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Bioavailability of Biosolids Molybdenum to Soybean Grain
Author(s) -
O'Connor G. A.,
Granato T. C.,
Basta N. T.
Publication year - 2001
Publication title -
journal of environmental quality
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.888
H-Index - 171
eISSN - 1537-2537
pISSN - 0047-2425
DOI - 10.2134/jeq2001.3051653x
Subject(s) - biosolids , agronomy , stover , forage , molybdenum , legume , soil water , pasture , environmental science , bioavailability , zoology , crop , chemistry , biology , soil science , environmental engineering , bioinformatics , inorganic chemistry
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.