Monitoring Onion Crop “Cipolla Rossa di Tropea Calabria IGP” Growth and Yield Response to Varying Nitrogen Fertilizer Application Rates Using UAV Imagery

Gaetano Messina,Salvatore Di Fazio,Michele Monti,Salvatore Praticò,Giuseppe Badagliacca,Giuseppe Modica

doi:10.3390/drones5030061

Gaetano Messina, Salvatore Di Fazio + Show 4 more

Open Access

https://doi.org/10.3390/drones5030061

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Journal: Drones	Publication Date: Jul 16, 2021
Citations: 18	License type: CC BY 4.0

Affiliation: University of Reggio Calabria

Abstract

Remote sensing (RS) platforms such as unmanned aerial vehicles (UAVs) represent an essential source of information in precision agriculture (PA) as they are able to provide images on a daily basis and at a very high resolution. In this framework, this study aims to identify the optimal level of nitrogen (N)-based nutrients for improved productivity in an onion field of “Cipolla Rossa di Tropea” (Tropea red onion). Following an experiment that involved the arrangement of nine plots in the onion field in a randomized complete block design (RCBD), with three replications, three different levels of N fertilization were compared: N150 (150 kg N ha−1), N180 (180 kg N ha−1), and e N210 (210 kg N ha−1). The crop cycle was monitored using multispectral (MS) UAV imagery, producing vigor maps and taking into account the yield of data. The soil-adjusted vegetation index (SAVI) was used to monitor the vigor of the crop. In addition, the coverage’s class onion was spatially identified using geographical object-based image classification (GEOBIA), observing differences in SAVI values obtained in plots subjected to differentiated N fertilizer treatment. The information retrieved from the analysis of soil properties (electrical conductivity, ammonium and nitrate nitrogen), yield performance and mean SAVI index data from each field plot showed significant relationships between the different indicators investigated. A higher onion yield was evident in plot N180, in which SAVI values were higher based on the production data.

Highlights

The International Society of Precision Agriculture (ISPAG) defines precision agriculture (PA) as “a management that gathers, processes and analyzes temporal, spatial and individual data and combines it with other information to support management decisions according to estimated variability for improved resource use efficiency, productivity, quality, profitability and sustainability of agricultural production” [1]
This study aims to identify the optimal level of nitrogen (N)-based nutrients for improved productivity in an onion field, comparing three different levels of N fertilization and the differences in yield obtained
Our results agree with the trend observed from the other studies, as argued above, highlighting a positive yield trend from N150 to N180 and decrease as the administered dose increases (N210). This evidence suggests that increasing the N dose up to 180 kg N ha−1 produces increasing benefits for plant metabolism and growth, stimulating crop yield of Tropea red onion; increased N dose beyond this threshold harmed production, triggering a vicious circle wherein the progressive increase of N application determined a reduction of nutrient assimilation from the crop due to the progressive increase of soil electrical conductivity (EC), and soil salinity, to which onion is susceptible

Summary

Introduction

The International Society of Precision Agriculture (ISPAG) defines precision agriculture (PA) as “a management that gathers, processes and analyzes temporal, spatial and individual data and combines it with other information to support management decisions according to estimated variability for improved resource use efficiency, productivity, quality, profitability and sustainability of agricultural production” [1]. RS techniques applied to onion crops could help the management of several field operations, including growth monitoring, localized fertilization and more in general, support the implementation of PA techniques In this framework, this study aims to identify the optimal level of nitrogen (N)-based nutrients for improved productivity in an onion field, comparing three different levels of N fertilization and the differences in yield obtained. Considering the economic importance of the Tropea red onion cultivation, the related highly specialized supply chain, and its close link with the territory, developing a rapid and reliable system for monitoring red onion growth and N nutrition status is desirable In this respect, UAV technology can be an essential instrument to support farmers in improving the sustainability of the onion agroecosystems. Only these studies have dealt with onion crop monitoring using UAV data in the PA framework [6,10,11,25,26,27,28,29,30]

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