Management of Annual Lespedeza for Seed or Herbage

Abstract

Annual lespedezas are warm-season forage legumes used for reseeding pasture, hay, or seed production. The two annual lespedeza species used most in the USA are commonly referred to as striate [Kummerowia striata (Thunb.) Schindler] and korean [K. stipulacea (Maxim.) Makino] lespedeza. The objective of this study was to evaluate herbage removal and regrowth to determine effective managements of annual lespedeza for optimum seed or herbage production, or both. ‘Marion’ (K. striata) and ‘Summit’ (K. stipulacea) lespedezas were harvested biweekly between mid-June to mid-October in 1987 and 1988. Regrowth herbage was harvested from each plot in mid-October. Seed was threshed from regrowth herbage. Yield of herbage, regrowth herbage, and seed were compared. Summit yielded more herbage at each harvest, but Marion yielded more regrowth and seed. Harvest of herbage reduced subsequent regrowth and seed yield. Producers seeking to maximize seed yields should avoid management practices that remove herbage after mid-June as seed yields will be reduced. Producers managing their annual lespedeza as a reseeding forage crop could reduce seed yields below levels required to regenerate stands if Summit or Marion were harvested after early- or late-September, respectively. Producers intending to harvest herbage and seed can achieve this from the same production site, but yields will be significantly less than stands managed for a single purpose. Research Question Annual lespedezas are grown alone or in pasture mixtures across a substantial portion of the grazing lands in the southeastern USA. They are warm-season, short-day flowering, herbage legumes. Frequently, farmers that grow annual lespedeza for herbage want to produce a commercial seed crop in the same growing season. Managing lespedeza for high hay yields can lead to poor seed production and failures of stands to persist through reseeding. Stands can renew annually through natural reseeding if managed properly. The objective of this study was to analyze herbage removal and regrowth of annual lespedeza to determine how to effectively manage this crop for optimum seed production, herbage production, or both. Literature Summary The two annual lespedeza species used most in the USA are Kummerowia striata (Thunb.) Schindler and K. stipulacea (Maxim.) Makino, which are commonly referred to as striate and korean lespedeza, respectively. Annual lespedezas are dependable reseeders, relatively tolerant of drought and pests, provide nutritious, nonbloating herbage, and are easily and inexpensively established. They are probably the easiest of the major legumes to establish as the seed can simply be broadcasted over existing grass sod or cereals in mid- to late-winter. Double cropping with small grain and annual lespedeza was a common practice in the 1930 to 1950s that provided producers with the options of using the annual lespedeza as pasture, hay, green manure, or a seed crop after the small grain was harvested. Little information is available on the growth and seed production of these commonly grown species. Study Description ‘Marion’ and ‘Summit’ annual lespedeza were sown in the field at 18 lb/acre at the Agronomy Research Center located near Columbia, MO (38° 49′ N lat) in April 1987 and 1988. Beginning on 15 June 1987 and 13 June 1988, all herbage was hand harvested 2.0 in. above the soil surface from a 10.8 sq ft subplot in each cultivar main plot replicated four times. Harvests of a new plot within each replication continued every 2 wk for 10 consecutive harvests. Plots that were harvested initially to determine amount of herbage produced since establishment as seedlings, were harvested again on 18 October to determine herbage regrowth. Herbage and regrowth herbage harvested from each plot were dried at 100 °F and weighed. Seed was threshed from regrowth herbage and from herbage harvested on 18 October, cleaned, and weighed. Applied Question Is there an optimum management timetable for the production of annual lespedeza herbage, seed, or both? Producers of annual lespedeza can employ effective management schemes for the different options. To maximize seed production, producers should refrain from mowing, haying, or grazing past mid-June as yields will be reduced. Producers looking to harvest both herbage and seed, in the same year, should not harvest Marion lespedeza after late-August or Summit lespedeza after late-July, because subsequent seed yields from the regrowth would not be commercially acceptable. Producers seeking to ensure a reseeding crop of annual lespedeza for herbage should not harvest or graze herbage after early-September.