The present study aimed at a determination of the formula allowing water content to be calculated for model degraded soil enriched with Biona-312 ion exchange substrate. To this end a mixture of sand and Biona- 312 was prepared which was monitored for water content changes. Moisture was determined both gravimetrically and reflectometrically (TOR method). To improve the reliability of the TOR method individual calibration was made. The specific calibration formula as polynomial of the third degree was found for water content determination in sand supplemented with Biona-312. The results confirmed the high potential of the TOR method in moisture monitoring, especially when individual calibration is done.