The Influence of Nitrogen Application Timing and Rate on Volunteer Corn Interference in Hybrid Corn

Volunteer corn (VC) in hybrid corn has become more prevalent in recent years and can reduce grain yield. Nitrogen (N) management can influence VC interference in corn. Field experiments were established to determine the effects of N fertilizer management and VC interference on hybrid corn growth and grain yield. Treatments consisted of three VC densities (control, 0 plants m⁻²; low density, 1 plant m⁻²; high density, 4 plants m⁻²) and six N fertilizer treatments (0 kg N ha⁻¹, 67 kg N ha⁻¹ at planting, 67 kg N ha⁻¹ at planting + 133 kg N ha⁻¹ at V5 corn growth stage, 67 kg N ha⁻¹ at planting + 133 kg N ha⁻¹ at V10 corn growth stage, 200 kg N ha⁻¹ at V5 corn growth stage, and 200 kg N ha⁻¹ at V10 corn growth stage). The effect of VC on hybrid corn was dependent on N rate. When 200 kg N ha⁻¹ was applied, regardless of application timing, hybrid corn dry weight, hybrid corn N content, and hybrid corn grain yield were reduced by the high VC density. However, when VC grain yield was added to hybrid corn grain yield, VC density did not affect total grain yield. When 0 and 67 kg N ha⁻¹ were applied, neither hybrid corn dry weight nor hybrid corn N content was affected by either VC density, but the high VC density reduced hybrid corn grain yield for both N rates by 19% and total grain yield by 9 and 10%, respectively. Application timing of N fertilizer had no effect on hybrid corn dry weight, N content, or grain yield. However, late N fertilizer applications (200 kg N ha⁻¹ at V10 and 67 kg N ha⁻¹ at planting +133 kg N ha⁻¹ at V10) resulted in greater VC N content, VC grain yield, and total yield. Assuming the harvestability of VC, the ability of a late N treatment (V10) to maximize total grain yield allows growers to use a late N application to reduce the competitive effects of VC in hybrid corn.Nomenclature: Corn, Zea mays L.