DOI: 10.5061/dryad.66t1g1k2g
title: Performance and refinement of nitrogen fertilization tools

description: Improving corn (Zea mays L.) N management is pertinent to economic and
 environmental objectives. However, there are limited comprehensive data
 sources to develop and test N fertilizer decision aid tools across a wide
 geographic range of soil and weather scenarios. Therefore, a
 public-industry partnership was formed to conduct standardized corn N rate
 response field studies throughout the U.S. Midwest. This research was
 conducted using a standardized protocol at 49 site-years across eight
 states over the 2014 to 2016 growing seasons with many soil, plant, and
 weather related measurements.
description: This dataset contains 49 site-years (2014–2016) of corn grain
 yield responses to added N fertilizer from eight U.S. Midwest states. Each
 site-year followed a standardized protocol which included the same 16 N
 rates, four replicates, two application timings (all at planting or the
 majority sidedressed; Table 1), N source (ammonium nitrate) from the same
 fertilizer production plant, site selection criteria (low and high
 productive soils within each state), data management, collaboration
 procedures, and explanatory variables. Additional background information
 and details about the standardized materials and methods, data management,
 and collaboration protocols are discussed in Kitchen, N. R.,
 Shanahan, J. F., Ransom, C. J., Bandura, C. J., Bean, G. M., Camberato, J.
 J., Carter, P. R., Clark, J. D., Ferguson, R. B., Fernández, F. G.,
 Franzen, D. W., Laboski, C. A. M., Nafziger, E. D., Qing, Z., Sawyer, J.
 E., & Shafer, M. (2017). A public–industry partnership for
 enhancing corn nitrogen research and datasets: Project description,
 methodology, and outcomes. <em>Agronomy Journal</em>,
 <em>109</em>(5), 2371–2388. https://doi.org/10.2134/agronj2017.04.0207 A summary of scientific findings and future use of this data can be found in Ransom, C. J., Clark, J., Bean, G. Mac, Bandura, C., Shafer, M. E., Kitchen, N. R., Camberato, J. J., Carter, P. R., Ferguson, R. B., Fernández, F., Franzen, D. W., Laboski, C. A. M., Myers, D. B., Nafziger, E. D., Sawyer, J. E., & Shanahan, J. (2021). Data from a public–industry partnership for enhancing corn nitrogen research. <em>Agronomy Journal</em>, agj2.20812. https://doi.org/10.1002/agj2.20812
description: Major issues were noted within the dataset and separately in a
 summary document. Those interested in using these data for further
 analysis are advised to familiarize themselves with these issues and are
 encouraged to consider working with authors that have first-hand knowledge
 of the study. The most prominent issues are listed here:
 A 2015 Nebraska site showed a limited response to N
 which was believed to result from the previous soybean (<em>Glycine
 max</em> [L.] Merr) crop being severely damaged from hail, resulting
 in grain left on the soil—which was a source of mineralizable
 N. Intensive precipitation events caused ponding with
 substantial N lost from the 2015 Missouri sites and extensive anoxic plant
 stress from the anaerobic conditions in the root zone.
 An errant 45 kg N ha<sup>-1 </sup>was applied on all
 treatments on a 2016 North Dakota site. For some analyzes, adjustments
 taking this error into account were done (e.g., EONR). A high wind event late in the
 vegetative growth development stages resulted in lodging at one of the
 2016 Iowa sites for all treatments, but especially affected treatments
 that received high N rates at planting. Shapefiles of the plot boundaries
 with the corresponding treatments are available in the
 "Plot_Boundaries_Shapefiles.zip" folder. Files are organized by
 year and by state with each site-year a separate shapefile.