Abdel-Aziz, W. H., Manal A. Abd Alla, Hassanin, A. H.E, Salwa S. El-Sayied( 2009). THE CHEMICAL FRACTIONATION OF SOIL IRON IN SOME EGYPTAIN
SOILS
J. Biol. Chem. Environ. Sci., 2009, Vol. 4(1): 751-764
Abstract: Twelve soil profiles representing the alluvial and calcareous soils of Egypt were investigated for the distribution and chemical fractions of soil iron as well as some relevant soil characteristics such as pH, ECe, OM, CaCO3 percentages and texture class. Statistical analysis was then preformed to correlate Fe fractions with soil constituents. The obtained data show that, total Fe content in the alluvial and calcareous soils ranged from 45000 to 64500 μg g-1, and 1150 to 23100 μg g-1 with average of 53293 and 5904.2 μg g-1, respectively. DTPA-extractable Fe varied from 4.5 to 20.65 μg g-1 and 1.6 to 3.5 μg g-1 with an average 10.47 and 2.98 μg g-1 in the alluvial and calcareous soils, respectively. A six-step sequential fractionation in the alluvial soils revealed that most of total Fe (4.5 – 7.78%) was present in the residual fraction. The percentages of soil Fe in the (soluble + exchangeable), carbonate, occluded and organic fractions varied from 0.001 to 9.94%, 2.29 to 8.95%, 0.2 to 0.89% and 0.38 to 2.0%, respectively. In the calcareous soils, Fe varied from,0.001 to 0.02%, 0.04 to 1.1%, 0.02 to 0.48%, 0.01 to 0.32% and 1.08 to27.83% for soluble +exchangeable, carbonate, occluded, organically and residual Fe respectively. Also, Fe fractions in the alluvial soils can be ranged in
the order: Residual > organic> occluded> water +exchangeable > carbonate In the calcareous soils the Fe fractions are very different being Residual> carbonate>occluded> organic> water + exchangeable. Factors affecting total, DTPA-extractable Fe and iron fractions were predicted through correlation coefficient which were computed and discussed.
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