Terrain Modifies the Response of Corn Grain Yield to the Presence of a Rye Cover Crop.

Rye as a cover crop has shown to have a positive effect on important soil properties, such as improving soil organic matter, reducing loss of excess inorganic nitrogen and preventing soil erosion. The presence of a rye cover crop can have both positive and negative effects on yield of the subsequent corn crop. Our preliminary results have shown variations amongst corn grain yields with regards to a rye cover crop and fallow plots at different topographical positions. Research fields with diverse topography were established at Michigan State University, Purdue University, and the University of Missouri. Yield data collected from all sites in 2011 through 2014 show that corn yields were negatively affected by the presence of a rye cover crop at each topographic position. An analysis of variance (ANOVA) of yield data during the 3-year period showed rye reduced corn yields by 519 kg ha^-1, 245 kg ha^-1 and 443 kg ha^-1 in the depression, slope, and summit, respectively. Individual analysis of yields per location shows a similar trend for each location by topographical position, except at Mason where corn yields were increased by 296 kg ha^-1, and 145 kg ha^-1 for slope and depression, respectively. Spring measurements of rye biomass show that depressions produced the most biomass that could lead to poor establishment and emergence of the subsequent corn crop.