Plant-Soil Interactions of Chromium
1984
James, Bruce R. | Bartlett, Richmond J.
Corn (Zea mays L. ‘N6A4C2’) and dwarf horticultural beans (Phaseolus vulgaris L. ‘common’) were grown in the growth chamber in a Typic Eutrochrept A horizon soil amended with Cr(OH)₃, tannery effluent, and tannery sewage sludge each at two levels, with and without citric acid added. Water-soluble Cr(VI) and Cr(III) were measured in unplanted soils periodically during the growth period and in bulk and rhizosphere soils of the planted treatments at harvest. Plant tops and roots were analyzed for dry weight and Cr. Soil separated from bean roots after 46 d of growth in a 10-mmol Cr(OH)₃ kg⁻¹ soil treatment contained less soluble Cr(VI) and more soluble Cr(III) than unplanted soil receiving the same Cr(III) treatment. The bean roots and tops in this treatment had higher levels of Cr than did plants grown in unamended soil. The level of Cr in bean roots after 46 d was highly correlated (r² = 0.99) with Cr(VI) levels in unplanted soils 1 to 3 d after seeding. Adding citric acid to the soil significantly increased Cr levels in bean shoots and roots grown in the Cr(OH)₃ treatment. Compared with controls, levels of Cr in bean tops were not increased in treatments with tannery effluent (0.5 and 1.0 mmol Cr(III) kg⁻¹ nor with tannery sewage sludge (1.0 and 10 mmol Cr(III) kg⁻¹), but root levels were increased in these treatments. Dry matter yields of corn roots and shoots were lowered in the 10-mmol Cr(OH)₃ treatments more than were yields of beans. Chromium levels in the roots and tops were increased in these treatments, especially if citric acid was added.
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