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

Authors: Kaspar, Thomas; Bakker, Matthew

Submitted to: Journal of Soil and Water Conservation
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/29/2015
Publication Date: 11/1/2015
Citation: Kaspar, T.C., Bakker, M.G. 2015. Biomass production of 12 winter cereal cover crop cultivars and their effect on subsequent no-till corn yield. Journal of Soil and Water Conservation. 70(6):142A-154A. doi: 10.2489/jswc.70.6.142A.

Interpretive Summary: Corn and soybean farmers in the upper Midwest are showing increasing interest in winter cover crops. Cover crops can improve the sustainability and resilience of corn and soybean production systems. At present, the most widely used cover crops in corn-soybean systems in the upper Midwest have been winter cereals. However, there have been isolated reports of corn yield reductions following winter rye cover crops and the risk of corn yield reductions will reduce the likelihood of farmers adopting cover crops. Although there are many possible causes of corn yield reductions following winter cereal cover crops, we suspect that there may be differences among winter cereal species or cultivars in their effect on corn yield. To test this idea seven winter rye cultivars, two winter triticale cultivars, and three winter wheat cultivars were planted following soybean harvest in four years to determine their effect on the following corn crop. We found that the twelve cultivars differed in growth and nitrogen uptake over the four years. Additionally, the winter cover crops reduced corn yield in only two of the four years, but two winter rye cultivars had no effect on corn yield in either year. This research shows that there are differences in growth and impact on corn yield among winter cereal cultivars. This research shows that the risk of corn yield reductions following winter cereal cover crops can be reduced by selecting or breeding winter cereal cover crops that do not negatively affect corn yield. Reducing the risk of yield losses will increase adoption of cover crops, which will improve the sustainability of cropping systems. This research will benefit seed producers and scientists because it shows that risk of corn yield reductions following winter cereal cover crops can be reduced by selecting or breeding winter cereal cover crops that do not negatively affect corn yield. It will also benefit farmers and general public because reducing the risk of yield losses will increase adoption of cover crops, which will improve the sustainability of cropping systems.

Technical Abstract: Cover crops can improve the sustainability and resilience of corn and soybean production systems. However, there have been isolated reports of corn yield reductions following winter rye cover crops. Although 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. Seven winter rye cultivars, two winter triticale cultivars, and three winter wheat cultivars were planted following soybean harvest in four years to determine: 1) whether biomass production and N uptake differed among the 12 cultivars and 2) whether the 12 cultivars differed in their impact on corn yield, harvest population, and other yield. 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. In fact, two winter rye cultivars did not significantly reduce corn yield in either of the two years in which yield was affected. 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.