Nitrogen fertilization rate and method influences water and nitrogen productivity of forage winter wheat

Abstract

<p>Spring‐seeded annual forages are well adapted to the Great Plains; however, the influence of application rate and method of N fertilization on winter wheat (WW) (<em>Triticum aestivum</em> L.) forage productivity is unknown. A field study was conducted in a factorial design for 3 yr to determine the influence of N application rate and method on water and N productivity of awnletted WW ‘Willow Creek’. Urea was either broadcast or banded at planting using N fertilization rates of 0, 28, 56, and 84 kg N ha−1. The N application rate × method interaction was significant only for WW height. Weed herbage was low at WW forage harvest, 19 kg ha−1. As N fertilization rate increased from 0 to 84 kg N ha−1, wheat stem density and height increased by 70 and 78%, respectively, and herbage increased by 58%. Increased N rate increased WW water use quadratically, but water productivity (kg biomass ha−1 mm−1) was 68% greater at 84 kg N ha−1. However, N application method did not influence water use or productivity. Banded N application increased N accumulation in WW herbage by 11% compared to broadcast N. Increasing N rate reduced N productivity by 24% compared to 0 kg N ha−1. Willow Creek WW produced greater herbage yield as N fertilization rate increased with banded application. Willow Creek is a highly productive fall‐planted forage in this predominantly spring‐planted small grain–grain legume region.</p>