SPRAY RESIDUES AND CROP ASSIMILATION OF ARSENIC AND LEAD

Abstract

During the productive period of commercial orchards sub-stantial amts. of inorganic spray residue compounds accumu-late in their surface soil zones of 6-8 inches depth. Succeed-ing crops of such food and forage plants as can tolerate the presence of spray residue compounds and still make fair growth may rightfully be suspected of absorbing greater than normal amts. of spray residue elements, particularly of As and Pb. In that situation it is reasonable to assume some danger to the welfare of both human beings and livestock, for both will be consumers of crops grown under these abnormal conditions. A series of expts. extending over a 3-yr. period in the growing of both food and forage crops in commercial orchard soils was recently completed. The summary of analytical data shows substantial increases over the normal for both As and Pb in all crops that proved to be adaptable to this treatment. The shallow-rooted food crops were not adaptable. When judged, however, by established tolerances for Pb and As in foodstuffs, none of the food and forage crops produced in the soils of spray residue content could properly be condemned.