Biomass And Nitrogen Accumulation In Switchgrass: Effects Of Soil And Environment

Grasslands are the basis of animal agriculture in the northeastern USA. Adapted warm-season grasses make a valuable contribution to grassland production in this region, but knowledge of the interactive effects between soils and environment on their production is limited. Our objective was to examine and evaluate the interactive effects of soils and environment on biomass and N accumulation by switchgrass (Panicum virgatum L. cv. Cave-n-Rock), an adapted warm-season grass. The study was conducted for 3 yr on four sites in central Pennsylvania selected to provide differences in soil water holding capacity and temperature regime. Switchgrass was treated with 0 and 84 kg N ha -1 as NH 4 NO 3 . Biweekly biomass samples were taken starting 15 June and continued until the grass reached heading stage, approximately 31 July. Biomass accumulation rates for this 31-d period ranged from 157 to 211 kg ha -1 d -1 . Soil N, N fertilization, and temperature controlled biomass accumulation rates. Total N uptake rates ranged from 1.49 to 2.63 kg ha -1 d -1 and were controlled by soil N levels and N fertilization. Fertilizer N recovery averaged about 40%, and was lowest where native soil N exceeded 2.0 g kg -1 .