|Stout W L,|
|Jung G A,|
Submitted to: Agronomy Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: February 22, 1994
Publication Date: N/A
Interpretive Summary: Less than half of the fertilizer nitrogen applied to forage grasses is used by the plant. The fertilizer nitrogen that is not used can move through the soil and into the ground water. In our study we tracked the uptake of nitrogen and the accumulation of biomass by switchgrass on four different soils in Pennsylvania. We found that switchgrass used fertilizer nitrogen less efficiently on the soil with the highest amount of native nitrogen, i.e., organic matter. On such soils, fertilizer nitrogen rates can be reduced without reducing biomass yield. This would in turn reduce costs to the farmer and the potential for groundwater contamination
Technical Abstract: Grasslands are the basis of animal agriculture in the Northeast USA. Adapted warm-season grasses can make a valuable contribution to grassland production in this region, but knowledge of the interactive effects between soils and environment on their production remains scant. Thus, our objective was to examine and evaluate the interactive effects of soils and environment on biomass and N accumulation by switchgrass, 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 (Panicum virgatum cv Cave-n-Rock) was treated with 0, and 84 kg N ha-1 as ammonium nitrate. Bi-weekly biomass samples were taken starting June 30 of each year and continued until the grass reached heading stage, approximately July 31. Biomass accumulation rates for this 31-day growth period ranged from 157 to 211 kg ha-1 day-1. Soil N, N fertilization, and temperature were major factors controlling biomass accumulation rates. Total N uptake rates ranged from 1.49 to 2.63 kg ha-1 day-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.