Using Decagon EC-5sensors for monitoring soil moisture

The aim of the study. To assess the possibilities of using the Decagon EC-5 sensor in research practice, especially under the conditions of its stationary installation; and to study with its help the dynamics of soil profile moistening and moisture migration under different weather conditions. Location and time of the study. The study was carried out on the territory of the Ust-Kamensky (forest-steppe) research station of the Institute of Soil Science and Agrochemistry of the Siberian Branch of the Russian Academy of Sciences (55.005507 N, 83.858635 E). The object of the study was the dark gray forest soil (Luvic Greyzemic Phaeozem). Five Decagon EC-5 sensors were installed at 9, 13, 18, 22 and 27cm depths in a small (30cm deep) soil pit and connected to the Em50 recorder. The necessary calibration was carried out beforehand. The sensors functioned from June 13 to July 7, 2017. Main results. The study showed that this device is suitable for a wide range of applications. According to the sensor readings, it was possible to trace the migration of moisture within the soil profile, as well as to differentiate it into gravitational and capillary water, as well as to establish the fact of precipitation with an accuracy of an hour and to calculate the precipitated amount. Statistical analysis of the obtained data showed low values of data variance and the coefficient of variation, which indicated high data homogeneity. The use of these sensors can improve the traditional flood method for determining the maximum soil water holding capacity. Moreover, detailed recording of soil moisture, provided by Decagon EC-5 sensors, in combination with Thermochron sensors for soil temperature recording, allows to study quantitative indicators of thermal gradient moisture flux at a new level. Conclusions. The study showed that Decagon EC-5 sensors comply with their technical specification and have good prospects for usage both in research and agricultural production. Provided its preliminary calibration and producing the calibration curves for the studied soils, the sensors allow quick and accurate measurement of the soil volumetric moisture content. The frequency and rate of sensor readings takes research on the dynamics and migration of moisture in soils to an entirely new level.