The article presents the possibilities of using time-domain reflectometry (TDR) to determine the water content and electrical conductivity of mineral soil with biochar addition. The TDR method consists in measuring the time of electromagnetic pulse transmission and reflection from the obstacle back to the source point. The impulse is a step signal of voltage. The reflected signal contains information on the dielectric properties of the material being tested. Therefore, qualitative, and quantitative properties of the material can be detected. The tests were carried out using a mobile reflectometric device as an electronic humidity and conductive meter. Based on the obtained results, the usefulness of reflectometric methods in the study of the water content and electrical conductivity of mineral soil was determined.