Management of salt-affected soils in the Nile Delta

Abstract

Salt-affected soils in the Nile Delta are formed as a result of climate and inappropriate soil management (secondary is important here because there is initial or primary salinity referring to the effect of parent material, but the Egyptian parent material is the mud which comes by the Nile stream and leached through 1,800 km, the distance between Egypt and Ethiopia). Irrigation water, water logging, and saline water intrusion of the Mediterranean are the three sources of different types of salt-affected soils in the Nile Delta. Saline, saline-sodic, and sodic soils have strong presence in the delta land and represent an average of 37% of the total cultivated soils. The south delta is threatened by sodicity according to the low-salinity soils and highly carbonated irrigation water, while the north delta contains the highest area of saline and saline-sodic soils reaching 46%. Poor drainage in addition to reuse of more than 10 billion cubic meters of saline drainage water supports the buildup of salinity and sodicity. Gypsum amendment (CaSO4·2H2O) associated with intermittent leaching is the common method used in reclaiming salt-affected soils in Egypt. Furrow irrigation and rice cultivation under ponding are another two methods to adapt and mitigate salinity and sodicity buildup in the delta lands. The dominant salts in the delta are saline and sodic soils are sodium sulfate (NaSO4) and sodium carbonate and bicarbonate (Na2CO3 and NaHCO3). The solubility of these salts decreases sharply with temperature decreases; accordingly the reclamation and leaching processes should be applied during the summer warm season only. Improving drainage and preventing industrial and sanitary wastes in agricultural drain is a must.