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Journal of Environmental Quality Abstract - Plant and Environment Interactions

Bioavailability of Biosolids Molybdenum to Soybean Grain


This article in JEQ

  1. Vol. 30 No. 5, p. 1653-1658
    Received: Oct 16, 2000

    * Corresponding author(s): gao@ufl.edu
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  1. G. A. O'Connor *a,
  2. T. C. Granatob and
  3. N. T. Bastac
  1. a Soil and Water Science Dep., Univ. of Florida, Gainesville, FL 32611-0510
    b Metro. Water Reclamation District Greater Chicago, 6001 W. Pershing Rd., Cicero, IL 60804
    c Dep. of Plant Soil Sciences, Oklahoma State Univ., Stillwater, OK 74078


Legumes grown in biosolids-amended soils and then fed to ruminants can represent problematic sources of molybdenum (Mo), but few field data are available to quantify the risk. We used a set of fields amended to high cumulative biosolids Mo loads (>18 kg ha−1) over 27 yr to generate additional data. Soybean [Glycine max (L.) Merr.] was grown on 29 fields (pH values >6.8) amended to a wide range of soil Mo loads. Soybean grain harvested from each field was analyzed for Mo and the concentrations regressed against soil Mo loads estimated from actual soil Mo concentrations in the 0- to 15-cm depth. Slopes of such linear regressions represent uptake coefficients (UC values) used by the USEPA to assess risk of biosolids Mo to ruminants fed forage grown on biosolids-amended land. The UC value for all 29 fields was estimated as 1.66, which agrees with the few soybean grain data in the literature. The UC value, however, is well below a conservative UC value of 4, recently recommended for all fresh legume materials fed to cattle. Soybean grain can contain high concentrations of Mo (>10 mg kg−1) and have low (<2:1) Cu to Mo ratios, which can exacerbate molybdenosis problems in cattle. However, soybean grain normally constitutes only ∼10% of dairy cattle diet, and other constituents (e.g., corn grain, stover, mineral supplements) are sufficient, or can be manipulated, to control molybdenosis.

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Copyright © 2001. American Society of Agronomy, Crop Science Society of America, Soil Science SocietyPublished in J. Environ. Qual.30:1653–1658.