The ions in soil solution maintain equilibrium with the adsorbed cations in the exchange complex, therefore, the objective of present study was to evaluate the behavior, and to obtain estimates of data of the soluble salts, in four soils of Rio Grande do Norte, irrigated with waters of increasing levels of electrical conductivity (EC) and relationship of sodium adsorption (SAR), at the end of two successive cycles of melon cultivation. The study was conducted in a greenhouse at Mossoró, Rio Grande do Norte, with four soil types, traditionally used for cantaloupe production, irrigated with solutions corresponding to eight EC (100, 250, 500, 750, 1,250, 1,750, 2,250 and 3,000 µS cm -1 ) and two SAR (4 and 12 (cmol L -1 ) 0,5 levels with there replications. The EC, pH of the saturation extract were appraised and soluble cations were determined to calculate SAR. The increment of the salinity of the water promoted elevation of the pH, EC, and of SAR in soils.