Growth responses of warm-season tallgrasses to dormant-season management

Abstract

A study on Conservation Reserve Program (CRP) land was established in southeastern Nebraska to determine the effect of dormant-season management on subsequent-year growth rates and yields of tallgrasses. The purpose of the management practices was removal of standing dead material and litter that negatively impact plant growth and grazing efficiency. Treatments consisted of a control with no residue manipulation and 5 residue manipulation practices including (1) October shredding and leaving residue; (2) October haying; (3) October intensive grazing; (4) March intensive grazing; and (5) spring prescribed burning. The study was conducted in 1994/95 and 1995/96 on a switchgrass (Panicum virgatum L.) monoculture and mixed stand of warm-season tallgrasses dominated by big bluestem (Andropogon gerardii Vitman) and little bluestem [Schizachyrium scoparium (Michx.) Nash]. The manipulation treatments effectively removed standing dead material without reducing yields in the growing season following application. Marked switchgrass tillers on the control plots increased (P < 0.1) in height at a more rapid rate than switchgrass on other treatments until late summer in both years. Rate of morphological development was similar (P > 0.1) for all treatments in 1995 and 1996. Rate of height increase and morphological development in big and little bluestem on the mixed grass site generally was comparable or slower on the manipulation treatments than the control in both years; however, big and little bluestem tillers grew relatively rapidly at the end of the 1995 growing season. Because the manipulation treatments generally did not increase tiller growth rates of the dominant grass species, potential harvest dates would be similar to those of untreated areas.