ABSTRACT
More than 600 water samples from different aquifers in a semi-arid region of northeastern of Brazil were studied. The analyses were conducted using a database of the Laboratory of Analysis of Water and Soil Fertility of the Department of Soils and Geology of Escola superior de Agricultura de Mossoró. The analyses of physical and chemical properties allowed the evaluation of the quality of the water for irrigation using classic indexes in literature such as Index of Saturation of Langelier (ISL), Sodium Adsorption Ratio (SAR), SAR adjusted (SARaj) and corrected SAR (SARcor). A large number of water samples presented salinity problems and high amounts of sodium in relation to the bivalent cations Ca and Mg. The largest incidence of water with salinity and sodium problems belonged to tubular wells. Depending on the way the SAR was calculated, some water samples shifted class when the abacus developed by United States Salinity Laboratory was used.
Key words:
quality of water; irrigation; semi-arid; salinity; sodium