Soil moisture sensor working principle

Soil Moisture Sensor, also known as Soil Moisture Sensor, Soil Moisture Meter, is a device used to measure the moisture content in the soil. The sensor consists of a stainless steel probe and a waterproof probe, which can be used for a long period of time by burying it in the soil and embankment for the purpose of fixed-point monitoring and on-line measurement of moisture content in the surface and deep soil layers. Used in conjunction with a data collector, the data can be uploaded to the cloud or other devices for analysis and processing via wireless transmission technology. It is often widely used in agriculture and horticulture to help farmers and horticulturists monitor the moisture required by plants, so as to better manage irrigation systems and improve crop yield and quality.

Soil moisture sensors can be categorized into many types based on different operating principles, such as capacitive, resistive, frequency-domain reflective, time-domain reflective, etc. Each type has its own characteristics and scope of application. The following are a few common working principles of soil moisture sensors:

1. Resistive sensors: Resistive soil moisture sensors utilize the effect of moisture in the soil on the electrical resistance value to measure moisture. These sensors usually contain two or more electrodes that are buried in the soil. As soil moisture increases, the conductivity of the soil increases, resulting in a decrease in the resistance value. Measuring the change in resistance value reflects the change in soil moisture. Resistive sensors are simple and easy to use, but have a greater effect on salinity and fertilizer.

2. Capacitive sensors: Capacitive soil moisture sensors measure moisture based on the effect of moisture in the soil on the dielectric constant. These sensors usually consist of two electrodes and the capacitance between them is related to the soil moisture. As soil moisture increases, the dielectric constant of the soil increases, resulting in an increase in the capacitance value. Measuring the change in capacitance value reflects the change in soil moisture. Capacitive sensors are usually suitable for long-term monitoring of soil moisture and have the advantages of low power consumption and low price.

3. FDR (Frequency Domain Reflection) Sensor: Frequency Domain Reflection soil moisture sensors measure soil moisture by transmitting and receiving electromagnetic waves. The electromagnetic waves in the sensor propagate through the soil, and the higher the moisture content, the slower the propagation speed. Changes in soil moisture can be inferred by measuring changes in the propagation time or phase of the electromagnetic waves.

FDR soil moisture sensors have the advantages of simple construction, low cost, and ease of use for a wide range of soil types and environmental conditions. However, compared to TDR sensors, FDR sensors may be slightly less accurate in complex soil structures or high salinity environments.

4. TDR (Time Domain Reflectance) Sensors: TDR soil moisture sensors utilize the propagation time of an electromagnetic pulse through the soil to measure soil moisture. By measuring the speed of electromagnetic wave propagation through the soil, the moisture content of the soil can be accurately calculated.

Advantages of TDR sensors include accurate moisture content measurement, independence from salts and fertilizers, high accuracy and stability. It is suitable for different types of soil. However, TDR sensors are more costly and require more complex data processing and calibration.

Overall, TDR sensors provide more accurate and reliable soil moisture measurements and are suitable for scientific research and high-precision needs, while FDR sensors are better suited to general needs in practical applications and provide easy, cost-effective soil moisture monitoring solutions. Choosing the right sensor depends on specific application needs and budget considerations.

In summary, capacitive, resistive, TDR and FDR sensors are all different technological means used to measure soil moisture, each with a specific working principle, advantages and disadvantages, and the right type of sensor can be selected according to specific application needs. Common application scenarios include agricultural irrigation, plant growth management, environmental monitoring and other fields.

Soil temperature and moisture sensor data sheet

NBL-S-TMC-Soil-temperature-and-moisture-conductivity-sensor.pdf

NBL-S-TMCS-Soil-temperature-humidity-salty-EC-sensor.pdf

NBL-S-THR-Soil-temperature-and-moisture-sensors-Instruction-Manual-V4.0.pdf

8-in-1-Soil-Composite-Sensor-Manual.pdf

7-in-1-Soil-Composite-Sensor-Manual.pdf