Arsenic Phytotoxicity on a Plainfield Sand as Affected by Ferric Sulfate or Aluminum Sulfate1
- D. R. Steevens,
- L. M. Walsh and
- D. R. Keeney2
Repeated use of arsenic (As) salts in orchards, cotton, and tobacco fields occasionally has caused phytotoxicity. A study was initiated to evaluate the effect of periodic applications of sodium arsenite (NaAsO2) which has been used extensively as a defoliant to kill potato vines in Wisconsin commercial potato fields. Sodium arsenite was applied in 1967 to a Plainfield sand at rates varying from 45 to 720 kg As/ha. In 1970, these field plots were subdivided and treated with ferric sulfate [Fe2(SO4)3] and aluminum sulfate [Al2(SO4)3] to attenuate As toxicity, planted to peas (Pisum sativum L.) and potatoes (Solanum tuberosum L.), and yields compared with those obtained in earlier investigations. Arsenic toxicity persisted over a period of four cropping seasons. Pea yields on As-treated soil tended to be higher with an application of Fe2(SO4)3 and lower with an application of Al2(SO4)3, although yields generally were not significantly changed by either material. Potato yields were not affected by application of Fe2(SO4)3, therefore, neither Fe2(SO4)3 or Al2(SO4)3 were effective at the rate used in reducing toxicity. Potato tuber peelings contained up to 53.7 ppm of As, but regardless of treatment, the tuber flesh did not exceed 1 ppm. Ferric sulfate or Al2(SO4)3 did not have a consistent effect on the concentration of As in potato peelings or tuber flesh. The As content of As-treated soil increased in the subsoil but decreased in the plow layer during four cropping seasons. The increase in subsoil As was found to a depth of 38 cm and 68 cm for treatments of 90 and 180 kg As/ha and 720 kg As/ha, respectively. Even considering the downward movement, all of the As applied in 1967 as NaAsO2 was not accounted for in the soil profile (0–83 cm).Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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