Burning and Grazing to Promote Persistence of Warm-Season Grasses Sown into a Cool-Season Pasture

Abstract

We combined burning and rotational grazing in an effort to promote persistence of recently established native grasses. The experiment took place on a farm in south-central Wisconsin on a cool-season grass pasture that was drill seeded with native warm-season grasses: big bluestem (<i>Andropogon gerardii</i>), Indiangrass (<i>Sorghastrum nutans</i>), and switchgrass (<i>Panicum virgatum</i>). We used a split-plot experimental design to assess native grass persistence under varying disturbance treatments (burned, burned-grazed, and grazed). We used a paired <i>t</i>-test to determine if the difference between 2006 and 2007 native grass density was significantly different from zero. Native grass tiller density increased under the burned (202%) and grazed (186%) treatments, but not the burned-grazed (29%) treatment. However, the actual native grass tiller numbers in 2007 were much higher in the burned-only than the grazed-only treatment (80 ± 10 tillers/m² and 2 ± 1 tillers/m², respectively). We found no loss to native grass tiller density when rotational grazing was applied to plots in the first year after two years of grazing exclusion with burning. In addition, we found that native grass cover was greatest in the burned treatment but not significantly different in the burned-grazed and grazed treatments. Our results suggest that the combined use of burning and grazing as a management tool for native grass persistence in pastures may be possible with deferred grazing during the establishment phase, but alternative timing, intensity, and types of grazing animals should be tested.