Bermudagrass [Cynodon dactylon (L.) Pers] is a warm-season perennial that is widely grown in the southern United States for pasture and hay. Like other warm-season plants, bermudagrass makes its best growth at 80-90°F. Growth is very slow when temperatures are below 60°F and tends to decline above 95°F. Climatically, Kentucky lies within a transition zone where extreme temperatures and rainfall changes occur within and between seasons. Cool-season grasses are well adapted to this zone, but forage productivity and quality typically reach seasonal lows during the mid-summer months. In most years, bermudagrass growth starts in late April and continues rapidly until mid-September when cooling temperatures limit growth. Thus, bermudagrass is very productive (Figure 1) during June, July, and August when cool-season grasses, such as tall fescue, orchardgrass, timothy, and Kentucky bluegrass, grow more slowly.
Bermudagrass can be successfully used as part of a forage program to supplement cool-season grass summer production. Wise use of cool-season perennial grasses and legumes in combination with bermudagrass can improve the odds of producing a year-round feed supply for beef animals. When using bermudagrass as far north as Kentucky, the potential for winterkill always exists and only the most winter-hardy varieties should be considered.
Bermudagrass varieties suitable for Kentucky’s environment cannot be established from seed. Stands must be established by “sprigging” rhizomes and stolon pieces into a prepared seedbed, making the cost of establishing bermudagrass quite high. Therefore, every effort should be made to follow recommended practices to obtain a good stand and cover the first year. One of the most important factors to consider in establishment is the selection of an adapted variety.
Extensive research programs with bermuda-grass have been under way in Georgia, Mississippi, Oklahoma, and other states for several years. New varieties are currently being evaluated in Kentucky for production, quality, and adaptability.
Tifton-44: Tifton-44 is a hybrid cross between Coastal bermuda and a bermudagrass that had survived in Berlin, Germany. It is a fine-stemmed, more winter-hardy variety that has survived as far north as Michigan. It starts growth earlier in the spring than most bermudagrasses and is more resistant to foliage diseases than Midland.
Quickstand: Quickstand was collected at the University of Kentucky Robinson Substation by Dr. Harold Rice and is currently being released by UK, SCS and USDA. Quickstand is high yielding and displays vigorous stolon production. It has fine stems that cure fast when cut for hay. It is shorter than Tifton-44 and makes a dense sod. Winter hardiness and yield exceeded that of Midland and other bermudagrasses tested at Beckley, West Virginia. Quickstand will be commercially available in 1993.
Midland: Midland is a hybrid between Coastal and a winter-hardy strain from Indiana. It is adapted to areas north of the southern Coastal Plains, where Coastal bermudagrass gives its best performance. It is a tall, leafy grass producing a more open sod than Tifton-44, Quickstand, and common bermudagrass. Although somewhat inferior in disease resistance and yield compared to other varieties, it is quite winter-hardy.
Hardie: Hardie is a hybrid selected from crosses collected in Turkey and Afghanistan in 1960. It is more winter-hardy than Midland and spreads faster on fine-textured soils. Hardie also has a higher forage yield potential and higher forage quality than Midland. Hardie demonstrated greater susceptibility to leaf diseases when compared to Tifton-44 and Quickstand in trials at the UK Robinson Substation.
Common: Common bermudagrass can be successfully grown in Kentucky, but is not as productive or winter-hardy as many of the other varieties. Although the term “common” is widely used, wide variation exists in common bermudagrass. Common, unlike many of the improved varieties, has a greater potential to become a pest since it does produce some viable seeds.
For best results, use only fresh, moist, healthy sprigs that have been grown under a good fertility program. When a mechanical sprig digger is not available, sprigs may be obtained by cross-cutting a bermudagrass sod with a heavy disk or field cultivator, then using a side delivery rake to collect the sprigs in windrows. Sprigs should be planted the day they are collected, if at all possible. Sprigs should be kept moist and cool and in the shade to ensure survivability if planting is delayed (Table 1).
For optimal production, lime, phosphorus (P), and potassium (K) should be added according to soil test to maintain a pH of 6.0-6.5 and bring soil test values into the high range. After preparing the soil and fertilizing, wait for a rain if the soil is extremely dry before sprigging. The number of live sprigs can drop by 50% the first two days after sprigging in a dry soil if no rain occurs.
In Kentucky, planting dates should be targeted to early May through mid-June if irrigation is not available. Sprigs can be planted mechanically with a machine designed specifically for sprigging. A commercial sprig planter reduces labor and improves the chances of placing live sprigs in good contact with the soil, permitting them to establish a root system quickly. Sprigs may also be broadcast and disked lightly into a well-prepared, weed-free seedbed or planted in rows by using a modified tobacco setter.
At least 20 bushels of sprigs per acre are recommended when bermudagrass is planted with a commercial sprigging machine (a bushel normally contains about 1,000 sprigs and is approximately equivalent to one square yard of bermuda sod). For faster coverage, when using slow-spreading varieties, or when using a sprigging method that leaves many sprigs in poor contact with the soil, up to 40 bu/ac might be more feasible.
Cultipacking after sprigging firms soil around the sprigs and aids establishment. Bermudagrass is not typically sprigged to a solid stand; hence, most of the first growing season is required to achieve complete ground cover. However, under good growing conditions, one grazing or a late summer hay harvest should be available.
Control of undesirable grasses and broadleaf weeds is very important in establishing bermudagrass. It is difficult to get good coverage of the desired species when weeds are present and competing for water, nutrients, and light. Currently, options for chemical weed control are extremely limited due to recent label changes for use in bermudagrass pastures. The use of 2,4-D is recommended as a post-emergence control of broadleaf weeds in bermudagrass when legumes have not been interseeded.
Under good management, bermudagrass is a high yielding forage that responds to high levels of N fertilization. The amount of nitrogen needed depends on the amount of production desired as shown in Figure 2. In a five-year study at the UK Robinson Substation, dry matter yields of Tifton-44 increased with increasing N rate up to 380 lb N/acre. Approximately 49 pounds of dry matter were produced for each pound of nitrogen applied up to 240 lb N/acre. Dry matter production fell to 25 pounds per pound of N applied at the 480 lb N/ac rate (Table 2).
For new seedings, improved weed control and greater fertilizer N-use efficiency will be obtained if fertilizer N applications (topdress with 30 to 60 lb N/ac) are delayed one month after sprigging. For established stands, nitrogen applications should be split (60 lb N/ac each) in order to get high production throughout the growing season. The first application should be made when spring green-up begins, with the remaining portions being applied after each “graze down” or hay cutting. The last application should be made by mid-August to fully use applied nitrogen before the grass becomes dormant following frost.
High yielding forage crops such as bermudagrass can remove as much as 360 pounds of potassium (K) and 40 pounds of phosphorus (P) per acre annually in harvested dry matter. Phosphorus is necessary to develop a healthy root system and stimulate vigorous top growth. Potassium is important for drought tolerance, disease resistance, rhizome development, and winter survival, especially under high nitrogen fertilization. In most soils, 50 to 75 pounds of P2O5 and 100 to 150 pounds K2O per acre applied annually are sufficient to maintain production. If growing legumes with bermudagrass, increase the amount of phosphorus and potassium and decrease the amount of nitrogen. For optimal production, P and K fertilizer should be added according to soil test to maintain adequate nutrient availability for the following crop.
Considerable interest exists in interseeding other forage species into bermudagrass to extend the growing season and improve forage quality. Research has shown several plant species to be compatible with bermudagrass. These include cereal rye or ryegrass (fall seeded each year), perennial legumes such as red and white clover, and winter annual legumes (vetch, arrowleaf clover, crimson clover). If annual legumes are not managed in such a manner that they reseed themselves, they must be seeded annually.
In a three-year study at the University of Kentucky, bermudagrass without nitrogen fertilizer was compared with bermudagrass-bigflower vetch, bermudagrass-red clover, and bermudagrass with three nitrogen rates (90, 180, and 270 lb/ac/yr) (Table 3). Bigflower vetch increased total annual dry matter productivity more than 90 lb N/ac, but less than 180 lb N/ac annually. The weed-free yield of bermudagrass without nitrogen fertilizer (2488 lb/ac) was less than half of the vetch-grass mixture. Over the same three-year period, red clover-bermudagrass produced approximately 900 lb/ac more dry matter annually than vetch-bermudagrass.
Both bigflower vetch and red clover were successful in limiting growth of winter-annual weeds, primarily henbit and chickweed. These winter-annual weeds constituted approximately 60 to 70% of the dry matter harvested from the check and N-fertilized grass plots prior to mid-June because they germinate and grow when temperatures are too low for bermudagrass.
Other studies have been conducted using rye fall-seeded into bermudagrass sod with different levels of nitrogen fertilization. In these studies, rye slightly suppressed the first bermudagrass crop, but severely suppressed the winter and spring weeds. Interseeded rye production varied with the level of nitrogen fertilization, producing up to 2700 lb/ac of dry matter when 90 lb/N/ac was applied. Rye did extend the grazing season by producing a range of 1100 to 2700 pounds of dry matter per acre during March, April, and May before bermudagrass growth started.
Bermudagrass attracts the interest of beef producers, not only because of its high yield potential, but because of its seasonal production pattern. Because bermudagrass flourishes during hot weather, when cool-season grasses are not as productive, it would appear to be a natural pasture crop to fill the summer slump period of cool-season grass pastures. While quantity is certainly important, quality should be considered in determining whether and where bermudagrass fits into a livestock-forage enterprise.
In all forage crops, quality tends to decrease with advancing maturity. As warm-season grasses such as bermudagrass mature, fiber concentrations increase and contribute to a decline in digestibility. Higher growth temperatures also hasten maturity and increase lignification (thickening of cell walls), which reduces digestibility. However, the forage quality of bermudagrass hay cut at 28-day intervals compares favorably with that of timothy, orchardgrass, and tall fescue hay cut at comparable stages of maturity (Table 4). Frequency of cut and nitrogen fertility influence both protein content and the digestibility of the dry matter. Although bermudagrass hay is not preferred for high-producing dairy cows, it can be used for growing replacement heifers, feeding dry dairy cows, horses, and all classes of beef animals.
Studies using bermudagrass for growing steers indicate highest quality and more rapid production gains during May and June than in July and August. Gains of 1.5 to 2.0 pounds per day are not uncommon during the earlier period, but performance of less than a 1.0-pound gain per day has been measured during July and August. While animal performance decreases during the hot summer, carrying capacity or production per acre has been shown to improve. Carrying capacity may increase as much as 20% during July over the June period.
In Kentucky, bermudagrass appears to fit best in the beef program when it is desirable to increase stocking rate in exchange for individual animal performance. This may be in a fall calving herd where a summer pasture is needed for heavy stocking. A heavily-stocked bermudagrass pasture can supply most of the nutritional requirements for maintaining dry beef cows. With a spring-calving herd, cows could also be concentrated on bermudagrass after the breeding season.
| Table 1. The effect of exposure and time of day on the survival of stored bermudagrass sprigs | |
| Exposure Period | Percent Live Sprigs |
| No Exposure | 100 |
| 8 hrs. - 9 a.m. to 5 p.m. -- Shaded and Moist | 100 |
| 2 hrs. - 9 a.m. to 11 a.m. -- Exposed | 194 |
| 4 hrs. - 9 a.m. to 1 p.m. -- Exposed | 172 |
| 2 hrs. - 12 noon to 2 p.m. -- Exposed | 130 |
| 4 hrs. - 12 noon to 4 p.m. -- Exposed | 103 |
| SOURCE: Texas A & M University | |
| Table 2. Dry matter produced per pound of applied N1 | ||||||
| N Applied | 1983 | 1984 | 1985 | 1986 | 1987 | Mean |
| lb/acre | lb dry matter/lb N | |||||
| 120 | 32.3 | 59.1 | 51.7 | 52.0 | 51.4 | 49.3 |
| 240 | 37.1 | 52.3 | 50.1 | 52.3 | 54.1 | 49.2 |
| 360 | 26.8 | 33.0 | 39.2 | 35.0 | 40.6 | 34.9 |
| 480 | 21.2 | 23.9 | 27.2 | 23.1 | 29.8 | 25.0 |
| 1Tifton-44 bermudagrass study conducted at the UK Robinson Substation. Thom and Rice, 1990. | ||||||
| Table 3. Dry matter (DM) production and percentages of legumes and weeds of bermudagrass swards at Lexington during a 3-year period from 1968-70 | |||
| Treatment | DM | Legumes | Weeds |
| lb/ac | % | ||
| Bermudagrass (No N) | 3600 | 0 | 31 |
| N 90 lb/ac | 5790 | 0 | 25 |
| N 180 lb/ac | 8600 | 0 | 20 |
| N 270 lb/ac | 10750 | 0 | 20 |
| Bermudagrass + Bigflower Vetch | 6640 | 40 | 12 |
| Bermudagrass + Red Clover | 7460 | 57 | 10 |
| SOURCE: Adapted from W.C. Templeton, Jr., and T.H. Taylor. Performance of Bigflower Vetch Seeded into Bermudagrass and Tall Fescue Swards. Agronomy Journal 1975. | |||
| Table 4. Approximate crude protein and total digestible (TDN) content of various hay crops | ||
| Type of Herbage | Approx. Usual Nutrient Level1 | |
| Crude Protein | TDN | |
| % | ||
| Alfalfa | 17-22 | 57-62 |
| Orchardgrass | 12-15 | 55-60 |
| Tall Fescue | 10-15 | 55-60 |
| Timothy | 8-12 | 58-62 |
| Bermudagrass | 9-11 | 50-56 |
| 1Based on recommended production and harvesting practices. Adapted from D.M. Ball, C.S. Hoveland, and G.D. Lacefield, Southern Forages 1991. | ||
