Previsão da salinização e sodicização em solos regados com águas salinas com uso de indicadores de qualidade do solo

Mestrado em Gestão e Conservação de Recursos Naturais - Instituto Superior de Agronomia / Universidade de ÉvoraThis work aims to predict the salinization and sodification in two soils when irrigated with saline waters combined with different fertigation levels. In a three years period, two experimental fields were set up with maize irrigated with a Triple emitter source (TES) irrigation system. The impact in the two soils (Hortic Antrosol and Eutric Fluvisol) was assessed through soil solution and soil samples collected at the end of each irrigation cycle and after the fall/winter rainfall washout of the soil. Electrical conductivity (EC) was used as a salinity indicator, and the exchangeable sodium percentage (ESP) and sodium adsorption ratio (SAR) were used to characterize soil sodicity. In order to predict soil quality, the relationship between such indicators were studied with a stepwise multiple regression analysis scheme in a total of 1500 observations. An exchangeable Na+ mass balance was established for each treatment to 60 cm depth, as the difference between the final and initial total masses. The results confirm that t the Fluvisol shows a tendency towards salinization, since insufficient Na+ lixiviation occurred throughout the soil profile even after the fall/winter rainy season. The Antrosol however showed favourable to salts lixiviation after the irrigation cycles and more so after the rainfall season