DESALINIZATION OF AN IRRIGATED, MOLE-DRAINED, SALINE CLAY LOAM SOIL

Abstract

Desalinization of an irrigated, saline, clay loam soil that had been drained with unlined and lined mole drains, at 0.7 m depth, was determined during a 10-yr reclamation period. Within 5 yr the mean electrical conductivity (EC) of the surface 60 cm of soil, for about one-half of the plot area, had been reduced from greater than 8 to less than 4 dS m−1. The mean EC for the plot area at the 0- to 60-cm and 0- to 180-cm depths declined in a logarithmic order with time. Desalinization of the surface 30 cm of soil was greater under the unlined drain regime than under the lined, but at 30- to 120-cm depths, desalinization was greater under the lined. The salts were mostly sodium, calcium and magnesium sulfates. Although the unlined mole drains had an average discharge of 24% of that from the lined, the average salt discharged through the unlined drains was 80% of that from the lined ones. The lined drains removed more salts over a greater range of depths. Key words: Desalinization, reclamation, mole drainage, soil salinity