scholarly journals CONFIDENCE ANALYSIS AND CALIBRATION OF A FC-28 SOIL MOISTURE SENSOR MOUNTED ON A MICROCONTROLLER PLATFORM

Nativa ◽  
2021 ◽  
Vol 9 (1) ◽  
pp. 123-128
Author(s):  
Fernando Ferreira Lima dos Santos ◽  
Leticia Cardoso Madureira Tavares ◽  
Guilherme de Moura Araújo ◽  
Lucas de Lima Casseres dos Santos ◽  
Caio Picinin Rocha Affonso Nogueira ◽  
...  

Nowadays, the global water crisis poses a great challenge to humanity and a risk to be managed by future generations. In order to use this resource consciously, it is known in the area of agricultural irrigation the need to evaluate the amount of water to be used. Among the soil moisture content determination methods, sensors, coupled to a programmable logic controller, emerge as an alternative to conventional laboratory methods, making the procedure faster and less labor intensive. In this sense, the present work aimed to evaluate the reliability and precision of a low-cost sensor to determine soil moisture content. It was concluded that the evaluated sensors did not present a known precision to estimate the level of soil moisture content. A FC-28 sensor coupled with a Arduino platform was used with three different soils (texture: low, medium and heavy), moisture ranging from 15 to 50%. The results indicated that soil texture influenced the readings, even at the same humidity. In addition, the evaluated sensors did not present replicability nor accuracy for less them 10% moisture differences. Therefore, there is need to calibrate each sensor individually. Keywords: arduino; irrigation; embedded systems.   Análise de confiabilidade e calibração do sensor de umidade do solo FC-28 montado em plataforma microcontroladora   RESUMO: Atualmente, a crise hídrica mundial representa um grande desafio à humanidade e um risco a ser gerenciado pelas gerações futuras. De forma a utilizar este recurso de forma consciente, estudos na área de irrigação agrícola apontam a necessidade de se estimar com precisão a quantidade de água a ser usada. Dentre os métodos de determinação da umidade do solo, os sensores, acoplados a um controlador lógico programável, surgem como uma alternativa aos métodos convencionais de laboratório, tornando o procedimento mais rápido e menos trabalhoso. Neste sentido, o presente trabalho avaliou a confiabilidade e precisão de um sensor de baixo custo para determinação da umidade do solo. Um sensor FC-28 associado à uma plataforma Arduino foi usado em três tipos diferentes de solos (texturas: leve, média e pesada), umidades variando de 15 a 50%. Concluiu-se que os sensores avaliados não apresentaram boa precisão para estimar o grau de umidade dos solos. A textura do solo influenciou diretamente as leituras dos sensores, mesmo para a mesma umidade. Além de não apresentaram replicabilidade nem precisão para diferenças menores de 15% nos valores de umidades. Portanto, é necessário calibrar cada sensor individualmente. Palavras-chave: arduino; irrigação; plataformas embarcadas.

Sensors ◽  
2021 ◽  
Vol 21 (16) ◽  
pp. 5387
Author(s):  
Abdelaziz M. Okasha ◽  
Hasnaa G. Ibrahim ◽  
Adel H. Elmetwalli ◽  
Khaled Mohamed Khedher ◽  
Zaher Mundher Yaseen ◽  
...  

Precise and quick estimates of soil moisture content for the purpose of irrigation scheduling are fundamentally important. They can be accomplished through the continuous monitoring of moisture content in the root zone area, which can be accomplished through automatic soil moisture sensors. Commercial soil moisture sensors are still expensive to be used by famers, particularly in developing countries, such as Egypt. This research aimed to design and calibrate a locally manufactured low-cost soil moisture sensor attached to a smart monitoring unit operated by Solar Photo Voltaic Cells (SPVC). The designed sensor was evaluated on clay textured soils in both lab and controlled greenhouse environments. The calibration results demonstrated a strong correlation between sensor readings and soil volumetric water content (θV). Higher soil moisture content was associated with decreased sensor output voltage with an average determination coefficient (R2) of 0.967 and a root-mean-square error (RMSE) of 0.014. A sensor-to-sensor variability test was performed yielding a 0.045 coefficient of variation. The results obtained from the real conditions demonstrated that the monitoring system for real-time sensing of soil moisture and environmental conditions inside the greenhouse could be a robust, accurate, and cost-effective tool for irrigation management.


2020 ◽  
Vol 39 (3) ◽  
pp. 911-917
Author(s):  
V. Ogwo ◽  
K.N. Ogbu ◽  
C.C. Anyadike ◽  
O.A. Nwoke ◽  
C.C. Mbajiorgu

The quantity and quality of water present in the soil determine to a greater extent the performance of agricultural crops. Real-time determination of moisture content has a greater advantage over the traditional gravimetric method of determining soil moisture content. Thus, this work was based on the design and construction of a cost effective digital capacitive soil moisture sensor for real-time measurement. The moisture sensors comprised four integrated units namely: power supply unit with a 9V DC battery as a power source, sensor unit with a locally sourced Printed Circuit Board (PCB) as the single sensing probe, control unit made up of PIC16f877 microcontroller programmed with a C language and the C source code compiled in Corporate Computer Services Compiler (CSS C) compiler development environment, and a 16x2 display unit which displays the readings in percentage moisture content (%MC) and capacitance (μF) of the soil obtained from the sensor on its screen. Standard gravimetric moisture content was carried out to get the calibration factor which was used to calibrate the sensor for reliability. The validation was done by taking the reprogrammed (calibrated) sensor to the field for further measurement, after which soil samples were collected for further gravimetric analysis. A regression equation was obtained by plotting the moisture content obtained from gravimetric method (%MCG) against that from sensor reading (%MCS) with a high degree correlation coefficient (R2) of 0.998. The developed capacitive soil moisture sensor is cheap, portable, reliable and easy to use even by local farmers. Keywords: Calibration, Capacitive sensor, Printed circuit board, Soil moisture content, Validation.


2016 ◽  
Vol 8 (4) ◽  
pp. 1959-1965 ◽  
Author(s):  
Jitendra Kumar ◽  
Neelam Patel ◽  
T. B. S. Rajput

Soil moisture sensor is an instrument for quick measurements of soil moisture content in the crop root zone on real time basis. The main objective of this research was development and evaluation of an indigenous sensor for precise irrigation scheduling. The various parts of sensor developed were ceramic cup, acrylic pipe, level sensor, tee, reducer, gland, cork, and end cap. The designed system was successfully tested on okra crop and calibrated with frequency domain reflectometry (FDR) by three methods of irrigation, i.e. check basin, furrow and drip, respectively. The average depth of water depletion in modified tensiometer by these methods was 27 to 35 cm at 50% management allowable depletion (MAD) of field capacity. This depth was useful for the level sensor to be installed inside modified tensiometer for real time irrigation scheduling. The correlation coefficient (R2) between soil moisture content obtained from the developed sensor and FDR was 0.963. Sensor network was integrated with global system for mobile communication (GSM), short message service (SMS) and drip head work to develop an automated irrigation system. This would enable farmers to effectively monitor and control water application in the field by sending command through SMS and receiving pumping status through the mobile phone.


Agriculture ◽  
2019 ◽  
Vol 9 (7) ◽  
pp. 141 ◽  
Author(s):  
Ekanayaka Achchillage Ayesha Dilrukshi Nagahage ◽  
Isura Sumeda Priyadarshana Nagahage ◽  
Takeshi Fujino

Readily available moisture in the root zone is very important for optimum plant growth. The available techniques to determine soil moisture content have practical limitations owing to their high cost, dependence on labor, and time consumption. We have developed a prototype for automated soil moisture monitoring using a low-cost capacitive soil moisture sensor (SKU:SEN0193) for data acquisition, connected to the internet. A soil-specific calibration was performed to integrate the sensor with the automated soil moisture monitoring system. The accuracy of the soil moisture measurements was compared with those of a gravimetric method and a well-established soil moisture sensor (SM-200, Delta-T Devices Ltd, Cambridge, UK). The root-mean-square error (RMSE) of the soil water contents obtained with the SKU:SEN0193 sensor function, the SM-200 manufacturer’s function, and the SM-200 soil-specific calibration function were 0.09, 0.07, and 0.06 cm3 cm−3, for samples in the dry to saturated range, and 0.05, 0.08, and 0.03 cm3 cm−3, for samples in the field capacity range. The repeatability of the measurements recorded with the developed calibration function support the potential use of the SKU:SEN0193 sensor to minimize the risk of soil moisture stress or excess water application.


Sensors ◽  
2019 ◽  
Vol 19 (3) ◽  
pp. 491 ◽  
Author(s):  
Juan González-Teruel ◽  
Roque Torres-Sánchez ◽  
Pedro Blaya-Ros ◽  
Ana Toledo-Moreo ◽  
Manuel Jiménez-Buendía ◽  
...  

Water is the main limiting factor in agricultural production as well as a scarce resource that needs to be optimized. The measurement of soil water with sensors is an efficient way for optimal irrigation management. However, commercial sensors are still too expensive for most farmers. This paper presents the design, development and calibration of a new capacitive low-cost soil moisture sensor that incorporates SDI-12 communication, allowing one to select the calibration equation for different soils. The sensor was calibrated in three different soils and its variability and accuracy were evaluated. Lower but cost-compensated accuracy was observed in comparing it with commercial sensors. Field tests have demonstrated the temperature influence on the sensor and its capability to efficiently detect irrigation and rainfall events.


2019 ◽  
Author(s):  
Anuradha Hadgil ◽  
Apoorva Joshi ◽  
Layak Ali ◽  
S. P. Sajjan

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