Soils are enriched with potassium (K) in areas with intensive agriculture, increasing the risk of K being transferred to the groundwater through leaching. Potassium leaching prediction can play an important role in improving fertilizer use efciency, helping to better understand and manage K leaching, and mitigate K loss. By analyzing the relationship between K losses and K testing in soils, we may be able to identify change points for each K extractant, indicating that K leaching would be accelerated beyond these points. To evaluate the extractability and leaching of K from 51 calcareous soils, laboratory experiments were performed. Eight extractants, including barium chloride (BaCl2), calcium chloride (CaCl2), nitric acid (HNO3), distilled water (H2O), sulfuric acid (H2SO4), Mehlich 3 (M3), sodium chloride (NaCl), and ammonium acetate (NH4OAc) were used in this study. Column leaching experiments were also conducted to study K leaching using distilled water and 0.01 M CaCl2. Signifcant relationships were observed between K leaching and some extractable K and calculated degree of K saturations (DKS) using split-line model. Change points were calculated from the relations between diferent K extractants and diferent calculated DKS with K leaching, which could be very useful in predicting the rate of K leaching from soils. This study recommended using extractants such as CaCl2, HNO3, and H2O instead of other extractants, such as NH4OAc, which is a common K extractant, to assess the risk of K losses. The DKS was calculated for the frst time in this study and were ftted better than extractants with K leaching, and the DKS could also be recommended to use as an environmental indicator for evaluating the possible risk of K leaching.
