Crop competition is key to good weed control, and a thick dense crop canopy will serve to suppress weeds for most of the growing season. Some weeds are highly sensitive to light and need light to germinate; all weeds need some amount of light in order for the weed seedlings to grow. Quickly establishing a thick crop canopy can greatly reduce the amount of sunlight available for weed seed germination and seedling growth. A dense, healthy crop may also outcompete weeds for other resources like water and nutrients.
Narrow row spacing can allow for faster canopy development. Research in soybean has shown that row spacing of 15 inches or less achieves faster canopy closure than in the traditional wide-row spacing. As a result, late season weed control is frequently better with narrow row spacing. Moreover, studies have reported up to a 20% increase in soybean yield with narrow row spacing compared to wide row spacing when combined with good weed management practices.
Watch this video to learn how row spacing in soybeans can contribute to weed management.
Researcher: Claudio Rubione, University of Delaware
Narrated by Victoria Ackroyd, USDA-ARS Beltsville, MD and University of Maryland
Video edits: Claudio Rubione, University of Delaware