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© 2008 Plant Management Network. Establishing Cool-season Perennial Grasses into Former Annual Grass Pastures in the Southern Great Plains Twain J. Butler and M. Anowarul Islam, The Noble Foundation, 2510 Sam Noble Parkway, Ardmore, OK 73401; and James P. Muir, Texas A&M University Agricultural Experiment Station, 1229 North US Hwy 281, Stephenville, TX 76401 Corresponding author: Twain Butler. tjbutler@noble.org Butler, T. J., Islam, M. A., and Muir, J. P. 2008. Establishing cool-season perennial grasses into former annual grass pastures in the southern Great Plains. Online. Forage and Grazinglands doi:10.1094/FG-2008-0911-01-RS. Abstract Cool-season perennial grasses have potential to improve seasonal forage distribution in the southern Great Plains. However, annual grasses like ryegrass (Lolium multiflorum Lam.) or rescuegrass (Bromus catharticus Vahl.) that naturally reseed can be more competitive than perennial grasses during establishment. Two adjacent experiments were conducted during 2004-2005 and 2005-2006 growing seasons to determine the best management strategies for establishing perennial grasses into naturally reseeding annual grass fields. In Experiment I, ryegrass was continuously grazed while in Experiment II, ryegrass was sprayed with glyphosate, N-(phosphonomethyl) glycine, in early May to prevent seed production. In both experiments, four cool-season perennial grass species ['Flecha' summer-dormant tall fescue (Festuca arundinacea Shreb.), ‘PDF584’ summer-active tall fescue, ‘NFHG4001’ hardinggrass (Phalaris aquatica L.), and 'Jose' tall wheatgrass (Thinopyrum ponticum (Podp.) Barkworth & D.R)] were either drilled or broadcast in September, October, or November. Establishment was generally poor in Experiment I (no spring glyphosate) compared to Experiment II (spring glyphosate application). Drilling seed, except for the September planting in 2005, resulted in greater forage yield than broadcasting seed. Planting in October followed by an autumn application of glyphosate after weed emergence generally resulted in greater establishment and subsequent forage production. Based on these results, it is recommended that annual weeds be controlled in spring, and then drill-seeded after precipitation occurs and temperatures decline in late September, followed by an application of glyphosate to control emerged weeds after planting. Potential of Cool-season Perennial Grasses Beef and dairy cattle producers in the southern Great Plains rely primarily on cool-season annual grasses for grazing during autumn to spring (13,14,16). However, unpredictable precipitation in autumn often delays planting of annual grasses, resulting in a lack of high quality forage for grazing during winter to early spring (12). Producers also are concerned with the production cost of annual forages. Furthermore, in the southern Plains, planting of annual grasses requires land to be fallowed for prolonged periods of time; as a consequence, precipitation and wind cause a substantial loss of soils and nutrients (2,10,18). In recent years, there is an increased interest from livestock producers and landowners in shifting from annually sown cool-season forages to more permanent perennial cool-season grass systems (3,7,8). Cool-season perennial grasses have forage potential in the southern regions (4,7,10,11,12), and may have lower production costs compared to cool-season annual grasses since they do not have to be reestablished each year (9). Producers who consider planting cool-season perennial grasses will more than likely attempt to convert existing fields where they have traditionally grazed out wheat (Triticum aestivum L.) and/or have volunteer annual ryegrass. However, naturally reseeding annual grasses like ryegrass or rescuegrass can be more competitive than perennial grasses during establishment (15), which may result in complete or partial stand failure of the perennial grasses (14). Currently there are no herbicides labeled for controlling annual grassy weeds in newly established perennial grasses, thus cultural practices and management will play an important role in their establishment (10,14). Reliable establishment methods must be developed before further research, such as persistence (7), can be evaluated for these cool-season perennial grasses. The objectives of this study were to determine the optimal planting date and seeding method for establishing four cool-season perennial grasses into pastures of the southern Great Plains infested with annual grassy weeds suppressed through either grazing or herbicide application. Procedures for Assessing Establishment of Cool-season Perennial Grasses Two adjacent experiments with a randomized complete block (split-split plot) design with four replications were conducted during 2004-2005 and 2005-2006 growing seasons near Vashti, TX (33°34'N, 98°1'W) on an Anocon (fine, mixed thermic Udic) loam soil (pH 5.8; NO3-N, 42 ppm ; P, 8 ppm; K, 140 ppm). In both experiments, main plots were three planting dates (September, October, and November), subplots were two seeding methods (broadcast or drilled), and sub-subplots were four cool-season perennial grasses [Flecha summer-dormant tall fescue, Noble Foundation (NF) experimental PDF584 summer-active tall fescue, NF experimental hardinggrass, and Jose tall wheatgrass]. Both experiments were fertilized with N at 36 lb/acre and P2O5 at 92 lb/acre (source: 18-46-0). In Experiment I (no spring glyphosate application), the ryegrass pasture was continuously grazed through May and no glyphosate was applied in the spring prior to perennial grass seeding in the autumn. In Experiment II, 1 lb ai/acre glyphosate was applied in early May to control annual grasses and prevent seed production. Seedbed preparation included conventional tillage with an offset disk in late summer (August) followed by a drag harrow and roller packer to ensure a level and firm seedbed. The September planting date was seeded to dry soil, while the October and November planting dates were seeded 7 days after precipitation occurred to germinate weeds, which were then sprayed with glyphosate at 0.75 lb ai/acre within two days of planting. In Experiment I, this treatment resulted in a single autumn application of glyphosate, while in Experiment II, this resulted in a sequential spring plus autumn application of glyphosate to prevent seed production in the spring and to control emerged weeds in the autumn. Plots, 6 by 25 ft, were seeded with a Hege (Hege Equipment Inc., Colwich, KS) no-till cone small-plot planter. In the drilled method, seed was placed approximately 0.25-inch deep via the coulters, while in the broadcast method, the drop tubes were removed from the coulters to allow seed to fall on the soil surface. In each year, summer-dormant tall fescue, summer-active tall fescue, hardinggrass, and tall wheatgrass were seeded at 18, 18, 8, and 18 lb pure live seed (PLS)/acre, respectively in both experiments The 2004-2005 plots were harvested in late February and early May in 2005 by hand-clipping 12 by 24-inch quadrats to 1-inch height for each of the four replications, while the 2005-2006 plots were harvested in early March and early May of 2006 following the same procedures. Species composition of the cool-season perennial grass and annual weeds in each plot were visually estimated and averaged across two observers each year. Weed composition primarily consisted of annual grassy weeds (annual ryegrass). Samples were dried at 110°F until moisture loss ceased. Cumulative yields are reported as pounds of dry matter (DM) per acre. Dependent variables (forage yield, weed yield, and total yield) from each experiment were subjected to analysis of variance using PROC GLM (SAS Institute Inc., Cary, NC) with treatment differences having P < 0.05 reported as significant. Means, where appropriate, were separated using Fisher’s Protected LSD test at P = 0.05 level of significance. Precipitation During the Growing Seasons Although precipitation amounts were similar in both growing seasons, which were defined as September until May, precipitation distribution was quite different (Fig. 1). Precipitation was 33 to 35% below the 30-year average of 21.7 inches for that period. In 2004-2005, the greater portion of the rain (11 inches) occurred in late autumn (October-December), which were considered as "good" establishment conditions. However in 2005-2006, most of the rain occurred in the spring (March-May), while only three inches were received in the autumn (September-December), which was considered "poor" establishment conditions.
Cool-season Perennial Grass Yields Year × planting date and year × seeding method interactions were significant (P < 0.05) for both experiments; therefore, means are reported by year (Fig. 2). In the 2004-2005 growing season, planting date × seeding method, planting date × species, and seeding method × species interactions were not significant (P > 0.05); therefore, means are pooled across all factors in both experiments. In the 2005-2006 growing season, planting date × seeding method and planting date × species interactions were significant (P > 0.05); therefore, means are reported by planting date. Seeding method × species interactions were not significant (P > 0.05); thus, means are pooled for these two variables.
Experiment I (no spring glyphosate application) Establishment and subsequent cool-season perennial grass DM production were low (0 to 18% of total yield) in both growing seasons in Experiment I (Table 1). Table 1. Effect of planting date and seeding method on forage dry matter (DM) yields of four cool-season perennial grasses and weeds (primarily annual ryegrass) for Experiment I (no spring application of glyphosate) at Vashti, TX.
x October planting date was seeded and then sprayed with glyphosate to control emerged weeds. y November planting date was seeded and then sprayed with glyphosate to control weeds. z Cool-season grass species did not differ among planting dates and seeding method in 2005-2006. Planting date. In the 2004-2005 growing season, planting date affected crop, weed, and total cumulative DM production. No precipitation occurred in September 2004; however, these plantings emerged in October after the first precipitation of the season. Cool-season perennial grass yields were greatest when plots were planted in October and glyphosate applied immediately after planting to control emerged weeds. Cool-season perennial grass yields did not differ between the September and November planting dates. This could be attributed to the greater competition from weeds in the September planting date and the shorter growing season with the November planting date and the lack of precipitation in the spring of 2005. Weed production decreased as planting date was delayed from September to October and November (followed by glyphosate application immediately after planting). Total cumulative DM production did not differ between the September and October planting dates; however, the November planting date yielded 63 to 64% less than the earlier planting dates. In the 2005-2006 growing season, planting date affected cool-season perennial grass production, but not weed or total cumulative DM production (Table 1). In early September, a 0.5-inch rainfall germinated most of the cool-season grasses; however, extreme high temperatures (102°F) along with dry soil conditions killed most of these seedlings. Cool-season perennial grass production generally increased as planting date was delayed; however weed and total cumulative production did not differ among planting dates. Weeds were controlled in the October and November planting dates, which should have reduced weed yield; however, new weeds emerged with each subsequent rainfall event. Overall the data suggest that planting cool-season perennial grasses too early is associated with potential mortality from drought, while planting too late may be associated with mortality from an early freeze (14). Seeding method. In both the 2004-2005 and 2005-2006 growing seasons, seeding methods affected cool-season perennial grass production, but not weed or total cumulative production. Drilling the seed at 0.25-inch depth generally yielded greater crop yield, except for the September 2005 planting date because of extreme high temperatures and limited precipitation that month. The results thus indicate the need to prepare a firm seedbed or drill seed to maximize soil-seed contact for better germination, emergence and establishment of cool-season perennial grasses (14). Cool-season perennial grass species. In early December 2004, temperatures reached 13°F, which caused some freezing injury, defined as percent necrotic leaf tissue, to the perennial grass seedlings. The summer-active tall fescue (7% freeze damage) and tall wheatgrass (2% freeze damage) were more cold-tolerant than the hardinggrass (71% freeze damage) or the summer-dormant tall fescue (58% freeze damage) (data not shown). However, this damage was relatively short-lived as the plants showed no freeze damage by early March, which was expected for these cool-season perennial grasses (12). In the 2004-2005 growing season, when early season (October-November) moisture was greater, summer-active tall fescue and summer-dormant tall fescue produced greater yields compared to hardinggrass and tall wheatgrass, and there was no difference between tall fescues or between hardinggrass and tall wheatgrass. Yields were so low (159 to 832 lb/acre) that it is difficult to make any conclusions regarding cool-season perennial grass species establishment. However, it was assumed that no glyphosate application in spring and weed competition in the autumn resulted in poor establishment. In the 2005-2006 growing season, for a given planting date or seeding method, forage yield of the four species did not differ, indicating that species choice might be less important than planting date or seeding method when establishing cool-season perennial grasses (14). Cold-injury does not seem to be a major concern in the southern Great Plains for these cool-season grasses (12), unless the injury occurs at an earlier growth stage. In December 2005, temperatures reached 8°F, which caused some short-term injury. Most of the Flecha seedlings from the November planting date were in the three- to four-leaf stage, which caused some stand thinning but did not affect DM yield. In contrast, in a nearby field, Flecha seedlings planted one week later at the two- to three-leaf stage were killed (data not presented). Experiment II (Spring Glyphosate Method) Planting date. In the 2004-2005 growing season, cool-season perennial grass yield did not differ between September and October planting dates. As previously mentioned, the September planting did not germinate until October precipitation occurred. The October planting followed by glyphosate to control emerged weeds reduced weed production and total cumulative production compared to the September planting date. Plots that were planted in October or November 2005 and received glyphosate immediately after planting, established better and produced more perennial grass than those planted in September 2005 due to the extreme high temperatures (102°F) and dry conditions that occurred that month. These data illustrate that the environment can have a greater impact on establishment than planting date alone and support the findings of Gates et al. (5) and Hopkins (6). As a general rule, seeds should be planted when moisture is expected and late enough to avoid high temperatures that occur in late August to mid-September and yet early enough for seedlings to become established (e.g., five-leaf stage) before a hard freeze (14). Therefore, optimal planting date should be between late September and late October for these cool-season perennial grasses based on the historical precipitation patterns in the southern Great Plains. Table 2. Effect of planting date and seeding method on forage dry matter (DM) yields of four cool-season perennial grasses and weeds (primarily annual ryegrass) for Experiment II (spring application of glyphosate) at Vashti, TX.
x October planting date was seeded and then sprayed with glyphosate to control emerged weeds. y November planting date was seeded and then sprayed with glyphosate to control weeds. z Cool-season grass species did not differ among planting dates and seeding method in 2005-2006. Seeding method. Seeding method affected cool-season crop establishment and production. In both 2004-2005 and 2005-2006 growing seasons, except for September 2005, drilling seed consistently provided better establishment and production than broadcasting, supporting the preliminary observations of Redmon (14). Therefore, drilling should be recommended over broadcasting seed of these cool-season perennial grasses. Cool-season perennial grass species. Crop yield of four grass species followed the same pattern in Experiment II as for Experiment 1 in both the 2004-2005 and 2005-2006 growing seasons. These data indicate that the four species respond similarly to planting date and seeding method. Summary and Conclusions Establishment of four cool-season perennial grasses was very poor in Experiment I (no spring glyphosate application), while establishment in Experiment II (spring glyphosate application) was good to excellent even though precipitation was below the long-term average in both years. Planting in October followed by an autumn application of glyphosate after weed emergence but before grass seedling emergence resulted in greater establishment and subsequent DM production. Drilling seed also resulted in greater establishment and production. Based on these data, it is recommended that annual weeds be controlled in spring prior to planting, subsequently drilling seed in autumn (late September to October) following declining temperatures and adequate rainfall to germinate weeds followed by glyphosate to control emerged weeds. This will provide the best chance for these cool-season perennial grasses to establish in fields known to have annual grassy-weeds. Literature Cited 1. Ball, D. M., Hoveland, C. S., and Lacefield, G. D. 2002. Forages for beef stockering. Pages 231-235 in: Southern Forages. 3rd Edn. D. M. Ball, C. S. Hoveland, and G. D. Lacefield, eds. Potash and Phosphate Inst., Norcross, GA. 2. Berg, W. A., Smith, S. J., and Coleman, G. A. 1988. Management effects on runoff, soil and nutrient losses from highly erodible soils in the Southern Plains. J. Soil Water Conserv. 3:407-410. 3. Christensen, L. A., and Norris, P. E. 1983. A comparison of tillage systems for reducing soil erosion and water pollution. USDA Agric. Econ. Rep. No. 499. Washington, DC. 4. Evers, G. W., Gabrysch, J. L., and Tackett, C. R. 1993. Performance of cool-season perennial grasses on poorly drained clay soils. Pages 6-8 in: Forage Research in Texas, PR-5080. Texas Agric. Exp. Stn., College Station, TX. 5. Gates, R. N., Hill, G. M., and Bouton, J. H. 1999. Wintering beef cattle on mixtures of ‘Georgia 5’ tall fescue and warm-season perennial grasses on Coastal Plains soils. J. Prod. Agric. 12:581-587. 6. Hopkins, A. A. 2005. Grazing tolerance of cool-season grasses planted as seeded sward plots and spaced plants. Crop Sci. 45:1559-1564. 7. Hopkins, A. A., and Alison, M. W. 2006. Stand persistence and animal performance for tall fescue endophyte combinations in the central USA. Agron. J. 98:1221-1226. 8. Hopkins, A. A., Krenzer, E. G., Horn, G. W., Goad, C. L., Redmon, L. A., Redfearn, D. D., and Reuter, R. R. 2003. Spring grazing seed yield of cool-season perennial grasses grown in the Southern Great Plains. Agron. J. 95:855-862. 9. Islam, M. A., Butler, T. J., Biermacher, J. T., Cook, B. J., Hopkins, A. A., and Bouton, J. H. 2006. Grazing economics of perennial versus annual grass system. Proc. of the 3rd Nat'l. Conf. on Grazing Lands, 10-13 December 2006. St. Louis, MO. The Grazing Lands Conversation Initiative and the Soc. for the Range Management, Wheat Ridge CO. 10. Kindiger, B., and Conley, T. 2002. Competition and survival of perennial cool-season grass forages seeded with winter wheat in the southern Great Plains. J. Sustain. Agric. 21:27-45. 11. Malinowski, D. P., Hopkins, A. A., Pinchak, W. E.,. Sij, J. W, and Ansley, R. J. 2003. Productivity and survival of defoliated wheatgrasses in the Rolling Plains of Texas. Agron. J. 95:614-626. 12. Malinowski, D. P., Zuo, H., Kramp, B. A., Muir, J. P., and Pinchak, W. E. 2005. Obligatory summer-dormant cool-season perennial grasses for semiarid environments of the southern Great Plains. Agron. J. 97:147-154. 13. Redfearn, D. D., Venuto, B. C., Pitman, W. D., Alison, M. W., and Ward, J. D. 2002. Cultivar and environmental effects on annual ryegrass forage yield, yield distribution, and nutritive value. Crop Sci. 42:2049-2054. 14. Redmon, L. A. 1999. Production Technology Forages Bulletin PT 99-1. Cool-season Perennial Grass in Oklahoma. Oklahoma Coop. Ext. Serv. Vol. 11 (1). Agron. Dept., Div. of Agric. Sci. and Natural Resources, Oklahoma State Univ., Stillwater, OK. 15. Rice, P. M., and Toney, J. C. 1998. Exotic weed control treatments for conservation of fescue grassland in Montana. Biol. Conserv. 85:83-95. 16. Rouquette, F. M., Jr., Bransby, D. I., and Riewe, M. E., 1997. Grazing and management of annual ryegrass. Pages 79-99 in: Ecology, Production, and Management of Lolium for Forage in the USA. F. M. Rouquette, Jr., and L. R. Nelson, eds. Spec. Publ. no. 24. CSSA, Madison, WI. 17. Smith, S. J., Sharpley, A. N., Naney, J. W., Berg, W. A., and Jones, O. R. 1991. Water quality impacts associated with wheat culture in the Southern Plains. J. Environ. Qual. 20:244-249. |
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