The application of irrigation water with high contents of carbonate and bicarbonate can contribute to pH elevation of the soils after some years of cultivation. This study had as its objective the evaluation of the irrigation water with respect to its carbonate and bicarbonate content, based on the concept of the Equivalent Calcium Carbonate (E CACO3) in the region of the Chapada do Apodi and Baixo Açu in the state of Rio Grande do Norte, Brazil. Considering an irrigation water depth of 400 mm, the results showed that the waters of the region of the Chapada do Apodi presented larger values of E CACO3 compared to those of the region of Baixo Açu. In the region of the Chapada do Apodi, independent of the origin, largest values of E CACO3 were found for the waters of the region of Mossoró, with an average of 765 kg ha-1 and the smallest value was observed for Grossos and Upanema with 626 kg ha-1. For the region of Baixo Açu, independent of the origin of the waters, the region of Ipanguassu presented the highest values of E CACO3 with an average of 654 kg ha-1 whereas the smallest values were found for the region of Carnaubais, with 580 kg ha-1.
alkalinity; precipitation of carbonate; deficiency nutritional; soil pH
