Schelt Technology

OPERATING PRINCIPLE: The WATERMARK sensor is a resistive device thatresponds to changes in soil moisture. Once planted in the soil, it exchangeswater with the surrounding soil thus staying in equilibrium with it.Soil water is an electrical conductor thereby providing a relative indication ofthe soil moisture status. As the soil dries, water is removed from the sensorand the resistance measurement increases. Conversely, when the soil isrewetted, the resistance lowers.The WATERMARK sensor is unique in that it takes its resistive measurementwithin a defined and consistent internal matrix material, rather than using thesurrounding soil as the measurement medium. This unique feature allows thesensor to have a stable and consistent calibration that does not need to beestablished for every installation.The relationship of ohm of resistance to centibars (cb) or kilopascals (kPa) ofsoil water tension is constant and built into the reading devices that are usedto interrogate the sensor. The sensor is calibrated to report soil water tension,or matric potential, which is the best reference of how readily available soil

This is a TEROS 12 sensor that measures soil moisture, temperature, and electroconductivity with Modbus digital output. This sensor is fit for a range of soil types and EC levels so you can be confident in the accuracy of your data. This sensor features a 1.01 liter volume of influence.

The TEROS 12 soil moisture sensor combines METER’s well-tested 70 MHz circuitry, a rugged epoxy fill, and salt-resistant, securely attached stainless steel needles that easily slip into soil. Low power consumption and high resolution provide increased precision over long periods of time. 

RTD sensing element 1/3DIN Pt100, with four-wire connection, Pt100 output or electrical signal in current or voltage (4 to 20mA or 0 ÷ 2Vdc), or in digital output on RS485/Modbus (with external interface). The sensing element is protected by a series of screens against direct sunlight and UV radiations, arranged to guarantee a natural ventilation to ground level. Its particular white reflective colour, cancels the warming effect induced on the sensing element, ensuring maximum accuracy. The sensor is manufactured according to WMO (World Meteorological Organization) standards.