The exchange cation determination is very important into the vegetal nutrition; therefore, its correct determination has special relevance for the development of fertilization programs.The objective of this work was the comparing of three methods for extraction of Ca 2+ and Mg 2+ in soil samples.For that, 14 samples of soil were selected from departments Córdoba and Sucre.Four methodologies for the extraction of Ca 2+ and Mg 2+ were evaluated: CH3COONH4 1.0 N pH 7.0, BaCl2 + TEA 1 N pH 8,2, CH3COONa 1 N pH 7 and Mehlich-1 (H2SO4 + HCl).It was found that the method AcONH4 is that more extracts Ca 2+ , followed of Mehlich-1 method, showing values of 44.9 and 30.8 cmol(+)/kg, respectively.For the case of the Mg 2+ , the Mg 2+ content was seen to be overestimated by the use of method AcONa, with average from 22.9 cmol(+)/kg.For the other methods, very homogenous values were determined.Finally, a significant correlation between the standard method and the method of AcONa was established.