The extractions of soil potassium (K) bychemical methods werecompared as predictors of plant-available K forpot-grownPinto beans (Phaseolus vulgaris) on Charmahal Va Bakhtyari-Iran soils. The treatments included two K levels [0 and 200 mg K kg-1 as potassium sulfate (K2SO4)] and 15 soils in a factorial experiment in a randomized block design with three replications.The result indicated that K application increased yield, K concentration and K uptake by bean. Relationships between methods werediscussed. The 8 extracting solutions used in this study wereclassified into3 groups on the basis of K extracted.The correlationstudies showed that 0.002 M SrCl2, 0.02 M SrCl2+0.05 M citric acid, and 1 M NaCl, could be used as available K extractants. Potassium critical levels by extractants were also determined by Cate-Nelson method. Potassium critical levels for 90% of relative yield were 38, 80, and 136 mg kg-1 for 0.002 M SrCl2, 0.02 M SrCl2 +0.05 M citric acid, and 1 M NaCl, respectively.
