ISSN 1313 - 8820 (print)ISSN 1314 - 412X (online)

Volume 11, Number 2June 2019

2019

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AGRICULTURAL SCIENCE AND TECHNOLOGY, VOL. 11, No 2, pp 133 - 137, 2019DOI: 10.15547/ast.2019.02.021

Production Systems

An automatic irrigation system for water optimization in the Algerian agricultural sector

O. Bouketir*

Department of Electrical Engineering, Faculty of Technology, University of Setif 1, 19000, Algeria

(Manuscript received 12 February 2019; accepted for publication 5 April 2019)

Abstract. Algeria is a vast country with three climatic types and different water resources. These resources are limited especially in the climatic zone two where most staple crops (e.g. wheat) are cultivated. To manage these water resources efficiently, traditional irrigation systems should be replaced by those based on advanced technological techniques. This paper introduces an irrigation system prototype constructed at the department of Electrical Engineering, University of Setif in Algeria. This prototype allows the control of the amount of water dispensed to the plant according to its soil moisture. The circuit was built around an Arduino microcontroller. A program was developed and burned into the microcontroller which was able to sense the amount of the moisture in the plant soil through a moisture sensor. According to this moisture quantity, the microcontroller is to take decision to on or off a small pump for an optimum time and flow speed. The pump was driven by a direct current motor which was controlled by a pulse width modulation dc-chopper. The system is enhanced by a liquid crystal display to inform the operator about the moisture percentage, status of the pump and its speed. ______________________________________________________________________________________________________________

Keywords: automatic irrigation, Arduino, dc-chopper, microcontroller, moisture, pulse width modulation

*e-mail: omrane@univ-setif.dz, omrane71@yahoo.com

Introduction

The need of introducing automatic and intelligent irriga-tion systems rises from the fact that water resources are limited almost everywhere in the world. In Algeria, the water resources whether for drinking or for irrigation are decreas-ing yearly due to two main factors: increase of population and low precipitation rate yearly (Laoubi and Yamao, 2009; Boualem et al., 2014; Abla et al., 2016). An efficient agricul-ture sector depends mainly on the irrigation methods (Laoubi and Yamao, 2009; Kumar et al., 2017) especially for crops which heavily rely on large quantity of water. Utilization of different technologies to improve the irrigation process has been practiced for a long time. These techniques which range from overhead sprinklers, to flood type feeding have various reverse effects such as dispensing more water than it is re-quired which leads to various types of plant infections. Trickle irrigation is a good solution to overcome such problems. In this technique water is slowly applied to the root area of the plant. Water is supplied whenever needed to keep adequate soil moisture and prevent moisture stress in the plant with-out wasting water resources. The soil moisture percentage is measured by a special sensor and it is fed back to a data acquisition system to use it for controlling the water pump. The moisture information could be used with other informa-tion and factors for selection of proper tillage tools (Yousef et al., 2018).

In order to implement such a technique an automatic sys-tem has to be put into effect. Various microcontroller-based systems have been developed for this purpose throughout the world (Kumar et al., 2017). An Atmega328 microcontroller based irrigation system (Malvi et al., 2017), is programmed to collect the input signal of changeable moisture circum-

stances of the earth via moisture detecting system. The soil moisture sensors are constructed using aluminum sheets and housed in easily available materials. The aim is to use the readily available material to construct low cost sensors. A design of an automatic irrigation system based on android application using Raspberry Pi microcontroller was present-ed in (Lorvanleuang and Zhao, 2018). Soil moisture and tem-perature sensors were used to help famers in Laos to control and monitor farms. This work facilitates the farm irrigation by switching the pump motor ON/OFF through a cell phone. This automatic irrigation system has a low cost and can be afford-able for many Lao farmers. In Atayero and Alatishe (2015) a design of a low-cost microcontroller-based irrigation con-troller was presented. This design aimed at managing irriga-tion for a small area of land based on real-time values of soil moisture and temperature in Nigeria. The developed system allowed users to set the desired soil moisture range suitable for the crop. It is enhanced with an LCD where these levels of moisture are displayed.

In order to maximize proper use of water, to minimize the cost of labor and to provide security, an automated irrigation system was developed by Ahmed et al. (2013) in Bangladesh. This system had a wireless messaging system that allowed for better understanding and maintenance of remote fields. A water level sensor was used instead of a moisture sensor. An adaptive control algorithm that offers significant water savings as well as saves the crops from being over flooded was adopted for the developed system. Three PIC microcon-trollers were used; two to control two irrigating pumps and one to control one pump that sucks excess water in case of flooding. An automatic irrigation system (Manoj and Hemal-atha, 2017) was designed and developed in which a pump motor is switched ON/OFF for a certain period of time de-

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pending on the moisture content in the soil. The project used an 8051 series microcontroller which was programmed to re-ceive input signal of varying moisture conditioning of the soil through sensing arrangement. This was achieved by using an Op-amp as comparator which acted as an interface between the sensing arrangement and the microcontroller. When the microcontroller receives the signal, it gives an output that drives a relay for operating the water pump and runs the wa-ter pump for certain amount of time. An LCD display was also interfaced to the microcontroller to display the status of the soil and the water pump.

A system that used a sprinkler for watering plants located in the pots was developed in (Ojha et al., 2016). This system was based on Arduino board, which consisted of ATmega328 microcontroller. The microcontroller was programmed in such a way that it senses the moisture level of the plants and supplies the water when required. This system could also be used for general plant care, as part of caring for small and large gardens. The plants need to be watered twice daily, morning and evening; so, the microcontroller was coded to water the plants in the gardens or farms twice a day.

The design and fabrication of a thermo-electric generator (TEG) and the implementation of an automated irrigation sys-tem using this TEG as a soil moisture detector was reported by Bathan et al. (2013). The TEG inserted in two heat exchang-ers was capable of finding the thermal difference between the air and the soil that establishes a relationship with the soil’s moisture condition. Being able to obtain the soil moisture level from the TEG’s output, a microcontroller is used to auto-mate the irrigation system. A PIC microcontroller performed the data acquisition as well as the control of the water pumps in irrigation. Solar energy was used to power the system. An automatic irrigation control system was developed and built around ATMEGA32 microcontroller which was programmed using embedded C language (Lawrence et al., 2015). Inputs were the signals from four sensors, namely soil moisture sensor using hygrometer module, water level sensor using the LM 324 Op-amp was configured here as comparator, light sensor with the aid of light dependent resistor and tempera-ture sensor using LM 35. The microcontroller processed the input signals by using the control software embedded in its internal ROM to generate three output signals. One signal was made to control a water pump that irrigated a garden, the second output signal was used to control a water pump that drew water from the river to the reservoir or storage tank. The function of the third signal was to switch a buzzer that alerts the gardener when there is shortage of water in a tank that supplies the garden. In the irrigation system reported by Gun-turi (2013), an 8051 microcontroller was programmed as giv-ing the interrupt signal to the sprinkler. A temperature sensor and a humidity sensor were connected to internal ports of the microcontroller via a comparator. Whenever there is a change in temperature and humidity of the surroundings, an interrupt signal is sent to the microcontroller and thus the sprinkler is activated. An analog rather than digitally-controlled irriga-tion system was developed by Felix et al. (2016) in Nigeria. A pumping mechanism was used to deliver the needed amount of water to the soil. The whole system was grouped into four

subsystems, namely: power supply, sensing unit, control unit and pumping subsystems which made up the automatic ir-rigation control system. A moisture sensor was constructed to model the electrical resistance of the soil; a regulated 12V power supply unit was constructed to power the system; the control circuit was implemented using an operational ampli-fier and a timer; and the pumping subsystem consisting of a submersible low-noise micro water pump was constructed using a small dc-operated motor.

The Automatic Irrigation system (Patidar and Belsare, 2015) was designed to optimize the water use for the agricul-ture crop. The system featured a wireless sensor network of soil moisture, temperature and humidity sensor placed into the root zone of the plant. The system was designed to meet the field conditions, to control the wastage of water in the field and to provide exact controlling of the field. This system included the monitoring of the field state by using ZigBee and GSM techniques.

An irrigation system was developed in (Ballla et al., 2017), and implemented with an embedded WEB system us-ing Wifi. The system was based on an ARM microcontroller programmed using embedded C language. The system used temperature and soil moisture. Various other works in this area have been reported in (Pasha and Yogesha, 2014; Sowah et al., 2014; Tale and Sowmya, 2016; Srilikhitha et al., 2017).

In the present paper we propose an energy-efficient pro-totype for an automatic irrigation system. The system was built around an Arduino microcontroller card. A Pulse Width Modulation (PWM) switching scheme was developed to switch a dc-chopper that drives the irrigating pump.

Material and methods

The choice of an irrigation system must result from the best compromise between the water resource (quantity and quality), the available labor, the soil and its topography. It must also ensure the maintenance of sustainable agriculture by making it possible to better manage the environmental risks associated with nitrate leaching and, in certain contexts, soil salinity. Automatic irrigation systems are very practical: when properly adjusted, they provide just the right amount of water in the right place, virtually effortless for the user. Most automatic systems combine different methods of water appli-cation. These are mainly retractable sprinklers, which retract into the soil when irrigation is complete, and localized irri-gation devices such as drippers and micro-sprinklers, which discharge water more slowly, to the zone, where the plant needs it most at ground level, just above the roots.

System design The developed prototype is based on an Arduino UNO

board. A C program is written, then implanted to the memory of the MC used to control a DC content motor. Rotational speed variation guarantees efficient power saving and an in-telligent irrigation process. The speed of the motor that drives the pump is changed by varying the supply voltage between the motor terminals. This is achieved by the PWM technique.

Figure 1 shows the block diagram of the designed system.

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It illustrates the relationship between the microcontroller and the inputs / outputs signals.

The humidity sensor measures soil moisture from the changes in soil electrical conductivity (soil resistance in-creases with drought). The sensor is simply connected with 2 wires on the measuring board (signal and GND). We took as an example the watering of the orchid during the realiza-tion of our project. The orchid needs moisture of about 85% (Sarmah et al., 2017), however, the warmer the weather, the more moisture it will need to grow. It is necessary to maintain at least 45% humidity at a temperature of 20°C.

The microcontroller card, Atmega 328 has 6 analog inputs (numbered from 0 to 5), each of which can provide 10-bit resolution (i.e., 1024 levels from 0 to 1023) using the very useful analogRead () function of the Arduino language. By default, these pins measure between the 0V (0 value) and the 5V (1023 value), but it is possible to change the upper refer-ence of the measurement range using the AREF pin and the Arduino language analogReference () function. The analog signal of the moisture sensor is fed to the microcontroller through analog input 0. The digital pins of the arduino can be configured as digital inputs or digital outputs; here we will configure one pin for output to control the pump motor. An-other digital output is for the PWM signal that controls the speed of the motor. The precentage of the soil moisture and the pump speed information are displayed through other con-figured output pins.

MethodologyBased on the percentage value of the read moisture, the

microcontroller takes an action according to the flowchart de-picted in Figure 2. The PWM signal is issued from the Arduino card according to the percentage of the moisture in order to drive the pump motor at speed maximum or medium. If the moisture percentage reaches 85%, a signal is produced to cut off the supply of the motor and hence stop the pump. The PWM signal produced by analogWrite instruction is applied to the gate of a MOSFET, which forms DC chopper (Figure 3) that supplies the pump motor. The speed of the pump will be proportional to the duty cycle of the output signal, which in turns is dependent on the percentage of the humidity. Pin 9 is used as the digital output from the Arduino board.

Figure 4 depicts a passage from the main source code that reads and displays the percentage of the humidity on the LCD.

Figure 5 is also a passage from the main source code that displays the state of the speed of the motor driving the water pump (“Pompe on Vitesse max” in French; means “Pump is on Max speed”). Similar codes are developed for the remain-ing two states of the pump speed as designated in the prec-edent flowchart (Figure 2).

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Results and discussion

The performance of the developed was tested through simulation of the design using ISIS-PROTEUS software and then the hardware implementation was carried out and the prototype was put into operation by watering a specific plant. The system performed as expected and the state of the pump and its speed together with the humidity percentage were dis-played successfully.

Simulation resultsBefore the hardware implementation of the system, a sim-

ulation design was carried out using ISIS PROTEUS simula-tion package. The schematic of the system is given on Figure 6. A 2X16 LCD type display has been associated with our de-vice to display any variation or internal and external action. Figure 7 shows the PWM output signal for 50% duty cycle at a medium speed.

Hardware implementationFor the hardware implementation of the irrigation system,

we needed the following components and devices:• 1 Arduino Uno board;• 1 LCD 2 * 16;• 1 water pump (I = 6V, I = 1A, r = 6Ω, d = 129 l/h);• 1 resistor (110KΩ);• 1 humidity sensor (YL-69);• 1 Smartphone charger (5V, 500mA) used as a regulated

power supply for the Arduino board;• 1 small tank of water;• Connection wires;• Charger (9V, 2A), used as a power supply for the pump’s

motor;• 1 IRF840 MOSFET transistor;• 1 freewheeling diode 1N4148.These devices and components are connected as men-

tioned above. A photograph of the implemented hardware is given on Figure 8. The prototype worked efficiently as in-tended.

The developed system could be enhanced by introduc-ing more factors that affect the water quantity supplied to the plant. The first of these factors is the type of the plant. Tem-perature of the soil and light intensity are also of importance in the plant growing. The system designer could perform a thorough investigation for a specific plant in a specific area to extract all the aspects that affect the irrigation of the plant. Then the system could be ameliorated by a keypad that allows the setting of these factors before it starts functioning. An artificial intelligence algorithm would be very efficient in con-trolling the watering process. Moreover, the system could be powered by a solar panel in remote areas. Finally, it could be enhanced by communication protocols to facilitate the offsite communication with the farmer.

Conclusion

In this paper a prototype of an automatic irrigation system was developed. The aim of this prototype was to study the

possibility of developing a real irrigation system that could help Algerian farmers to water their crops efficiently espe-cially in areas where water is less available. The prototype was built around an Arduino Uno card. In order to measure the moisture of the soil, a humidity sensor was used to input this value to the microcontroller. A program was developed for the data acquisition and processing by the Arduino which was able to output a PWM signal to control a dc chopper that drives the pump’s motor. The system is enhanced by an LCD that displays the percentage of the soil moisture and the state of the speed of the motor that drives the pump. A simula-tion of the designed system was carried out before its hard-ware implementation. ISIS-PROTEUS package was used for

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the simulation. A hardware prototype of the system was built and implemented after the success of the simulation process. Though the developed prototype performed as it was expect-ed, it would be more efficient and better performing if it is enhanced by introducing more factors that affect the water quantity supplied to the plant. The first of these factors is the type of the plant. Temperature of the soil and light intensity are also of importance in plant growing. Finally, the system could be powered by a solar panel in remote areas.

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