Forage Production and Nutritive Value of Three Lespedeza Cultivars Intercropped into Continuous No-Till Winter Wheat

Annual lespedezas [Kummerowia stipulacea (Maxim) Makino] have the potential to produce high quality forage during late summer when warm season forages are low in production and quality. A field study was conducted from 1992 through 1994 to determine DM, N, and digestible dry matter (DDM) production of three annual lespedeza cultivars (Korean, Kobe, and Marion). These cultivars were intercropped into two different continuous winter wheat (Triticum aestivum L.) production systems. Wheat was established in the fall under low tillage procedures in a 24-arce field, and grazed by steers from mid-November to mid-March at a stocking rate of 1 steer/acre. Before the wheat had reached the jointing stage, small plots were identified within the 24-acre wheat field. Inoculated lespedeza seeds were sown into the standing winter wheat in these plots, but grazing was continued on the plots and the field. At jointing, grazing was terminated on half of the plots (UNGRAZED), while the other half of the plots were grazed (GRAZED) until early May. Samples of lespedeza were collected at 18 to 20 d intervals beginning in late-June and ending in late-September, in time for the next wheat crop to be planted. All treatments were fixed in space and repeated on the same plots each year. Data were analyzed within year as a randomized complete block with cultivar as the main effect. In 1993 and 1994 Kobe produced DM, N, and DDM more (P < 0.05) under the UNGRAZED than the GRAZED management system. Management system had no effect on DM, N or DDM yield of Korean. When precipitation was above normal, Marion yielded more (P < 0.05) DM in the UNGRAZED plots than in the GRAZED plots, but Marion yield was inferior to that of Kobe and Korean under dry conditions. These results suggest that lespedeza can be intercropped in winter wheat to produce high quality forage during the summer. The availability of high quality forage, especially in late summer, can add sustainability to the livestock component of integrated livestock and winter wheat production systems in the southern Great Plains (SGP). Research QuestionA viable livestock enterprise in the southern Great Plains (SGP) requires a constant supply of high quality forage to reduce the cost of supplemental feed. Livestock systems in SGP are seasonally integrated to use winter wheat pasture and warm season perennial grasses. Livestock are used to grazing winter wheat in the fall and winter, but in the spring the producers must select one of two options: (i) continuing to graze the wheat at a higher stocking rate, or (ii) terminate grazing to produce a grain crop. In either option, the fields are fallowed for 90 to 120d during the summer. If tillage is used to keep the fields free of weeds during the summer, soil loss due to wind erosion is increased. At the same time that the producer is managing the fallow wheat fields, the livestock component of the enterprise needs high quality forage to offset the decline in forage quality of the perennial warm season grasses The objective of this study was to determine the feasibility of using annual les-pedeza intercropped into winter wheat to provide high quality forage in late summer when warm season perennial grasses are low in quality. Literature SummaryAnnual lespedezas are warm season herbaceous legumes that are most productive when cool season legumes or warm and cool season grasses are unproductive. These lespedezas are dependable reseeders, relatively tolerant to drought and pests, and can provide high quality nonbloating forage. Annual lespedezas are considered to be relatively free of diseases and will persist for years when allowed to reseed. Little information is available on the seasonal forage production capabilities and nutritive value of annual lespedezas under different continuous no-till winter wheat production systems in the SGP region. Study DescriptionA 3-yr field study was conducted from 1992 through 1994 to evaluate three annual lespedeza cultivars (Korean, Kobe, and Marion) on a Norge silt loam near El Reno, OK. Each spring, lespedeza seeds were inoculated and seeded with Brillion seeder into winter wheat that was being grazed by cattle. At wheat jointing, grazing was terminated on half of the plots (UNGRAZED), while grazing was continued on the other half of the plots (GRAZED). Samples were collected at 18 to 20 d intervals beginning in late June and ending in September, and analyzed for dry matter (DM), N, and in vitro dry matter digestibility (IVDMD) content. Yield of N and digestible DM was calculated by multiplying N and IVDMD concentrations by DM yield. Applied QuestionsAre DM yield and N produced by lespedezas intercropped into no-till winter wheat affected by grazing management of the wheat crop? The amount of DM and N accumulated by three different lespedeza cultivars (Korean, Kobe, and Marion) were affected by the variation in daily temperature and precipitation amounts and patterns. Grazing management of winter wheat altered the amount of residue cover, which in turn affected soil temperature and soil water evaporation; this resulted in a management × cultivar interaction. In years when soil moisture was limiting, late maturing cultivar (Kobe), and plots with wheat residue (UNGRAZED) produced more DM than plots of early maturity cultivars (Korean and Marion), and with little residue left on the soil surface (GRAZED). Lespedeza can be intercropped with winter wheat to produce high quality forage during late summer when the quantity and quality of warm season grasses are declining, but spring management of the wheat fields can affect the amount of DM produced.