Distribution of trace metals in some sandy soils under citrus production
1993
Zhu, B. | Alva, A.K.
Changes in soil chemical properties affect distribution of trace metals among various fractions of soils. Trace metals (Cu, Zn, Mn, Cr, and Pb) in the readily soluble (exchangeable plus sorbed), organically bound, precipitate, and residual forms were studied using seven sandy soils from Florida under intensive citrus production. In most soils, the readily soluble form of each metal represented a small portion of the total metal content. The organically bound and precipitate forms of Cu accounted for 44 to 73% and 17 to 48% of total Cu, respectively. Less than 100% of total Cu was present as the residual form. Major portion of Mn in these soils existed as the precipitate form and that of Cr as the residual form. Zinc and Pb were more evenly distributed among the organically bound, precipitate, and residual forms. An increase in soil pH increased the organically bound Zn and the precipitate form of Cu, Zn, and Cr while decreasing the organically bound Cu, Cr, and Pb and the readily soluble forms of Mn and Zn. An increase in total soil Cu content decreased the organically bound while increasing the precipitate form of Cu. The results of this study demonstrate that agricultural practices such as liming and fertilization changed the distribution of trace metals in soils, which will in turn affect their availability to citrus plants.
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