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© 2005 Plant Management Network. Warm-Season Grass Production Responses to Site and Defoliation Frequency John H. Fike, Assistant Professor, Crop and Soil Environmental Sciences, Virginia Polytechnic Institute and State University, Blacksburg 24061; Chris D. Teutsch, Assistant Professor, Southern Piedmont Agricultural Research and Extension Center, Virginia Polytechnic Institute and State University, Blackstone 23824; and Daniel L. Ward, VA-MD Regional College of Veterinary Medicine, Virginia Polytechnic Institute and State University, Blacksburg 24061 Corresponding author: John H. Fike. jfike@vt.edu Fike, J. H., Teutsch, C. D., and Ward, D. L. 2005. Warm-season grass production responses to site and defoliation frequency. Online. Forage and Grazinglands doi:10.1094/FG-2005-0824-01-RS. Abstract Seasonal yield of ‘Midland 99,’ ‘Ozark,’ ‘Quickstand,’ ‘Tifton 44,’ and ‘Wrangler’ bermudagrasses (Cynodon dactylon L.); Caucasian bluestem (Bothriochloa caucasica Trin.); and ‘Red River’ crabgrass (Digitaria ciliaris Retz.) were compared with ‘Kentucky-31’ and ‘Jesup Max-Q’ tall fescues (Festuca arundinacea Schreb). Forages were established in two geographically and climatologically distinct regions of Virginia. The Ridge/Valley site is near Blacksburg (elevation 1772 ft) and the Southern Piedmont site is near Blackstone (elevation 446 ft). Two-, 4-, and 6-week cutting frequencies were imposed. Although not always significant, the trend was for yield to increase as cutting frequency decreased. There were year × site × frequency x forage interactions. Tall fescues had the greatest yield in the Ridge/Valley but were intermediate in the Southern Piedmont. High yields of Midland 99 and Tifton 44 at the Southern Piedmont site suggest sprigged hybrids have potential for the region. Seeded warm-season perennials (Caucasian bluestem or Wrangler bermudagrass) would likely have greater utility for the Ridge/Valley. Warm-season grasses have potential to boost forage system output across diverse regions within the transition zone but attention to species and cultivar selection is needed. Introduction Warm-season grasses are of increasing interest to producers in the upper reaches of the transition zone to fill the summer slump of cool-season perennial grasses. However, little regional information about them is available. Hybrid bermudagrass may have the most potential, but sprigged varieties might not be readily adopted by producers because of a lack of sprigs and sprigging equipment. Seeded bermudagrasses may be a suitable alternative but have had only limited testing outside their region of development. Other potential warm-season grasses include Caucasian bluestem and crabgrass. Caucasian bluestem performed well in a test of forage-livestock systems in Virginia, USA (1) and Red River crabgrass has shown promise in Virginia’s Southern Piedmont region (6). Objectives were to determine annual forage production under three clipping frequencies in two geographically and climatologically distinct regions of Virginia. Warm-season forages included Midland 99, Ozark, Quickstand, Tifton 44, and Wrangler bermudagrasses; Caucasian bluestem; and Red River crabgrass. Production comparisons were made against Kentucky-31 and Jesup tall fescues, containing wild and introduced endophytes (Neothyphodium coenophialum), respectively. Management of Experimental Plots Establishment. In April 2000, dormant sprigs of Tifton 44, Midland 99, Ozark, and Quickstand bermudagrass were started in a greenhouse. Sprigs were planted into prepared beds on 28 June and 10 July 2000 at the Southern Piedmont Agriculture Research and Extension Center, Blackstone, VA and the Kentland Research Farm, Blacksburg, VA, respectively. Site descriptions and weather data are presented in Table 1 and Figs. 1 and 2. Table 1. Experimental location, geographic region, elevation, soil series, latitude and longitude where warm-season grass productivity in response to cutting frequency was studied in Virginia.
Plots were 5 ft × 10 ft at the Southern Piedmont site and 5 ft × 15 ft at the Ridge/Valley site. Planting density was approximately 0.32 sprigs per ft2. Wrangler bermudagrass, Caucasian bluestem, and Red River crabgrass were seeded with a plot seeder at 10, 5, and 5 lb of pure live seed per acre, respectively. Tall fescue was planted in early October 2000 at 15 lb of seed per acre. At the Ridge/Valley site, stands in tall fescue plots were poor and thus re-seeded April 2001. For the same reason, Caucasian bluestem was re-seeded at the Southern Piedmont on 21 July 2001. Borders (1 ft) between plots at both sites were maintained with applications of glyphosate [(N-phosphonomethyl)glycine] (0.8 lb ai/acre) or paraquat (1,1’-dimethyl-4,4’-bipyridinium ion) (0.6 lb ai/acre) and by hand weeding. Red River crabgrass, the only annual species tested, is capable of self-reseeding. At the Ridge/Valley site, self-seeding stands were excellent in 2001, but not in 2002. Plots were thus tilled and reseeded on 23 June 2002 due to poor self-reseeding. In 2003, plots at both the Ridge/Valley and Southern Piedmont sites were reseeded on 3 May and 24 April, respectively, to encourage earlier crabgrass production. Plot management. Phosphorus and K were maintained at high levels based on soil test. Soil pH was kept above 6.0. Nitrogen was applied at a rate of 300 lb/acre/year (as NH4NO3) in split applications of 100 lb/acre. Nitrogen was applied in March, May, and early August for tall fescue and April, June, and early August for warm-season grasses. In spring, dormant warm-season plots were treated with glyphosate (0.8 lb ai/acre) or 2,4-D [(2,4-dichlorophenoxy) acetic acid] (0.8 lb ai/acre) for broadleaf weed control. All but crabgrass plots were treated with MSMA [monsodium methanearsonate] (1 lb ai/acre) in spring 2002 to control crabgrass. MSMA also was applied to Southern Piedmont plots in 2003. Isoxaflutole [5-cyclopropyl-4-(2-methylsulphonyl-4-trifluoromethyl-benzoyl) isoxazole] was applied (0.05 lb ai/acre) to all but the crabgrass plots at the Ridge/Valley site in 2002 and 2003 to suppress nimblewill (Muhlenbergia schreberi L.). Harvest management. In 2001, plots were harvested at 4-, 6-, and 8-week cutting frequencies to encourage stand establishment. In 2002 and 2003, plots were harvested at 2-, 4-, and 6-week cutting frequencies. Only data from 2002 and 2003 are presented. Tall fescue harvests began 2 and 18 April 2002 at Southern Piedmont and Ridge/Valley sites, respectively. Cold weather delayed tall fescue growth and subsequent untimely rainfall delayed harvest in 2003. Initial harvests began 23 April and 1 May for the respective sites that year. Each season, warm-season grass plots were harvested within frequency treatments after canopies reached a minimum height of 8 inches. Harvest seasons for the Southern Piedmont and Ridge/Valley sites concluded 11 and 26 December 2002 and 7 and 31 October 2003. Yields were determined by cutting a swath (1.75 ft at Ridge/Valley and 4 ft at Southern Piedmont) through the center of each plot to a 3-inch stubble height. Subsamples were collected for dry matter determination. Data analysis. Experimental design at each site was a randomized complete block in a split plot arrangement of treatments with four replicates. Cutting frequency was the whole plot; forage species were subplots. Data were analyzed across years and sites using Mixed Model procedures of SAS (SAS Institute, Inc., Cary, NC). Block (i.e., replication) and frequency × block within years and sites were treated as random effects in the model. Large numbers of comparisons increase the potential of Type I error. Thus, the Bonferroni method was used to control the family-wise error rate in determining differences among cutting frequencies for a given forage within each site-year combination. Total annual herbage production varied substantially by site and by forage species (Figs. 3 to 6). Significant (P < 0.01) year × site × frequency × forage interactions were observed but not unexpected given large differences among forages and between years and sites. This interaction was largely driven by three factors: (i) greater production of tall fescues and seeded warm-season grasses at the Ridge/Valley site; (ii) a differential response to cutting frequency (across forage species) that occurred each year between the two sites; and (iii) limited response of crabgrass to cutting frequency within each site-year combination. Data are presented for each site-year combination (Figs. 3 to 6). Within site-year combinations, significant forage × frequency interactions occurred and the interaction means are presented.
Ridge/Valley Site Tall fescue was the most productive forage at the Ridge/Valley location (Figs. 3 and 4) and yield did not differ between cultivars. However, tall fescue had about a 75-day longer growing season on average. Averaged across cutting frequencies, Midland 99 and Quickstand bermudagrasses had the greatest warm-season forage yields. Quickstand, the only cultivar selected from the northern transition zone, was not as tall or thick-stemmed as the other sprigged bermudagrasses but spread aggressively, formed a thick sod, and had a denser canopy (Fig. 7). Results with Quickstand suggest the benefit of selections from regionally-adapted germplasm. Tifton 44 was slower to cover the plots at the Ridge/Valley site, limiting seasonal forage production in 2001 (data not shown). This observation matches those by Mueller et al. (3) in which Tifton 44 covered plots more rapidly on sandy soils but took longer to cover plots on clay loam. Ozark was slow to produce rhizomes and cover the plots, resulting in low yields. Ozark was easily distinguishable from other bermudagrasses into the third growing season (2002) given marked upright morphological characteristics of the mother plants (Fig. 7).
Wrangler-seeded bermudagrass and Caucasian bluestem production was similar to the bermudagrass hybrids. These forages may hold particular promise for the region because they can be established from seed. Yield of Red River crabgrass was substantially lower in 2002-2003 (4000 to 6000 lb/acre) than 2001 (11,000 lb/acre) due to poor reseeding. Soil pH and MgCO2 may have affected germination because plots were amended with dolomitic lime (4). Similar responses have been observed in West Virginia (David Belesky, personal communication, 2003). Cutting frequency did not influence crabgrass yields. At the Ridge/Valley site, no benefit was obtained by delaying harvest of any forage from 2-week to 4-week in 2002. The yield response to a 6-week cutting frequency was positive for all forages except Midland 99 and Red River crabgrass (forage × frequency interaction; P < 0.01). In 2003, the pattern of response to cutting frequency changed (year × frequency interaction; P < 0.01). Delaying harvest from 2-week to 4-week increased herbage production 18% across all forages but yields were not different between 4- and 6-week cutting frequencies (forage × frequency interaction; P < 0.01). This was likely due to higher rainfall in 2003. On heavier soils, a 4-week defoliation frequency appears near optimum for maximum biomass production under high moisture and moderate light conditions, perhaps due to limited light penetration of the canopy. Southern Piedmont Site Bermudagrasses were more productive at the Southern Piedmont (Figs. 5 and 6) than at the Ridge/Valley site. The Southern Piedmont had warmer temperatures (Figs. 1 and 2) which favored growth of warm-season grasses and limited production of cool-season grasses. Over cutting frequencies, Midland 99 and Tifton 44 were the site’s highest yielding forages followed by Quickstand bermudagrass. Tall fescue biomass production was intermediate, averaging about 80% that of Midland 99 despite an average 60-day longer growing season. However, this was largely due to the reduced production during a drought year (2002) and the benefit of a 6-week cutting frequency for bermudagrass in 2003. Ozark bermudagrass was not as productive: yields were similar to Quickstand only at 6-week cutting frequency. Production of Caucasian bluestem, Red River crabgrass, and Wrangler bermudagrass (all seeded forages) was markedly lower at the Southern Piedmont than at the Ridge/Valley site. Stand maturity may have affected Caucasian bluestem. Results with another Bothriochola (5) suggest winter tiller survival may have been reduced by low soil moisture. Reasons for the poor performance of Wrangler and Red River at the Southern Piedmont site are not clear; both forages have performed well in other research at that site (6). Forages typically were more sensitive to cutting frequency at the Southern Piedmont than at the Ridge/Valley site. Although not always significant, the trend was for yield to increase as cutting frequency decreased. Reductions in root growth with increased clipping frequency (2) would limit root mass and rooting depth. Thus, more pronounced yield response to reduced cutting frequency might be expected under dry conditions as occurred in 2002. However, in 2002, a lack of yield response from 4- to 6-week cutting interval was observed with Quickstand, Tifton 44, and Wrangler bermudagrasses at the Southern Piedmont. Quickstand and Wrangler formed especially thick sod, and these three forages may have exploited available soil water more rapidly than the other forages, limiting response to longer regrowth interval. The generally greater response to longer harvest intervals at the Southern Piedmont than at the Ridge/Valley site suggests that moisture was the primary limiting factor for production at that site. Even during a year of record rainfall, 2003, a period of below-normal precipitation occurred during summer (Fig. 2). The A soil horizon at the Southern Piedmont site has a high sand content and the site typically has greater evaporative demand. These conditions make the soils more prone to moisture deficit than the clay loam of the Ridge/Valley. Conclusions Most warm-season grasses in this study began biomass production as tall fescue production began to decline. Therefore, a combination of warm- and cool-season forages would provide more uniform forage production throughout the year. At the Ridge/Valley site, production from tall fescues and seeded warm-season species was more stable from year to year. Yields of Caucasian bluestem and Wrangler were similar to top-yielding bermudagrass hybrids. Hybrid bermudagrasses have the greatest potential for forage systems in the Southern Piedmont, where temperatures are warmer, provided infrastructural limitations can be met. Seeded warm-season species appear less suitable given lower yields and greater year-to-year variability. Crabgrass, a warm-season annual, was less dependable and lower yielding than perennials. With ample moisture, a 4-week cutting interval appeared near-optimum on clay loam soils; on sandy soils, maximum yields were attained with 6-week harvests. Bermudagrasses had relatively stable yields across weather extremes because of excellent drought tolerance, and should be superior for managing risk, particularly in the Southern Piedmont. Acknowledgments The authors thank the Virginia Agriculture Council for support of this research. Thanks to Charles Taliaferro (Oklahoma State University) for provision of bermudagrass sprigs and to Leroy Mack and Gene McVey, Johnston Seed Company, for Wrangler bermudagrass seed. Thanks also to R. L. Dalrymple and Joe Bouton, (Noble Foundation, Enid Oklahoma) for supplying crabgrass and tall fescue seeds, respectively. Literature Cited 1. Allen, V. G., Fontenot, J. P., and Brock, R. A. 2000. Forage systems for production of stocker steers in the upper south. J. Anim. Sci. 2000. 78:1973–1982 2. Crider, F. J. 1955. Root growth stoppage resulting from defoliation of grass. USDA Tech. Bull. 1102, Washington, DC. 3. Mueller, J. P., Green, J. T., Nelson, L. A., and Hall, J. V. 1992. Establishment of two bermudagrasses in three soil environments. Agron. J. 84:38-43. 4. Pierce, G. L., Warren, S. L., Mikkelsen, R. L., and Linker, H. M. 1999. Effects of soil calcium and pH on seed germination and subsequent growth of large crabgrass (Digitaria sanguinalis). Weed Technol. 13:421-424. 5. Teague, W. R., and Dowhower, S. L. 2002. Irrigation impact on harvest efficiency in grazed Old World bluestem. J. Range Manage. 55:260-265. |
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