Seasonality in the quality of irrigation water in dams Acaraú River Basin, Ceará

Knowledge of salt concentration and consequently the quality of irrigation water is of utmost importance in irrigation management since it may limit its use , severely altering the chemical and physical characteristics of the soil . This study was conducted at Bacia do Rio Acaraú, located in the northwest of the state of Ceará. Five samples were collected over a year of six ponds in the region, in the period August 2009 to July 2010 and on each collection was performed using four replications with the end 120 samples throughout the period and all points were geo-referenced . Evaluated parameters were : electrical conductivity of water (ECw) , hydrogen potential (pH) , cations (Ca2 + , Mg2 + , Na + and K +) and anions . Generally waters containing high concentrations of bicarbonate ions, has a great tendency for precipitation of Ca and Mg , the waters of the dams studied in the period between September 2009 and April 2010 are , with normal irrigation except for the parameters calcium, magnesium , chloride and carbonate. This study shows the need for monitoring of the basin for decision making and development of agricultural activities and public policies for the better performance of local agriculture , since the climatic conditions prevailing in the analyzed region favor a higher risk of salinity and sodicity along the year from higher temperatures.