Will high usage of synthetic chelating agents eventually harm soils?

Abstract

To test the hypothesis that long‐usage of metal chelates on soils will eventually result in abnormal plant nutrition, bush bean plants (Phaseolus vulgaris L. cv. Improved Tendergreen) were grown in Yolo loam soil which had been equilibrated with high levels of DTPA and EDDHA as Na salts; the levels were 500 and 1000 ng/g for each. Two crops of plants were grown at different points in the leaching stages. Yields were not affected by the treatments. Several trace elements were elevated in leaves after partial leaching and, after apparent complete leaching, Mn was elevated in primary leaves of 3 of 4 chelate treatments but in only one of four treatments in trifoliate leaves. There was a residual effect on Zn and P in primary leaves but not in trifoliate leaves. There was no real indication of adverse effects of the high levels of chelating agents after they had been leached from the soil.

Key words:

• DTPA
• EDDHA
• chelate toxicity
• soil‐chelate interactions