agriculture Article Effect of Nitrogen Fertilization on the Dynamics of Concentration and Uptake of Selected Microelements in the Biomass of Miscanthus x giganteus Izabela Gol˛ ab-Bogacz 1 , Waldemar Helios 2 , Andrzej Kotecki 2 , Marcin Kozak 2 and Anna Jama-Rodze ´ nska 2, *   Citation: Gol ˛ ab-Bogacz, I.; Helios, W.; Kotecki, A.; Kozak, M.; Jama-Rodze ´ nska, A. Effect of Nitrogen Fertilization on the Dynamics of Concentration and Uptake of Selected Microelements in the Biomass of Miscanthus x giganteus. Agriculture 2021, 11, 360. https:// doi.org/10.3390/agriculture11040360 Academic Editor: Andreas S. Pacholski Received: 25 February 2021 Accepted: 13 April 2021 Published: 16 April 2021 Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affil- iations. Copyright: © 2021 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/licenses/by/ 4.0/). 1 Bugaj Sp. z o.o, Bugaj Zakrzewski 5, 97-512 Kodr ˛ ab, Poland; iza.golab@o2.pl 2 Institute of Agroecology and Plant Production, Wroclaw University of Environmental and Life Sciences, Pl Grunwaldzki 24A, 50-363 Wroclaw, Poland; waldemar.helios@upwr.edu.pl (W.H.); andrzej.kotecki@upwr.edu.pl (A.K.); marcin.kozak@upwr.edu.pl (M.K.) * Correspondence: anna.jama@upwr.edu.pl; Tel.: +48-713-201-627 Abstract: This paper presents the effects of nitrogen (N) fertilization on the concentration of selected micronutrients as an important issue in reducing combustion-induced air pollution. We studied the effects of the dose of 60 kg ha −1 N in different terms of biomass sampling on the concentration and uptake of iron (Fe), manganese (Mn), zinc (Zn), and copper (Cu) in the dry matter of the underground and aerial parts of Miscanthus x giganteus in the years 2014–2016. The order of microelement concentra- tions (mg kg −1 ) in rhizomes and the aboveground parts of plants was as follows: Fe > Mn > Zn > Cu. N fertilization had no significant effect on the concentrations of the selected microelements in the Mischanthus biomass (except for the Mn concentration in the stems and Cu in the leaves). The results indicated that the quality of the combustion biomass did not worsen under nitrogen fertilization. During the whole vegetation period, the iron concentration increased in the rhizomes and decreased for Zn and Cu. In the aboveground parts of the plant, the concentrations of all tested elements decreased. In turn, the uptake of Fe, Mn, Zn, and Cu (except for Fe in the stems) by rhizomes and the aboveground parts of Mischanthus depended significantly on the N fertilization. Keywords: N application; translocation Fe; Mn; Zn; Cu; rhizomes; aboveground parts of plants; Miscanthus 1. Introduction Increasing concentrations of greenhouse gases, the global growth of energy de- mand, and rapidly decreasing reserves of fossil fuels cause renewable energy sources, including biomass, the center of interest for scientists and many sectors of industry [1,2]. The benefits of bioenergy crops, apart from the high yield potential, is cultivation on marginal land, which is characterized by low productivity of other field crops [3,4]. Due to the specific chemical structure and high calorific value, plant biomass can be destined for various conversion processes to produce liquid, gaseous, and solid fuels [5–7]. Plant biomass currently accounts for only 3% of basic energy consumption in highly developed countries [6,8]. Carbon dioxide (CO2) is also present during the biomass combustion process. However, since it comes from harvested or combustion plants that absorbed it from the atmosphere in the first place, these are not additional quantities [6,9]. Part of the carbon is stored in the soil [10]. Among perennial grasses, Miscanthus x giganteus is characterized by a high potential yield and low humidity of the harvested biomass [9]. Miscanthus x giganteus is also a tolerant plant for moderate concentrations of heavy metals and microelements in the soil [11]. The production of such plants depends on the climate conditions. In the current, fast-changing temperature conditions, Miscanthus x giganteus was shown to be 59% more productive compared to maize grain in field studies [12]. Miscanthus x giganteus is more efficient compared to other C4 cold resistant biomass crops, such as altered grass [12]. Agriculture 2021, 11, 360. https://doi.org/10.3390/agriculture11040360 https://www.mdpi.com/journal/agriculture