A Portable Pull-Out Soil Profile Moisture Sensor Based on High-Frequency Capacitance

Area of Science:

• Agricultural Engineering
• Soil Science
• Sensor Technology

Background:

• Soil moisture is critical for efficient agricultural irrigation.
• Accurate, real-time soil moisture data is needed for effective water management.
• Existing methods can be complex, costly, or lack in situ capabilities.

Purpose of the Study:

• To design and validate a portable, low-cost sensor for in situ soil profile moisture detection.
• To develop a device based on high-frequency capacitance principles.
• To enable simple and fast measurement of moisture content at various soil depths.

Main Methods:

• A portable pull-out sensor was developed using high-frequency capacitance.
• The sensor comprises a moisture-sensing probe and a data processing unit.
• An adjustable tie rod allows measurement at different soil layers, with data sent to a smartphone app.

Main Results:

• Indoor tests showed a detection height of 130 mm and radius of 96 mm, with a model fitting R² of 0.972.
• Verification tests yielded a root mean square error (RMSE) of 0.02 m³/m³.
• Mean bias error (MBE) was ±0.009 m³/m³, with a maximum error of ±0.039 m³/m³.

Conclusions:

• The designed sensor offers a wide detection range and high accuracy for soil moisture measurement.
• Its portable and user-friendly design makes it suitable for in situ agricultural applications.
• This technology facilitates improved irrigation management through accessible soil moisture data.