Alfalfa as an Alternative to Bermudagrass for Pastured Stocker Cattle Systems in the Southern USA

Alfalfa (Medicago sativa L.) may support better stocker calf gains than common bermudagrass [Cynodon dactylis (L.) Pers.] in the southern USA. Yearling heifers (Bos taurus3 B. indicus) grazed each type of pasture for 2 yr on a Coastal Plain soil in southwest Arkansas. Alfalfa stand counts declined linearly with time after planting. Spring forage mass was greater for alfalfa than bermudagrass, but summer dormancy of alfalfa resulted in a summer forage mass advantage for bermudagrass. Bermudagrass provided a longer grazing season (115– 168 d for bermudagrass vs. 66–156 d for alfalfa, P, 0.01), more animal grazing days (1040–1452 vs. 594–1221 d, P , 0.01), and fewer grazing interruptions than alfalfa. Average daily gain (ADG, 462 vs. 319 g d21, P , 0.05) and total liveweight gain (664 vs. 447 kg ha, P , 0.05) were greater for alfalfa than bermudagrass in Year 2. In both years, heifers grazing alfalfa made the same amount of liveweight gain in less time than heifers grazing bermudagrass. The bermudagrass system had a negative net return across the trial period. Net return for the alfalfa system was dependent on the value of harvested hay. When alfalfa hay value reached $95Mg of dry matter (DM), net return was greater for the alfalfa system than for the bermudagrass system ($59 vs. $2148 ha, P , 0.05). On a Coastal Plain soil, renovation of common bermudagrass to alfalfa pasture can be economically feasible under a dual stocker/hay production system. N varieties with improved grazing tolerance (Counce et al., 1984; Smith et al., 1989) have increased interest in alfalfa for pasture throughout the USA, including the southern regions. Bermudagrass is a typical summer pasture in the southern USA, but performance of stocker cattle often is poor on this forage during hot, dry, midsummer weather (Duble et al., 1971; Utley et al., 1974; Greene et al., 1990). This has been attributed to reduced forage growth and nutritive value late in the season and increased maintenance energy requirements of heavier cattle (Hill et al., 2001). Alfalfa was more drought tolerant than bermudagrass when grown in a mixture with Coastal bermudagrass on a Coastal Plain soil with slight acidity in the subsoil to 1.2 m (Haby et al., 1999), and therefore alfalfa may be able to sustain greater cattle gains during summer dry periods. Under ideal conditions, stocker cattle grazing alfalfa had ADG up to 1500 g d and liveweight production up to 1946 kg ha (Popp et al., 2000), but ADG (881 g d21) and liveweight gain (556 kg ha) have been lower in the Coastal Plains region (Hoveland et al., 1988; Bates et al., 1996). By comparison, cattle grazing hybrid bermudagrass pastures in the Coastal Plains region had ADG up to 940 g d (Conrad et al., 1981) and liveweight gains up to 1260 kg ha (Greene et al., 1990). Common bermudagrass typically yields less than hybrids in hay trials (Hill et al., 2001) and might be expected to produce lower animal gains as well. Common is the prevalent bermudagrass type in most unimproved pastures (Fribourg et al., 1979), probably because of the convenience of establishment from seed plus good persistence under extensive pasture management. Two major drawbacks to increased use of alfalfa on Coastal Plain soils are poor hay-drying weather and poor stand persistence related to subsoil acidity, low soil fertility, poor drainage (Haby et al., 1997, 1999), and high pest and disease pressures (Melton et al., 1988;Hoveland et al., 1996b). Grazing alfalfa offers a solution to the haydrying problem, and Haby et al. (1997) showed that fertility and pH limitations of Coastal Plains soils can be managed and alfalfa grown with water tables as high as 45 cm below the soil surface. Grazing-tolerant alfalfa varieties have persisted for 2 (Bouton and Gates, 2003) to 3 (Counce et al., 1984) yr under grazing in Georgia. Renovation of common bermudagrass pastures to alfalfa may present a useful production system to producers if returns can cover cost of alfalfa establishment and maintenance. We compared intensive management of common bermudagrass pastures against their renovation to alfalfa pasture for stocker cattle on a Coastal Plain soil. Our objectives were to compare forage mass, forage quality, stocker calf performance, and profitability of the two systems in the hot, humid southeastern USA. MATERIALS AND METHODS Pasture Establishment The trial was conducted on an Ora fine sandy loam (fineloamy, siliceous, semiactive, thermic Typic Fragiudults) in Hope, AR (338409 N, 938359 W, 107 m above sea level). Four 0.81-ha common bermudagrass pastures were renovated to alfalfa. Initial soil pH and Al concentrations in alfalfa pastures were 6.1 and 0 mg kg at 0 to 15 cm in the soil profile, 6.5 and 0.6 mg kg at 15 to 30 cm, 5.7 and 0.7 mg kg at 30 to 61 cm, 5.1 and 6.4 mg kg at 61 to 91 cm, and 4.9 and 9.7 mg kg at 91 to 122 cm. Lime was applied in June at 5400 kg ha to K.A. Cassida, USDA-ARS, Appalachian Farming Systems Research Center, 1224 Airport Rd., Beaver, WV, 25813; C.B. Stewart and S.A. Gunter, Southwest Res. and Ext. Center, Division of Agric., Univ. of Arkansas, 362 Hwy. 174 North, Hope, AR 71801; V.A. Haby, Texas Agric. Exp. Stn., Texas A&M Univ. System, P.O. Box 200, Overton, TX 75684. This research was supported by a grant from the Southern Region Sustainable Agriculture Research and Education Program. Company and trade names are used for the convenience of the reader and do not imply endorsement by USDA over comparable products. Received 16 Mar. 2005. *Corresponding author (kim.cassida@ars. usda.gov). Published in Agron. J. 98:705–713 (2006). Grazing Management doi:10.2134/agronj2005.0081 a American Society of Agronomy 677 S. Segoe Rd., Madison, WI 53711 USA Abbreviations: ADF, acid detergent fiber; ADG, average daily gain; a.e., acid equivalent; CP, crude protein; DM, dry matter; NDF, neutral detergent fiber. R e p ro d u c e d fr o m A g ro n o m y J o u rn a l. P u b lis h e d b y A m e ri c a n S o c ie ty o f A g ro n o m y . A ll c o p y ri g h ts re s e rv e d . 705 Published online May 3, 2006