Fig. 4. Example of the evolution of the potential in the tension chamber apparatus for the peat substrate treatment using the tensiometer located on the upper plate (upper tensiometer, both corrected and uncorrected), and the tensiometer located at the bottom of the cylinder (lower tensiometer) showing five drainage response curve. The data from the upper tensiometer was corrected by adding a positive pressure value corresponding to the suction associated with the column height to eliminate the effect because of this hanging water column on the upper tensiometer reading.