MSU Agriculture Innovation Day Soil Moisture Sensors Irrometer Sentek Irrometer can be the least expensive option, and a handheld reading tool can measure soil water tension in multiple sites, but not continuously. Watermark Monitor is a data logger that automatically reads and records up to 8 sensors at a selected interval. Tensiometer measures the actual soil water tension, which indicates the effort required by root system to extract water from the soil. Watermark Soil Moisture Sensor is a solid state electrical resistance sensing device, which is another method to measure soil water tension. Sentek can measure volumetric water content at multiple depths, and is sensitive. Measures volumetric water content from dry to saturation. Remote monitoring system. Measures soil moisture every 4 inch up to 4 ft depth. Uses Frequency domain reflectometry, which measures the soil dielectric by placing the soil between two electrical plates to form a capacitor. Converted from a scaled frequency reading using a default calibration equation. Sentek EnviroSCAN METER Group METER Group system is slightly more expensive, but not as much as Campbell Scientific system. This system is easy to set up (plug and play) and operate. EC-5 Low cost volumetric water content sensor, which is measured by dielectric constant of the media using capacitance/frequency domain technology. Affordable and ideal for large sensor networks. 10HS Large volume soil moisture sensor. Similar to EC-5 but better at averaging varying soil moisture. Tero12 Measures volumetric water content, electrical conductivity, and temperature. Robust steel needles for easy installation and better soil-sensor contact. Less than 1% sensor to sensor variability. Most expensive sensor among EC-5, 10HS, and Tero 12, but it is the most accurate. EM 60G Remote monitoring system. Six sensor ports. Built-in solar panel and rechargeable battery. Handheld reading tool Tensiometer Watermark Soil Moisture Sensor Watermark Monitor Campbell Scientific Campbell scientific is the most reliable and accurate system, but it is expensive and complex to set up. CR 1000 data logger collects and stores data and is reliable for extreme environment. This can be converted to a remote monitoring system with cellular modem and solar panel. CS 616 Measures volumetric water content from 0% to saturation. Is high accuracy and high precision (±2.5% volumetric water content) Uses time-domain reflectometry, which means the speed of an electromagnetic signal passing through a material varies with the dielectric of the material. CS 616 CR 1000 data logger Critical consideration Teros 12 EM 60G EC-5 10HS Sensor only measures within few inches of the sensor’s location. This means: Sensor must be installed in place where represents the field. Sensor installation must ensure good contact between sensor-soil, avoid air gap. MSU Contact Steve Miller, mill1229@msu.edu Lyndon Kelley, kelleyl@anr.msu.edu Younsuk Dong, dongyoun@msu.edu