Location: Plant Science ResearchTitle: Satellite images reveal patterns in crop rotations with alfalfa) Author
Submitted to: Forage Focus
Publication Type: Trade journal
Publication Acceptance Date: 4/1/2014
Publication Date: 5/1/2014
Citation: Yost, M.A., Russelle, M.P., Coulter, J.A., Bolstad, P.V. 2014. Satellite images reveal patterns in crop rotations with alfalfa. Forage Focus. May 2014. p. 4-5. Interpretive Summary:
Technical Abstract: Crops that follow alfalfa in rotation usually benefit from: i) reduced nitrogen (N) requirement from fertilizer or manure; ii) increased yield potential than when following other crops; and iii) reduced weed, insect, and disease pressure. Although benefits of alfalfa in crop rotations often depend on how long alfalfa is kept in production, limited data exist on this for the Upper Midwest, where about one-third of the nation’s alfalfa is produced. Additionally, no data are available that describe geographic patterns in which crops are grown after alfalfa. We combined USDA Cropland Data Layers for 2006 to 2012 to describe geographic trends in alfalfa production length and the two crops that follow alfalfa in six midwestern states. Shorter alfalfa stands (2-4 years, including the seeding year) were most frequent in northern and central Iowa, southeastern South Dakota, eastern Nebraska, and nearly everywhere south of Interstate 94 in Minnesota. Longer stands (5-7+ years) were most frequent across the Dakotas (except near the Red River Valley and southeast South Dakota), in Nebraska, and in northern Minnesota. Wisconsin had several areas of both shorter (2-4 years) and longer (5-7+ years) alfalfa production lengths. Corn was the most frequent first-year crop after alfalfa in all states except North Dakota. Soybean, which usually requires no N fertilizer, was the first-year crop in 15% of cases across the Dakotas, Minnesota, and Iowa, but was less prevalent in Nebraska and Wisconsin. Corn was the second-year crop produced by one-half to three-fourth of growers in all states except North Dakota, where it was grown less frequently. Soybean was the second-year crop in 25 to 37% of cases across each state except Wisconsin, where soybean was only half as frequent. These are the first geographic estimates describing crop rotation patterns of alfalfa and annual crops in the Upper Midwest. Such descriptions should improve estimates of economic and environmental benefits of alfalfa in crop rotations, aid in planning of fertilizer need assessments for alfalfa and the crops that follow, and help focus the development of education and research on best crop rotation practices. It is apparent that more research is needed in this region to document the potential yield benefit and recovery of N from alfalfa in soybean, small grains, or other crops.