Comparison of botanical composition, soil carbon content, and root distribution of subirrigated meadows in the Nebraska Sandhills

Characterizing vegetation composition, carbon/nitrogen (C/N) content of soils, and root-mass distribution is critical to understanding carbon sequestration potential of subirrigated meadows in the Nebraska Sandhills. Five subirrigated meadows dominated by cool-season (C₃) graminoids and five meadows dominated by warm-season (C₄) grasses were selected throughout the Nebraska Sandhills. Vegetation, soil carbon and nitrogen, and root-mass density distribution were sampled in each meadow. Meadows dominated by C₃ vegetation had 12% greater (P < 0.1) yields than meadows dominated by C₄ vegetation. Total root-mass density was 30% greater (P < 0.1) in C4-dominated meadows than C³-dominated meadows. Total carbon and nitrogen content was 65% and 53% greater (P < 0.1), respectively, in the A horizon of C₃-dominated meadows, but was 43% and 52% greater (P < 0.1), respectively, in the C horizon of C₄-dominated meadows. Although meadows dominated by C₃ vegetation had more carbon in the soil profile, much of the carbon in C₃-dominated meadows appeared to be recalcitrant C₄ carbon from historic vegetation.