Impacts of Summer Interseeded Cover Crops On Corn Yield, Late Season Soil Cover, and Late-Emerging Weed Pressure in No-till Systems.

Baling of corn (Zea mays L.) residue has become a common practice, reducing the amount of soil residue remaining after harvest.  Cold fall temperatures in South Dakota (SD) and dry conditions do not allow for the establishment of cover crops after corn harvest.  The objectives of this study were to determine if a cover crop mixture could be established in the corn canopy, suppress late emerging weeds without compromising corn yield, and increase soil surface residue remaining after harvest.  A cover crop mixture containing 5.4 kg/ha crimson clover (Trifolium incarnatum), 8.9 kg/ha winter wheat (Triticum aestivum), and 9.8 kg/ha lentil (Lens culinaris) were drill (DRL) or broadcast (BRD) interseeded into corn at the V5 growth stage at Andover and Trail City, SD  at two field positions, summit and toeslope.  Cover crop, weeds, and corn were harvested at corn physiological maturity.  Cover crop and broadleaf and grass weeds were separated, dried, and weighed.  Planting with a drill resulted in a better cover crop establishment than the broadcast method.  Crimson clover was the most abundant cover crop species that survived at harvest at Trail City, while winter wheat was the most abundant at Andover.  Cover crops did not influence corn yield or broadleaf weed biomass.  Cover crops, however, did reduce grass weed biomass at both field positions and provided about 30% soil cover.  These data suggest that cover crops have the ability to reduce grass weed biomass without compromising corn yield and provide fall cover to protect soil after corn baling.  The cover crop mixture may only need a limited mix of species, since only one species dominated at harvest, which would decrease seed costs.