Mehlich 3 method as substituent to the HCl method for extraction of copper and zinc in soils from Southern Brazil with high levels of organic matter/Metodo Mehlich 3 como substituinte ao HCl para extracao de cobre e zinco em solos com alto teor de materia organica do sul do Brasil

In this study were compared two methods of extraction of copper (Cu) and zinc (Zn) in soils with organic matter (OM) higher than 50g [kg.sup.-1]. The extraction methods compared were: Extraction with HCl O.lmol [L.sup.-1] (standard method for the states of Rio Grande do Sul and Santa Catarina) and Mehlich 3. This work was performed at the Laboratory of 5011 Chemistry and Fertility, Santa Catarina State University (UDESC), in 2009. The two extraction methods were applied to 286 soil samples from the Soil Analysis Public Laboratory of UDESC, all with more than 50g [kg.sup.-1] OM. The copper and zinc in extracts were determined by flame atomic absorption spectrometry. The results showed significant correlation between the methods, Cu (r=0.80) and Zn (r=0.93). The solution Mehlich 3 extracted more copper and less zinc when compared to the solution of HCl 0.'mol [L.sup.-1]. The Mehlich 3 proved to be efficient in the extraction of copper and zinc in soils with high OM content, which may replace the current method.