Binary exchange of calcium, magnesium, potassium and sodium in calcareous soils in Kurdistan region of Iraq

Abstract

The objective of this research was to look into the binary exchange in four calcareous soils. The ion adsorption was carried by Batch equilibrium method used to saturate the soil samples with sodium, potassium, calcium and magnesium ions, separately, to get Sodium–Soil, Potassium–Soil, Calcium–Soil and Magnesium–Soil. The mean Kd (L kg–1) scores in various binary systems were arranged as follows: Calcium – Magnesium (18. 7) > Magnesium– Sodium(18.66) >Magnesium – Calcium (17.69) > Calcium – Sodium (15.59) > Magnesium – Potassium (14.31) > Calcium – Potassium (14.26) > Potassium – Sodium (6.5) >Potassium – Magnesium (6.32) > Potassium – Calcium (5.83) > Sodium – Magnesium (4.09) > Sodium – Calcium (4.01) > Sodium – Potassium (3.38).The average values of vanselow selectivity coefficients in different binary exchange systems of cation followed this order: Sodium – Potassium (9.88) > Sodium – Calcium (8.42) > Sodium – Magnesium (8.31) > Potassium – Sodium (5.92) > Potassium – Calcium (5.55) > Potassium – Magnesium (5.34) > Calcium – Potassium (3.17) > Magnesium – Potassium (3.07) > Calcium – Sodium (2.93) > Magnesium – Calcium (2.39) > Calcium – Magnesium (2.17)> Magnesium – Sodium (1.99).