Today, farmers usually work on large portions of land that are partitioned to grow different types of crops. During the dry season, they practice irrigation farming. There is a shortage of water for irrigation, and it is not possible for a person to monitor the amount of water content in the soil, in order to keep the root of the plant moist, or to detect it in real time. This study aims to address the water shortage problem, that is often faced by farmers using irrigation systems, by providing an autonomous sensor interface for the remote monitoring and control of the supply of water to the soil, thereby removing much of the effort required by farmers.
Recently, the use of intelligent sensory techniques has gained a significant amount of attention by farmers who practice irrigation agriculture. These techniques have been applied in agriculture to plan numerous activities and tasks appropriately, by utilizing limited resources with less human intervention. Aeroponics is a modern agricultural method that is commonly practiced around the world. In this system, plants are cultivated under complete control conditions in a growth chamber, by way of a light misting of a nutrient solution, replacing the soil medium. These nutrient mists are ejected through atomization nozzles on a periodic basis. During the plant cultivation period, many parameters are optimized, including temperature, humidity, light intensity, water nutrient solution level, pH and EC levels, CO2
concentration, atomization time, and atomization interval time, in order to enhance plant growth [1
With the present technological advancements, there is a greater demand for specialized information regarding agricultural practices. This is because much of agricultural studies are based on exploratory investigations, on a local scale, using ground data by employing a single remote sensor. In addition, the methods employed mostly depend on local knowledge of management practices, environment, and biological materials. These limitations call for a new direction toward smart irrigating [2
A scheme for the optimal watering of agricultural crops, using a wireless sensor network, has been previously presented by the authors [3
]. In that study, the main goal was to design and develop a control system using a sensor node in the crop field, with data management and application control, through a smart phone and web application interface. The proposed scheme provides three components: (1) The hardware control box, (2) web-based application, and (3) mobile application. In addition, the system allows either, automatic, or manual control, by the user. The results showed the usefulness of this system in agriculture, by reducing cost and increasing agricultural productivity.
The use of internet of things (IoT) technology for agricultural practices has been demonstrated in monitoring citrus soil moisture and nutrients, the integration of fertilization and an irrigation decision support system. Significant achievements have been made. These include, a single-point, multi-layer citrus soil temperature and humidity detection, wireless sensor node and citrus precision fertilization, and the construction of an irrigation management decision support system. This approach can help farmers improve the use of fertilizers in the irrigation system. In addition, it increases the precision of citrus production, and reduces labor costs and pollution, caused by the application of chemical fertilizers to the soil [4
In a smart irrigation system, the design and fabrication of a self-powered and autonomous fringing-field capacitive sensor, used to measure soil water content, is possible. This kind of sensor is manufactured using a conventional printed circuit board (PCB) and incorporates a porous ceramic material. The design allows the energy-harvesting module to operate, based on the condition that the micro-sprinkler spinner irrigates the soil, and the supercapacitor is fully charged to 5 V in approximately three hours during the first irrigation. Subsequently, with the supercapacitor fully charged, the system can supply power from the supercapacitor for approximately 23 d, without any energy being harvested [5
Agricultural practices have been the most important means of living over the course of human evolution. Hence, humans depend on a wide range of agricultural products in nearly every facet of life. The process involved in the artificial application of water to farmlands, in assisting the growth of plants, is referred to as irrigation agriculture. This process has become a great advantage in complementing agricultural activities, especially in the dry season. Irrigation plays a vital role in advancing the agricultural, educational, and economic growth of the nation as a whole. The traditional method of farming is undertaken manually, by engaging individual farmers in almost all stages of crop development and monitoring and control of the processes involved at all stages of irrigation farming. From time-to-time, these processes are replaced with semi-automated and automated processes, to provide assistance to farmers and improve agricultural productivity. The four traditional irrigation practices are ditch irrigation, drip irrigation, terraced irrigation, and the use of a sprinkler system. Owing to the increased demand for agricultural raw materials for industrial use and human consumption, irrigation tends to attract a significant amount of attention, particularly in the developed and underdeveloped world. In the traditional system, the farmers apply water to plants mechanically at different stages of plant development, to assist in the growth and development lifecycle. However, an inadequate supply of water to plants affects plant growth, and the scarcity of water has become a global issue, particularly in the irrigation system, which is specifically caused by global warming. Various human activities, including the burning of fuel, industrial activities, and deforestation have been the major causes of the depletion of the ozone layer and inadequate rainfall, particularly affecting plant growth and development. The traditional approach to irrigation, involves the use of watering cans and water channels, which must be manually monitored and controlled. This causes a significant amount of water to be wasted and misused. Therefore, an autonomous sensor interface, for a smart IoT-based irrigation system, must have components that both monitor and control the water levels available to plants, without failure or the need for human intervention [6
Agricultural practices use 85% of the available freshwater resources worldwide. The high demand and consumption of water, owing to rapid human population growth and agricultural practices are the dominant factors of water consumption. Accordingly, urgent attention is required to create techniques and strategies, based on science and technology, in order to maintain and sustain the use of water for agricultural development. The idea of an autonomous sensor interface for an IoT-based irrigation monitoring and control system results from plant watering management requirements. Hence, modern Internet technology is essential for resolving the challenges of the limited supply of water to farms, and providing better lasting solutions for irrigation management and control. A wireless sensor network (WSN) can be used in conjunction with IoT for a smart irrigation system. Therefore, the use of WSN can provide the means of communication, computation, and sensing information from near and remote places. The combination of IoT and sensor network technology facilitates the proper use and management of water resources for a smart irrigation system. This will help boost smart agricultural practices and produce higher crop yields annually [7
The salient contributions of this article are as follows:
A low-cost autonomous sensor interface is proposed to determine whether watering is required for plants, based on the information obtained from the monitoring and control of the soil water content.
A monitoring and control system (implemented prototype) that supplies the amounts of water, required by plants to avoid drying, is designed.
The system should stop the water supply when the required amount has been supplied to plants.
A convenient sensor-based interface architecture and web portal are provided so that the user can monitor the system remotely.
This study is of paramount importance, not only to farmers that practice irrigation farming, but also to the expansion of economic growth in general. This method encourages irrigation farming by reducing the high levels of supervision required by farms to ensure the supply of water to farms, by using wireless sensor network and IoT technology. The rest of the article is organized as follows: Section 2
discusses the system design methodology; Section 3
discusses the system implementation; Section 4
presents the experimental results and discussion; and Section 5
provides the concluding remarks and describes future work.
1.2. Related Works
Many studies have contributed toward a smart irrigation system. The high demand for food requires rapid improvement in food production technology. Several researchers have made significant efforts to find a solution for irrigation farming. However, these efforts have yet to provide an efficient solution to the problems of the present irrigation system.
The review paper by Imran et al. [1
] contributes significant knowledge regarding early fault detection and diagnosis in Aeroponics, using wireless sensor networks. The Aeroponics technique allows the farmer to monitor several parameters, without using laboratory instruments, and the farmer has the ability to control the entire system remotely. In addition, this technique provides valuable information, essential for plant researchers and a greater understanding of how the key parameters of Aeroponics relate to plant growth in the system.
The review paper by Agnés et al. [2
] provides an extensive study of remote sensing for crop mapping practices. The authors emphasize that there is a need to have specialized information regarding agricultural practices. The study is categorized into three groups of practices: Crop succession, cropping pattern, and cropping techniques. The authors observed that the majority of studies were based on exploratory investigations, tested on a local scale, using ground data by employing a single remote sensor. In addition, the methods employed mostly depend on local knowledge, based on management practices, environment, and biological materials. These limitations can be used to identify future research directions, which include the use of land stratification, multi-sensor data combination, and expert knowledge-driven methods. The authors concluded by proposing that new spatial technologies, particularly the sentinel constellation, are anticipated to advance the monitoring of cropping practices in the context of food security, and to provide the best administration of agro-environmental issues. An interesting system was presented for the optimal watering of agricultural crops, which employ the use of a wireless sensor network [3
]. The proposed system provides the capabilities of manual and automatic control of crops by the application user.
ZigBee technology, artificial intelligence, and decision support technology have also been employed [4
] to monitor the moisture content of citrus soil. This study provided insight into the application of IoT for agricultural practices in the monitoring of citrus soil moisture and nutrients, and the integration of fertilization, as well as an irrigation decision support system. Remarkable advancements were made, including single-point multi-layer citrus soil temperature and humidity detection, wireless sensor nodes and citrus precision fertilization, and an irrigation management decision support system. The results of their study indicated that the system can help a farmer improve the use of fertilizers in an irrigation system. In addition, the system increases the precision of citrus production, and reduces the labor cost and pollution caused by the application of chemical fertilizers to the soil.
The design and fabrication of a self-powered and autonomous fringing field capacitive sensor, to measure soil water content, was presented [5
]. The sensor used was manufactured using a conventional PCB and in which a porous ceramic material was incorporated. To obtain the sensor reading, the authors used a circuit containing a 10-kHz triangle wave generator, AC amplifier, precision rectifier, and micro-controller. This approach developed a complete irrigation control system that integrates the sensor, an energy-harvesting module, composed of a micro-generator installed on top of a micro-sprinkler spinner, and a DC/DC converter circuit that charges a 1-F supercapacitor. The design allows the energy-harvesting module to operate on the condition that the micro-sprinkler spinner irrigates the soil, and the supercapacitor is fully charged to 5 V, in approximately 3 h, during the first irrigation. Subsequently, with the super-capacitor fully charged, the system was capable of supplying power from the super-capacitor for approximately 23 d, without any energy being harvested.
The Yogesh et al. study [6
] demonstrates that the watering system controller sends transitory information. It presents the output from the sensor and presents the possibility of being programmed to enhance system performance. The moisture sensor connects to devices via a remote network and transmits the sensed information, within a time interval, synchronized to the Internet, to provide guidelines on how the system is to be operated. The soil moisture sensor is controlled by the watering system if the solenoid valve is in an open state. These two components are the major building blocks of irrigation system control. Therefore, the systematic control of the irrigation field should be adopted. For instance, the moisture sensor should operate in a controlled range, e.g., when the moisture value is lower or higher than the set threshold value, the solenoid valve controls the operation by opening, or closing the valve, respectively.
The Arduino board was utilized in [7
], which consists of an ATmega 328 microcontroller. The microcontroller is programmed in such a way as to sense the moisture level of the plants. The design was undertaken to supply the required amount of water to the plants. The system is utilized for plant maintenance and monitoring of the entire farm land. Thus, the plants can be watered twice daily, in the morning and the evening. Hence, the use of a microcontroller plays a vital role in the watering and monitoring of the plants on a daily basis.
Marie et al. [9
] reported that the sensed data, regarding the quantity of water content level in the soil, that was obtained from a moisture sensor, can significantly improve the agricultural yield. This would motivate researchers to perform extensive studies in various fields of interest that are related to the irrigation systems. A significant advancement in measuring the development of plant growth is the minimization of the costs of irrigation management, particularly for a mechanized watering system. This approach would significantly reduce water wastage and lessen the amount of human power required for the continuous monitoring of the source of water supply in an irrigation system. The use of a feedback-based system would efficiently help track and manage resources, compared with open-loop systems, that are at the expense of higher complexities. Thus, soil moisture is difficult to correctly measure, and the target moisture content levels are difficult to sustain.
The continuous increase in the demand for agricultural products and raw materials has necessitated a rapid improvement in the development of food technology [10
]. Therefore, only agricultural practices can provide the solution to this problem. The use of an automated irrigation system has triggered the continuous demand for agricultural farm products. The available water resources are scarce, and the inadequacy of land and water has resulted in a decrease in the volume of water worldwide. Farmers normally employ an irrigation system during the dry season. In irrigation agriculture, two important aspects must be considered: Information on the fertility of the soil, and; the content of soil moisture. Famers have employed different methods and techniques in an irrigation system to reduce the dependence on rainfall as a major source of water supply to the soil. The most commonly used technique is the use of electrical energy, combined with an on-and-off scheduling control system to power the irrigation system. Other available techniques operate based on atmospheric climate conditions. The use of smart microcontrollers, used to sense the climatic conditions and determine the supply of water in real-time, is an important technique for a smart irrigation system. This approach employs the following: Internet-based monitoring using servers; general packet radio service modem; global system for mobile communication; and wireless monitoring using Bluetooth and WSNs.
Many farmers require financial aid to innovate their agricultural practices. Numerous master frameworks have been provided to assist farmers boost agricultural productivity. Nevertheless, these primary frameworks depend on a base-learning approach. Therefore, a master system framework, that integrates IoT technology, is highly recommended, as it will exploit the continuously generated real-time data [11
Gabriel et al. [12
] emphasized that the majority of farmers cannot afford to use sophisticated technologies for agricultural practices. It is now of paramount importance that more effective, cheaper solutions need to be implemented. The study proposed building virtual organizations of agents, that can communicate between each other, while monitoring crops in a farmland. Simple and low-cost sensor architecture helps farmers monitor and optimize the growth of their crops, by restructuring the amount of resources the crops require at each stage of their development. The approach employs the use of Platform for automatic coNstruction of orGanizations of intElligent agents (PANGEA) architecture to overcome the limitations of hardware and processing capabilities. The designed system is capable of collecting heterogeneous information from its environment using sensors for temperature, solar radiation, humidity, pH, moisture, and wind. The main finding of their approach is that the solution can merge heterogeneous data from sensors and produce a response adapted to each situation. The authors presented a case study to validate the proposed system. However, its drawback is that it is not economically feasible to use a TV screen to monitor the condition of crops in this context. Further, the monitored data are presented in real time, which may affect the monitoring of the crop moisture level, thereby resulting in poor crop yield.
The design of SmartFarmNet, which is an IoT-based platform that provides the services of collection of environmental, soil, fertilization, and irrigation data, was presented in [13
]. The system autonomously correlates such data, and filters out invalid data from the viewpoint of evaluating crop performance, providing forecasting information, and formulating recommendations for a specific farmland. The proposed SmartFarmNet possesses the capability of integrating virtually any IoT device, including commercially available sensors, cameras, and weather stations, and has the ability to store the captured data in the cloud for performance analysis and recommendations. In conclusion, SmartFarmNet was presented as the first and, presently, the largest system in the world to offer crop performance analysis and recommendations.
Chandan and Pramitee [14
] presents a smart irrigation system. The system is cost effective and affordable by middle-class farmers. The 21st century is characterized by automation technology that plays an important role in human life. This technology allows devices to be controlled automatically to provide comfort, reduce energy consumption, increase efficiency and save time. The machine automation and control used by the modern industries are not cost effective and cannot be used by the local farmers. In contrast, their work presents a low-cost irrigation system that can be afforded by Indian farmers. The paper’s main objective is to automatically control the water motor that selects the direction of water flow in a pipe with the aid of soil moisture sensor. The information regarding the operation of the motor, and the direction of the water flow in the farmland, is sent by SMS to the users’ mobile phones.
Karthikeswari and Mithraderi [15
] designed a low-cost automated irrigation system using wireless sensor network and GPRS module. The work was aimed at reducing the manual monitoring of the farmland and using GPRS technology to provide information to users. The system can determine whether free electricity supply is being used or electric motors are used for pumping water to the farmland. This will prevent misuse of the electricity supply to pumping mechanisms. And hence, reduces water wastage.
A review of irrigation system and economical and generic automatic irrigation system, using GSM-Bluetooth for irrigation remote monitoring system was presented by Purnima and Reddy [16
]. The proposed system possesses the features of low cost, low power consumption for remote monitoring and control of sensors, using SMS and GSM module. The proposed system notifies the users about any abnormal circumstance that may arise. These include lower moisture content, temperature rise, CO2
concentration etc. The information regarding these parameters is sent to the Famer’s mobile phone via GSM or Bluetooth modules for appropriate action.
Archana and Priya [17
] presents an automatic plant watering system. The research work focuses on the water scarceness and the need for a smart and efficient way of irrigation. The authors implemented a humidity sensor to detect the soil humidity in the agricultural farmland. The system supplies the adequate water requirement to the irrigated farmland. The authors employed the use of microcontroller to supply water to the irrigation field. Sensors are buried in the soil to sense the water content of the soil. The sensors are activated when there is a presence, or no presence, of water in the field. Once the sensor identifies dry soil, it activates the microcontroller and pump water to the field.
Ferrarezi et al. [18
] developed automated irrigation controllers that employ the use of capacitance sensors and data loggers to supply water to plants on demand. The limitation of the proposed approach was the cost implications, due to data loggers and software programs, to build and control the system controllers. However, the use of low-cost open-source microcontrollers provides a better way to build a sensor-based irrigation controller for irrigation agriculture and domestic use. The authors built an automated irrigation system employing microcontroller, capacitance moisture sensors, and solenoid valves. The proposed system efficiently monitored and controlled the volumetric water content thresholds of (0.2, 0.3, 0.4, and 0.5 m3
) with Panama red hibiscus (Hibiscus acetosella) in a peat substrate. The system operates both on regular 24 V alternating current solenoid valves and latching 6 V to 18 V direct current solenoid valves. The technology employed has an average cost. The microcontroller used and accessories cost $
107, four capacitance soil moisture sensors cost $
440, and four solenoid valves cost $
120. The total cost an estimated value of $
667 US Dollars. However, our proposed approach is more cost effective, and is only valued at $
79 USD. Other approaches are the automatic irrigation based on monitoring plant transpiration, hyperspectral remote sensing for detecting soil salinization using ProSpecTIR-VS aerial imagery and sensor simulation, and high temperature AlGaN/GaN membrane-based pressure sensors are provided by the respective authors in [19
This study attempts to address the limitations of the above-mentioned approaches by their respective authors. Accordingly, this work could identify the following limitations, which we intend to rectify: (1) the use of sprinklers as a means of water supply to the soil; (2) the use of a semi-automated system, which does not monitor or control the soil moisture content, and the lack of descriptive analysis to assist the farmer in tracking the moisture content level of the soil on the Internet; and (3) a low-cost and flexible design architecture for real-time monitoring and control of soil moisture content.