High-population corn stands and narrow rows reduced weed growth and seed production in Pennsylvania dairy system trials.
A Penn State research project is examining whether changes in corn planting strategies can provide dairy farmers with another way to manage weeds while reducing reliance on herbicides.
Plant Science PhD student Noelle Connors is studying the use of short-stature corn hybrids in Pennsylvania dairy systems. Many dairy operations use double-cropping, growing corn silage before planting a winter small-grain silage crop.
Weed management in these systems often depends on herbicides, but Connors is investigating whether stronger crop competition can provide effective suppression.
The research builds on earlier findings that dense corn stands, and narrower rows can limit weed development by increasing crop shading. Conventional corn varieties, however, may be more likely to lodge when planted at high populations. Short-stature hybrids are designed with improved standability, potentially allowing producers to increase plant density without sacrificing crop performance.
Connors compared short-stature and conventional hybrids under several planting arrangements, including high populations and 15-inch rows instead of the standard 30-inch spacing.
Researchers also introduced burcucumber, common cocklebur and Palmer amaranth at different points during crop development to examine how emergence timing affected competition.
The team tracked weed biomass and seed production along with corn silage yield and forage quality. Measurements of sunlight penetration, soil moisture, and soil temperature provided additional information about how the planting systems affected growing conditions.
Higher corn populations generally increased silage yields, while forage quality showed relatively little variation among treatments. Weed emergence timing was also important, with weeds appearing later in the season generally producing less biomass and fewer seeds.
The narrow-row, high-density system delivered the greatest weed suppression. "This practice has the potential to reduce weed biomass and seed production by up to 99% depending on species, emergence timing, and environmental conditions," Connors said.
The study uses a no-till, double-cropping system with dairy manure as a primary nitrogen source. Researchers say the strategy could support regenerative farming goals by strengthening crop competition, potentially reducing herbicide use and maintaining productive forage systems.
Photo Credit: gettyimages-luc-pouliot