BIG BLUESTEM RESPONSE TO FERTILIZER AND DEFOLIATION ON THE LOUISIANA COASTAL PLAIN

Although big bluestem (Andropogon gerardii Vitman) is used for forage and conservation in the Great Plains, potentially useful Louisiana ecotypes have received little attention. Cloned plants from a robust big bluestem plant collected near Rosepine, LA were assessed for responses to fertilizer and defoliation in a field evaluation of potential forage value. Annual application of nitrogen fertilizer at 50 kg ha^?1 did not increase herbage yield until the third year. Clipping twice annually decreased productivity compared to once annually after the second year. Fertilizer effects on forage nutritive value were small. Clipping improved late-season nutritive value largely due to greater stem development of previously undefoliated plants. Limited responsiveness to fertilization and detrimental effects of repeated defoliation on productivity indicate that even this robust local big bluestem ecotype provides little potential as a pasture plant. Potential is indicated for other uses including wildlife habitat and grassland ecosystems managed for conservation purposes.