Atrazine, Spring Burning, and Nitrogen for Improvement of Tallgrass Prairie

Abstract

Spring application of atra&c [2-chloro-4-(ethylan&io)-6-(isopropylamino)-s-triazine] (1.1 kg w* a.i.), burning, and nitrogen (33 kg ha" as ammonium nitrate) were evaluated alone and in all combinations for improvement of mid-seral tailgrass prairie in northcentral Oklahoma. Studies were initiated in 1984 (Study I) and 1985 (Study II). Precipitation and successional status of the vegetation at treatment application were higher for Study II than for Study I. Atrazine effectively reduced forbs and annual grasses for 2 years after appIIcatlon. Atrazine stimulated warm-season perennial grasses but did not generally increase total herbage production. Burning was similar to l trazine for annual grass control in both studies. Burning was also similar to atrazine for forb control in Study I but had no impact on forb production in Study II. Burning increased perennial grass production only in the second year of Study I. Burning decreased total herbage pro&&on in the flmt year of Study I by reducing annual grasses and forbs but did not affect total.perbage production on other dates. Nitrogen did not consistently increase perennial grass production but did increase forb production by 258-388% when applied alone. Both atrazine and burning rapidly shifted spa&s composition in favor of desirable perennial grasses. Nitrogen was not as effective ln changing species composition either alone or in combtition with &azine and burning. The number and complexity of treatment responses declined as successional status and/or precipitation improved.

Tebuthiuron Use in Restoring Degraded Tallgrass Prairies and Warm-season Grass Pastures

“…The decrease in cool-season graminoids and increase in warm-season grasses was similar to results seen with atrazine (Dill et al, 1986;Gillen et al, 1987;Waller and Schmidt, 1983). In Trial 4 all herbicides except imazapic + glyphosate appeared to be ineffective.…”

“…Few herbicides are effective at reducing cool-season grasses without damaging desirable warm-season grasses. Applications of atrazine, in the spring, and glyphosate, in the spring or fall, have been used to reduce cool-season grasses, including smooth bromegrass, with limited damage to warm-season grasses if applied when warm-season grasses were dormant (Dill et al, 1986;Gillen et al, 1987;Willson and Stubbendieck, 1996). Waller and Schmidt (1983) reported a single late-spring application of glyphosate or atrazine led to a rapid recovery of warm-season grass remnants in overgrazed native pastures in eastern Nebraska.…”

Inconsistent outcomes of heterogeneity-based management underscore importance of matching evaluation to conservation objectives

“…b. Marvin Klemme Experimental Research Range (Gillen et al, 2000 and. c. Stillwater Research Range , Gillen et al, 1987and Mesonet, 2011. d. Tallgrass Prairie Preserve (Coppedge et al, 2008, Hamilton, 2007and Mesonet, 2011.…”

“…g. Estimated annual primary productivity of native vegetation not recently disturbed by grazing or fertilization. Published data were used for Cooper (Gillen and Sims, 2004), Klemme (Gillen et al, 2000), Stillwater (Gillen et al, 1987), and the Grand River Grasslands (McGranahan et al, 2013). Unpublished data on end-of-season biomass one year after fire from at least one year within the study period included here were used to estimate annual primary productivity at the TGPP.…”

Influence of Improvement Practices on Big Bluestem and Indiangrass Seed Production in Tallgrass Prairies

“…Influence of these treatments on seed yield of grasses in native prairies was not assessed. Spring burning, fertilization, and atrazine [6-chloro-N-ethyl-N'-(l -methylethyl)-1 ,3,5-triazine-2,4-diamine] have been used to manipulate botanical composition and improve herbage productivity of warm-season grasses in southern and central Great Plains tallgrass prairies (Gillen et al 1987, Masters et al 1992). Studies were conducted to evaluate the influence of these improvement practices on reproductive stem density and seed production of big bluestem and indiangrass [Sorghastrum nutans (L.) Nash] growing in tallgrass prairies.…”