Especially in treatments T1 and T4 its value was almost twice the control. On the contrary, for soil S2 potassium leached from the treatments was lower than the control, and particularly for T1 and T2. The outcoming average potassium concentration was, at the most, 0.2% for S1 and 0.06% for S2 of the incoming concentration when spreading OMW (either treated or untreated), whereas it was the lowest using composted pomace. The average potassium con- centration eventually reaching water table was always negligible regardless of the treatments for both soils