To identify the soil salinity and sodium risk, due to irrigation management, was carried out a comparative study of the Electric Conductivity (EC) and Sodium Adsorption Ration (SAR) values, between an irrigated area and an undisturbed land (MN). The investigation occurred at two Irrigated Districts: Baixo Acaraú (DIBAU) and Araras Norte (DIPAN) sited in Acaraú watershed, Ceará, Brazil. Soils samples were collected, in 0-30 m; 30-60 m; 60-90 m and 90-120 cm layers, in bimestrial period, from May/2003 to September/2005. Analyses were carried out at Embrapa Soil and Water Laboratory. To identify if the addition of salts in the soils were statistically significant the Wilcoxon paired test was applied. The EC increments were higher in DIPAN with an average of 250%, while in DIBAU the average reached 50%. The total rainfall registered in 2004 was enough to guide the irrigated soils in DIBAU to a similar condition of undisturbed land area. The same did not occur with the soil in DIPAN. The medium values of SAR increments in DIBAU were around 200%. An increasing of SAR was not registered at DIPAN. Therefore, the soils of DIBAU showed higher tendency to sodium problems, while the soils at DIPAN presented a higher risk of salinity. Despite of the registered increments, EC and SAR values were lower than those of salinity and sodium soils, respectively. Also, results showed that the action of rainfall in the leaching process of salts was higher at DIBAU, due to the soil texture (sand soils).
salinity; leaching; sodium adsorption
