Reducing the germinable weed seedbank with soil disturbance and cover crops

Abstract

Mirsky SB, Gallandt ER, Mortensen DA, Curran WS & Shumway DL (2010). Reducing the germinable weed seedbank with soil disturbance and cover crops. Weed Research50, 341–352.SummaryEcologically based weed management relies heavily on a greater integration of cultural and mechanical control tactics than conventional weed management. As such, management outcomes are more dependent on biotic interactions among the crop, weed and methods of management. In this study, we assessed the influence of soil disturbance and cover cropping on the germinable seedbank of Chenopodium album, Abutilon theophrasti and Setaria spp. across a range of initial weed seedbank densities. Cover crop system treatments ranged from greater reliance on tillage at one extreme, to a greater reliance on cover cropping to accomplish weed suppression at the other. In general, seedbank losses to germination were highest when soil disturbance was associated with cover cropping. Of the five cover crop systems (1 year duration), the summer fallow and the yellow mustard/buckwheat/winter rape mixture consistently decreased the weed seedbank. The magnitude of decline in these high disturbance systems reached complete depletion of the Setaria spp. germinable seedbank and an 85% and 80% reduction for C. album and A. theophrasti respectively. Both systems included tilling the soil three to four times throughout the growing season. In contrast, treatments which involved less soil disturbance had weed escapes that set seed in one or more site years. Cover crop systems that stimulated weed seed germination and where weeds were either suppressed by the cover crop or where subsequent tillage provided control, resulted in the greatest weed seedbank declines.