Improvement of Eastern Nebraska Tallgrass Range Using Atrazine or Glyphosate Herbicide Treatments

Abstract

Two herbicide treatments were initiated in southeastern Nebraska on a Wymore silty clay loam (clayey range site) during the spring of 1979, to change species composition of overgrazed, native range from cool- to warm-season grasses. Treatments consisted of late spring applications of atrazine [2-chloro-4-(ethylamino)-6-(isopropylamino)-s-triazione] at 2.24 kg/ha, and glyphosate [N-(phosphonomethyl)glycine] at 1.12 kg/ha. Both herbicide treatments significantly (P<.05) reduced smooth brome (Bromus inermis Leyss.) and Kentucky bluegrass (Poa pratensis L.) production and relative species composition while increasing big bluestem (Andropogon gerardii Vitman) in 1979 and the effects were maintained during the second growing season. Warm-season herbage yield, primarily big bluestem, was greater following herbicide treatments (5345 kg/ha) compared to control (1610 kg/ha). Herbage yields of cool-season grasses from herbicide treated plots were reduced. However, total herbage yield was higher on herbicide treated plots during the first and second year after treatment. Total, warm-season and cool-season herbage yields for both years were not different between atrazine and glyphosate treated plots. Both herbicide treatments have potential for rapid recovery of overgrazed, native tallgrass prairies in eastern Nebraska when sufficient warm-season tallgrass remnants are present.