WWRC 94-03
Comparison of Ammonium Bicarbonate-DTPA, Ammonium Carbonate, and Ammonium Oxalate to Assess the Availability of Molybdenum in Mine Spoils and Soils
Abstract
A variety of extractants has been used to assess the availability of
molybdenum (Mo) in soils. Most of the extractants have been studied from a
deficiency aspect rather than for soils with Mo toxicity, and none of them have
been used to extract available Mo from mine spoils. The purpose of this study was
to examine the potential of different chemical extractants for assessing the
availability of Mo in mine spoils and soils. One mine spoil and three soils were
treated with sodium molybdate and then subjected to wetting and drying cycles for
two months. These spoil/soils were extracted with ammonium bicarbonate DTPA
(AB-DTPA), ammonium carbonate, and ammonium oxalate solution for available
Mo. Crested wheatgrass (Agropyron cristatum) and alfalfa (Medicago saliva) were
grown in the spoil/soils in a greenhouse to determine plant uptake of Mo.
Additionally, four mine spoils and six soils were extracted and analyzed for
available Mo as mentioned above. The results obtained by these three extractants
were highly correlated. It was found that ammonium oxalate extracts the greatest
amount of Mo among the three extractants from spoil/soils since it dissolves some
adsorbed Mo from Fe-oxide and Al-oxide. The changes in pH of spoil/soils did
not have a significant effect on the amount of Mo extracted by any of these
methods. The relationships between Mo uptake and Mo extracted by each method
were all significant at 1% level. None of the extractants were clearly better or
worse than the others. All three methods can be used to assess Mo availability,
and potential toxicity from plant uptake of Mo from reclaimed spoils.
Water Resources Publications List
Water Resources Data System Library |
Water Resources Data System Homepage
