Cool Season Grass Cover Crops Following Corn Silage Harvest and Manure Application.

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. Alternative cool season grasses, including including triticale (x Triticosecale), annual ryegrass (Lolium multiflorum) and barley (Hordeum vulgare), may provide different benefits and increase diversity of options for growers. Fall manure applications are often a necessity, but can pose environmental challenges; planting of cover crops with fall manure can reduce nitrate leaching, but may immobilize plant available nitrogen (N). We have first year data quantifying N uptake and release with and without manure with fall planted grass cover crops. With increasing N application rate treatments in the subsequent corn silage crop, optimum N rates were also determined, as affected by cover crops. The study was conducted at Arlington, Hancock, Lancaster, and Marshfield, WI, to represent a variety of soil types. Whole plot treatments included cereal rye, annual ryegrass, triticale, barley, and no cover crop both with and without liquid dairy manure. Split plot treatments were N rates of 56, 112, 168, 224, 280 kg N ha^-1 applied as urea with urease enzyme inhibitor at planting. Soil nitrate concentrations at winterkill, preplant and presidedress were lower with cover crops compared to the control. Optimum N rate varied depending on cover crop and location. These results indicate that alternative cover crops are viable for use by Wisconsin growers seeking ecosystem and production benefits.