Tillage and Grazing Impact on Annual Crop Yields Following Conversion from Perennial Grass to Annual Crops

Abstract

Interest in transitioning from perennial grasses to annual crops should increase because of renewed interest in including a perennial phase in annual crop rotations. Different tillage options for converting from perennial grasses to annual crops were evaluated at the Northern Great Plains Research Laboratory, USDA-ARS, in Mandan, ND. Previously, the study site evaluated intermediate wheatgrass [Thynopyrum intermedium (Host) Barkworth & D.R. Dewey] persistence when grazed at the early vegetative, mid-culm elongation, or late boot morphological stages. Soybeans [Glycine max (L.) Merr.] in 2005, corn (Zea mays L.) in 2006, flax (Linum usitatissimum L.) in 2007, and spring wheat (Triticum aestivum L.) in 2008 were seeded using either no-till (NT) or minimum till (MT). Tillage interacted with grazing history to impact soybean yields, total weed density in flax, and weedy grasses, such as green foxtail [Setaria viridis L. (Beauv.)], barnyardgrass [Echinochloa crus-galli L. (Beauv.)] and Kentucky bluegrass (Poa pratensis L.) in spring wheat. The use of NT generally resulted in greater yields and lower weed densities than MT, but even 4-years later, grazing still had an impact on weed populations. Our data suggest that producers should use NT rather than MT when converting from perennial grass to an annual cropping system.