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Title: Cover crop water use

Author
item Nielsen, David
item LYON, DREW - Washington State University
item HERGERT, GARY - University Of Nebraska
item HIGGINS, ROBERT - University Of Nebraska
item Calderon, Francisco
item Vigil, Merle

Submitted to: CSA News
Publication Type: Research Notes
Publication Acceptance Date: 5/5/2015
Publication Date: 6/10/2015
Citation: Nielsen, D.C., Lyon, D.J., Hergert, G.W., Higgins, R.K., Calderon, F.J., Vigil, M.F. 2015. Cover crop water use. CSA News. Available: http://www.crops.org/publications/CSA/pdfs/60/6/12.

Interpretive Summary: Claims have been made that cover crops grown in mixtures use far less water than single-species plantings of cover crops. An additional claim is that cover crops grown in mixtures will use less water than is lost by evaporation from fallow. This study shows that cover crops grown in mixtures use water similarly to cover crops grown in single-species plantings. Additionally cover crops grown in mixtures or as single species will use, on average, 1.8 times more water than is lost from fallow by evaporation. Hence, farmers in the semi-arid central Great Plains should be cautious when considering implementing the use of cover crops in their farming operations as there is a high likelihood that subsequent crop yields will be decreased due to the cover crop water use.

Technical Abstract: Cover crops are being widely promoted because of soil health benefits. However, semi-arid dryland production systems, chronically short of water for crop production, may not be able to profitably withstand the yield reduction that follows cover crops because of cover crop water use. Some studies suggest cover crop mixtures should use far less water than single-species plantings, and that cover crop mixtures will use less water than is lost by evaporation from fallow, potentially improving chances of successful cover crop use. In the May-June 2015 issue of Agronomy Journal, researchers report on a two-year study from two central Great Plains locations where water use from single-species cover crop plantings was compared with water use from a 10-species mixture. The team found that single-species plantings used the same amount of water as a 10-species mixture, and that cover crops grown in mixtures will use, on average, 1.8 times more water than is lost by evaporation from fallow. Central Great Plains dryland farmers should be cautious when considering the use of cover crops in their farming operations as there is a high likelihood that subsequent crop yields will be decreased due to the cover crop water use, even when grown in mixtures.