Weed Community Dynamics and Suppression in Tilled and No-Tillage Transitional Organic Winter Rye–Soybean Systems

Abstract Grower adoption of no-tillage (NT) approaches to organic soybean production has been limited, in part because of the perceived risks of ineffective cover crop management and lack of season-long weed suppression. We conducted research in 2008 and 2009 to assess those risks by quantifying the effects of winter rye cover-crop management (tilling, crimping, or mowing), soybean planting date (mid May or early June), and row width (19 or 76 cm) on weed recruitment, emergence patterns, season-long suppression, and late-season weed community composition in transitional organic production systems. The weed plant community consisted largely of summer annual species in each year, with velvetleaf or common lambsquarters as the most abundant species. Seedling recruitment from the soil seedbank varied between years, but velvetleaf recruitment was consistently greater in the tilled rye than in the NT rye treatments. Weed emergence tended to peak early in the season in the tilled rye treatment, but in the NT rye...