod rooting strength (5). Therefore, volumetric soil moisture was measured and analyzed as a covariate in both years the study was conducted. Soil moisture levels (v/v) were determined at the time root pulls were conducted using a Trime-FM moisture meter, 5.1 cm probe (MESA Systems Co., Medfield, MA) inserted vertically into the soil. Five measurements were taken at random locations within each plot and then averaged. Soil temperature. Soil temperature was measured using a digital thermometer (Fisher Scientific, Waltham, MA) while the December covered plots were still covered in the spring of each year to determine the effect of the covers on soil temperature. The soil temperature was measured at a depth of 5 cm. Five measurements were taken at random locations within each plot and then averaged. Statistical analyses. Turfgrass color and soil temperature data were analyzed using analysis of variance. Mean separations were analyzed using Tukey’s Honestly Significant Difference Test at a 0.05 level of probability utilizing Agricultural Research Manager (ARM, Gylling Data Management Inc., Brookings, SD) statistical software. The statistical analyses of the rooting strength data can be divided into two segments: (i) comparison of the effect of sod installation dates within each root pull date; and (ii) comparison of the effect of sod installation dates over different root pull dates. Rooting strength data were analyzed using analysis of variance with means separated using Tukey’s Honestly Significant Difference Test utilizing SAS v. 9.1 (SAS Institute Inc., Cary, NC). Volumetric soil moisture was analyzed as a covariate to ensure any differences observed in the root pull data was not attributed to differences in soil moisture between treatments or between root pull dates. Sod Installation Timing Effects on Kentucky Bluegrass Turfgrass color. December treatments that were covered exhibited higher color ratings in the spring of each year lasting from early April when the covers were removed until the beginning of May (Tables 3 and 4) (Fig. 1). The increased color ratings were most likely due to the increase in soil temperature (Table 5) beneath the covers.
Table 3. The effect of turfgrass covers on turfgrass color, 2006.
x Color was rated on a 1 to 9 scale, with 1 = brown turf, 6 = acceptable, and 9 = dark green turf. y Treatments were installed on 2 December 2005. z Means in a column followed by the same letter are not significantly different (P < 0.05) as determined by Tukey’s honestly significant difference test. Table 4. The effect of turfgrass covers on turfgrass color, 2007.
x Color was rated on a 1 to 9 scale, with 1 = brown turf, 6 = acceptable, and 9 = dark green turf. y Treatments were installed on 5 December 2006. z Means in a column followed by the same letter are not significantly different (P < 0.05) as determined by Tukey’s honestly significant difference test. Table 5. The effect of turfgrass covers on soil temperature, 2006 and 2007.
x Soil temperature was measured using a digital thermometer at a depth of 5 cm. y Covers were removed on 6 April 2006 and 10 April 2007, respectively z Means in a column followed by the same letter are not significantly different (P < 0.05) as determined by Tukey’s honestly significant difference test. Rooting strength. The effect of soil moisture on rooting strength was not significant for all root pull dates (data not shown). December covered treatments consistently increased rooting strength over all other treatments in 2006 (Fig. 2). December covered and uncovered treatments consistently increased rooting strength over all other installation dates in 2007 (Fig. 3). These data indicate a considerable advantage to late fall sod installation for more extensive root development throughout the subsequent growing season. Additionally, during both years of the study late fall installed sod (December covered and uncovered) produced similar or higher rooting strength in May of the subsequent growing season compared to rooting strength values in August (Figs. 4 and 5). This suggests that athletic fields established in December may be ready for play in May of the next year. This is extremely valuable information for many athletic field managers that have intense field use in the fall coupled with spring and early summer athletic field use the next year. In both years the study was conducted, sod rooting strength was constant or decreased from June through August (Figs. 4 and 5). These data strongly show that very little root development occurs from June through August. The primary increase in rooting strength in the 2006-2007 study occurred from April to May in both the December and December covered treatments (Fig. 5). These data also show that late fall installed sod is an attractive alternative to spring establishment since wet field conditions often make installation efforts in early spring extremely challenging. If spring installation is imperative, establishing sod as early as possible in the growing season is essential to enable the turfgrass to produce the highest possible rooting strength prior to fall athletic field use. With the exception of the December uncovered treatment in 2006-2007, no significant increases in rooting strength occurred from May to June (Figs. 4 and 5), indicating that installation by early April would be highly desirable. The rooting strength of the December sodded treatments was less dependent on covers in 2007. This may be attributed to higher air temperatures in December 2006 than in December 2005 (Fig. 6).
Conclusions Late fall sod installation is an attractive alternative to traditional spring sod installation for three main reasons: (i) sod rooting strength will be considerably greater than spring or early summer installed sod throughout the growing season; (ii) the greatest root development occurs fairly early in spring (i.e., April to May) when sod installations are typically difficult due to wet soil conditions, busy contractors, or anticipated athletic field use; and (iii) based on the rooting strength data collected, athletic fields established in early December will likely be ready to use in May of the next year. Another advantage to late fall sod installations is having the ability to re-establish an athletic field during a time when typical field use is minimal. Based on the differences produced using the turfgrass covers, between year 1 and year 2, if spring athletic field use is anticipated and/or maximum root development is desired the newly sodded field should be covered from the sod installation date until shoot growth begins in the spring. The turfgrass covers will also ensure better turfgrass color early in the spring. Acknowledgment Authors would like to thank Bob Hudzik, Head of Stadium Operations and Athletic Grounds at the Pennsylvania State University, a well-respected industry leader, innovator, and mentor in the turfgrass profession, for sparking the idea for this research. Literature Cited 1. Cockerham, S. T. 1989. Cleated-shoe traffic concentration on a football field. Calif. Turfgr. Cult. 39:11-12. 2. King, J. W., and Beard, J. B. 1969. Measuring rooting of sodded turfs. Agron. J. 61:497-498 3. King, J. W., and Beard, J. B. 1972. Postharvest cultural practices affecting the rooting of Kentucky bluegrass sods grown on organic and mineral soils. Agron. J. 64:259-262. 5. Nektarios P. A. 2005. Correlation of sod vertical detachment force with root growth and soil moisture in turf polystands. Int. Turfgr. Soc. Res. J. 10:416-421. 6. Nektarios P. A., Tsoggarakis, G. Nikolopoulou, A. E. and Gourlias D.. 2005. Fertilization program and resin foam soil amendment effects on sod establishment. HortScience 40:22,475-479. 7. Parks, O.C. and Henderlong P.R.. 1967. Germination and seedling growth rate of ten common Turfgrasses. P. W. Va. Acad. Sci. 39:132-140. 8. Peacock, C. H., and Dudeck, A. E. 1985. A comparison of sod type and fertilization during turf establishment. HortScience 20:108-109. 9. Schmidt, R. E., White, R. H., and Bingham, S. W. 1986. Technique to measure rooting of sods grown in small containers. Agron. J. 78:212-216. |
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