Studies on Free Iron Oxides and Readily Available Iron in Red, Lateritic and Alluvial Soils of West Bengal

Department of Agricultural Chemistry and Soil Science, Bidhan Chandra Krishi Viswa Vidyalaya, Kalyani, West Bengal. Manuscript received 23 July 1975; accepted 14 November 1975 Four different methods have been employed for estimation of free iron oxides in red, lateritic and alluvial soils of West Bengal. In case of the alluvial soils maximal free iron oxides were removed by Jaeksoo's dithionite-citrate procedure (method-I). Deb's dithionite-tartrate (method-ll) and Truog's ammonium sulphide-oxalic acid (method-III) procedures extracted almost same quantities of free iron while Deb's photolytic acid ammonium oxalate (method-lV) one removed the least amount of it. For the red and lateritic soils the above order is : method-I > method-II> method-III>method-IV. The combined exchangeable ferrous, ferric and dilute acid soluble iron have also been determined In the above soils and effect of pH on the extraction of readily available iron by (N)- ammonium acetate have been studied. A steady decrease in the amount of Iron extracted with increase in pH of the equilibriated solution was observed in all cases