Evaluation of Nitrogen Uptake Patterns in Spring and Winter Wheat in Western Oregon

Abstract

An understanding of the ground nitrogen (N) uptake pattern for wheat (Triticum aestivum L.) is essential to facilitate nitrogen management. The purpose of this study was to determine the nitrogen uptake pattern of spring and winter wheat grown in western Oregon, USA. Data used in this study were obtained from three different trials. For spring wheat rotation trials five spring wheat cultivars were used. Fertilizer N (16-16-16-4) at the rate of 140 kg ha⁻¹ was applied at the time of planting. In small plot rotation trials five fertilizer treatments - 0, 50, 100,150 and 200 kg N ha⁻¹ - were used. Rotations include winter wheat following clover and winter wheat following oat. The N uptake and dry matter yield of winter wheat were also determined from unfertilized plots of wheat trial. The maximum N uptake for spring wheat and winter wheat were at 1100 and 2000 accumulated growing degree days (GDD), before Feekes 10, respectively. The maximum N uptake rate for spring wheat, 0.038 kg N GDD⁻¹, occurred at 750 GDD and the peak N uptake was observed approximately 35 days after Feekes 2. Nitrogen uptake in winter wheat was significantly affected by rotations.