Effects of Nitrogen Fertilization, Burning, and Grazing on Reserve Constituents of Big Bluestem

Abstract

During 1972 and 1973, the effects of nitrogen fertilization, burning, and grazing on total nonstructural carbohydrate (TNC) and nitrogen reserves of big bluestem (Andropogon gerardi Vitman) were studied in the Kansas Flint Hills. TNC and nitrogen reserves were lowered when growth exceeded photosynthetic production and nutrient assimilation. TNC reserves were lowest in unburned, heavily fertilized, pastures; nitrogen in storage organs increased linearly as nitrogen fertilization was increased. TNC was higher in burned than in unburned pastures, regardless of fertilization rate. Increasing the grazing rate when nitrogen fertilization was increased had little effect on reserves at senescence.