BIG BLUESTEM PRODUCTION AND FORAGE QUALITY RESPONSES TO BURNING DATE AND FERTILIZER IN TALLGRASS PRAIRIES

Tallgrass prairies are an important source of hay and summer forage in the Great Plains. A study was conducted in 1989 and 1990 on two excellent condition tallgrass prairies in eastern Nebraska to determine if the production and forage quality of big bluestem (Andropogon gerardii var gerardii Vitman), the dominant warm-season grass, could be manipulated by burning on different dates in the spring and applying fertilizer. Vegetation was harvested at approximately 30-d intervals from mid-June to mid-August. Big bluestem was separated from the vegetation, weighed, analyzed for in vitro dry matter disappearance (IVDMD), crude protein concentration (CP), and neutral detergent fiber concentration (NDF). Early or mid-spring burning increased June forage production by at least 52%, and mid-or late-spring burning increased August forage production by at least 70% compared with no burning. In June 1989 and 1990, big bluestem IVDMD was greatest on areas burned in late spring. Late-spring burning increased CP in June by at least 15% when compared with all other burn treatments, and increased CP in July by 8% compared with early spring burning. Fertilization increased CP in June by 22% and in July by 23% and 17% in 1989 and 1990, respectively, when compared with nonfertilized big bluestem. Burning in early, mid-, or late spring 1989 decreased NDF in June and August when compared with no burning. The quantity and quality of big bluestem forage available during the summer can be improved by spring burning and fertilization.