Title page for ETD etd-11212012-040212
|Type of Document
||Response of corn to high levels of CuSO4 and ZnSOsub>4 applications
||Master of Science
|Martens, David C.
|McKenna, James R.
|Donohue, Stephen J.
|Hawkins, George W.
|Date of Defense
High levels of Cu and Zn application to agricultural soils are considered to pose a potential hazard
to plants and animals. The levels of Cu and Zn which can be safely added to cropland have yet to be established. This study was conducted on a Davidson silty clay (Rhodic Paleudult) to determine
the response of corn (Zea mays L.) to cumulative application of up to 469 kg Cu and 1032 kg Zn ha-1 as sulfates over the 22-year period from 1967 through 1988. Neither corn grain nor silage yield
was affected by the metal additions even though the cumulative amount of Cu and Zn added exceeded
the maximum allowable Cu and Zn loading rates based on the U.S. Environmental Protection
Agency guidelines (i.e., 250 kg Cu and 560 kg Zn ha-1) for this soil. The twenty-first
annual application of Cu as CuSO4, increased Cu concentrations in ear leaves. However, Cu concentrations
in ear leaves were unaffected by the twenty-second year of Cu application. Concentrations
of Zn in ear leaves were increased by the high level of Zn application during the two years
of the study. Twenty·f1rst year Cu and Zn concentrations in com grain were not increased by the
high levels of Cu and Zn sulfates. All grain and ear leaf Cu and Zn concentrations were within the
normal ranges from the high amount of metal application. The DTPA extractable Cu and Zn in
the soil increased with an increase in level of applied Cu and Zn. More Cu and Zn were extracted
from the soil by the Mehlich-3 method than by the DTPA method. This higher rate of extraction
was attributed to the ethylenediaminetetraacetic acid (EDTA) in the Mehlich-3 solution.
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