Availability and fractionation of trace elements in arid calcareous soils

Abstract

Thirty seven soil samples were collected from seven agricultural regions in Saudi Arabia to investigate trace element availability and fractionation distribution. Di-ethylene tri-amine penta acetic acid extractable micronutrients ranged from 1.1 to 11.5 μg g-1 for Fe, 0.2-3.7 μg g-1 for Zn, 0.48-13.0 μg g-1 for Mn, and 0.2-3.7 μg g-1 for Cu. Based on published critical levels, Cu was sufficient for most crops in all soils. Four soil samples were low in Mn, 28 were low in Zn, and 31 were low in Fe. Fractionation of micronutrients (Fe, Cu, Zn, and Mn) in selected seven soil samples revealed that the exchangeable fractions were the smallest, with Zn and Cu below detection limits. Carbonate bound fractions showed the micronutrient concentrations in the order Mn < oxide bound