Forage production in tall wheatgrass pasture according to nitrogen availability and topographic position

Abstract

The goal of this work was to evaluate forage production of tall wheatgrass (Thinopyrum ponticum [Podp.] Barkworth & D.R. Dewey Phil) as a function of nitrogen (N) availability and elevation positions. Seven sites were selected on the basis of their elevation and in each, two treatments were evaluated: N- (0 kg N ha-1 ha) and N+ (300 kg N ha-1)]. An interaction between the position of sites and N rate was found for final accumulated above-ground biomass (AB). At N+ sites there was significant variation, whereas at N- sites no variation was observed. Variability in AB was mainly due to differences in radiation use efficiency. The data showed a negative correlation between elevation of experimental sites and AB. This would indicate that the factor that limited the forage production varies with elevation. Soil moisture content (SMC) could be this restrictive factor because of its negative correlation with elevation. Inconclusion, small variations in the elevation of sites could affect water availability and therefore affect forage productivity when there is not limiting N.