Comparison between electro‐ultrafiltration and extraction methods for the determination of k fractions in some soils of southern Italy

Abstract

Nine K‐rich soils belonging to three Orders often found in Southern Italy (Inceptisol, Alfisol, Vertisol) were extracted with H₂O, CaCl₂, NH₄OAc, HCl, Mehlich, HNO₃ reagents for K and the results were compared to the EUF method. Significant correlations between the reagent extracted K and EUF K were found. The results allowed us to distinguish three basic K fractions: (i) actually available, (ii) quickly released reserve and (iii) slowly released reserve. The EUF provided both quantitative and qualitative data, suitable for a “dynamic” diagnosis of K soil fertility saving time and reagents. The EUF curves showed an unexpected strong K affinity for Inceptisol, the soil which was richest in K.

Key words:

• EUF K
• K availability
• K extractions
• South Italian Soils