AU Grazer - A Sericea Lespedeza that Tolerates Heavy Grazing

by Dr. Don Ball (Extension Agronomist/Alumni Professor) and Dr. Jorge Mosjidis (Professor), Department of Agronomy and Soils, Auburn University , with appreciation for research assistance of Mr. Stevan Nigntengale , Mr. Randall Rawls, and Chet Norris Superintendents at the E.V. Smith Research Farm Plant Breeding Unit, the Upper Coastal Plain Substation, and the Tennessee Valley Research and Extension Center , respectively.

Sericea lespedeza is a forage crop that has been changed a great deal since it was first introduced into the United States in the early part of the 20th century. The first sericea introduced was coarse, stemmy, and unpalatable to grazing animals. Much of the sericea that volunteers in pastures and waste areas in Alabama today is of this type, which contrasts sharply with the leafy forage types developed through plant breeding through the years, mostly at Auburn University.

Sericea lespedeza offers numerous advantages as a forage crop. It is a drought-tolerant, non-bloating perennial legume; it is resistant to diseases and is rarely attacked by insects; and mature plants are quite competitive with grasses. It is much more tolerant of soil acidity than most other legumes and, though it responds to applications of potassium and phosphorus when these elements are highly deficient, it is also quite tolerant of low fertility.

Forage yields of sericea are good, and forage quality of improved varieties is better than most warm season perennial grasses. It is a surprisingly economical forage crop to grow due to the fact that it does not require any nitrogen fertilizer, and relatively little phosphorus, potassium, or lime. It has also been well documented that sericea is an excellent soil builder due to its tendency to shed leaves that add organic matter to the soil and improve soil tilth.

AU Grazer, a sericea lespedeza variety released by Auburn University, promises to substantially increase the usefulness of this forage crop. A disadvantage of sericea has always been that though it is tolerant of many factors that cause problems with other forage crops, it has been quite sensitive to grazing, thus limiting its usefulness as a pasture species. This new variety tolerates frequent and/or close grazing.

In a study at the Tennessee Valley Research and Extension Center at Belle Mina, AU Grazer had about 50% higher survival than Serala in1997 (measured as stems present after grazing in relation to initial number of stems) after being heavily grazed by beef cattle in 1996 (see table). Also the populations showed an average of about 40% higher forage yield than Serala in the spring of 1997 after the grazing pressure had been terminated, which is an indication of good recovery.

Performance of AU Grazer (average of the six populations that make up AU Grazer) and other sericea lespedeza cultivars relative to Serala. Survival number of stems present, and forage yield (dry matter) in 1997.

Sericea is 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 most warm season perennial grasses.

Its ability to grow in poor, droughty soil makes sericea lespedeza 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 in which most pastures are dominated by cool season forage crops, especially on sites where other forage crops are not well adapted.

Tannins, which are 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 varieties, 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 extremely long periods of time, but this is rare. Animal performance (in terms of gain per animal, though not necessarily in terms of gain per acre) will be slightly lower on the new variety than on low tannin types, but vigor and persistence under close grazing will be much greater.

AU Grazer can also be used as a hay crop. Preservation of sericea lespedeza forage as hay has a major effect with regard to reducing tannin content. Because sericea hay has a lower tannin content than fresh forage, ruminant intake and digestibility are increased.

Sericea lespedeza is normally planted at the rate of 20 to 30 pounds/acre in mid-spring. This plant has poor seedling vigor and thus is 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 and others having livestock with similar nutritional requirements, it will be more feasible than ever to use sericea as a forage crop now that seed of a grazing-tolerant sericea variety is available. Seed of AU Grazer is currently available from Sims Seed Company, Union Springs, AL (334) 738-2619.

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