As a result of applying arsenicals as herbicides, desiccants, or soil sterilants, soil As levels can increase under some conditions. Three arsenicals, sodium arsenite, (NaAsO2), cacodylic acid, (hydroxydimethylarsine oxide), and MSMA (monosodium methanearsonate) were applied to bare soil at 1, 2, and 10 times the recommended maximum application rates. After incorporation, radishes (Raphanus sativus L.) and soybeans [Glycine max (L.) Merr.] were planted as indicator crops to assess the phytotoxicity of accumulated soil As residues. Soil As residues increased at all levels of application. However, only 50% of the As applied at 10 times the recommended rate was found after seven annual applications, regardless of the source. Total losses of As from the soil averaged 14 to 15% of that applied each year. At 10 times the recommended rate, As generally reduced radish and soybean yields, but seldom reduced yields at the two lower rates. Results indicated little danger of As residue accumulating to phytotoxic levels under normal application rates.
