A Public–Industry Partnership for Enhancing Corn Nitrogen Research and Datasets: Project Description, Methodology, and Outcomes

Abstract

Core Ideas The geographic scope, scale, and unique collaborative arrangement warrant documenting details of this work. The purpose of this article is to describe how the research was undertaken, reasons for the research methods, and the project's potential value. The project generated a valuable dataset across a wide array of weather and soils that allows evaluation of N decision tools. Due to economic and environmental consequences of N lost from fertilizer applications in corn (Zea mays L.), considerable public and industry attention has been devoted to the development of N decision tools. Needed are research and databases and associated metadata, at numerous locations and years to represent a wide geographic range of soil and weather scenarios, for evaluating tool performance. The goals of this research were to conduct standardized corn N rate response field studies to evaluate the performance of multiple public‐domain N decision tools across diverse soils and environmental conditions, develop and publish new agronomic science for improved crop N management, and train new scientists. The geographic scope, scale, and unique collaborative arrangement warrant documenting details of this research. The objectives of this paper are to describe how the research was undertaken, reasons for the methods, and the project's anticipated value. The project was initiated in a partnership between eight U.S. Midwest land‐grant universities, USDA‐ARS, and DuPont Pioneer. Research using a standardized protocol was conducted over the 2014 through 2016 growing seasons, yielding a total of 49 sites. Preliminary observations of soil and crop variables measured from each site revealed a magnitude of differences in soil properties (e.g., texture and organic matter) as well as differences in agronomic and economic responses to applied N. The project has generated a valuable dataset across a wide array of weather and soils that allows investigators to perform robust evaluation of N use in corn and N decision tools.

Corn nitrogen rate recommendation tools’ performance across eight US midwest corn belt states

“…In contrast, five sites resulted in high EONR values (>300 kg N ha −1 ), assumed to be the result of excessive precipitation likely resulting in conditions producing denitrification at sites with fine‐textured soils and leaching at sites with coarse‐textured soils. A summary of the yield response to added N in this study has been previously published (Kitchen et al., ). Average EONR across all sites was 169 kg N ha −1 (SD = 83) and 159 kg N ha −1 (SD = 70) for at‐planting and split N applications, respectively.…”

“…Grain yield in response to N fertilizer treatments was used to calculate the EONR on a site level as described in Kitchen et al. (), using proven quadratic or quadratic‐plateau modeling methods (Cerrato & Blackmer, ; Scharf et al., ). The EONR values were calculated for all N fertilizer applied at‐planting (hereafter referred to as “at‐planting”), and N split applied between an at‐planting and a sidedress applications (hereafter referred to as “split”).…”

“…Kitchen et al. () detailed the sampling and NO 3 –N analysis protocols for the PPNT tool. Two of the 49 sites did not complete PPNT sampling, so this tool was evaluated using 47 of the 49 sites.…”

“…About half the sites were on farmers' fields and the other half on University research stations. All states followed a similar protocol for plot research implementation including site selection, weather data collection, soil and plant sample timing and collection methodology, N application timing, N source, and N rates, with specific details described in Kitchen et al (2017). The average plot dimension was 3-m wide and 15-m long.…”

“…Still, all tools were compared against EONR rather than the optimal N rate, as EONR is more meaningful to farmers for maximizing their profits, and currently is the more common metric for tool comparison (Kachanoski & Fairchild, 1996;Lory & Scharf, 2003;Sawyer and Mallarino, 2017;Vanotti & Bundy, 1994). Grain yield in response to N fertilizer treatments was used to calculate the EONR on a site level as described in Kitchen et al (2017), using proven quadratic or quadratic-plateau modeling methods (Cerrato & Blackmer, 1990;Scharf et al, 2005). The EONR values were calculated for all N fertilizer applied at-planting (hereafter referred to as "at-planting"), and N split applied between an at-planting and a sidedress applications (hereafter referred to as "split").…”