Seeding cool-season grasses into unimproved warm-season pasture in the southern Great Plains of the United States

摘要

Limited availability of herbage during the cool season creates a problem of a supply of nutrients for livestock producers throughout the southern Great Plains of the USA and, particularly, on small farms where resource constraints limit possible mitigating strategies. Six cool-season grasses were individually sown into clean-tilled ground, no-till drilled into stubble of Korean lespedeza [Kummerowia stipulacea (Maxim) Makino] or no-till over-sown into dormant unimproved warm-season pastures. The dry matter (DM) yields of mixtures of cool and warm-season herbage species were measured to test their potential for increasing cool-season herbage production in a low-input pasture environment. Only mixtures containing Italian ryegrass (Lolium multiflorum Lam) produced greater year-round DM yields than undisturbed warm-season pasture with all establishment methods. When cool-season grass was no-till seeded into existing warm-season pasture, there was on average a 0p"61 kg DM increase in year-round herbage production for each 1p"0 kg DM of cool-season grass herbage produced. Sowing into stubble of Korean lespedeza, or into clean-tilled ground, required 700 or 1400 kg DM hap#, respectively, of cool-season production before the year-round DM yield of each species equalled that of undisturbed warm-season pasture. Productive pastures of perennial cool-season grasses were not sustained beyond two growing seasons with tall wheatgrass [Elytrigia elongata (Host) Nevski], intermediate wheatgrass [Elytrigia intermedia (Host) Nevski] and a creeping wheatgrass (Elytrigia repens L.) x bluebunch wheatgrass [Pseudoroegneria spicata (Pursh)] hybrid. Lack of persistence and low productivity limit the usefulness of cool-season perennial grasses for over-seeding unimproved warm-season pasture in the southern Great Plains.