Designing Low-Cost Capacitive-Based Soil Moisture Sensor and Smart Monitoring Unit Operated by Solar Cells for Greenhouse Irrigation Management.

Abdelaziz M Okasha,Zaher Mundher Yaseen,Salah Elsayed,Khaled Mohamed Khedher,Adel H Elmetwalli,Hasnaa G Ibrahim

doi:10.3390/s21165387

Abstract

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.

Highlights

Irrigation is generally based on the personal perspective of the farmer, and there is an urgent need to change from traditionally used methods of monitoring irrigation scheduling that depend on a farmer’s experience to precision monitoring methods that are based on advanced scientific devices and advances in modern technologies that provide low-cost and effective solutions that improve different agricultural practices
When the probe was inserted into a wet soil, the sensor capacitance rose to 300 pF upwards, which is associated with lower cut of frequency of 53.05 kHz downwards
The results demonstrate a direct relationship between the actual values of θ V and the predicted values that are based on linear regression equations for every sensor

Summary

Introduction

It is known that water scarcity is one of the biggest challenges and crises facing Egypt as a result of climate change, in addition to the construction of many development projects within the Nile basin countries (e.g., Ethiopia, Sudan) [10]. In this context, irrigation is generally based on the personal perspective of the farmer, and there is an urgent need to change from traditionally used methods of monitoring irrigation scheduling that depend on a farmer’s experience to precision monitoring methods that are based on advanced scientific devices and advances in modern technologies that provide low-cost and effective solutions that improve different agricultural practices. Most growers will use modern technologies when they are affordable [11]

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