Cover Crop Biomass and Corn Yield Following 13 Rye, Wheat and Triticale Cultivars Used as Winter Cover Crops.

Winter cover crops have the potential to reduce nitrate leaching and erosion in corn-soybean rotations in the upper Midwest. The cover crop growing season between harvest and planting of corn and soybean, however, is short and cold.  Additionally, previous studies in Iowa have indicated that winter rye cover crops can reduce yield of the following corn crop, if the cover crop is killed immediately before corn planting.  Few studies have looked at different cultivars of winter rye, wheat, and triticale to determine if there are differences in biomass production and impact on corn yield when these cultivars are used as winter cover crops.  Seven rye, four wheat, and two triticale cultivars were planted with a grain drill following soybean harvest in three years, 2005 to 2007.  Cover crop shoot biomass samples were collected in the following spring and corn population, yield parameters, and grain yield were measured in the following fall.  Averaged over the three years, cover crop shoot biomass varied by a factor of two among cover crop cultivars.  Corn yield was affected by cover crop cultivar, year, and the interaction of year and cultivar.  Corn yield was significantly reduced following a winter cover crop in 2006 and 2007, but not in 2008.  Cultivars also differed in their effect on corn yield in 2006 and 2007.  In those years, winter cover crops seemed to reduce corn yield by reducing plant population and number of ears.