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

EMJ Soil Oxygen Sensor MIJ-03

Environmental Measurement Japan (EMJ) is the original manufacturer of the EMJ Soil Oxygen Sensor MIJ-03.


・Can be used for long term observation with easy set-up.
・Automatic temperature compensation.
・No influence by the rain or other waters.
・Easy span calibration.
・Not require to do the zero calibration. 0% Oxygen = 0 mV output.


Difference between dissolved oxygen sensor and soil oxygen sensor MIJ-03

Dissolved oxygen Sensor:
Sensor that measures oxygen dissolved in water. The normal measurement range excluding supersaturation is 20mg/L measured in ppb units. In the case of permanent installation, be careful of electrode contamination.

Soil oxygen sensor MIJ-03:
Since soil is rarely flooded, an soil oxygen sensor MIJ-03 developed to solve the problem that the dissolved oxygen sensor cannot measure for long term measurement because dissolved oxygen sensor need water to measure oxygen. Since MIJ-03 structure does not care for direct contact between the electrodes and the soil so no maintenance need and permanent installation is possible. The normal measurement range is 0 to 20.9%. Soil oxygen can never be higher than 20.9% of atmospheric oxygen. As a special case, rice field have a period of both  flooding and drainage so both dissolved oxygen sensor and soil oxygen sensor MIJ-03 are often use together for this particular field.

Soil Oxygen Sensor MIJ-03 

MIJ-03 developed by our company Environmental Measurement Japan in April 2006. MIJ-03 soil oxygen sensor is used for the measurement of the root aspiration. MIJ-03 detects the density of oxygen in the soil by % order without any difficulties, it simply digs up the hole in the soil and lay this sensor into the ground. An usual usage of this sensor is laid in a vertical direction at intervals of 20 to 50 cm. Researchers can measure the vertical profile of the O2 in the soil.

Why we recommend the MIJ-03?

As above picture shown, MIJ-03 is built from a rigid thermoplastic, that allows long-term stability in most environmental conditions; thus it’s life time is maximum about 10 years.

Most users are not willing to maintenance the sensors; MIJ-03  is friendly to those users because it need only minimum maintenance. Once the sensor is installed in the soil, you do not need to care about maintenance.

MIJ-03 can be connected to EMJ data logger MIJ-12 or MIJ-01. If you have your own data logger you may be able to connect MIJ-03 Soil Oxygen Sensor; this is because it has a voltage output that can be supported by any compatible data logging system.


Figure 1.
Measured oxygen and pF at same time. Although there are fluctuations due to irrigation, it is interesting that it is not rapid.

Figure 2.
Data at north area of Hokkaido (Measurements of O2、CO2、PAR)

Theory Galvanic Battery + Porous membrane sheet
Shape 40mm, Length 78 mm (Cable support joint is 50mm height extra.)
Output 45 – 65mV at 20.9%O2 (Users must check the output at the air before set-up)
Weight 220 grams (Include cables)
Cable length 5m (+/white, -/Black, Shield cable)
Temperature effect At R.H. 100 % and O2 20.9%. Sensor output is 20.8% at 5, 19.4% at 40 degree. At R.H. 0% and O2 20.9%. It is not influence from the temperature effect.
Temperature 0 – 40 degree when in use