Abstract
This study was conducted to reveal the conditions and parameters which control dissolution and release of indogentic potassium in some Hammam Al-Alil soils northern Iraq, representing Aridisols order. Three pedons were selected having different soil series namely (462CCE, 453CCW and 451CCW). The study included using successive extraction with 6.25M HCl, under reflux conditions for 100 mint. to determe the amount and rates of release exchangeable and non-exchangeable potassium in some calcareous soil periphery of semictite and illite minerals according to the amount of release of mica-K. by using a kinetic diffusion parabolic equation. The results showed that amount of released potassium was reduced by increasing extraction time, and the variation in chemical, physical and mineralogical properties of the soil samples have a great effect on each amount, rate, and pathway reaction of potassium release between soil series, also the results showed that the pathway reaction of K-release consist of two segments according to the parabolic diffusion equation. The first segment represented exchangeable phase that was more than the second phase (non-exchangeable) in its amount and rate of release . Fertility evaluation of the results according to amount and rate of K-release from mica-K referred that all soils samples has a moderate reserve with low release rate, therefore the K-reserve of soils could be mapped by soil series using this method of classification such mapping would provide data on the extent availability of reserves in both short term (i.e.) the crop over a growing season and long term.
