Extractability of iodine from soils using different methods in relation to soil properties

Variations in the iodine distribution in soil may occur due to the different soil parameters. There is a general consensus that the extractability of iodine from soils can provide useful information on the bioavailability of iodine. The purpose of this study was to compare the results of three methods namely Kesari et al. (Chem Anal 43:201-207, Kesari et al. 1998) (KM), Sandell and Kolthoff (J Am Chem Soc 56(6):1426-1426, Sandell and Kolthoff 1934) (SK), and titration method (DeMaeyer et al. 1979) (TM) for the iodine determination in soils, under different types of use and management. Soil properties were correlated with the availability of iodine. Results showed that iodine contents were higher in the forest and pasture soils compared to the barren soil. A superior recovery of iodine was achieved by KM and this also showed a greater relationship of iodine contents with soil properties. The extractability of iodine contents was positively associated with cation exchange capacity (CEC) and organic carbon (OC) and negatively related to soil pH. The relationship of iodine with soil properties predicted the substantial effects of land uses on the extractability of iodine contents from soils. It was confirmed that iodine variations in soils were largely dependent upon soil properties as well as extraction methods.