One of the most widely adapted and resilient forages just got a little better.
AU Grazer, a new sericea lespedeza variety, tolerates frequent and/or close grazing. It'll make sericea more useful by reducing the amount of management needed to make the crop persist in pastures.
Although sericea lespedeza suffers from an image problem, it has a lot to offer. It's a drought-tolerant, non-bloating perennial legume that's resistant to diseases and is rarely attacked by insects. It's much more tolerant of soil acidity than most other legumes and, though it responds to applications of potassium and phosphorus when they're highly deficient, it's also quite tolerant of low fertility.
It's widely adapted in the Southeast, but is best-suited for use as a pasture plant on well-drained clay or loam soils from southern Ohio to central Alabama and from eastern Oklahoma to the Atlantic coast. Forage yields are good and forage quality of improved varieties is better than that of most warm-season perennial grasses.
Its ability to grow in poor, droughty soil makes it a popular choice for stabilizing critical areas such as roadbanks and mine reclamation sites. However, it can also fill a niche on many livestock farms in areas where most pastures are dominated by cool-season forages, especially on sites where other forages aren't well-adapted.
One of the main disadvantages of using sericea for pasture has been its sensitivity to heavy grazing. To avoid stand loss it's been necessary to maintain a stubble height of at least 4" throughout the growing season, which requires a fairly high level of grazing management.
AU Grazer, the new grazing-tolerant variety from Auburn University, counters that problem. It was developed using breeding techniques similar to those used in the development of grazing-tolerant alfalfa varieties.
Tannins, compounds that naturally occur in sericea lespedeza and some other forage plants, reduce the intake and digestibility of fresh forage. Consequently, forage-type sericea varieties are often categorized as being high-tannin or low-tannin types. AU Grazer has higher tannin levels than low-tannin types, but this is not a serious problem.
Livestock often show preference for grasses when first exposed to sericea, but will eat it readily after a week or two.
Intake may eventually decline if animals only have access to high-tannin sericea for very long periods, but that's rare. Animal performance will be slightly lower on the new variety than on low-tannin types, but vigor and persistence under close grazing will be much greater.
Sericea lespedeza is normally planted at 20-30 lbs/acre in mid-spring. It has poor seedling vigor so it's normally planted in pure stands.
However, where adapted, a cool-season perennial grass such as tall fescue can be drilled into established sericea with high probability of obtaining a mixed sericea-grass stand. For many beef cow-calf producers, this will be more feasible now that seed of a grazing-tolerant sericea variety is available.
Don Ball is an extension agronomist and Jorge Mosjidis is a professor of agronomy, both at Auburn University.