Agronomy 2023, 13, 412. https://doi.org/10.3390/agronomy13020412 www.mdpi.com/journal/agronomy Article Baseline for Brassica carinata Components of Nitrogen-Use Efficiency in Southern South America Sebastián Bonansea, Oswaldo R. Ernst and Sebastián R. Mazzilli * Facultad de Agronomía, Estación Experimental Mario Alberto Cassinoni, Universidad de la República. Ruta 3, km 363, Paysandú 60000, Uruguay * Correspondence: smazzilli@fagro.edu.uy Abstract: Biofuels play an important role in the reduction of greenhouse gas emissions, but their production results in greenhouse gases such as nitrous oxide (N2O), mainly from nitrogen (N) fertilization. Brassica carinata (carinata) is an unexplored winter crop in the world’s main cropping areas, with multiple applications (cover crop, jet biofuel, and animal feed, among others). We analyzed a set of on-farm fertilization experiments (2016–2018) in southern South America using quantile regression to establish a baseline for both seed yield (YSEED) and the different components of nitrogen-use efficiency (NUE). Maximum YSEED for the 50th and 90th percentiles ranged from 2.5 to 3.5 Mg ha −1 , with a N availability of 150–160 kg ha −1 (soil + fertilization). The NUE ranged from 3 to 13 kg seed per kg of N available. Carinata, in the absence of other limiting factors, had a high N uptake (NUPT) capacity (1.0 to 1.5 kg ha −1 NUPT per kg ha −1 N available [soil + fertilization]). The explored N fertilization rates had no significant influence on oil concentrations (455 to 517 g kg −1 ) and protein concentrations (192 to 253 g kg −1 ). The region has a high potential for carinata production, with a high capacity to take up available N. Keywords: Brassica; nitrogen fertilization; bioenergy crop; seed yield; nitrogen uptake efficiency; nitrogen-utilization efficiency 1. Introduction In a globalized commodity and energy market with global climate change driven by greenhouse gas (GHG) emissions, new crops in different regions are being explored for their mitigation potential through bioenergy production. This represents an opportunity for the agricultural sector. However, the sector also accounts for about 14% of anthropogenic GHG emissions [1], and it is responsible for 85% of global nitrous oxide (N2O) emissions, mainly from soils (due to nitrification and denitrification processes) [2– 4]. N2O is a GHG with a global warming potential (GWP) approximately 265–310 times higher than that of CO2. Crop field management (nitrogen fertilizer, crop rotation, tillage, etc.) contributes between 42 and 80% to the total emissions from biofuel feedstock production [5], mainly in the form of N2O emissions, depending on the nitrogen (N) fertilization rate [2,6]. The use of N fertilizers is an essential input to obtain high grain yields from annual crops [7]. However, excessive N application increases potential N2O emissions [1,6]. This tradeoff between sustainable grain and high-quality production and a cascade of environmental concerns has identified higher N use efficiency (NUE) as an essential requirement for bioenergy production based on annual industrial crops [8]. Brassica carinata A. Brown (carinata), known as “Ethiopian Mustard” or “Abyssinian Mustard” [9], is an unexplored winter crop in the world’s main cropping areas, introduced mainly for its oil quality (high proportion of erucic acid, 40–45%) for biofuel production and other industrial applications (e.g., plastics, lubricants, paints, and animal feed) [10–14]. The main regions where carinata research is ongoing are Canada (in the Citation: Bonansea, S.; Ernst, O.R.; Mazzilli, S.R. Baseline for Brassica carinata Components of Nitrogen- Use Efficiency in Southern South America. Agronomy 2023, 13, 412. https://doi.org/10.3390/ agronomy13020412 Academic Editor: Wei Zhang Received: 28 December 2022 Revised: 17 January 2023 Accepted: 26 January 2023 Published: 30 January 2023 Copyright: © 2023 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https://creativecommons.org/license s/by/4.0/).