Irrigation management and hydrosalinity balance in a semi-arid area of the middle Ebro river basin (Spain)

The analysis of irrigation and drainage management and their effects on the loading of salts is important for the control of on-site and off-site salinity effects of irrigated agriculture in semi-arid areas. We evaluated the irrigation management and performed the hydrosalinity balance in the D-XI hydrological basin of the Monegros II system (Aragón, Spain) by measuring or estimating the volume, salt concentration and salt mass in the water inputs (irrigation, precipitation and Canal seepage) and outputs (evapotranspiration and drainage) during the period June 1997–September 1998. This area is irrigated by solid-set sprinklers and center pivots, and corn and alfalfa account for 90% of the 470 ha irrigated land. The soils are low in salts (only 10% of the irrigated land is salt-affected), but shallow (<2 m) and impervious lutites high in salts (average ECe=10.8 dS m−1) and sodium (average SARe=20 (meq l−1)0.5) are present in about 30% of the study area.