Multisensor probe for soil monitoring

A probe for soil monitoring has been developed in this work. This instrument allows the measurement of three parameters: oxygen concentration, temperature, and relative humidity of the interstitial air in soil at root depth. The oxygen sensor is based on the quenching of phosphorescent octaethylporphyrin complex. A full description and characterization of the instrument are carried out. Their applications in an initial step under controlled conditions in the laboratory and then closer to real situations are also shown. First, the sensor probe was characterized inside a climatic chamber, then in a lysimeter. Finally, the instrument was tested in planted soil, for which it was buried in a pot containing an Ilex × meserveae (Blue Angel) tree. In the two first steps, the effects of temperature and humidity were studied, as well as response and recovery behaviour, detection limit, quantification limit, and time drift. In the last step, oxygen evolution during waterlogging experiments was determined with two different holly trees, one three years old and the other two years old; a comparison of the results for the two trees was performed.