Submitted to: Agronomy Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: 11/11/2002
Publication Date: 11/11/2002
Citation: MORTENSON, M.C., SCHUMAN, G.E., INGRAM, L. INTERSEEDING FALCATA ALFALFA (MEDICAGO SATIVA SSP. FALCATA) INTO NATIVE RANGELANDS: I. SOIL CARBON AND NITROGEN DYNAMICS. AGRONOMY ABSTRACTS. 2002. Interpretive Summary:
Technical Abstract: Rising atmospheric CO2 levels have led to research to assess management strategies that increase C sequestration in soils. Fertilization of nitrogen deficient rangelands can increase production and C seqestration. Rangelands in northwestern South Dakota that were interseeded with yellow-flowering alfalfa (Medicago sativa ssp. falcata) over the past 40 years were selected to evaluate the effect of this practice on soil N and C storage. Experimental sites were selected that had been interseeded in 1965, 1987, and 1998. Adjacent control sites for each interseeding date were also established. Soil samples collected in 2001 showed increases in soil N of 2.9, 0.6, and 1.4 Mg N/Ha in the surface 1-meter soil depth compared to non-interseeded areas for the 1965, 1987, and 1998 dates, respectively. The additional fixed N also resulted in more C being sequestered in the soil. An additional 11.8, 9.1, and 4.7 Mg C/ha in the 1965, 1987, and 1998 interseeded sites, respectively, compared to the untreated rangeland. The practice of interseeding alfalfa into native rangelands has been shown to increase soil N through symbiotic fixation. The N provided through fixation and the subsequent aboveground biomass can help mitigate the effects of rising atmospheric CO2 through increased C sequestration.