Journal of Applied Sciences1812-56541812-5662Asian Network for Scientific Information10.3923/jas.2009.3335.3342RezaeiM.NaeiniS.A.R. Movahedi122009918The rate of K^{+} release from soils can significantly influence K^{+} fertility of soils. The objectives of this study were investigated the effect of different calcium concentrations (0, 0.028, 0.057, 0.085, 0.128 and 0.171 mg L^{-1}) and different ammonium concentrations (0, 40, 60, 90, 120 and 140 mg L^{-1}) on potassium isothermal desorption kinetics of diluted suspensions of a soil, the Iranian natural clinoptilolite zeolite and their incorporation (within 2 and 1800 h), application of some kinetic models and correlation between potassium desorption kinetic coefficients of the best models with the calcium concentration. Potassium desorption was initially fast (first 192 h) with Ca^{2+} and NH_{4}^{+} addition and continued during next stage (192-1800 h) with low speed until the end of the experiment. Also, increasing the Ca^{2+} and NH_{4}^{+} solution concentration increased the potassium desorption in all of treatments. The potassium released from NH_{4}^{+} treatments was more than Ca^{2+} treatment in equal equivalent of Ca^{2+} and NH_{4}^{+}. Zeolite decreased K^{+} desorption rate by incorption with soil. The kinetic equations used to estimate data were zero order, first order, simple Elovich, parabolic diffusion and power function. The Elovich model described the desorption processes on soil and soil+zeolit and zeolite in NH_{4}^{+} treatment (0.6282<0.990). Elovich, first order, zero order and power function models described desorption processes, respectively for zeolite well (0.872<0.97). The models indicated that K^{+} desorption was diffusion controlled. Result shows that zeolite release K^{+} slowly.]]>Aharoni, C. and D.L. Sparks,1991Aharoni, C., D.L. Sparks, S. Levinson and I. Ravina,1991Allen, E.R. and D.W. Ming,1995Carter, D.L., M.D. Heilman and C.L. Gonzalez,1965Chapman, H.D.,1965Cooney, E., N.A. Booker, D.C. Shallcross and G.W. Stevens,1999Dhillon, S.K. and K.S. Dhillon,1990Guo, X., L. Zenga, X. Li and H.S. Park,2008Havlin, J.L., D.G. westfall and S.R. Olsen,1985Jalali, M.,2006Jalali, M.,2007Jardin, P.M. and D.L. Sparks,1984Kithome, M., J.W. Paul, L.M. Lavkulich and A.A Bomke,1998Kittrick, J.A. and E.W. Hope,1963Klute, A.,1986Lopez-Pineiro, A. and A.G. Navarro,1997Martin, H.W. and D.L. Sparks,1983Mehra, O.P. and M.L. Jackson,1960Mustscher, H.,1995Rezaei, M. and S.A.R. Movahedi Naeini,2009Rezaei, M. and S.A.R. Movahedi Naeeni,2008Rezaei, M., D. Akhzari, A. Keshavarzi, M.Z. Alaedin, V. Taheri and S.A.R. Movahedi Naeeni,2008Rhoades, J.D.,1996Schouwenburg, J., Ch. Van and A.C. Schuffelen,1963Scott, A.D.,1968Selim, H.M. and M.C. Archer,1997Sparks, D.L.,1989Sparks, D.L. and W.C. Liebhardt,1981Rao, S.S., A. Swarup, A.R. Subba and V. Goptal,1999Steffens, D. and D.L. Sparks,1997Tehrani, R.M.A. and A.A. Salari,2005Walkley, A. and I.A. Black,1934Weatherley, L.R. and N.D. Miladinovic,2004Wilson, G.V., F.E. Rhoton and H.M. Selim,2004Zhou, J.M. and P.M. Huang,2007