STP01 soil temperature sensor

Improved accuracy & quality assurance

STP01 soil temperature profile sensor offers an accurate temperature difference measurement at five measurement locations at 0.02, 0.05, 0.1, 0.2 and 0.5 m below the soil surface. It also has a well specified and fixed distance between the measurement locations. STP01 contains 5 matched thermocouples, at locations A to E in figure 5, and one reference temperature sensor (Pt100 type) at location E at 0.5 m depth. By having the reference temperature measurement in the sensor and only measuring differential thermocouple voltages (relative to the reference  at 0.5 m), the uncertainty of the  temperature difference measurement is very low: ± 0.02 °C is attainable. Simple copper-conductor signal wire is used in STP01’s cable. As an extra, a heating wire is incorporated in STP01. Analysis of the temperature change during the heating interval serves as a self-test. Soil temperature sensors are preferably left in the soil for as long as possible, so that the soil properties become representative of natural conditions. Using self-testing, the user no longer needs to take sensors to the laboratory to verify their stable performance. The result is a much improved accuracy & quality assurance of the measurement relative to measurements with conventional sensor types.