USE THE THERMODYNAMIC CRITERIA FOR EVALUATES OF POTASSIUM AVAILABILITY IN CALCAREOUS SOILS FOR THE MIDDLE EUPHRATES REGION

	USE THE THERMODYNAMIC CRITERIA FOR EVALUATES OF POTASSIUM AVAILABILITY IN CALCAREOUS SOILS FOR THE MIDDLE EUPHRATES REGION
Euphrates Journal of Agriculture Science
Article 1, Volume 5, Issue 3, 2013, Pages 217-226
Abstract
The study included potassium availability in Calcareous soils for the Middle Euphrates region. Results of thermodynamic criteria showed that ionicactivity ranged between 0.0013 -0.0071mol l-1, the intercept ΔK range betwee 0.10-0.60 Cmol kg-1. The results show that the soil which releases significant amounts of potassium fixes smaller amount of it as in soils of (Al-kadi and Al-suhalah and Al-Mashrou, Al-Kwauss and Al-Dagharah); these soils contains the Smectite clay mineral. Soils of (Al- Rushdiyah, Al-Glees) were low in Smectite and high in Mica clay minerals and they fix potassium more than the released quantity. The Al- Abbasiyah soil behaves in between. Potassium intensity was between 1.77 and 2.59 for the surface layer and between 2.07 and 2.76 for the sub layer. The studied soils were classified into soils of convenient potassium level (Al-kadi, Al-suhalah, Al-Mashrou, Al-Kwauss) and soils of deficient potassium level (Al-Rushdiyah, Al-Abbasiyah, Al-Glees, Al-Dagharah). Values of free energy within the range -2930 to-3930 cal mol-1. According to Woodruff, 1955 all studied soils suffer from potassium defiency except the soils of (Al-Kwauss, and Al-Mashrou) where potassium supply was sufficient. Gapon cocnstant was between 1.3 – 31.1 mol -1 l ½. Potassium of all soils of medium availability.

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