1.Andrew, N.S. 1989. Relationship between Soil potassium forms and mineralogy. Soil Sci. Soc. Amer. J. 52: 1023-1028.
2.Andrist-Rangel, Y., Simonsson, M., Andersson, S., Öborn, I., and Hillier, S. 2006. Mineralogical budggeting of potassium in soil: A basis for understanding standard measures of reserve potassium. J. Plant Nutr. Soil Sci. 169: 605-615.
3.Andrist-Rangel, Y. 2008. Quantifying mineral sources of potassium in agricultural soils. Doctoral Thesis Swedish University of Agricultural Sciences Uppsala. 126p.
4.Andrist-Rangel, Y., Hillier, S., Öborn, I., Lilly, A., Towers, W., Edwards, A., and Paterson, E. 2010. Assessing potassium reserves in northern temperate grassland soils: A perspective based on quantitative mineralogical analysis and aqua-regia extractable potassium. Geoderma. 158: 303-314.
5.Asadian, O. 2003. Khalkhal-Rezvanshahr geology map, 1:100,000 scale. National Geological Organization of Iran. (In Persian)
6.Barre, P., Velde, B., Fontaine, C., Catel, N., and Abbadie, L. 2008. Which 2:1 clay minerals are involved in the soil potassium reservoir? Insights from potassium addition or removal experiments on three temperate grassland soil clay assemblages.Geoderma. 146: 216-223.
7.Basak, B., and Biswas, D. 2009. Influence of potassium solubilizing microorganism
(Bascillus mucilaginosus) and waste mica on potassium uptake dynamics by Sudan grass (Sorghum vulgare Pers.) grown under two Alfisols. Plant Soil. 317: 235-255.
8.Bertsch, P.M., and Thomas, G.W. 1985. Potassium status of temperate region soils,
P 131-162. In: R.D. Munson (Ed.), Potassium in Agriculture, ASA. CSSA. SSSA. Madison, WI.
9.Bouyoucos, G.J. 1962. Hydrometer method improved for making particle size analysis of soils. Agron. J. 54: 464-465.
10.Chapman, H.D. 1965. Cation exchange capacity. In: Methods of soil analysis. Part 2. Black, C.A. (ed.). American Society of Agronomy, Madison, Wisconsin, USA.
11.Chen, M., and Ma, L.Q. 2001. Comparison of three aqua regia digestion methods for 20 Florida soils. Soil Sci. Soc. Amer. J. 65: 491-499.
12.Dordipour, E., Khormali, F., and Alaeddin, M.Z. 2012. Investigating the availability and different forms of potassium in Gorgan region. Research Publication, No. 90-2-354. Gorgan University of Agricultural Sciences and Natural Resources. (In Persian)
13.Farshadirad, A., Dordipour, E., Khormali, F., and Kiani, F. 2011. Potassium forms in soil and its separates in some loess and loess-like soils of Golestan providence. J. Water Soil Cons. 18: 3. 1-16. (In Persian)
14.Gholizadeh, A. 2014. Yield evaluation of flue-cured tobacco genotypes with low chlorine absorption in Aliabad area, Golestan Province. Tirtash Research and Education Center. Iranian Tobacco Company. (In Persian)
15.Hatami, H., Karimi, A.R., Fotovat, A., and Khademi, H. 2013. Investigating the effect of grain size and extractant type on the different forms of potassium in micaceous minerals and potassium feldspars. J. Water Soil Cons. 20:1. 115-132. (In Persian)
16.Helmke, P.A., and Sparks, D.L. 1996. Lithium, sodium and potassium, P 551-574.
In: Sparks, D.L., Page, A.L., Helmke, P.A., Loeppert, R.H., Sultanpour, P.N., Tabatabai, M.A., Jhonston, C.T. and Sumner, M.E. (eds.), Methods of soil analysis, part 2, Chemical and microbiological properties. Soil Science Society of America. WI. USA.
17.Hosseinifard, S.J., Khademi, H., and Kalbasi, M. 2010. Different forms of soil potassium
as affected by the age of pistachio (Pistacia vera L.) trees in Rafsanjan, Iran. Geoderma. 155: 289-297.
18.Hosseinpur, A., Kalbasy, M., and Khademy, H. 2000. Release rate of nonexchaneable potassium from soils of GillanProvince.
Iran. J. Agric. Sci. 35: 2. 347-355. (In Persian)
19.International Potash Institute Bulletin 11. 1988. Fertilizing for high quality and yield tobacco. International Potash Institute. Bern/ Switzerland.
20.Iranian Tobacco Company. 2014. Agricultural Statistics Iranian Tobacco Company.
(In Persian)
21.Khabbaz-Nia, A.R., and Sadeghi, A. 2003. Sari geology map, 1:100,000 scale. National Geological Organization of Iran. (In Persian)
22.Khan, H.R., Chowdhury, M.S., Elahi, S.F., Hussain, M.S., and Adachi, T. 1993. Potassium status and release characteristics of twelve floodplain soils of Bangladesh. Soil phys. Cond. Plant Growth. Jpn. 68: 15-24.
23.Knudsen, D., Peterson, G.A., and Pratt, P.F. 1982. Lithium, sodium and potassium.
P 225-246. In: A.L. Page et al. (Eds.), Methods of Soil Analysis. Part 2, American Society of Agronomy, Madison, WI.
24.Loganathan, P., Dickson, A.A., and Isirimah, N.O. 1995. Potassium supplying capacity of soils formed on different geological deposits in the Niger delta region of Nigeria. Geoderma. 65: 109-120.
25.Malakouti, M.J., and Homaee, M. 2003. Soil Fertility of arid and semi-arid regions. Second edition. TarbiatModaresUniversity Press, 494p. (In Persian)
26.Martin, H.W., and Sparks, D.L. 1985. On the behavior of non exchangeable potassium in soils. Communications in Soil Science and Plant Analysis. 16: 133-162.
27.Mc Grath, S.P., and Loveland, P.J. 1992. The soil geochemical atlas of England and wales. Blackie Academic and Professional, Glasgow.
28.Page, A.L., Miller, R.H., and Keeney, D.R. 1982. Methods of soil analysis, chemical
and microbiological properties, Part 2. Agronomy Monographs, ASA-SSA, Madison, WI. Pp: 581-593.
29.Rao, B.K.R., Bailey, J., and Wingwafi, R.W. 2011. Comparison of three digestion methods for total soil potassium estimation in soils of Papua New Guinea derived from varying parent materials. Communications in Soil Science and Plant Analysis, 42: 1259-1265.
30.Reiman, C., Siewers, U., Tarvainen, T., Bityukova, L., Eriksson, J., Giucis, A., Gregorauskiene, V., Lukashev, V.K., Matinian, N.N., and Pasieczna, A. 2003. Agricultural soils in northern Europe. A geochemical atlas. E. Schweizerbart'sche Verlagsbuchhandlung, Stuttgart, Germany, 279p.
31.Richards, J.E., and Bates, T.E. 1989. Studies on the potassium-supplying capacities of southern Ontario soils: III. Measurement of available K. Can. J. Soil Sci. 69: 596-610.
32.Salardini, A.A. 2006. Soil Fertility. University of Tehran Press. 434p. (In Persian)
33.Salminen, R., Chekushin, V., Tenhola, M., Bogatyrev, I., Fedotova, E., Tomilina, O., Zhdanova, L., Glavatskikh, S.P., Selenok, I., Gregorauskiene ,V., Kashulina, G., Niskavaara, H., Polischuok, A., and Rissanen, K. 2004. Geochemical Atlas of Eastern Barents Region. Elsevier, Amsterdam.
34.Sharpley, N.A., and Smith, S.J. 1988. Distribution of potassium forms in virgin and cultivated soils of the U.S.A. Geoderma. 42: 317-329.
35.Smolders, E., Brans, K., Foldi, A., and Merckx, R. 1999. Cadmium fixation in soils measured by isotopic dilution. Soil Sci. Soc. Amer. J. 63: 78-85.
36.Soil Survey Staff. 2010. Keys to soil taxonomy, eleventh edition. U.S., Department of Agriculture. NRCS.
37.Tophighy, H. 1995. Kinetics of nonexchangable potassium release from paddy soils of north ofIran. Comparison and evaluation kinetics equations of first order, zero order and parabolic diffusion.
Iran. J. Agric. Sci. 4: 26. 27-40. (In Persian)
38.Walkley, A., and Black, I.A. 1934. An examination of the Degtjareff method for determining soil organic matter and a proposed modification of the chromic acid titration method.
Soil Science. 37: 29-38.
39.Yang, T.Z., Ming, L.L., Wei, X., and Jin-hua, F. 2007. Characteristics of potassium- enriched, flue-cured tobacco genotype in potassium absorption, accumulation and in-ward potassium currents of root cortex. Agricultural Sciences in China. 6: 12. 1479-1486.
40.Zamani Pedram, M., and Hosseini, H. 2004. Gorgan geology map, 1:100,000 scale. National Geological Organization of Iran. (In Persian)
)