Uranium (U) occurs naturally in low concentrations in rock, soil, and water. The background concentration of U in soil ranges from 0.3 to 12.0 mg kg-1. The U behavior in soils is very complicated, this because U can be associated with numerous compounds and phases and many factors affect its behavior in soil. The main goals of the present work were to evaluate different extraction methods for U from soil, find out which of these methods will best predict the plant uptake of U and investigate

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... e of the factors affecting the extractability of U and its availability for plants. Four soil sample groups were collected covering a wide range of U concentration in soils. Some of them were derived from previously conducted greenhouse, incubation and long term P fertilization experiments. The others were collected from the mining area of Schneeberg, Saxony. Acid ammonium acetate-EDTA (AAAc-EDTA), ammonium acetate (NH4Ac) at pH 7.0, diethylene triamine pentaacetic acid (DTPA), and soil solution obtained by centrifugation (7,000 rpm for 20 min) were used for U extraction. The U content in the solutions was measured by ICP-QMS. The results revealed that AAAc-EDTA, NH4Ac, DTPA and soil solution extractants had different capacities to extract U from soil. The AAAc-EDTA and NH4Ac were the best predictors for U uptake by maize, while DTPA and AAAc-EDTA extractants were the best indicators for the U uptake by sunflower. Maize had a lower ability to mobilize U into the soil after harvesting than sunflower and faba bean plants. The total U in soil found to be one of the most important factors affecting the extractability of U. Soil pH and P had inconsistent effects on the U extractability. Their impacts on the extractable U were depending on the samples source. The presence and the type of organic materials in soil had various effects on the availability of U. The effect of storage time was found to be one of the factors affecting the availability of U in soil.