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© 2009 Plant Management Network. Fall and Winter Management Affect Spring Growth and Nutritive Value of Tifton 85 Bermudagrass R. A. Reis, Department of Animal Science, Universidade Estadual Paulista-UNESP/Jaboticabal-SP, Brazil; Y. C. Newman, University of Florida, Gainesville, FL 32611-0500; A. Hernández Garay, Colegio de Postgraduados, Montecillo, Texcoco, Edo de México, México CP56230; L. E. Sollenberger, P.O. Box 110500, University of Florida, Gainesville, FL 32611-0500; L. M. Premazzi, Universidade de Sao Paulo, Piracicaba, Brazil; and D. Urbano, Instituto Nacional de Investigaciones Agrícolas (INIA) Mérida, Venezuela Corresponding author: L. E. Sollenberger. lesollen@ufl.edu Reis, R. A., Newman, Y. C., Hernández Garay, A., Sollenberger, L. E., Premazzi, L. M., and Urbano, D. 2009. Fall and winter management affect spring growth and nutritive value of Tifton 85 bermudagrass. Online. Forage and Grazinglands doi:10.1094/FG-2009-0102-01-RS. Abstract Spring regrowth of ‘Tifton 85’ bermudagrass (Cynodon spp.) has been slow or stands have appeared weakened in some years in North Florida following overseeding with cool-season annuals. This 2-year experiment compared effects of (i) different bermudagrass sod management practices in fall and (ii) winter/spring grazing management of overseeded cool-season forages on subsequent spring and early-summer productivity of Tifton 85 bermudagrass. For overseeded pastures, postgraze stubble height of cool-season forages during winter/spring did not affect bermudagrass production in spring/early summer. Early-season bermudagrass yield generally was greater for pastures not overseeded the previous fall than those that were overseeded with cool-season forages; however, bermudagrass yields by July were as great or greater in plots that had been overseeded compared to unseeded controls. In plots that were not overseeded, leaving an 8-inch bermudagrass stubble entering winter resulted in greater early-season bermudagrass yields the following year than leaving a 2-inch stubble. The results of this study suggest that early-season growth of Tifton 85 bermudagrass may be reduced either by overseeding cool-season forages or by leaving insufficient bermudagrass residue in fall. There were, however, no long-term negative effects on bermudagrass stands of any of the management options tested. Introduction Bermudagrasses (Cynodon dactylon) are important forages in the southeastern USA, but they generally produce a large proportion of their seasonal yield during the summer resulting in a cool-season forage deficit (7). Overseeding cool-season annual species into bermudagrass sods is a commonly used method for enhancing the seasonal distribution of forage yield and increasing the nutritive value of forage on offer (5,9). Reduced spring regrowth has been observed for some hybrid bermudagrass pastures that were overseeded with temperate forages and grazed during the cool season (3). Tifton 85 bermudagrass has been widely adopted by producers in the southeastern USA because of its greater yield and digestibility than ‘Coastal’ (2). Because many producers are interested in overseeding Tifton 85 with cool-season annual forages, it is important to understand the impact of fall and winter management treatments on subsequent Tifton 85 bermudagrass performance. Tifton 85 is unique among the most-used bermudagrasses in the southeastern USA because it is an interspecific hybrid between a bermudagrass and ‘Tifton 68,’ a stargrass (Cynodon nlemfuensis) (2). Stargrasses are strongly stoloniferous and lack rhizomes. As a result, the morphology of Tifton 85 differs from hybrid bermudagrass cultivars like Coastal which have more rhizomes and form a denser sod (2). These differences may affect the response of Tifton 85 to overseeding. This study was conducted to evaluate the effects of bermudagrass sod management in fall, overseeding, and winter grazing management of overseeded cool-season species on Tifton 85 bermudagrass production the following spring and early summer. Site of the Experiment The experiment was conducted from October 1998 through July 2000 near Gainesville, FL (29°38’N, 82°22’W), in a well-established, 4-year-old stand of Tifton 85 bermudagrass. The soil was a Sparr fine sand (loamy, siliceous, hyperpermic Grossarenic Paleudult) with a pH of 6.6 and average nutrient concentration of 38 (medium), 44 (medium), and 112 (high) ppm for Mehlich-I extractable P, K, and Mg, respectively. Rainfall during the 2 years of experimentation was 46.5 and 53.4 inches during the periods from October 1998 to September 1999 and from October 1999 to September 2000, respectively (Table 1). Table 1. Monthly rainfall amount measured at the research site during the experimental period and 30-year average monthly rainfall for Gainesville, FL.
Management Practices Tested There were seven treatments evaluated (Table 2). Four of the seven treatments (Numbers 1 to 4 in Table 2) were winter and spring grazing strategies for a cool-season forage mixture that was overseeded into bermudagrass. These grazing strategies were defined based on post-grazing stubble height (3 or 5 inches) during winter (through March) and spring (April-June). The specific treatments for the overseeded plots were (i) 3-inch stubble when grazed during both seasons, (ii) 3-inch stubble during winter and 5 inches during spring, (iii) 5-inch stubble during winter and 3 inches during spring, and (iv) 5-inch stubble during both seasons (Table 2). These treatments were selected to provide a range of cool-season forage cover for dormant bermudagrass during winter and spring and a range in competition to bermudagrass during spring regrowth. The other three treatments (Numbers 5 to 7 in Table 2) were bermudagrass controls that were not overseeded to cool-season forages, but management of the bermudagrass fall residue was varied (Table 2). Residue was grazed to a height of 8 inches at the end of the grazing season and not clipped (tall stubble, Treatment 5), grazed to 8 inches and then clipped to 2 inches at the end of the grazing season with the residue removed (short stubble, Treatment 6), and Treatment 6 plus a Tye Pasture Pleaser drill was passed over the plot (no seed planted) on the day that overseeded plots were planted (Treatment 7). These control treatments were selected to represent a range in pasture stubble going into winter and also to determine if the mechanical action of drilling the cool-season forages negatively affected the strongly stoloniferous Tifton 85 bermudagrass. Table 2. Description of the seven cool-season management treatments applied to Tifton 85 bermudagrass sods.
× Mixture included rye, annual ryegrass, crimson clover, and red clover. y Only overseeded plots were grazed during winter and spring. Plot size was 1110 ft² (33.3 × 33.3 ft), and the seven treatments were arranged in three replicates of a randomized complete block design for a total of 21 plots. The cool-season forage mixture included ‘Grazemaster’ rye (Secale cereale, a multiple-cultivar blend recommended for pastures), ‘Surrey’ annual ryegrass (Lolium multiflorum), ‘Flame’ crimson clover (Trifolium incarnatum), and ‘Cherokee’ red clover (T. pratense). The cool-season grasses were overseeded using a Tye Pasture Pleaser drill at planting rates of 50 lb/acre for rye and 13 lb/acre for ryegrass. The legumes were broadcast seeded at 8 lb/acre of crimson clover and 5 lb/acre of red clover. After broadcasting the legumes, one pass was made over the plots using a cultipacker. Planting dates were October 23, 1998 and November 3, 1999. Fertilization Nitrogen was applied at 40 lb/acre approximately 3 weeks (November 12, 1998 and November 22, 1999) after planting to all overseeded plots and again on February 10, 1999 and March 1, 2000, following the first grazing of each year. All plots, including those that were not overseeded, received N at 40 lb/acre on March 30 and April 27, 1999 and on April 5 and May 5, 2000. Total N applied was 160 lb/acre/year on the overseeded plots and 80 lb/acre/year on the plots that were not overseeded. Phosphorus and K were applied to overseeded plots at rates of 25 and 100 lb/acre on December 28, 1998, and at rates of 18 and 65 lb/acre on November 20, 1999. An additional application of K at 75 lb/acre was made to all plots in April of each year. Grazing and Sampling Plots were grazed on February 9, March 29, April 26, and June 18, 1999; and on February 29, April 4, May 4, and June 20, 2000. During winter and spring, grazing was initiated when cool-season forages were 8-inches tall and during summer when Tifton 85 was 12-inches tall. Yearling beef heifers were used to graze the plots to the target stubble height as defined by treatment during winter and spring (3 or 5 inches) and to 6 inches during summer. Sufficient animals were assigned to each plot such that grazing was completed in 2 to 6 hours. Before and after each grazing event, herbage mass was clipped to a 1.5-inch stubble in two representative 2.7-ft² quadrats per plot. Two additional quadrats of the same size were clipped from each plot pregraze, and the fresh herbage was hand separated into rye-ryegrass, clover, bermudagrass, weed, and dead fractions. Herbage was dried at 140°F for 48 h. After weighing the pregraze fractions, all live herbage within a plot was composited for laboratory analyses of crude protein using a micro-Kjeldahl technique and in vitro digestion using a modified two-stage procedure (6). All responses were analyzed using the PROC MIXED procedure of SAS (SAS Institute Inc., Cary, NC). Replicate and its interactions were considered random effects. Year and interactions with year were considered fixed because of the potential for carryover effects from year to year. Cool-season forage accumulation during winter and spring was compared only for the four overseeded treatments (Numbers 1 to 4 in Table 2) using the LSMEANS procedure of SAS (SAS Institute Inc.). For grazing events when bermudagrass herbage was present, single degree of freedom contrasts were used to compare the three controls (Treatments 5 to 7) with the average of the four overseeded treatments (Treatments 1 to 4) and to make comparisons among the three controls. Treatments were considered different when P ≤ 0.05. The means reported are least squares means. Cool-Season Forage Production Post-graze stubble height during winter and spring affected total forage and cool-season legume production, but had no effect on production of cool-season grasses and weeds (Table 3). Grazing to a 5-inch stubble in both seasons resulted in lowest cool-season production of legume and total forage, probably because of greater accumulation of ungrazed residual in these pastures. Component and total forage production during the cool season in this study was similar to that reported by Fontaneli et al. (5) at the same location. Table 3. Effect of winter and spring post-graze stubble height of a cool-season forage mixture on forage accumulation of red plus crimson clovers (legumes), rye plus annual ryegrass (grasses), weeds, and total forage×.
× There was no treatment × year interaction (P > 0.05). y Number following the words winter or spring is post-graze stubble height in inches to which pastures were grazed during this season. z Means within a column followed by the same letter are not different by PDIFF (P ≤ 0.05). In the current study, there were year effects on herbage accumulation of cool-season grasses and legumes. Cool-season legume production was greater in 2000 (1100 lb/acre) than 1999 (280 lb/acre) for all winter and spring grazing treatments (P < 0.05), likely because of the three-fold greater March rainfall in 2000 than 1999 (Table 1). In North Florida, crimson and red clover are most productive during March through May (5), thus lack of rainfall during that period in 1999 (3.7 vs. the average of 10 inches) affected their yield greatly. Similarly in Georgia, Burton and DeVane (1) found that cool-season legumes yielded nearly half of their total production in a May harvest. Tifton 85 Bermudagrass Production In 1999, bermudagrass forage was present in the pastures at pregraze sampling for the April 26 grazing, but in 2000, there was no bermudagrass at grazing in early May and measurable quantities were not present until the June grazing. Greater early spring rain in 2000 (Table 1) probably stimulated cool-season herbage production and provided a less desirable light environment for early initiation of bermudagrass growth. April 1999 data show that overseeding with cool-season forages reduced bermudagrass early season growth by nearly 400 lb/acre compared with plots that were grazed to 8 inches and not overseeded the previous fall and by nearly 200 lb/acre compared with plots that were grazed to 2 inches and not overseeded (Table 4). The response pattern was similar in 2000, but in that year, only control plots with an 8-inch fall stubble out-yielded the overseeded plots (1610 vs. 990 lb/acre). In North Carolina, summer Coastal bermudagrass hay yield was 18.1 and 50% greater when it was not overseeded than when rye or annual ryegrass, respectively, were seeded into the bermudagrass in fall (3). This response is likely because of cool-season annual grasses shading the newly developing tillers of bermudagrass and delaying their regrowth. This argument is supported by observed greater suppression of bermudagrass yield by annual ryegrass than rye. Annual ryegrass is later maturing than rye and has been found to be more competitive with recovering warm-season grasses for a greater portion of the spring and early summer (4). Table 4. Tifton 85 bermudagrass forage mass at spring and early
× Overseeded = the average of the four treatments for which Tifton 85
General patterns of response among the control treatments (not overseeded) were similar in the 2 years of the current study. Tifton 85 production the following spring was greater for the 8-inch fall stubble treatment than for the 2-inch stubble plots over which the drill was passed. Likewise in both years, the response to fall bermudagrass stubble height was similar for the controls. In 1999, leaving a taller stubble in fall resulted in nearly 200 lb/acre more bermudagrass forage the following April, and in 2000 there was strong trend (P = 0.09) favoring the 8-inch vs. the 2-inch fall stubble (1610 vs. 1070 lb/acre). In Texas, first harvest yields of Coastal bermudagrass were 270 lb/acre greater for plots that had been cut to a 4-inch compared with a 1-inch stubble the previous fall (4). It is not clear that an 8-inch stubble is necessary for Tifton 85, but the results of the current study favor a fall stubble of greater than 2 inches. There was no difference in bermudagrass production in either year between the overseeded plots and the non-overseeded control plots that were defoliated to a 2-inch stubble followed by a pass with the drill (Table 4). The fact that bermudagrass yield reduction occurred without competition from cool-season forages suggests that the reductions observed in overseeded plots may be due in part to physical effects of the drill on the sod. In a study evaluating fall sod treatments of Coastal bermudagrass in Texas, Evers (4) reported that light disking reduced first-harvest bermudagrass yields the following spring by an average of 600 to 700 lb/acre whether the area was overseeded with cool-season forages or not. Thus, it appears that physical disturbance of bermudagrass sods during preparation for overseeding in fall has carryover effects in the first harvest or grazing of the next growing season. An additional sampling of plots in the current study was carried out in June 1999 and July 2000 to assess treatment impacts beyond the first grazing event in which bermudagrass contributed biomass. In 1999, there was no difference in bermudagrass yield between overseeded plots and non-overseeded plots that were grazed in fall to 8 inches (2470 vs. 2280 lb/acre). However, both 2-inch stubble control treatments had lesser yield (average of 1520 lb/acre) than overseeded plots, suggesting some carryover effect of the short stubble even into June. In July 2000, there were no differences in bermudagrass yield among treatments (data not presented). Thus, in all cases, average bermudagrass production by the second grazing was as great, or greater in overseeded than control plots. Although bermudagrass production by the time of first grazing was negatively affected by overseeding, the effect was short-lived and had disappeared by later dates; however, the effect of short stubble in the preceding fall carried over into June in both years. Nutritive Value Crude protein and in vitro digestibility data are from total pregraze herbage and not only the bermudagrass fraction. In April 1999, herbage crude protein and digestibility were greater for overseeded plots than any of the controls (Tables 5 and 6). This is a function of the continued presence of cool-season grass and legume herbage as well as the contribution of legumes to soil nitrogen status. Increases in herbage CP have been associated with increases in percentage of legumes in bermudagrass swards (8). The response of crude protein was similar in 2000 (Table 5), but in the second year there were no differences in digestibility between any of the controls and the average of the overseeded treatments. Table 5. Crude protein of pre-graze herbage mass (to a 1.5-inch stubble)
× Overseeded = the average of the four treatments for which Tifton 85
Table 6. In vitro organic matter digestibility of pre-graze herbage mass
× Overseeded = the average of the four treatments for which Tifton 85
Summary and Management Implications Slow spring regrowth or reduced summer yield has been observed for hybrid bermudagrass pastures or hay fields that were overseeded with temperate forages and grazed during the cool season. Although reduction in spring/early summer bermudagrass production occurred in this study (300 to 600 lb/acre when compared to non-overseeded plots with tallest fall bermudagrass stubble), there was no indication of stand deterioration associated with overseeding in this environment. In fact, by June 1999 and July 2000 bermudagrass production was at least as great for overseeded pastures as for any of the non-overseeded controls. In addition to the effect observed for overseeding, fall bermudagrass sod management affected early-season bermudagrass production in both years. An 8-inch fall stubble resulted in approximately 200 to 500 lb/acre greater production than a 2-inch stubble, and the negative effect of a short fall stubble carried over into June each year. Therefore, it is concluded that Tifton 85 bermudagrass can be overseeded with cool-season annual forages to extend the grazing season in North Florida and similar environments without negatively impacting Tifton 85 persistence and with relatively small negative effects on early-season bermudagrass yields. In situations where Tifton 85 is not overseeded, leaving taller bermudagrass stubble in fall will likely increase yields the following spring compared with leaving only a 2-inch stubble. Literature Cited 1. Burton, G. W., and DeVane, E. H. 1992. Growing legumes with ‘Coastal’ bermudagrass in the lower coastal plain. J. Prod. Agric. 5:278-281. 2. Burton, G. W., Gates, R. N., and Hill, G. M. 1993. Registration of ‘Tifton 85’ bermudagrass. Crop Sci. 33:644-645. 3. Chamblee, S. D., and Muller, J. P. 1999. Extending the grazing season: growth of annual or perennial grasses or legumes in mixture with hybrid bermudagrass. Tech. Bull. 315. North Carolina State Univ., Raleigh, NC. 5. Fontaneli, R. S., Sollenberger, L. E., and Staples, C. R. 2000. Seeding date effects on yield and nutritive value of cool-season annual forage mixtures. Soil Crop Sci. Soc. Florida Proc. 59:60-67. 6. Moore, J. E., and Mott, G. O. 1974. Recovery of residual organic matter from in vitro digestion of forages. J. Dairy Sci. 57:1258-1259. 7. Sinclair, T. R., Ray, J. D., Mislevy, P., and Premazzi, L. M. 2003. Growth of subtropical forage grasses under extended photoperiod during short-daylength months. Crop Sci. 43:618-623. 8. Stringer, W. C., Khalilian, A., Undersander, D. J., Stapleton, G. S., and Bridges, W. C. Jr. 1994. Row spacing and nitrogen: Effect on alfalfa-bermudagrass yield and botanical composition. Agron. J. 86:72-76. 9. Vendramini, J. M. B., Sollenberger, L. E., Dubeux, J. C. B. Jr., Interrante, S. M., Stewart, R. L. Jr., and Arthington, J. D. 2006. Concentrate supplementation effects on forage characteristics and performance of early weaned calves grazing rye-ryegrass pastures. Crop Sci. 46:1595-1600. |
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