Agricultural Research Division of IANR


Date of this Version



Published in Agron. J. 108:243–256 (2016)


U.S. Government Work


Crop production systems in the water-limited environment

of the semiarid 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. Mixtures

have reportedly shown less yield-reducing effects on subsequent

crops than single-species plantings. 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 before 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.