Abstract
To study the effect of magnesium on cation exchange characteristics, soil samples were collected from salt-affected soils of five locations from Al-Jazeera northern irrigation project of Nenava province-Iraq. Cation exchange experiment between Ca and Mg in the presence of sodium was carried out to quantify the Mg on the accumulation samples with ten electrolyte solutions using chloride salts of NaCl, MgCl2.6H2O and CaCl2.2H2O with ratio of Na: Ca + Mg ranging from 1: 9 to 9: 1. the SAR ranging from (0-40) and the total concentration of the chloride solutions was 100 mmolcl-1. Revealing soils preference for calcium and magnesium was conducted by using electrolyte solutions with different Mg/Ca ratios. The results showed that the selectivity coefficient values of Mg-Ca ranged between (0.466-0.810) with an average 0.622 which reflect that Ca and Mg are not identical in their exchange behavior and the studied soils showed a preference for Ca in comparison with Mg. The examined soils had a tendency to accumulate exchangeable Na when Mg rather than Ca was the complementary cation, the Na-Mg systems had between 11.5-23.7% more exchangeable Na with an average of 19%.
