Grass weed interference and nitrogen accumulation in no-tillage corn

Abstract

Abstract No-tillage field studies were conducted in 1999 and 2000 at Columbia, MO, to determine the interaction of grass weed interference and side-dressed N fertilization on corn and weed growth, corn yield, and the N content of the soil and plant biomass at various intervals early in the growing season and at harvest. Ammonium nitrate (112 kg N ha−1) was applied before planting. A herbicide was applied to the entire experimental area before planting to control winter vegetation and to reduce broadleaf weed emergence. A mixture of large crabgrass, giant foxtail, and barnyardgrass was allowed to reinfest the experiment after corn planting and was sprayed with glyphosate when the weeds were 8, 15, 23, or 31 cm tall. Each removal date treatment was duplicated; one series received 45 kg N ha−1 side-dressed when the corn was approximately 60 cm tall, and the other series received no additional N. Corn dry weight and the N content of the corn biomass early in the growing season were similar between the weed-fr...