<b>Impact of Nitrification Inhibitor Centuro</b><sup><strong>TM </strong></sup><b> on Field-Scale N Balances in Maize</b>
Creators: name: Elliot, Malley
Publisher: name: Purdue University Graduate School
Year: 2025
Subjects: classificationCode: 300210
subject: Sustainable agricultural development
classificationCode: 300204
subject: Agricultural management of nutrients

description: Nitrification inhibitors have been shown to increase maize (<i>Zea mays</i> L.) yield and tissue N, but their environmental co-benefits are less studied. Our objective was to determine the impact of a novel nitrification inhibitor (Centuro<sup>TM</sup>) on grain yield, N concentrations of grain and stover, losses of N to surface waters as NO<sub>3</sub>-N, and losses to the atmosphere as the potent greenhouse gas, N<sub>2</sub>O. This study was conducted from January 2021 to December 2023 using 10 x 30-m tile-drained lysimeters at Purdue’s Water Quality Field Station (WQFS). Centuro<sup>TM</sup> was applied to the maize component of a conventional maize-soybean (<i>Glycine max</i> L. Merr.) rotation receiving 157 kg N ha<sup>-1</sup> as urea-ammonium nitrate (UAN) as a pre-plant application. Two ongoing WQFS treatments were selected as controls. Continuous maize receiving 180 kg N ha<sup>-1</sup> applied pre-plant has a history of similar yields and nitrate load losses when compared to rotational maize receiving 157 kg N ha<sup>‑1</sup> without a nitrification inhibitor. A maize-soy rotation that included a rye (<i>Secale cereale</i> L.) cover crop, harvested at anthesis, that received 135 kg N ha<sup>-1</sup> as a side-dress application served as an N stewardship control. Grain and stover yields were obtained at maturity, tissues were dried, and N concentration of milled tissues were analyzed. Water flow rates and water samples were obtained daily (when tiles lines flowed), NO<sub>3</sub>-N concentrations of samples were measured, and annual NO<sub>3</sub>-N load losses determined as the product of NO<sub>3</sub>-N concentration and flow. The static chamber method was used to measure N<sub>2</sub>O levels at weekly intervals from April to December. The experimental design was a randomized complete-block design with 4 replicates. Mixed effects models’ analysis was used to partition variation into treatment, year, and replication effects and corresponding interactions. Where F-tests were significant (p &lt; 0.10), an LSD was calculated. Grain yield of maize receiving Centuro<sup>TM</sup> with 157 kg N ha<sup>-1</sup> was numerically higher (avg. 1.1 Mg ha<sup>-1</sup>) but statistically similar to continuous maize receiving 180 kg N ha<sup>-1</sup>, and both were higher than the maize-soybean + rye receiving 135 kg N ha<sup>-1</sup>. Maize grain N concentrations were similar for the Centuro<sup>TM</sup> treatment and the continuous maize receiving 180 kg N ha<sup>-1</sup>. Annual tile flow volume was highly variable between plots and did not differ among treatments. Flow weighted NO<sub>3</sub>-N concentrations of the Centuro<sup>TM</sup> plots with maize were lower in 2 of 3 plot series when compared to continuous maize receiving 180 kg N ha<sup>-1</sup>, while N<sub>2</sub>O emissions were consistently lower in the Centuro<sup>TM</sup> treated plots. Inclusion of this nitrification inhibitor often improved environmental performance of maize in a maize-soy rotation receiving 157 kg N ha<sup>-1</sup>, while maintaining high grain yields when compared to continuous maize receiving 180 kg N ha<sup>-1</sup>.