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item Schuman, Gerald
item Mortenson, Matthew

Submitted to: Western Society of Soil Science
Publication Type: Proceedings
Publication Acceptance Date: 5/3/2002
Publication Date: 6/3/2002
Citation: Schuman, G.E., Mortenson, M.C. 2002. The effects of interseeded alfalfa on native rangeland soils. p. 11. Proceedings of the Western Society of Soil Science Annual meeting.

Interpretive Summary:

Technical Abstract: Rising atmospheric CO2 concentration impacts on global change have spurred research in the field of soil carbon sequestration. Rangeland soils, generally nitrogen and water deficient, have shown potential as a sink for carbon through management practices and plant community improvement. Introducing leguminous, nitrogen fixing plants can increase available nitrogen for the native plant community, which will also increase plant water-use-efficiency. This study evaluated the effects of interseeding rangelands with yellow-flowered alfalfa (Medicago sativa ssp. falcata) on soil quality, soil carbon storage, forage production and quality. The Smith Ranch in northwestern South Dakota has been interseeding "falcata," which is drought and grazing tolerant, for over 40 years and sites were chosen that were interseeded in 1998, 1987 and 1965. Data shows that in addition to increasing forage production by 42, 143, and 68% for the 1998, 1987, and 1965 sites, protein content of native plants was increased on the interseeded sites by 8 to 33% compared to adjacent control areas, varying by species. Soil carbon in the top 1 m depth increased 4, 8, and 17% for the 1998, 1987 and 1965 interseeded soils compared to controls, resulting in the addition of 4.8, 9.1 and 11.8 Mg C ha-1 of carbon per hectare. Since there are 161 Mha of rangelands, much of which lies in the Great Plains, the practice of interseeding, where adaptable, would significantly increase carbon storage in the soil and improve forage production and quality.