Asian Journal of Plant Sciences1682-39741812-5697Asian Network for Scientific Information10.3923/ajps.2005.164.170AzadMd. Abul Kalam IshikawaKatsumi ChowdhuryA.K. IslamNaima 2200542The research was undertaken in order to assess effects of different extraction periods to extract exchangeable zinc (Zn) in some soils of Bangladesh. Six soils from different sites in Bangladesh such as Tea soil, Madhupur soil, Ishurdi soil, Saline soil, Farm soil (Bangladesh Agricultural University, BAU) and poorly drained soil were collected for extracting zinc with various extraction periods using EDTA (ethylenediamine tetra acetate), HCl, ASI (Agro service international) and CH3COONH4 (ammonium acetate) as extractant materials. The six different extraction periods applied in this study were 1, 2, 4, 8, 16 and 24 h for the assessment of suitable period in releasing exchangeable Zn at maximum levels, was chalked out. The results showed that the maximum amount of Zn was extracted significantly from the maximum soils within the beginning hours (1, 2 and 4 h) of extraction period, although the quantity of Zn increased with the elapse of time up to 8 h, but these increments were not identically differentiated. An exception occurred in the poorly drained soil, this soil with all the reagents exhibited significant increments of Zn extracted by the periods from 1 to 8 h. The amount of exchangeable zinc extracted by CH3COONH4 increased gradually along with the extraction periods up to 4 h and then the changes were not significantly happened with the rest experimental periods (8, 16 and 24 h). The average amount of extractable Zn was higher by HCl and lower by ASI, as well as the highest concentration of extracted Zn observed with the minimum extraction period of 4 h in applying the maximum reagents for all the soils. The results apparently suggest that the 4 h extraction period could be considered as suitable for extracting zinc, cause it exposed the maximum extraction of exchangeable soil Zn compared to other periods.]]>Keller, C., S.P. McGrath and S.J. Dunham,20023115501560Berti, W.R. and L.W. Jakobs,19962510251032Krebs, R., S. K. Gupta, G. Furrer and R. Schulin,1998271823Norvell, W.A. and R.M. Welch,1993Hordeum vulgare L. Cv. Hearta): Studies using an N-(2-hydroxyethyl) ethylenedinitrilotriacetic acid-buffered nutrient solution technique. I. Zinc ion requirements.]]>101619625Whatmuff, M.S.,20024010411056Cabral, A. and G. Lefebvre,1998102329344Luo, Y.M. and P. Christie,199827335342Martinez, C.E. and H.L. Motto,2000107153158Shuman, L.M.,19992814421447Dutta, D., B. Mandal and L.N. Mandal,1989147187195Tucker, T.C. and L.T. Kurtz,195519477481Sakal, R., B.P. Singh, A.P. Singh, R.B. Sinha, S.P. Singh and S.N. Jha,196834191193Sakal, R., A.P. Singh, B.P. Singh, R.B. Sinha, S.N. Jha and S.P. Singh,198533672675Sakal, R., A.P. Singh, B.P. Singh and R.B. Sinha,198479417428Trieweiler, J.F. and W.L. Lindsay,1969334954Stewatr, J.A. and K.C. Berger,1965100244250Kirtick, J.A. and E.W. Hope,196396319325Walkley, A. and I.A. Black,1934372938Kalembasa, S.J. and D.S. Jenkinson,19732410851090Blakemore, L.C., P.L. Searle and B.K. Daly,19871987Chowdhury, A.K., R.G. Mclaren, R.S. Swift and K.C. Cameron,19922314511459Barrow, N.J.,198637295302Chowdhury, A.K.,19901990Takkar, P.N. and M.S. Mann,197519420430McLaren, R.G., R.S. Swift and B.F. Quin,198427207217Haldar, M. and L.N. Mandal,197953203213Sauchelli, V.,1969Ponnamperuma, F.N.,1980