A Study of potassium adsorption in some soils north of Dhi-Qar province in Iraq

Abstract

To study the phenomenon of potassium adsorption to some soils in northern Dhi-Qar Governorate / southern Iraq with different characteristics, which included agricultural and non-agricultural sites such as Al-Shatrah, Al-Nasr, Al-Dawaya, Al-Rifai, Qalat Sukar, and Al-Fajr, 1 g of soil was taken and potassium was added to it at levels (0, 20, 40, 60, 80). 100, 120, 140) mg L−1, prepared from potassium chloride KCl, and complete the volume to 50 ml with a solution of 0.01 M CaCl2. The concepts of thermal symmetry of adsorption equations were tested (Langmuir, Freundlich). The results of the study showed that the adsorption equations succeeded in describing the adsorption of potassium by soil samples, but these equations differed in their efficiency depending on the soil properties of agricultural and non-agricultural sites. The Langmuir equation was the most efficient in describing the adsorption of potassium by soil samples of non-agricultural sites because it obtained the highest values of the coefficient of determination R2 compared to the Freundlich equation. The results of the study also showed that the amount of potassium absorbed by the soil increased with the increase in the amount of potassium added to the balance solution, and the amount absorbed differed according to the characteristics of the soil and the sites studied. The values of the diffusion coefficient (Kd) decreased with an increase in the concentration of potassium added to the soil, and its value increased in the soil of non-agricultural sites compared to agricultural sites, where the value of (Kd) for the soil of non-agricultural sites ranged between (2.60 - 11.75) L kg−1 and for agricultural sites between (2.70-11.25) L kg−1.