The work was conducted in the Experimental Area of Guaro, belonging to EPICA Holguin, with the aim of studying the Inter-cationic relationships in a Dark Plastic Gleyzoso soil. To do this we used the results obtained in 2002 and 2007 from the laboratory tests for soil samples taken at a depth of 0-20 cm, in the eight treatments of phosphorus experiment. Exchangeable cations were determined and calculated, taking as a starting point the data, inter-cationic relationships in soil. The Ca / Mg and Ca / K + Mg are in the optimal range for these soils, secondly, potassium, for its small proportion in respect to the other two elements does not influence the variation of this ratio. The low values obtained below 0.1, in the relationship K / Ca and K / Mg deficiency indicate an exchangeable potassium deficit.