Effect of subsurface drainage system on ground-water table, soil salinity and crop yield in Melka Sadi pilot drainage scheme
1996
Fentaw Abegaz (IAR, Addis Abeba (Ethiopia))
Subsurface drainage systems were installed occupying some 25 ha of alluvial soils in the Melka Sadi State Farm as a pilot drainage scheme to determine the effectiveness of subsurface drainage systems in controlling groundwater-table depth and soil salinity level for sustainable crop production during 1986 to 1990. The area consists of land affected by secondary salinization caused by the cumulative effect of capillary rise from the groundwater and poor irrigation-water management. Measuring the daily hydraulic head from the mid-drain piezometer, the groundwater-table depth was calculated and the result was plotted on the groundwater contour map. Comparison of this result with that of the pre-drainage contour map, revealed that the mean groundwater-table was maintained between the drainage criteria (1.5 m from ground surface) and the drain depth (2 m) during the growing season by the subsurface drainage system. The soil salinity status during the monitoring period in the pilot drainage scheme was investigated and the electrical conductivity (ECe) level was compared with that of the pre-drainage result (1983). In 1989 and 1990 average values of 66 percent and 78 percent, respectively, of the initial ECe of the whole soil profile had disappeared due to the subsurface drainage system.
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