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Enabling better global research outcomes in soil, plant & environmental monitoring.

MP406C 4-20 Milliamp Sensor

The MP406C with integrated 4–20 mA output interface has an analogue current loop output of 4–20 mA which can be used directly by industry standard irrigation controllers and cabling power systems and hence is ideal for use in Parks and Gardens, Golf Courses and similar installations.

Measure volumetric moisture content of soils and other material for scientific research, agriculture and civil engineering.

The MP406 has a reinforced body and stainless steel needles making it ideal for use in extreme environments such as mine sites, landfills and saline soils as well as standard agricultural soils. The quality manufacture of the MP406 leaves it with a lifespan of 20+ years in the most extreme environmental conditions.

The MP406 is the best sensor available for any serious researcher or scientist to measure accurately the moisture of soils in the field. Measurements are not affected by temperature or salinity. The MP406 can be used to take continuous measurements over time through permanent or temporary burial and connection to a soil moisture meter (SMM).

The MP406 is also used to measure the moisture content in materials used in mining, roadway and buildings. The material that can be measured by the MP406 is often soil but can be any composition of non-metallic powdered, liquid or solid substance into which the needles are inserted. It is especially suitable for mineral stock piles, mine tailings and sand for batch mixing of concrete.

The MP406 Soil Moisture Sensor can also measure soil water potential via the SMM Soil Moisture Meter and a soil water characteristic curve.

MP406C Soil Moisture Sensor Features

  • 4 to 20mA applications
  • Volumetric Soil Water Content (%) or can simultaneously measure soil water potential
  • Highly accurate and precise
  • Robust, stainless steel needles and epoxy body
  • Measures in saline, toxic and high temperature soils
  • Rapid measurement
  • Can be buried for up to 20 years

 

mp406-tdr-01 mp406-oven-01

MP406 uses the standing wave principle of measurement. It is equivalent to a Time Domain Reflectometry (TDR) sensor without the need for a complex and expensive pulse generator. MP406 is a high accuracy, precision sensor with +/- 1% VWC accuracy following soil-specific calibration and 0.01% VWC resolution.

  • The MP406 is ideally supported by the Soil Moisture Meter (SMM), a wireless, stand-alone logging instrument available from ICT International. With the SMM, MP406 sensors can be individually calibrated for maximum accuracy.
  • The SMM can support up to 5 x MP406 sensors.
  • For complete monitoring solutions, the MP406 is used in combination with the MP306 soil volumetric moisture content sensor, tensiometers for soil water potential, ICTO2 soil oxygen sensor, or the ICT International automatic weather station.

MP406 Accuracy

The results from measurement of absolute volumetric soil water percent (VSW%) from prepared soil samples using the MP406 are given below (Figure 1). This result is typical of the results obtained from comparative testing of the MP406 in prepared soil samples, for a wide range of agricultural soils.

Standing Wave Technology and hence the MP406 are not affected by changes in temperature or salinity of the soil or material being measured and hence the values of VSW% are equivalent to oven dried water content.

What is Standing Wave?

The standing wave technique uses an oscillator to generate an electrical field in order to detect the dielectric properties of a substrate of interest. The parallel needles of an MP406 act as a coaxial transmission line to generate a signal. The amplitude of the signal is related to the dielectric constant which in turn is directly related to moisture content.

Results

The results from measurement of absolute volumetric soil water percent (VSW%) from prepared soil samples using the MP406 are given alongside. This result is typical of the results obtained from comparative testing of the MP406 in prepared soil samples, for a wide range of agricultural soils. Standing Wave Technology and hence the MP406 are not affected by changes in temperature or salinity of the soil or material being measured and hence the values of VSW% are equivalent to oven dried water content.

Polynomial Look-up Table

Linearisation tables can be added to Data Loggers using the following data:
Converting Data Table for MP406. From VSW% to mV & mA

Soil moisture VSW%
Millivolts Volts
0% 120 0.120
5% 210 0.210
10% 310 0.310
15% 415 0.415
20% 510 0.510
25% 610 0.610
30% 720 0.720
35% 825 0.825
40% 895 0.895
45% 955 0.955
50% 1005 1.005
55% 1015 1.015
60% 1025 1.025
65% 1035 1.035
70% 1045 1.045
75% 1055 1.055
80% 1065 1.065
85% 1070 1.070
90% 1080 1.080
95% 1095 1.095
100% 1106 1.106

 

MP406C 24V Soil Moisture Probe

Measurement

Measurement Range 0-100 VSW%
Accuracy +/- 1%
Resolution 0.01% VSW%
Response Time Less than 0.5 seconds
Stabilisation Time 3 seconds approximately from power-up

Interface

Input Requirements ICTMP406C-12 System: 10.5V~18V
ICTMP406C-24 System: 14V ~28V *Please note: Not compatible with 24V battery systems.
Power Consumption 4 to 20 mA

Mechanical

Total Length 210 mm
Needle Length 60 mm
Needle Seperation 12 mm
Needles Stainless Steel (Grade 316) – does not corrode in saline solutions
Exterior ABS Plastic
Cable 4.5m Standard

Other

Environment Designed for permanent or temporary burial

 

MP406C Barewire R1-1