MICROELEMENT CONCENTRATIONS IN MARYLAND AIR-CURED TOBACCO

In an effort to expand the data base concerning heavy metal concentrations in Maryland tobacco and to acquire information on the nutritional status for Cu, 402 samples of cured tobacco collected on farms over the period 1980 to 1983 were analyzed for their Zn, Mn, Pb, Ni, and Cd contents, and the Cu contents were examined in 198 samples from 1982 and 1983. Mean concentrations for individual metals in mg/kg were: Zn (43.6), Cu (7.6), Mn (192), Pb (1.92), Ni (1.20), and Cd (2.26). Approximately 5% of the samples contained Zn, Cu, Ni, Pb, or Cd concentrations higher than expected for these elements in Maryland tobacco. Some 25% of the samples contained Mn levels within the range 332-2400 mg/kg which were likely caused by low soil pH conditions. A total of 5% of the cured samples were borderline deficient in Zn (less-than-or-equal-to 18 mg/kg), and 27% were considered deficient in Cu (less-than-or-equal-to 5.2 mg/kg). Problems associated with inadequate limiting programs and the use of croplands for municipal waste disposal were discussed.