1. Analysis of 13 Years of Nitrogen Rate and Timing Work in Oklahoma Winter Wheat

In 1999, Raun and Johnson estimated that the worlds nitrogen use efficiency (NUE) in cereal grains was 33%. After two decades of improvement (Omara et al, 2019) revised the prior world NUE for cereal grains to 35%. This improvement can be partially attributed to the change in producer practices of timing of nitrogen applications from an all pre-plant application to a split application of both pre-pant and in-season. The experiment that is analyzed within this study was established in 2009 with... S. Akin, B. Arnall