Type of soil moisture sensor

Soil moisture sensor is an important tool in modern agriculture and horticulture. These devices measure the amount of water present in the soil, an important parameter in managing irrigation and ensuring that plants get the right amount of water.

In this article, we will discuss the different types of soil moisture sensors, how they work, and their applications in agriculture and horticulture.

Type of soil moisture sensor

There are several types of soil moisture sensors on the market, each with its advantages and limitations. Some common types of soil moisture sensors are:

Capacitive soil moisture sensor: Capacitive sensors measure the dielectric constant of soil, which is proportional to the water content. These sensors consist of two electrodes placed in the soil and connected to electrical circuits. The circuit generates alternating electric fields between the electrodes and measures the capacitance between the electrodes. Capacitance values vary with soil water content and are used to calculate soil water content.

Tensiometer: Tensiometer measures soil moisture tension or suction using a ceramic or plastic cup filled with distilled water. A porous ceramic or plastic tip is attached to the bottom of the cup and inserted into the soil. The tension in the soil pulls water away from the top, creating negative pressure, which can be measured with a pressure gauge. The lower the pressure, the drier the soil.

Time domain reflectometry (TDR) sensors :TDR sensors measure soil water content by sending short electrical pulses into the soil and measuring the time it takes for them to reflect back to the sensor. The speed of the electrical pulse depends on the permittivity of the soil, which is proportional to the water content of the soil.

Resistive soil moisture sensor: The resistive sensor measures the soil resistance between two probes. Resistance values vary with soil water content and are used to calculate soil water content.

Neutron probe: A neutron probe is a radioactive method of measuring soil moisture. These sensors emit small amounts of neutron radiation into the soil, which interacts with hydrogen in the soil's water molecules. The detectors measure the amount of radiation reflected back, which is proportional to the amount of water.

How does the soil moisture sensor work

Different types of sensors work differently. However, most soil moisture sensors work by measuring the dielectric constant of the soil, which is proportional to the water content.

Capacitive soil moisture sensors work by generating an electric field between two electrodes placed in the soil. Capacitance values between electrodes vary with water content and are used to calculate soil moisture.

Tensiometers measure soil moisture tension or suction using ceramic or plastic cups filled with distilled water. Tension in the soil pulls water away from the top, creating negative pressure, which is measured with a pressure gauge.

The TDR sensor sends a short electrical pulse into the soil and measures how long it takes for it to bounce back to the sensor. The speed of the electrical pulse depends on the permittivity of the soil, which is proportional to the water content of the soil.

Resistive soil moisture sensors measure the soil resistance between two probes. Resistance values vary with soil water content and are used to calculate soil water content.

Neutron detectors emit small amounts of neutron radiation into the soil, which interacts with hydrogen in soil water molecules. The detectors measure the amount of radiation reflected back, which is proportional to the amount of water.