Incorporating alfalfa into rangelands increases forage yield and quality while improving the soil, say scientists at the USDA-ARS Northern Great Plains Research Laboratory in Mandan, ND.

They added alfalfa to a mixed-grass rangeland to assess the effects on soil organic carbon and total nitrogen. Carbon and nitrogen levels were determined over a four-year period for three interseeded alfalfa varieties, one hay-type and two grazing-type alfalfas.

Four years later, sites with two interseeded alfalfa varieties (Vernal and Anik) had greater soil carbon and nitrogen than the non-alfalfa control, but only within the top 4”. Within an equivalent mass of surface soil, carbon and nitrogen stocks increased significantly during the four-year period under the interseeded alfalfa treatments.

“Though results from this study are short-term, interseeding grazing or hay-type alfalfas into rangelands of the Northern Great Plains appears to be a viable management intervention for increasing soil carbon and nitrogen stocks,” the scientists wrote.