Classificação de águas de poços para uso em irrigação de acordo com a razão de adsorção de sódio (RAS)

Abstract

The main use of water in the country, in terms of quantity used, is for irrigation. For regions that suffer from continuous scarcity of water, as in Brazilian semiarid’s case, the installation of wells is an efficient way for obtaining it. However, wells built in crystalline soils tend to store saline waters. The effect of these salts over the characteristics of irrigated soils is of great importance for the maintenance of productive capacity. Therefore, the analyses of the physicochemical parameters are necessary in order to determine whether the water can be used without harm to the soil. That said, the present work aims to verify the sodium hazard and the salinity hazard of fifteen groundwaters from three regions of the State of Ceará. The hardness, calcium, magnesium, sodium and conductivity parameters were performed at the Laboratório de Química Ambiental in NUTEC. Using the sodium adsorption ratio and the conductivity, the water samples were classified according to their sodium hazard and salinity hazard. The obtained results show that groundwaters from Midwest and North Center regions can be used without presenting great risks, but for groundwaters from Northeast regions there is a very high risk of salinization and a substantial risk of sodification of soils, so these waters are not suitable for irrigation.