Cover crop effect on subsequent wheat yield and water use efficiency in the central great plains

Authors: Nielsen, David; LYON, DREW - Washington State University; HIGGINS, ROBERT - University Of Nebraska; HOLMAN, JOHNATHAN - Kansas State University; HERGERT, GARY - University Of Nebraska; Vigil, Merle

Submitted to: Agronomy Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/1/2015
Publication Date: 10/30/2015
Publication URL: http://handle.nal.usda.gov/10113/61912
Citation: Nielsen, D.C., Lyon, D.J., Higgins, R.K., Holman, J.D., Hergert, G.W., Vigil, M.F. 2015. Cover crop effect on subsequent wheat yield and water use efficiency in the central great plains. Agronomy Journal. 108:243-256.

Interpretive Summary: Cover crops grown in mixtures are reported to produce less detrimental impact on subsequent winter wheat yields than cover crops grown as single species. This finding needs to be verified for the water-limited environment of the central Great Plains. A 2-yr study was conducted in Akron, CO and Sidney, NE to measure wheat yield, water use, and water use efficiency following flax, oat, pea, rapeseed, and a 10-species mixture grown as spring-planted cover crops. Wheat yields were reduced an average of 10% compared with wheat on fallow regardless of whether the cover crop was grown as a single species or as a mixture. Yield reductions were greater under drier conditions. This average yield reduction was lower than seen in previous studies, most likely the result of wetter conditions and the relatively poorer condition of the residue cover in the fallow treatment compared with previous studies. Water use efficiency of wheat production was not different among the various previous-crop treatments. If a farmer desires to use a cover crop in his cropping system, there appears to be no reason to use a cover crop mixture (typically more expensive than single-species plantings) in place of a single species cover crop.

Technical Abstract: Crop production systems in the water-limited environment of the semi-arid central Great Plains may not have potential to profitably use cover crops because of lowered subsequent wheat (Triticum asestivum L.) yields following the cover crop. Cover crop mixtures have reportedly shown less yield-reducing effects on subsequent crops than single-species plantings of cover crops. This study was conducted to determine winter wheat yields following both mixtures and single-species plantings of spring-planted cover crops. The study was conducted at Akron, CO and Sidney, NE during the 2012-2013 and 2013-2014 wheat growing seasons under both rainfed and irrigated conditions. Precipitation storage efficiency prior to wheat planting, wheat water use, biomass, and yield were measured and water use efficiency and harvest index were calculated for wheat following four single-species cover crops (flax (Linum usitatissimum L.), oat (Avena sativa L.), pea (Pisum sativum ssp. arvense L. Poir), rapeseed (Brassica napus L.)), a 10-species mixture, and a fallow treatment with proso millet ((Panicum miliaceum L.) residue. There was an average 10% reduction in wheat yield following a cover crop compared with following fallow, regardless of whether the cover crop was grown in a mixture or in a single-species planting. Yield reductions were greater under drier conditions. The slope of the wheat water use-yield relationship was not significantly different for wheat following the mixture (11.80 kg ha-1 mm-1) than for wheat following single-species plantings (12.32-13.57 kg ha-1 mm-1). The greater expense associated with a cover crop mixture compared with a single species is not justified.