Empirical Approach of Leaching Curves for Determining the Efficiency of Reclaiming Saline-Sodic Soils in Sahl El-Tina, Sinai, Egypt

摘要

Columns experiment was conducted to determine desalinization and desodification leaching curves of a clay saline-sodic soil. Soil samples were collected from Sahl El-Tina plain, Northern Sinai Governorate, Egypt. Soil columns were amended with agricultural normal gypsum "NG", phosphogypsum "PG" and calcium chloride "CaCl₂.2H₂O". Gypsum Requirements (GR) were calculated according to USDA equation. Calculated amount of gypsum was mixed with whole soil matrix (30-cm). Leaching was done using intermittent ponding method so as to add portions to the already saturated soil columns; and obtained leachates equal to the added portions. Desalinization and desodification curves showed that all treatments reduced soil salinity and sodicity, with a superiority of calcium chloride in reducing soil salinity and sodicity. In addition, the Hoffman’s approach was adopted to estimate the leaching constant ( k ) of amendments. Desalinization and desodification curves showed that application of calcium chloride appears to have a strong effect on ( k ) values. The leaching constants ( k ) of control, NG, PG and CaCl₂.2H₂O gave averaged values of 0.39, 0.27, 0.25 and 0.19 for desalinization and 0.35, 0.28, 0.27 and 0.16 for desodification, respectively. The lower values of ( k ) in CaCl₂.2H₂O treatment depicted lower amounts of water required for leaching and reclamation compared to other treatments. This study suggests that Leaching curves represent a very good method to determine the efficiency of amendments and the optimum depth of leaching water needed for successful reclamation.