Iot Based Hydroponic System With Supplementary Led Light For Smart Home Farming of Lettuce [PDF]

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2018 15th International Conference on Electrical Engineering/Electronics, Computer, Telecommunications and Information Technology



IoT based hydroponic system with supplementary LED light for smart home farming of lettuce T. Namgyel1, S. Siyang1, C. Khunarak1, T. Pobkrut2, J. Norbu1, T. Chaiyasit1 and T. Kerdcharoen 1, 2, 3* 1



Materials Science and Engineering, Faculty of Science, Mahidol University, Bangkok 10400, Thailand 2 Department of Physics, Faculty of Science, Mahidol University, Bangkok 10400, Thailand 3 NANOTEC Center of Excellence, Mahidol University, National Nanotechnology Center, Bangkok, Thailand *Corresponding author: [email protected]



As agriculture is undergoing industrialization, contemporary farming architype demands advanced automated system enabled by internet for communication. Current farmers in the field requires to be equipped with relevant knowledge on environment, crop information and monitoring to execute informed and timely decisions for maximum yield. Integration of IoT in such domain would help farmers to gather, store and share the data in real-time. Quires of farmers will be addressed intelligently through various devices with high accessibility [5].



Abstract— Current agriculture advancement is being challenged like never before with sustainable food production and security in a demographically obese world. Climate change is another major challenge that contemporary farming practice tries to overcome. Conventional soil dependent farming practices make farmers vulnerable to various manifestations of climate change. Different technologies were employed to enable farming practices to adapt and build resilience against irregular microclimate shifts. It is imperative that modern farmers need to be equipped with precise management and monitoring of the crop system with access to the scientific data about the field environment to execute intelligent and informed decisions in time. Alternate farming technology like hydroponic culture technique and integration of smart artificial light and IoT system are deemed promising solutions to the aforementioned problems. In this study, we have developed a smart hydroponic system with LED lighting technology enabled by IoT system. Plants were hydroponically cultured under various treatments and morphological parameters were measured and characterized. The plants treated with blue supplementary LED light resulted in greater accumulation of biomass, leaf density, leaf area and pigment content. IoT devices and software applications were incorporated to transmit and display of system information online. The system was successful in archiving data real time for end user access.



With the infusion of smart technologies in agriculture, alternate urban farming technique like hydroponics have evolved. Hydroponic culture method is an environmentally friendly technique of growing crops using essential nutrient elements without soil. Recently, cultivation of crops hydroponically has become successful and is perceived capable to feed the rapid growing population around the world. The advent of the artificial LED lightning technology into the urban farming further boosted the yield and production. LED technology provides advanced advantages such as low radiating temperature, extended durability, long operative lifespan, small volume, zero toxic radiation, highly efficient in energy conversion and specific wavelength [6] which lacks in conventional farming. Although controlled indoor environment system with artificial light to cultivate plants has been developed, the infusion of IoT that empowers control and monitoring is yet to mature in urban farming.



Keywords— hydroponics; internet of things (IoT); LED; urban farming.



I.



INTRODUCTION



The present work of ours is the modulation of the conventional hydroponic culture with the supplementary LED lightening technology enabled by internet of things (IoT).



The Internet of Things is a system of network consisting automatic and intelligent devices and machines implanted with sensors and software for data processing and sharing through internet [1]. Internet of Things has infinite benefits and its influence are rooting in our day to day life opening new avenues for innovation, creativity and connected society. IoT has found its grounds of applications in numerous fields such as healthcare supervision, industries, property management [2]: robotics, administering security, sport gadgets, electronic nose, smart shoes, wearable electronic nose [3], wireless sensor network and precision agriculture [4]. Advancement of technology evolution in urban farming over the years has culminated in the insertion of Internet of Things (IoT) in the perspective of innovation to improve agricultural yields and adapt resilience against the challenges such as climate change, environmental friendliness and food security. Farming which is based on IoT is deemed innovative shift of paradigm from the conventional farming method to smart agriculture.



978-1-5386-3555-1/18/$31.00 ©2018 IEEE



Fig.1. IoT based hydroponic system in the field.



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2018 15th International Conference on Electrical Engineering/Electronics, Computer, Telecommunications and Information Technology A hydroponic system in an open greenhouse was designed to simulate an urban setting with different treatments of supplementary LED light arrays controlled and regulated by the micro controller unit. Air temperature, relative humidity, nutrient solution temperature and solar energy are monitored real-time with camera capable of real-time pictorial transmission for physiological monitoring of plant. The system controller unit is embedded with Wi-Fi module to transmit data to the cloud database. The system consisted of automated micro controller unit programmed to collect data, synchronize and upload to website for easy access to farmers for executing intelligent decisions and monitoring [7]. Butterhead lettuce was cultured in the hydroponic system and its physiological parameters and pigment contents are characterized. II.



Fig. 3. Schematic of IoT architecture in hydroponic system.



B. System controller unit System controller unit consists of IoT devices such as Arduino Mega 2560, sensors, RTC, NodeMCU, actuators and camera. Arduino Mega is programmed to regulate the supplementary LED lighting photoperiod by operating in conjunction with RTC and HL-52S 2 channel relay module. Relay is activated with 5 V of input sourced from the microcontroller. Air temperature and relative humidity is measured using SHT15 sensor housed inside stack of circular louver adjacent to controller box (see Fig .3). A water proof temperature sensor is affixed in the nutrient solution tank to measure and monitor the nutrient temperature. Four ML8511 sensors was mounted at the top of each growing segment for measuring the solar energy. Surveillance camera with the capability of online real-time pictorial transmission was mounted on the system controller stand to keep track of the physiological growth of the plants.



METHODOLOGY



A. Framework of IoT prototype Wireless sensor networks (WSNs) is composed of different processors with the sensor nodes, sensitive probes and indicators for evaluating the environment with very low power consumption. Communication in WSNs doesn’t come at the cost of harming environment. Since it is wireless its convenient and inexpensive to materialize the system for environment application [8]. WSNs embraces three modes of transmission: Zigbee, Bluetooth and Wi-Fi [4]. This work employed Wi-Fi module as the mode of data transmission and monitoring considering the network coverage proximity range. Fig. 2 illustrates the fundamental framework of IoT system integration. The framework configuration assimilates cloud database service, various machines and software as cardinal components of a prototype system. The upper part of the figure depicts various devices employed in the systems including actuators. The mid sections represents the cloud service for data storage. Data from different sensors are read and registered for storage in the cloud database. The end section of the figure demonstrates the data analysis, graphical visualization and online archive of the data from the system. Wi-Fi module is the gate way for data transmission form the system to server, enabling synchronized communication over the different IoT units and transfiguration of data organization for easy user accessibility through different channels of multimedia.



Weather board was embedded in the system controller unit to read and receive data from different sensors and transmit to NodeMCU embedded with ESP8266 Wi-Fi microprocessor. Data flow from sensors were uploaded to server through local Wi-Fi network to register the data storage in the database for evaluation and easy accessibility for the end users. The schematic of the IoT architecture is illustrated in Fig. 3. C. Online data transmitter and software application The principal advantage of the smart system architecture lies in its ability to monitor and make data accessible to the users in real time. The system integrated with weather board and Arduino Mega 2560 which delivers 16 analog pins and each pin with the capacity to provide 10 bits resolution. Weather board was regulated at 5V from Arduino connected to various sensing platforms such as nutrient solution sensor, temperature and humidity sensor and UV sensors. Data transmitter used NodeMCU which operated at 3.3V logic to channel data to the database. RX pin of NodeMCU connected to TX pin in weather board transmits the analog data at the baud rate of 9600. Every minute, NodeMCU with 10 bit ADC transmit the data to the control center through local Wi-Fi network and then upload to the MySQL cloud database. Hypertext Preprocessor (PHP), JavaScript are embedded in Hypertext Markup Language (HTML) to visualize the accumulated data into line plot for the window display in the website. Fig. 4 shows the flow chart of the data transmitter node.



Fig. 2. IoT system framework.



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2018 15th International Conference on Electrical Engineering/Electronics, Computer, Telecommunications and Information Technology D663 = Absorbance of sample at 663 nm D645 = Absorbance of sample at 645 nm IV.



A. plant growth and morphology Plants grown under the treatment of blue supplementary light had the maximum leaf density/plant that was 43.2 % more than plants under sunlight (see table.1). Likewise, leaf density of plants treated with red+blue and red supplementary light were respectively 42.4 % and 23.7 % more compared to plants grown under the natural light. Leaf density exhibited quantitative variance from 13 DAS although average leaf count at 10 DAS was equal. With reference to table.1, the plants treated with blue supplementary light possessed highest average LA. Average LA of plants treated with blue, red+blue and red were, respectively, 62.8%, 57.5% and 56.4 % more compared to plants cultivated under natural sunlit. Such demonstration of leaf expansion in response to the irradiance of blue light during growth validates the interpretation that blue light stimulates leaf enlargement. Proliferation in leaf density and enlargement of leaf development occurs largely as the result of increase in palisade parenchyma [12] and penetration of light is enhanced by the palisade tissues [13].



Fig. 4. Flow chart of transmitter node.



III.



EXPERIMENT DETAILS



A. Conditions and materials for plant culture Coated seeds of Butterhead lettuce (Lactuca Sativa L.) were germinated before the experiment. Seedlings were transferred to hydroponic system 7 days after sowing (DAS). Nutrient solution was disseminated in the system through pump with a continuous flow rate of 0.058L/s. Electrical conductivity and pH of the nutrient solution was monitored and maintained within the range of 1150-1250 μScm-1 and 5.5-6.0, respectively. Daily average solar irradiance plants received was 70.7 W/m2. The average air temperature, relative humidity and the temperature level of the nutrient solution was maintained and recorded at 32.4/29.8 °C (day/night), 76.6 %, 30.7/29.5 °C (day/night) respectively.



TABLE 1. Comparison of growth parameters irradiated under different light treatments: red LED (R), blue LED (B), red+blue LED (R+B) and sunlight (S). Parameters Leaf density LA (cm2)



B. Supplemental artificial lightning module The architecture of the hydroponic system was compartmentalized into four growing segments (see Fig. 3). First three segments were irradiated with deep red LEDs (640660 nm), deep royal blue LEDs (440-450 nm) and combination of deep red LEDs (640-660 nm) and deep royal blue LEDs (440-450 nm) with the ratio of (1:1) respectively. Solar radiation was the sole light source in fourth growing segment. 3 W high power LED chip beads with about 5 years lifespan were embedded on 20 mm star based aluminum heat sink PCB for heat dissipation. Constant electric current LED driver of 600 mA were connected to LEDs. The photoperiod of supplementary lighting treatments was 16-h a day: the treatment initiated from 4 a.m. till 8 p.m. LED arrays were stationed 25 cm above the culture PVC pipes.



R 36.5 1855.37



Treatments B R+B 42.25 42 1931.27 1868.21



S 29.5 1186.29



Fig. 5 shows the average FW measurement of plants under different treatments of lights. Plants treated with blue supplementary light accumulated greater FW in comparison to other light source. FW of plants grown under blue, red+blue and red were respectively 71.5 %, 69.1 % and 64.9 % greater than plants under sunlight. Supplementary LED light also affected the accumulation of DW. Fig. 6 shows the result of shoot DW of plants under different light treatments. Average DW accumulation of plants treated with blue light was 139.2 % higher than plants grown under sunlight. Similarly, average DW of plants treated with red+blue and red supplementary were respectively, 112.2 % and 51.5 % higher than plants grown under sunlight. Plants with larger LA had greater exposure of leaf to photon interception enabling better accumulation of biomass [10]. Blue light prevents the loss of energy through the process of photorespiration and stimulates photosynthesis with the regulation of stomatal opening for maximum CO2 intake [14].



C. Measurement of plant physiology and chlorophyll (chl) Measurements included fresh weight (FW), leaf area (LA), leaf density, dry weight (DW). DW was obtained after drying lettuce in an electric at 60°C for 3 days. Chl was eluted from 0.1g of FW sample with 20 ml of 80 % acetone solution and kept in the dark area until the leaves turned white [9]. Optical density was measured using Spectrophotometer at 663 nm and 645 nm for chl a and chl b respectively [10] from the following equation [11]. Chl a (mg/l) = 12.7 D663 + 2.69 D645 Chl b (mg/l) = 22.9 D645 + 0.02 D663



RESULT AND DISCUSSION



(1)



Fig. 5. Average fresh weight of plants under different treatments.



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2018 15th International Conference on Electrical Engineering/Electronics, Computer, Telecommunications and Information Technology ACKNOWLEDGMENT This project was supported by Mahidol University, National Nanotechnology Center (NANOTEC) and Thailand International Cooperation Agency (TICA). The authors gratefully thank the members of Center of Intelligent Materials and Systems (CIMS) at Mahidol University for their time and valuable contributions. REFERENCES [1] Fig. 6. Average dry weight of plants under different treatments. [2]



B. Chlorophyll content Chlorophyll is a green pigment responsible for captivation of light for photosynthesis. All plants regardless of the treatments, had higher chl a content then chl b (see Fig.7). Chl a plays a vital role in the process of photosynthesis by conducting excited electrons to sugar manufacturing molecules [15]. Plants cultured under blue supplementary light contented highest Chl a and Chl b that were respectively 38.5 % and 46.3 % greater than plants under sunlight. Plants treated with red supplementary light had lowest chl a and chl b level that were about 44 % lesser than plants under sunlight. Results show that chl content of lettuce grown under blue light were significantly higher than compared to lettuce under other lights. Lettuce bearing greater accumulation of chl a and chl b would exhibit better growth because these pigments eradicate reactive oxygen molecules induced by light, therefore, enabling superior absorption of light for photosynthesis [15].



[3]



[4]



[5]



[6]



[7]



[8]



[9]



V.



[10]



Fig. 7. Absorption spectra of chlorophyll a and b under different treatments.



[11]



VI. CONCLUSION



[12]



In smart urban farming, crop monitoring and yield are of paramount importance. In this study, hydroponic culture was modulated with supplementary LED light and sensor networks enabled by IoT system for plant monitoring and optimized production. The system allowed us to do comparative study and our result indicated that blue supplementary LED light fostered positive effects on lettuce growth, morphology and pigment content. Real time system data display and access enabled by IoT system was successful. This technology proved suitable and beneficial in urban setting for year round crop production with precise plant management.



[13]



[14]



[15]



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