Nitrogen resorption in prairie biomass feedstocks with different diversity

High-diversity mixtures of native perennial vegetation could be ideal biomass feedstocks for marginal farmland in the Midwestern United States. These feedstocks are highly productive and should require less fertilizer than the monoculture feedstocks typically used for biomass production. One factor that could alter the relative need for fertilizer between feedstocks is nitrogen (N) resorption (seasonal translocation of N to roots). In this study, we examined N resorption in switchgrass plants grown in feedstocks with different diversity (1, 5, 16, and 32 species). The low diversity mixtures contained only C4 grasses while the high diversity mixtures also contained forbs and legumes. Plants that produced an inflorescence had higher N resorption than plant that did not, regardless of feedstock diversity. By contrast, we did not detect differences in N resorption between feedstocks. Our results suggest that differences in N resorption will not compensate for faster N depletion in low-diversity feedstocks