agronomy Article Tall Fescue (Schedonorus arundinaceus (Schreb.) Dumort.) Turfgrass Cultivars Performance under Reduced N Fertilization Marco Schiavon 1 , Cristina Pornaro 2, * and Stefano Macolino 2   Citation: Schiavon, M.; Pornaro, C.; Macolino, S. Tall Fescue (Schedonorus arundinaceus (Schreb.) Dumort.) Turfgrass Cultivars Performance under Reduced N Fertilization. Agronomy 2021, 11, 193. https:// doi.org/10.3390/agronomy11020193 Received: 23 December 2020 Accepted: 16 January 2021 Published: 20 January 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 Environmental Horticulture Department, Fort Lauderdale Research and Education Center, University of Florida, Davie, FL 33314, USA; marcoschiavon@ufl.edu 2 Department of Agronomy, Food, Natural Resources, Animals, and Environment, University of Padova, 35020 Legnaro, Padova, Italy; stefano.macolino@unipd.it * Correspondence: Cristina.pornaro@unipd.it Abstract: The identification of minimal N requirements for sustaining turfgrass quality and function- ality became necessary to reduce N fertilization inputs and avoid potential environmental impacts in the European Union. A two year study was conducted at Padova University in Legnaro, northeastern Italy to investigate the performance of four tall fescue (Schedonorus arundinaceus (Schreb.) Dumort.) cultivars (‘Lexington’, ‘Rhambler SRP’, ‘Rhizing star’, and ‘Thunderstruck’) fertilized twice per year at either 75 or 150 kg N ha −1 year −1 . Turfgrass was evaluated every two weeks for turfgrass visual quality, percent green cover (PGR) as well as dark green color index (DGCI) through digital image analysis and normalized difference vegetation index (NDVI). ‘Rhizing star’ was the only cultivar that showed poor adaptation to the environment, achieving acceptable turfgrass quality (6.0 or higher) only during June and July 2019. Turf fertilized at 150 kg N ha −1 year −1 generally showed higher performance than 75 kg N ha −1 year −1 , however, the increase in turfgrass quality was mostly negligible and detected only during the winter months. Results suggest that well adapted tall fescue cultivars could be fertilized at 75 kg N ha −1 year −1 in Northern Italy. Keywords: N requirement; percent green cover; dark green color index; NDVI 1. Introduction Northern Italy, with its mild winters and hot and dry summers, is considered a transition zone where both cool- and warm-season turfgrass species can be grown success- fully [1]. However, long winter dormancy periods, favor the use of cool- over warm-season species in those zones, since most of cool-season turfgrasses are able to maintain color year-round [2,3]. Among cool-season species, tall fescue (Schedonorus arundinaceus (Schreb.) Dumort.) is one of the most commonly used grasses in the region thanks to its high tol- erance to warm temperatures and drought avoidance due to its ability to use water deep in the soil profile, and its shade and salinity tolerance [4–9]. It can also be successfully used in heavily trafficked turf areas due to its high wear tolerance similar to perennial ryegrass [10]. Reducing N fertilization in agriculture to avoid potential environmental impacts has been encouraged in current European Union Policies [11]. Nitrogen is the most required element for turfgrass growth and development [12]. However, its inconsistent availability in the soil makes seasonal N fertilizations necessary to maintain acceptable turfgrass quality throughout the year. Suggested yearly rate of N fertilization for tall fescue has been reported to be between 200 and 270 kg N ha −1 year −1 [13,14]. For better turfgrass quality, the suggested N rate should be split in at least two applications, one in the spring and one in the fall [13]. Nevertheless, Grossi et al. [15], investigating timing of fall N fertilization in Italy, concluded that a single application of 100 kg N ha −1 through a quick release N source such as ammonium sulfate, was not enough to maintain acceptable tall fescue quality and color through the whole winter. Similar results were observed in Maryland by Agronomy 2021, 11, 193. https://doi.org/10.3390/agronomy11020193 https://www.mdpi.com/journal/agronomy