Designing and field calibration of low-cost microcontroller-based soil moisture sensor for subsurface drip-irrigation...

Area of Science:

• Agricultural Engineering
• Soil Science
• Sensor Technology

Background:

• Accurate soil moisture monitoring is crucial for efficient irrigation management.
• Existing commercial sensors can be expensive, limiting widespread adoption.
• Variability in sensor placement can affect soil moisture readings.

Purpose of the Study:

• To ruggedize, calibrate, and evaluate a cost-effective capacitive sensor system (SEN0193) for soil moisture monitoring.
• To develop a predictive model for soil moisture levels using sensor output voltage.
• To assess the sensor system's performance against a commercial sensor and its suitability for irrigation management.

Main Methods:

• Ruggedization and calibration of the SEN0193 capacitive sensor system.
• Laboratory and field testing to assess sensor-to-sensor variability.
• Regression analysis to develop a soil moisture prediction model based on sensor output voltage (ADC).
• Comparison with a commercial SM150T sensor for Volumetric Water Content (VMC) measurement in a sugarcane field.

Main Results:

• The developed low-cost sensor system demonstrated high accuracy with Mean Absolute Error of 1.56%, Root Mean Square Error of 0.36, and Relative Absolute Error of 0.65.
• A strong positive correlation (Spearman rank coefficient > 0.98) was found between the low-cost sensor and the commercial SM150T sensor for VMC prediction.
• The sensor system exhibited consistent and reliable performance in field conditions without practical issues.

Conclusions:

• The calibrated low-cost capacitive soil moisture sensor system performs comparably to commercial sensors.
• This sensor system offers a viable, cost-effective solution for accurate soil moisture monitoring.
• The technology can be effectively utilized for optimizing irrigation management and improving irrigation efficiency.