MileSight EM500-SMTC is a wireless sensor designed for monitoring soil condition, by measuring soil temperature, relative humidity and electrical conductivity; and transmitting data using LoRaWAN® technology.

With low power consumption and a high capacity internal battery, the EM500-SMTC can work up to an estimated 10 years depending on transmit frequency.

What is soil moisture? 

Soil moisture is simply the amount of water captured and contained within soil. It is dependent on a range of factors, including precipitation or irrigation, temperature, humidity and soil type.

Each soil type (Loam, Sandy and Clay) holds moisture differently. It’s important to know your soil type and understand it’s characteristics to help interpret soil moisture readings. The moisture state of soil is estimated by measuring several conditions, including soil temperature, soil humidity and electrical conductivity.  

How to interpret the data? 

The EM500-SMTC can only measure 1 litre of soil around, therefore best results are obtained by burying the sensor probe in a representative area with the major soil type, typical terrain and average yield to get accurate results. 

The EM500-SMTC has four output metrics:

• Temperature in °C. Most crops require soil temperatures of 10°C.
• Moisture in RH% (Relative Humidity). Most plants grow best with relative humidity of over 50%, with optimal range between 50% - 60%.
• Electrical Conductivity in µs/cm (microSiemens per cm). 

Electrical Conductivity 

Electrical conductivity serves as an indicator of soil salinity, which, in turn, reflects the concentration of salts in the soil. Very high EC values of >16000µS/cm is an indication of strong saline soils while EC values below 2000 µS/cm show poor or non-saline soil. 

Optimal EC range is 1100 µs/cm to 5700 µs/cm with the average soil EC being 3028.12 µS/cm.