ABSTRACT
Field experiments were conducted to monitor the Mo concentrations in wheat (Triticum vulgare) and alfalfa (Medicago sativa L.) grown on two acidic mine spoils amended with fly ash. Changes in plant-available Mo were determined by three extraction methods: (1) Grigg’s reagent (acidified ammonium oxalate), (2) Dowex 1 x 8 anion exchange resin, and (3) 0.1 M NaOH. Molybdenum concentrations of wheat and alfalfa plants grown during the first year on fly ash-amended mine spoils were > 10 mg/kg and Cu to Mo ratios were < 2. These levels of Mo and Cu to Mo ratios in feed for cattle or sheep would be considered hazardous and require Cu supplementation. Alfalfa grown on fly ash-amended plots were higher than those of the control plots. Soil Mo concentrations determined by an anion exchange resin and 0.1 M NaOH were related to Mo concentrations of the crops; however, Mo extracted by Grigg’s reagent was not significantly related to concentrations of Mo in plants.
