Winter Rye Cover Crop and Forage Comparison Following Corn Silage in South Central Wisconsin.

Winter rye (Secale cereale) is commonly used in the upper Midwest as a cover crop to prevent soil erosion, and can be planted in the fall after early harvested crops such as corn silage. Winter rye can also be harvested as a forage crop in the spring, thus diversifying forage options. Fall manure applications are often a necessity, but can pose environmental challenges; planting of cover crops with fall manure can reduce nitrate leaching, but can also immobilize plant available nitrogen (N). We have conducted a three-year study to quantify N uptake and N removal from rye-cover or rye-silage and to evaluate how use of cover or silage crops alters optimal N fertilizer rate for the subsequent corn silage crop. The study was conducted at Arlington, WI. Whole plot treatments included rye as a winter forage (123 kg seed ha^-1), rye as a cover crop (123 kg seed ha^-1), and no rye. All plots received liquid dairy manure prior to rye planting in September of all three field seasons. Split plot treatments were N rates of 67, 112, and 179 kg N ha^-1 applied as ammonium nitrate at sidedress. Soil nitrate concentrations at preplant and presidedress were lower with rye cover or rye silage compared to the control. However, optimum N rate did not differ between the control and rye cover. In 2012, corn silage yield following rye silage was significantly lower than other treatments, but in 2013 the corn silage yields were not as suppressed by the rye silage. These results indicate that a rye silage-corn silage system in Wisconsin could result in greater forage production while simultaneously protecting groundwater quality and reducing soil erosion.