Biomass production of 12 winter cereal cover crop cultivars and their effect on subsequent no-till corn yield

Abstract

Cover crops can improve the sustainability and resilience of corn (Zea mays L.) and soybean (Glycine max L. Merr.) production systems. At present, the most widely used cover crops in corn–soybean systems in the upper Midwest United States have been winter cereals. However, there have been isolated reports of corn yield reductions following winter rye (Secale cereale L.) cover crops, and the risk of corn yield reductions will reduce the likelihood of farmers adopting cover crops. Although the exact mechanism is unknown and there are many possible causes of corn yield reductions following winter cereal cover crops, we hypothesize that there may be differences among winter cereal species or cultivars in their effect on corn yield. Additionally, there have been no evaluations of shoot growth and nitrogen (N) uptake of winter cereal cultivars used as cover crops in the upper Midwest. Seven winter rye cultivars, 2 winter triticale (× Triticosecale Wittmack) cultivars, and 3 winter wheat (Triticum aestivum L.) cultivars were planted following soybean harvest and grown as a winter cover crops preceding corn in four years to determine whether the 12 cultivars differed in (1) biomass production and N uptake, and (2) impact on corn yield, harvest population, and other yield parameters. The 12 cover crop cultivars differed in each of the four years for shoot dry weight, shoot N concentration, and total shoot N content. In general, the winter rye cultivars had greater shoot biomass, lower shoot N concentrations, and higher total shoot N contents than the winter triticale and winter wheat cultivars. The winter cereal cultivars decreased corn yield in two of the four years, and the yield effect varied among cultivars. Some cultivars of all three species caused corn yield decreases, with no indication that winter rye had a greater effect than did winter wheat or winter triticale. Four winter rye cultivars did not significantly reduce corn yield in either of the two years in which yield was reduced. In general, the decreases in corn yield following the winter cereal cover crops were related to decreases in harvest population and increases in the number of barren plants, but were not strongly related to cover crop shoot dry weight within years. Our study shows that there are genotypic differences among winter cereal cultivars for their performance as cover crops and their effect on corn yields.