Agriculture is the basic concept and the only source of the wide variety of economic food supply of our country and the world. Indian soil is good for agriculture, and many types of crops are grown in India. However, the biggest and most prosperous development of Indian agriculture is agriculture, which can protect the crops and maximize the production [1]. The onion (Allium cepa) is a major vegetable crop grown in arid locations around the world. According to the onion production survey of the year 2020, India is the top most onion producer country shares around 17.14%, that is, global production is 104.53 mt out of Indian 26.74 mt onion production the total world production. Maharashtra is the first largest onion producer state in India at 42.73%, that is, India’s production is 26.74 mt out of Maharashtra’s 13.30 mt onion production [2]. Table 1 also shows that India belongs to the top five countries in onion production, consumption, and export for the year 2020. The onion’s unique ability to grow in various soil types and climates contributed to its global popularity. It is popular for its adaptability and ease of cultivation. Due to their high concentration of vitamins, minerals, antioxidants, and other bioactive compounds, onions provide numerous health and nutritional benefits. As the onion is very useful and cultivated all over the world, the supply of onions throughout the year is important. To achieve a year-round onion supply, various strategies are employed, including staggered planting and harvesting schedules, storage technologies, and the cultivation of different onion varieties that mature at different times. Onions contributed about 246 billion Indian rupees to the Indian economy in the financial year 2022 [3]. This value was the highest gross value of the output recorded in recent years. The Indian economy depends on agriculture, which especially depends on the production of onion. In the 2022–23 season, the central government will maintain 3 lakh tons of onion as buffer stock. The buffer stock is maintained to meet any exigencies and for price stabilization, if rates go up significantly during the lean supply season [4].
Onion production, consumption, and export analysis of top three countries for the year 2020
| Country | Production (m/tons) | Export (m/tons) | Worldwide % share of export |
|---|---|---|---|
| India | 26.73 | 1.448 | 17.14% |
| China | 23.660 | 881.3 | 10.43% |
| USA | 3.821 | 365.4 | 4.32% |
| Egypt | 3.156 | 369.2 | 4.37% |
| Turkey | 2.280 | 220.7 | 2.61% |
It is important to store onions properly to supply them throughout the year and ensure that farmers can earn a fair living from them. Agriculture is India’s main occupation, and the entire economy depends on it. This study aims to find ways to extend the storage life of onions. In India, onions can be harvested in two seasons: Kharif and Rabbi. Kharif-harvested onions do not have a longer storage life than Rabbi-harvested onions, so the focus should be on extending the storage life of Rabbi-harvested onions, which are harvested from April to May [5]. It is essential to store onions during both summer and winter, using different systems for temperature control. Internet of Things (IoT)-based storage monitoring significantly increases onion yield and farmers’ income. Real-time and wireless monitoring is needed in the cold stores to verify the uniform airflow distribution through the onion containers, location, and concentric layer, including uniformity [6].
This paper is organized in the following Sections (I–VI). Section II describes the comprehensive literature survey on IoT-based onion storage monitoring systems for the period from 1980 to 2024 in brief. Section III discusses current technologies available in the market for IoT-based onion storage monitoring systems in India as well as all over the world. Limitations (challenges) of current technologies available in the market for IoT-based onion storage monitoring systems in India as well as all over the world are discussed in Section IV. Emerging technologies/future opportunities in IoT-based onion storage monitoring systems are explained in Section V. Finally, it is concluded with how IoT-based onion storage monitoring systems are useful to reduce the onion losses at the time of storage and enhance the market value of onion. This review paper is mainly used to study current technologies available in the market for IoT-based onion storage monitoring systems in India as well as all over the world such as wireless sensor networks (WSNs), range technologies, and cloud services. Limitations (challenges) of current technologies available in the market for IoT-based onion storage monitoring systems in India as well as all over the world as power is a big issue in developing countries like India, and security is also a big issue in IoT systems. Additionally, emerging technologies/future opportunities in IoT-based onion storage monitoring systems such as in the future can be included by adding automation and robotics for sorting and grading of onions [7].
This review article aims to provide an in-depth review of recent developments in the domain of IoT-based onion storage systems from the year 1980 to 2023 [8]. It includes selective articles from Scopus, Science Direct, Web of Science, Google Scholar, and IEEE Xplore libraries. The main aim of this paper is to provide a better overview of the various categories of different storage systems.
Most of the work focuses on the technical aspects of onion quality management, storage, packing, and postpackaging and storage factors. An improved understanding of this will provide an opportunity to improve the implementation of an onion IoT framework of empirical research, which aims to contribute to the better use of the temperature forecast and weather information. The IoT journey began in 1999 as of 2024; there are approximately 17.08 billion IoT devices globally. This figure has been growing rapidly, with an increase of about 2 billion devices from the previous year. The proliferation of IoT devices is expected to continue, reaching around 29.42 billion by the end of 2030. The enhanced IoT-based systems generally comprised of a gateway, cloud servers, WSN, temperature, Relative Humidity (RH) data loggers, reverse osmosis membranes, etc. [9].
WSNs have been used in warehouses to develop an IoT-based and ethylene photodetector to detect the concentration of gases produced by the ripening process during the storage period and were also generally integrated into some IoT-based systems [10].
In 1980–1990, as we see from Table 2, the term IoT was first coined by Kevin Ashton, a British technology pioneer. But before the term IoT was launched when onions were first cultivated in the Middle East and Central Asia, they were an important food and medicinal plant. Therefore, in many countries, studies are being conducted on efficient and safe storage methods and monitoring systems for onions. The traditional methods of onion storage can be based on drying. However, modern methods are considering the creation of artificial drying conditions and non-evaporation conditions [11]. From 1980 to 1990, the general data handling system of the computer system was established, and many studies were conducted in the United States to systematically manage agricultural data.
Evolution of IoT (from 1999 to 2024)
| Phase | Researcher/lab | Year | Description |
|---|---|---|---|
| First phase | Kevin Ashton | 1999 | Kevin Ashton, a British entrepreneur, coins the term “Internet of Things” and discusses the concept. |
| Second phase | Auto-ID labs | 2000 onward | Auto-ID labs, a network of research labs, conducts pioneering work in RFID technology and IoT connectivity. |
| Third phase | Various researchers/labs | 2010 onward | Multiple researchers and labs contribute to IoT advancements, expanding its application into various domains. |
| Fourth phase | Cloud providers (e.g., AWS) | 2015 onward | Cloud providers, such as AWS, offer scalable infrastructure for storing and processing IoT data. |
| Current phase | Various researchers/labs | Ongoing | Researchers and labs worldwide continue to innovate in IoT technologies, exploring areas, such as edge computing |
| Future phase | Various researchers/labs | Ongoing | Ongoing researchers focus on integrating IoT with emerging technologies such as AI, blockchain, and 5G for future applications. |
AI, Artificial intelligence; AWS, Amazon Web Services; IoT, Internet of Things.
In 1990–2000, the first computerized system for onion storage in the Netherlands was installed in 2000. Several other growers followed, and the price of a computerized control system became affordable because the costs of electronics had decreased significantly [12]. The computer took over the work of the manual control of the storage climate, but sensors, electrical equipment, and software of the installation took more time than expected to function properly. There were problems with the sensors, preparation of data, computer crashes, and reading errors. Often, the physical condition of the stored product or curing behavior has been wrongly assessed. Whether the sensors provided accurate values also could not be verified. After stabilizing the installation, the onion storage proceeded as expected, but the obstacles were many in practice [13].
From 2000 to 2010, with the advent of precision equipment including Global Positioning System (GPS) in the 21st century, precision sensors, actuators, robotics, drones, as well as management information systems in agriculture, or agriculture 4.0, and big data are advancing rapidly [14]. This should also contribute to optimizing onion storage, such as sprinkler systems for flexible, controlled with the various drying and curing requirements of onions; accurate airflow direction systems to avoid dead air zones; temperature, humidity, and gas analyzing sensors to control aeration; robotics for the automatic loading and retrieval of bulk storage materials; approaches for purifying air from volatile organic compounds (VOCs) and fungi before use with controlled storage systems; and sensors for monitoring the presence of VOCs in storage buildings [15].
Different sensors are used in IoT-based onion storage monitoring systems
| Sensor type | Example | Function | Parameter monitored | Specifications |
|---|---|---|---|---|
| Temperature sensor | DHT22 | Measures ambient temperature | Temperature (°C/°F) | Accuracy: ±0.4°C and range: −41–80°C |
| Humidity sensor | DHT22 | Measures moisture levels in the air | Relative humidity (%) | Accuracy: ±2%–6% and range: 0%–100% |
| Soil moisture sensor | VH400 | Monitors the moisture content of the soil | Soil moisture (VWC, m3/m3) | Output: analog and range: 0%–46% VWC |
| Light sensor | BH1750 | Measures light intensity | Light intensity (lux) | Range: 0–65,545 lux and accuracy: ±20% |
| Gas sensor | MQ135 | Detects gases, such as NH3, CO2, and benzene | Gas concentration (ppm) | Sensitivity: 10–250 ppm for NH3 and CO2 |
| pH sensor | SEN0161 | Measures the acidity or alkalinity of the soil | pH level | Range: 0–14 pH and accuracy: ±0.1 pH |
| Pressure sensor | BMP280 | Monitors air pressure within storage areas | Pressure (Pa, kPa) | Range: 300–1,100 hPa and accuracy: ±1 hPa |
| CO2 sensor | MH-Z19B | Measures carbon dioxide levels | CO2 concentration (ppm) | Range: 0–5,000 ppm and accuracy: ±50 ppm |
| Ethylene sensor | MiCS-5524 | Detects ethylene gas, indicating ripening | Ethylene concentration (ppm) | Sensitivity: 1–100 ppm |
| Proximity sensor | HC-SR04 | Detects the presence of objects or movement | Distance (cm, m) | Range: 2–400 cm and accuracy: ±3 mm |
| Airflow sensor | FS7-15 | Measures the speed and flow of air | Airflow rate (m/s, CFM) | Range: 0–15 m/s and accuracy: ±0.2 m/s |
| Weight sensor | HX711 + load cell | Measures the weight of stored onions | Weight (kg, lbs) | Capacity: 0–50 kg and accuracy: ±0.01 kg |
| UV sensor | GUVA-S12SD | Monitors UV radiation exposure | UV index | Range: 0–10 UV index and sensitivity: 0.1 |
| RFID sensor | MFRC522 | Identifies tagged objects using radio waves | RFID tags | Frequency: 13.56 MHz and range: 2–5 cm |
| Camera/visual sensor | Raspberry Pi Camera V2 | Captures images or video for visual monitoring | Image/video feed | Resolution: 8 MP and frame rate: 30 fps |
CFM, Cubic Feet per Minute; IoT, Internet of Things; RFID, Radio Frequency Identification; UV, Ultraviolet; VWC, Volumetric Water Content.
In 2011–2020, Evolution of Onion Storage Monitoring System. Digital monitoring of onion storage conditions is performed independently by a so-called “onion eye.” The onion eye has the appearance of an in-house gadget and, when connected to 220 V, makes it possible to read the temperature measured in the massif of the stored products, displays some graphic symbols on the scale, and illustrates the control of the technical state of the storage cooling system [16]. Simultaneously, the near warehouse secretary has the opportunity to listen to the characteristic sound alarm signals emitted by the device when certain events occur that require urgent intervention to correct them [17].
Communication protocols used in IoT-based onion storage monitoring systems
| Communication protocol | Frequency band | Range | Data rate | Power consumption | Typical uses |
|---|---|---|---|---|---|
| Wi-Fi (802.11) | 2.4 GHz and 5 GHz | Up to 100 m (indoor) | Up to 600 Mbps (802.11n) | High | Real-time monitoring and control |
| Zigbee (IEEE 802.15.4) | 2.4 GHz and 900 MHz | Up to 100 m | 20–250 kbps | Low | Sensor networks and low-power applications |
| BLE | 2.4 GHz | Up to 100 m | 125 kbps to 2 Mbps | ery low | Short-range communication and mobile integration |
| LoRaWAN | 433 MHz, 868 MHz, and 915 MHz | Up to 15 km (rural) and 5 km (urban) | 0.3–50 kbps | Very low | Long-range communication and rural areas |
| NB-IoT | Licensed LTE spectrum (varies by region) | Up to 35 km | Up to 250 kbps | Low | Cellular connectivity and urban and rural areas |
| Sigfox | 868 MHz (EU) and 902 MHz (US) | Up to 50 km (rural) and 10 km (urban) | 100 bps | Very low | Ultra-narrowband, long-range communication |
| RFID | 125 kHz, 13.56 MHz, and 860–960 MHz | Up to several meters | Up to 640 kbps | Passive (no battery) or low (active tags) | Asset tracking and inventory management |
| Cellular (3G/4G/5G) | Licensed bands (varies by region) | Up to several km | Up to 10 Gbps (5G) | High | Wide-area connectivity and real-time data |
| Z-Wave | 868.42 MHz (EU) and 908.42 MHz (US) | Up to 100 m | Up to 100 kbps | Low | Home automation and low-power applications |
| Ethernet | Wired | Up to 100 m (cable length) | Up to 10 Gbps | N/A (wired power) | High-speed, reliable communication |
BLE, Bluetooth low energy; IoT, Internet of Things; LoRaWAN, Long Range Wide Area Network; LTE, Long-Term Evolution; NB-IoT, Narrowband Internet of Things.
In 2020–2022, the Coronavirus Disease 2019 (COVID-19) pandemic period accelerated the adoption of IoT in health care, remote work, and logistics. During this period, IoT penetration mainly was in health care, how services can be provided from remote locations, and E-commerce captures all markets. In this period, GPS for location tracking is mostly used. In the year 2020, Miss. Kalyani Shinde from Nashik has suggested modification in onion storage and registered her company as a private limited. In the year 2021, she tested her first module to sense the methane gas emitted by rotten onions and communicated these data through the local server to her central office [18].
Different cloud service providers for IoT-based onion storage monitoring systems
| Cloud service provider | Services | Description | Key features | Use case |
|---|---|---|---|---|
| AWS | AWS IoT Core | Connects IoT devices to the cloud, enabling secure communication and data processing. | Device management, data analytics, and ML integration | Real-time monitoring, data storage, and analytics |
| Microsoft Azure | Azure IoT Hub | Centralized service for managing IoT devices and ingesting data for processing. | Device provisioning, data routing, and integration with Azure services | Device management, telemetry, and control |
| Google Cloud Platform | Google Cloud IoT Core | Securely connects, manages, and ingests data from globally dispersed IoT devices. | Device manager, protocol bridges, and real-time analytics | Large-scale deployment, data processing, and analytics |
| IBM Cloud | IBM Watson IoT Platform | Provides a managed service for IoT device connectivity and data processing. | Real-time data visualization, device management, and analytics | Industrial IoT applications and predictive maintenance |
| Oracle Cloud | Oracle IoT Cloud Service | Enables connection and management of IoT devices with integrated analytics. | Device virtualization, data analytics, and application integration | Supply chain management and asset tracking |
| SAP | SAP IoT | Integrates IoT data with business processes to provide real-time insights. | Business process integration, analytics, and digital twins | Business process optimization and real-time insights |
| Think Speak | Thing Speak IoT Platform | Collects and stores sensor data in the cloud, enabling real-time data analysis. | Real-time data collection, MATLAB (MathWorks, Natick, Massachusetts, United States) analytics, and visualization | Academic projects and small-scale monitoring |
| Particle | Particle Cloud | Manages IoT devices and provides an integrated platform for data processing. | Device management, real-time updates, and integrations | Prototyping and small to medium-scale deployments |
| Cisco | Cisco IoT Cloud Connect | Provides secure and scalable IoT connectivity and management. | Secure device connectivity, data management, and analytics | Secure communication and enterprise IoT solutions |
| Siemens | Siemens Mind Sphere | Industrial IoT as a service platform connecting devices and enterprise systems. | Industrial analytics, digital twins, and application development | Manufacturing and industrial automation |
| PTC | PTC Thing Worx | Provides a platform for building IoT applications with real-time data integration. | Rapid application development, analytics, and device management | Smart manufacturing and connected products |
AWS, Amazon Web Services; IoT, Internet of Things; ML, machine learning; PTC, Positive Temperature Coefficient; SAP, Systems, Applications, and Products in Data Processing.
Summarizing current technologies available in the market vs. emerging technologies (future scope) for IoT-based onion storage monitoring system
| Sr. No. | Technology | Current technologies | Emerging technologies (future scope) |
|---|---|---|---|
| 1. | Sensing technology | Temperature sensors (e.g., DS18B20) and humidity sensors (e.g., DHT11) | Advanced sensors (e.g., Li DAR and hyper spectral imaging) for real-time monitoring |
| 2. | Communication protocol | Wi-Fi, Bluetooth, and Zig bee | 5G, NB-IoT, and LoRa WAN for low-power, wide-area networks |
| 3. | Data analytics | Cloud-based platforms (e.g., AWS, Google Cloud), ML algorithms (e.g., regression, decision trees) | Edge computing, AI, and DL for real-time decision making |
| 4. | Power management | Battery-powered devices, solar-powered devices | Energy harvesting technologies (e.g., piezoelectric and thermoelectric) for self-sustaining systems |
| 5. | Security | Encryption algorithms (e.g., AES and RSA) and secure communication protocols (e.g., TLS and SSL) | Block chain-based security and homomorphic encryption for secure data processing |
| 6. | User interface | Web-based dashboards and mobile apps | Voice assistants (e.g., Alexa and Google Assistant) and AR interfaces for immersive experiences |
| 7. | Storage | Cloud storage (e.g., AWS S3 and Google Cloud Storage) and local storage (e.g., SD cards and hard drives) | Distributed storage solutions (e.g., block chain-based storage) and Edge storage for reduced latency |
AI, Artificial intelligence; AR, augmented reality; AWS, Amazon Web Services; DL, deep learning; IoT, Internet of Things; ML, machine learning; RSA, Rivest-Shamir-Adleman (encryption algorithm); SD, Secure Digital; SSL, Secure Sockets Layer; TLS, Transport Layer Security.
In 2022–2024, after the pandemic, IoT continues to expand into various industries, including agriculture, transportation, and retail. From 2021 to 2024, the problem was investigated taking into account the modernity and progress in the field of electronics and telecommunications [19]. The presence of a radio module allows remote data collection or the development of dedicated software that, viewed from a mobile phone or computer from the internet, emulates an on-site sensor or monitoring station. People using a specially IoT-based application that can view temperature changes and alarm statuses analyze the collected data over a certain period (graphics and diagrams) and notify them by sending an Short Message Service (SMS) on a mobile phone or an e-mail regarding the status of the technical condition of the storage or if there are significant temperature fluctuations in the massif of the harvested products, exceeding the limit values assumed [20].
Currently, operated IoT-based systems utilize a monitoring terminal equipped with various kinds of sensors based on the application requirement integrated with a microcontroller. In the existing Wi-Fi or Wireless Local Area Network (WLAN)-based systems, the temperature, humidity, CO2 concentration, and air exchange rate are the most widely monitored parameters to prevent the quality deterioration of the onion [21]. It was also observed that the reviewed IoT-based onion storage monitoring systems use protocols and standards including MQTT, AMQP, CoAP, and HTTP. In addition, Cambium Networks is the only company that offers complete IoT solutions to monitor the onion storage environment in real time [22].
This minimizes the loss of the produce and maintains its quality for a longer period. Moreover, the output from smart storage systems also informs about the health status of the products inside it without disturbing the equilibrium conditions [23]. The whole setup of an IoT-based system includes a sensor module, actuator module, Global System for Mobile Communications (GSM) module, controlling module, password protection for unauthorized operation, and the location in the monitoring system. Restrained access to the storage system makes them efficient and free from any mental stress that could cause affected storage products [24]. The fuzzy inference system has also been tested to provide the best solution for the complicated problems related to post-harvest storage. Hence, the innovation in the onion storage system to reduce the cost of production and wastage and improve the shelf life and quality of onion. This modern technological approach makes the onion market smart, and the farmers rely on it for more production and their welfare in the future [25].
The enhanced IoT-based systems generally comprised of a gateway, cloud servers, WSN, temperature, RH data loggers, reverse osmosis membranes, etc. WSNs have been used in warehouses to develop an IoT-based ethylene photodetector to detect the concentration of gases produced by the ripening process during the storage period and were also generally integrated into some IoT-based systems [26]. Cold stores, that is, warehouses and containers, and the storage of shallots were observed to be practiced in cold storage C (2°C and 90%–95% RH) and spacious aeration at Moisture Holding (MH). The control and Supervisory Control and Data Acquisition (SCADA) systems, which were earlier manual, are transformed into IoT-based systems/platforms. IoT platforms, that is, Thing Speak, Thing Worx, and Willer wireless IoT platforms, are used by researchers in onion storage experiments [27].
Various types of sensors can collect the characteristic data of onions and their storage rooms, such as temperature, relative humidity, CO2, O2, and ethylene gas concentrations. Specific qualities, including sugar content, can be measured using a near- infrared spectroscopy (NIRS) sensor. To quickly and accurately assess the color of onions, a color sensor can be used. To detect the size of onions, machine vision technology can be adopted [28].
Sensors integrated with IoT devices can collect the considered vegetable-related data, which can be gathered through various communication protocols, such as Bluetooth, Wi-Fi, Zig Bee, and Long Range (LoRa). The IoT-based storage monitoring system uses various sensors, and a network-based storage monitoring system uses wireless sensor system devices collecting such data [29].
For the design and implementation of an IoT-based onion storage monitoring system, one has to consider numerous factors such as remote sensing, data acquisition, data transmission, and storage that can be linked to relay sensory information from an onion cold storage to an IoT-based monitoring and control system for onion quality preservation [30]. However, there is a lack of comprehensive data on the current usage of principles of IoT in terms of ontology for cold storage conditions. For the sustainable development of the storage preservation of onions, which are important food crops, it is of the utmost importance to monitor the stored onions accurately. Since traditional systems have not reached satisfactory levels up to now, a more technological approach is becoming necessary [31].
The most notable internet source is technological development. The expansion of internet technology not only connects people around the world for communication but also has emerged as a crucial platform to integrate electronic devices with computations [32]. The main operating principle of any IoT system is the internet, but developing countries like India have poor internet connectivity in some rural areas [33].
Recent advances in IoT services have supported the use of various sensors and devices to collect information from the field. These devices need power and have power constraints, which depend directly on the battery [34]. Most conventional batteries are lithium-based and provide a suitable amount of energy for a long period. Agricultural IoT devices have not been established for the same energy storage period, requiring a large lithium-ion battery for long-term energy supply [35]. On the contrary, the sensor also can save energy by using a low-capacity battery; however, this setup results in the IoT sensor not performing accurately its work. Consequently, careful battery calibration is important to prolong the IoT sensor in the field. Due to such battery constraints, the sensing interval is one of the most important factors that influence the IoT sensor. Therefore, there is a need to provide high power to IoT sensors, as well as the sensing interval to consider the required power and energy of the sensor [36].
The use of IoT services introduces new concerns related to data security and privacy. Since the onion is a farm product, the owner wants to conceal the storage information from others [37]. Unauthorized access to the data can lead to the loss of privacy. The individual will also face limitations on maximizing profits from the storage release if competitors in the market gain access to the information [38]. In terms of security, ensuring the integrity of the data collected from the sensors and its transfer to the secure storage server is of paramount importance. Data corruption is a plausible scenario, and potential attackers could also inject statistical anomalies into the data [39].
Under these difficulties, selection of the best and optimal available communication interface under a certain range of conditions becomes critical. For an upcoming IoT application, a device interface must manage energy, power consumption, coverage, data rate, and cost along with accounting for path loss and multi-path interference. Consequently, engineers must evaluate different communication network technologies before deciding on an interface for an IoT device, including evaluation of the form factor of the interfaces [41]. Interoperability in access is also crucial for lock-in mitigation, as organizations and governmental agencies can generally source the best devices for the job. Given the diverse range of IoT communication networks, hubs and gateways play a very vital role in this scenario as there are many devices and units to control and analyze which spread across the IoT communication network. Hence, the IoT gateway needs to be flexible in terms of supporting different communication protocols and capable of managing the connection of various IoT devices. Only by this means will digitized operational systems be largely feasible. In summary, lack of interoperability is a significant challenge that faces engineers and developers in terms of operating and using IoT technology [42].
In this section, we covered gaps in exciting work of IoT-based systems, objectives of proposed research work, methodology, and techniques to be used for proposed research work.
The applications of IoT in agriculture have been extensively discussed, particularly concerning future system enhancements. It is crucial to take special care of onion storage during the summer months when temperatures exceed the acceptable range. Traditional methods of onion preservation can result in a loss rate of up to 80%, which is unsustainable for farmers. To address this issue, the Directorate of Onion and Garlic Research (DOGR) under the Indian Council of Agricultural Research (ICAR) has proposed two storage structures: a low-cost bottom-ventilated single-row storage and a bottom-and-side ventilated two-row storage system [43]. By implementing these methods, onion storage losses can be reduced by up to 40%. Maintaining ideal storage conditions is essential to increasing the shelf life of onion bulbs and reducing postharvest storage losses by as much as 10%. The optimal storage conditions for onions include a temperature range of 0–15°C and a relative humidity of 30%–45% when stored at ambient conditions. In cold storage, the best conditions are 0°C with 65%–70% relative humidity. Although the cost of cold storage is relatively high, it results in only about 5% of storage losses over 6 months, mainly due to moisture loss. To prevent significant fluctuations in the ambient conditions of the storage area, it is important to regularly monitor both temperature and relative humidity [44].
The objective is to review the existing literature on monitoring and control systems for onion storage. We aim to develop and implement a monitoring system specifically for onions. This system will monitor real-time parameters necessary for onion storage, including temperature, humidity, indications of rotting, water cooling control for the roof, and device management. Additionally, we plan to incorporate an artificial intelligence (AI)-based control mechanism to enhance the quality of stored onions. Finally, we will validate the results of our implementation [45].
First, a review of the existing literature on onion storage monitoring and control systems will be conducted. This will include an examination of the technologies currently used in onion storage. To implement the monitoring system in hardware, we can utilize temperature sensors, humidity sensors, and gas sensors. Based on specific conditions, appropriate temperature, humidity, and gas sensors will be selected. In addition, output devices such as exhaust fans, roof-mounted water sprinklers, Liquid Crystal Displays (LCDs), buzzers, and heaters will be employed. The status of all parameters, including temperature, humidity, signs of rotting, roof cooling, and device control, will be managed through a GSM module or Wi-Fi module [46]. An AI-based intelligent mechanism will be utilized by a microprocessor or computer to make appropriate control decisions for the onion storage system. These decisions will be executed in real time, allowing for effective management of the storage conditions through the IoT.
The expected outcome is to reduce overall onion storage losses due to rotting and to create a fully automated system that controls all parameters using AI algorithms. This system will continuously measure and display temperature, humidity, and rotting gas levels on a 16 × 2 LCD screen. Based on the measured temperature, the system will manage the ambient conditions of the onion storage by turning the fan and water sprinkler on or off, which is particularly necessary during the summer season. According to the measured humidity, the heater will also be turned on or off, as this is typically required during the rainy season. Furthermore, the system will communicate the status of rotting gas levels to the farmer and provide additional guidance as needed [47].
The recent emerging technologies are likely to address various technological challenges of IoT networks for both Machine-Type Communications (MTCs) and sensors. The emerging technologies consist of a WSN, Software Defined Radio (SDR), Internet Protocols (IPv6), and Open System Interconnection (OSI) Layer-2 for the control and monitoring of the storage system parameters. The performance of future used sensors will measure in terms of the operating distance, response time, and power consumption according to protocol parameters. Finally, the emerging sensor and network with all technological components are assembled to perform data acquisition, storage temperature control, and send notifications on inadequate storage conditions, as well as to conduct a long-term experiment [48].
Due to the onion storage being large both temperature and humidity distribution and the necessity for an independent monitoring system, the network size is relatively large. Considering these disadvantages, it is inappropriate to use ZigBee for an onion storage monitoring system network. After considering the actual situation of receiving units, WLAN or Wi-Fi seems more appropriate to reduce the maintenance and development costs. Although employing a WLAN or Wi-Fi method can reduce the costs, these methods are not suitable for use in onion storage buildings because it is relatively difficult to provide the corresponding network infrastructure. To address this problem, in addition to the potential demand of a network infrastructure, the network coverage distance, as well as compatibility between the monitoring and existing equipment, should also be considered when establishing a real-time monitoring system [49].
The performance of an IoT-based onion storage monitoring system mainly depends on the communication between nodes. Nowadays, Radio Frequency Identification (RFID), ZigBee, WLAN, and Wi-Fi are the most commonly used technologies. RFID is just used for data communication and access to the network and does not completely implement a network. The network size and maintenance cost are major concerns for considering the use of RFID. ZigBee is the most widely used IEEE 802.15.4 standard for WSNs. Using ZigBee, nodes can form a network, communicate, and transmit data quite efficiently in a small area, with low-power consumption and low cost. The main disadvantage of ZigBee is poor network scalability, which means a small network size and relatively short transmission distance [50].
Blockchain is a decentralized and distributed digital ledger of all transactions. Data are stored in a secure, encrypted, immutable, and append-only ledger or record of events. The transaction updates are distributed to all the participants in the business network. The block chain can be defined as an open-source technology, similar to the internet itself, and fundamentally designed to enable trusted connective technology across the world. It originated to mitigate trust issues in virtual currency and extended to multiple use-cases, such as smart contracts, data sharing, and supply chain management, and monetized by using varying economic transaction models [51]. Physician and steward are two central entities that manage and control this secure data management system over a multi-enterprise business network. This concept contains the potential to change the operational underpinning of numerous businesses, including financial services, agriculture, health care, real estate, and government.
AI is enabling many new capabilities within IoT, such as combined AI-IoT systems for real-time health and asset monitoring, building automation, advanced physical security systems, and advanced process automation in industrial IoT. Many experts anticipate that machine learning (ML) and optimization technologies, along with the other forms of AI, will take a leadership role in the deployment and operation of mission critical IoT systems [52]. This is anticipated to be problematic as it is becoming increasingly clear that current IoT platforms are not up to the challenges presented by AI-driven analytics, and AI-driven IoT platforms will require considerable restructuring to improve system integration and intelligence such that the systems support effective visualization and decision support.
Automation and robotics are an important part of the IoT-based onion storage monitoring system. Automation can enhance the efficiency and effectiveness of the onion storage, handling and storing large quantities of onions. Robotics aids in performing unpleasant duties that upsurge the productivity and worker satisfaction [53]. The available robotic applications in the onion storage are limited and require some research by the developers. This scientific curiosity about agricultural robotics application could supply a deeper comprehension of the special norms in agricultural robotics. The agricultural robotic application is thoroughly successful in performing crop tasks in agronomic production and can be suggested in stored product management. Several robotics-based applications have been developed or are being developed that focus on multiple farm applications such as weeding, fruit, vegetable service, precise chemical management, planting, and harvesting [54]. This section provides an extensive review of existing technologies and futuristic technologies, particularly focusing on the context of IoT-based onion storage monitoring solutions. Owing to the usability and advantages of IoT in implementing custom solutions, it is crucial to investigate new research domains regarding the IoT-based onion storage monitoring problem.
In this systematic review, comprehensive literature survey was conducted on potential of onion monitoring system to monitor storage of onions. Onion is one of the main spices used by the local community and also abroad. However, improper handling during storage leads to an increase in physiological factors for onion damage. Therefore, a proper storage technique needs to be developed. Information and communication technology can be utilized for storage monitoring conditions and can be used in determining the shelf life of onions in storage. It was found that monitoring of the proposed onion storage system was still limited to feasibility testing with IoT techniques. The system that has emerged today utilizes the concept of the IoT. This paper presents a review of onion storage monitoring systems. This approach is helpful to researchers, developers, and engineers who want to contribute to the future of farming. In ancient India, farming was traditional. A decade ago, Indian agriculture began to transition from conventional to smart farming techniques. In recent years, onion monitoring involved the use of rotten gas sensors in bottom- and side-ventilated onion storage structures. However, this technique is not sufficient to improve the quality of onion storage. In the future, monitoring systems should have intelligent decision-making capabilities that can respond to changes in the environment and market value. In the coming years, this system will be an IoT-based real-time monitoring and control system.