Grasslands are the basis of animal agriculture in the northeastern USA
. Adapted warm-season grasses make a valuable contribution to grasslan
d production in this region, but knowledge of the interactive effects
between soils and environment on their production is limited. Our obje
ctive was to examine and evaluate the interactive effects of soils and
environment on biomass and N accumulation by switchgrass (Panicum vir
gatum 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 reg
ime. Switchgrass was treated with 0 and 84 kg N ha(-1) as NH4NO3. Biwe
ekly biomass samples were taken starting 15 June and continued until t
he grass reached heading stage, approximately 31 July. Biomass accumul
ation rates for this 31-d period ranged from 157 to 211 kg ha(-1) d(-1
). Soil N, N fertilization, and temperature controlled biomass accumul
ation 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. Fertili
zer N recovery averaged about 40%, and was lowest where native soil N
exceeded 2.0 g kg(-1).