Management of Salt-affected Soils in the NCEW "Shemshemia" Irrigation Scheme in Upper Gash Valley

To enhance food security and to develop sustainable agricultural production, large-scale irrigation schemes have been developed in the coastal plains and in the western lowlands of Eritrea.

DCG Report No. 20 | Mhereteab Tesfai, Virginia Dawod and Kiflemariam Abreha | March 2002

However, most of the irrigated soils in these areas are predominantly affected by salts presumably from the weathering of rocks and/or minerals containing salt compounds and/or the use of saline or sodium–rich groundwater for irrigation. Therefore, there is an urgent need to investigate and learn how to deal with the problem of salt-affected soils before larger areas are put under irrigation. In other words, managing the salt affected soils requires a detail description of the nature and properties of the soils and water.

Saline soils may be controlled with careful irrigation management, but sodic soils (with structural collapse) present a much more difficult management problem. Because the reclamation of sodic soils involves not only leaching out the soluble salts but also replacing exchangeable sodium with calcium and improving the physical properties of the soils. It is, therefore, essential that signs of developing SAS, particularly sodicity problems, be recognised at an early stage, so that preventative control measures can be put in place and on time.

The main objectives of this study are:

  1. To determine the extent and degree of soil and water salinity and/or sodicity in Shemshemia irrigation scheme;
  2. To recommend possible soil chemical, physical, and/or biological amendments in order to improve or reclaim the salt-affected soils;
  3. To produce an appropriate preventative checklist for unaffected sodic areas so as to prevent any future salt and/or sodium hazards in the Shemshemia irrigation scheme and its vicinity.

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