The low power soil moisture sensor is our latest version and except other aspects, special optimization for power consumption and signal output under low power model has been specially done.  The sensor has 2 kinds of function optional: single mosture version and temperature+moisture model.

The soil moisture sensor is featured wtih high accuracy, quick response, stable signal output(no drift), etc. Each sensor is calibrated by the actual drying and weighing method of soil before leaving the factory.This sensor is suitable for low  power supply( lithium battery), 3.3Vdc and the power supply range is 2-5v.

Woring Principle

The volume water content in the soil has a fixed functional relationship with the dielectric constant of the soil, which is almost independent of the soil and the salt contained in the water.The capacitance between the middle probe and the probes on both sides is measured by frequency domain measurement method. The capacitance is directly proportional to the dielectric constant.Then after AD conversion, single chip microcomputer operation processing, nonlinear correction and DA conversion output, the linear voltage (current or 485 signal) output proportional to the soil volume water content can be obtained.


  • Low power consumption, average current < 10mA
  • High measurement accuracy, fast response, stable output signal, no random jump and drift
  • Vacuum filling, excellent sealing, completely prevent water from invading from any direction, and can be immersed in water for a long time
  • The moisture probe is made of high-quality stainless steel, which can withstand long-term electrolysis and is more resistant to the corrosion of acid, alkali and salt in the soil.
  • High measurement accuracy, reliable performance, less affected by soil salt content, suitable for various kinds of soil
  • Both sides of soil moisture sensor have concave convex structure, which is easy to hold, beautiful and durable. It is packed with anti-static pearl cotton for safer transportation and storage
  • It has multi-directional anti-mis-connection protection for power wire, ground wire and signal wire

Technical Parameter:

  • Power supply:2-5V suitable for battery power
  • Static current: peak<30mA; average<10mA, ultra-low power consumption
  • Voltage output:0-2V(Load resistor>30K Ohm; Output impedance 0 ohm)
  • RS485 output: Standard RS485 (MODBUS-RTU protocol)
  • Measurement range of soil moisture: volume water content,0-50%,0-100% or customization
  • Accuracy of moisture: <3%(0-53%); <5%(>53%)
  • Measurement range of temp.:-30℃ - +70℃(Voltage output); -40℃ - +90℃(RS485 output)
  • Accuracy of temp.:<0.4℃(-10℃ - +70℃); <0.6℃(other range)
  • Response time: Power-on<0.1S, Refresh period<0.5S
  • Measurement of stabilization time: 0.1S
  • Working temp. range:-40℃ - +80℃


1).Rapid measurement method:

2).Buried survey method: