Submitted to: International Rangeland Congress
Publication Type: Abstract Only
Publication Acceptance Date: 6/20/2003
Publication Date: 7/26/2003
Citation: Schuman, G.E., Mortenson, M.C., Ingram, L.J. 2003. Interseeding medicago sativa ssp. falcata into rangelands to enhance carbon sequestration and forage production. Proceedings: II International Rangeland Congress, Rangelands in the New Millenium. Durbin, South Africa. CD.
Technical Abstract: Rangelands of the U.S. Great Plains can generally be characterized as having low nitrogen levels, which along with water, are considered the major limiting factors in forage production. The purpose of this research was to assess the effect of interseeding Medicago sativa ssp. falcata on native rangelands of northwestern South Dakota, U.S.A., on soil carbon and nitrogen balances and forage production and quality. In 2001, sampling was undertaken on a chronosequence of native rangeland sites that had been interseeded with 'falcata' in 1965, 1987, and 1998 and on adjoining native rangeland sites that were not interseeded. Soil textures of the sites ranged from fine sandy loam to loam and were Typic Haploboroll's or Typic Argiboroll's. Measurement of soil organic carbon, to a depth of 1-m, exhibited increases of 4, 8 and 17% for the 1998, 1987, and 1965 interseeding, respectively, compared to the respective native rangeland sites. Forage production increased by 42, 143, and 68% on the 1998, 1987, and 1965 interseeded sites. A portion of the observed differences between age class can be attributed to the inherent properties of these three soils with the 1965 site being shallower and less fertile soil than the other two soils. Production of 'falcata' contributed from 710 kg/ha on the 1998 interseeding to 1732 kg/ha on the 1987 interseeding. Protein content of the grass and forb species on the interseeded sites were increased by 8 to 33% on the 1965 and 1987 interseeded sites and varied by species. The significant increases in soil organic carbon sequestration, forage production and forage quality demonstrate the potential of this practice to improve rangeland health and assist in the mitigation of elevated atmospheric carbon dioxide levels.