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Irrigation is essential for agriculture, but it can also be a significant source of water waste. By measuring the amount of water in the soil, farmers can optimize their irrigation and reduce their water consumption. There are various types of sensors that can be used to measure soil moisture, such as tensiometers, resistive, capacitive, or TDR probes.
The choice of sensor will depend on the type of soil, the type of crop and the needs of the farmer.
The resistive sensor is a type of soil moisture sensor that works by measuring the electrical resistance of the soil. When the ground is wet, the electrical resistance is low. When the ground is dry, the electrical resistance is high. Resistive sensors are generally used in sandy and silty soils.
The capacitive sensor is a type of soil moisture sensor that works by measuring the electrical capacity of the soil. When the ground is wet, the electrical capacity is high. When the ground is dry, the electrical capacity is low. Capacitive sensors are generally used in sandy and silty soils.
Frequency scattering reflection (FDR) is a non-destructive technique that measures the water content in soil by sending an electrical signal into the ground and measuring the diffusion of the signal. The amount of water in the ground affects the spread of the signal. FDR sensors are generally used in sandy, silty, and clay soils.
Time-of-flight reflection tomography (TDR) is a non-destructive technique that measures the water content in soil by sending an electrical impulse into the ground and measuring the pulse's return time. The amount of water in the ground affects the speed of propagation of the electrical impulse. TDR sensors are generally used in sandy, silty, and clay soils.
3-electrode TDR probes are the most common, but there are also 2-electrode and 4-electrode TDR probes.
