ROLE OF WATER IRRIGATION ON POTASSIUM RELEASE IN SOME CALCAREUS SOILS OF NORTHERN IRAQ

Abstract

A laboratory study was conducted to determine the effect of irrigation water quality on capacity and rate of potassium release in some calcareous soils in Nineveh province. It was constructed by miscible displacement technique with natural un disturbed soil columns using chlorine and sulfuric water of two different textured soils from location of Zummar of clayey and Sheikh Mohammed of loamy silt texture for ten irrigation epochs on the basis of porosity volume (PV). Results indicated for presence values of desorbed potassium rate with increase of porosity volumes passed through soil columns. Sulfuric water caused more desorption of potassium in comparison with chlorine water. Desorption capacity rate were 1.93, 2.92 c.mole.kg-1 for Sheikh Mohammed and Zummar locations respectively by using sulfuric water, while desorbed potassium by using chlorine water for the same Soils were 1.12, 2.01 c.mole.kg-1. Mathematical description for desorption process appeared harmony of diffusion equation, power function equation, first order equation, zero order equation, while Elovitch equation did not describe desorption process with the same efficiency. K+ desorption rate due to diffusion equation by using chlorine water were 0.06, 1.2 c.mole.kg-1.min-½ for the Soil of Sheikh Mohammed and Zummar locations respectively, yet using sulfuric water increased desorption rate which were 0.14, 0.22 c.mole.kg-1.min-½ for the same locations respectively.