Comparative study of soil test methods for determination of plant available potassium in Bulgarian arable soils

This comparative study was aimed at estimating analytical behavior of methods for determination plant available potassium applied to Bulgarian arable soils and reveal the relationship between amount extractable K. Twenty-four samples from two traditional agricultural regions in Bulgaria were studied. Soil extracted by NH4OAc/HOAc pH 4.5 (AA), diluted double acid (Mehlich 1), CaCl2, BaCl2 a modified acetate/lactate method (ALM) determined Flame AES. The factors influencing accuracy identified uncertainty estimated. expanded (in mg K2O (100 g dry soil)-1): 0.10 (ALM), 0.64 0.17 (CaCl2) 1.1 (AA). revealed that factor which mainly influence soil calibration AES determination. obtained results showed lowered following order . ALM procedure correlated with AA, BaCl2-K, CaCl2 –K Mehlich 1 - K 0.05 level significance. 1.2 5.8 times more than other did. provided base further on correlation fertility indices particular types climatic Bulgaria.