Prairie

Abstract

Many permanent pastures in the western corn belt and eastern Great Plains are composed of Kentucky bluegrass (Poa pratensis L.), downy brome (Bromus tectorum L.), and broadleaf weeds. Although many of these pastures have never been tilled, the tallgrass prairie that once existed on these sites has disappeared due to years of mismanagement. Research has been undertaken to reestablish the productive vegetation in these pastures by sod-seeding into chemically treated sod. Using atrazine [2 chloro-4-ethylamino-6-(isopropylamino)-s-trazine] at 2.2 kg/ha kills all of the Kentucky bluegrass, provides season-long annual weed control, and provides an excellent seedbed for big bluestem (Andropogon gerardt) and switchgrass (Panicum virgatum) since these grasses are atrazine resistant at the seedling stage. An excellent stand generally resuits, with the warm-season grasses reaching full maturity during the seeding year. Glyphosate [N(phosphonomethyl glycine)] can be used to kill the vegetation, and any grass species can be seeded in the dead sod since there is no chemical residue. Annual weeds can start growth immediately; however, since the soil is not disturbed the weed problem is often not serious. The most interesting aspect of this research is that we found remnant native tallgrass vegetation still existing in these pastures even though the tallgrass prairie had vanished many years ago. In eastern Nebraska big bluestem often is the major remnant left. With a single application of atrazine and grazing protection for one year, these depleted weedy, bluegrass pastures were turned into tall warm-season grassland in one year just by releasing the competition suppressing the existing native remnants. Although this restored pasture does not have the composition of a true prairie, producers can benefit by encouraging the native remnants that may still exist. While big bluestem was by far the most abundant remnant species reappearing on our treated sites, we have seen some little bluestem, sideoats grama, tall and prairie dropseed, western wheatgrass, and, in pastures that are not severely depleted, Indiangrass. A producer can determine whether there are sufficient native remnants in a pasture by apply2 ing a strip of atrazine in the spring and placing some exclosures there to protect the treated area from grazing. If native remnants appear, treatment of the pasture can then occur the following spring. More details on these studies, including seedling establishment and remnant warm-season grass yields, can be obtained from our article: "Sod seeding perennial grasses into eastern Nebraska sod," by J. F. Samson and L. E. Moser. 1982. Agronomy Journal 74:1055-60. Reprints are available.