Submitted to: Journal of Environmental Quality
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/7/2000
Publication Date: N/A
Citation: Interpretive Summary: Beneficial use of biosolids (treated municipal sewage sludge) as a nutrient source for corn production is an attractive alternative to landfilling or incineration of this material. Concern has been expressed about the development of molybdenosis [a molybdenum (Mo)-induced copper (Cu) deficiency] in ruminant animals consuming corn produced on biosolids amended soils. To address this concern, corn uptake of Mo was measured in long-term field experiments conducted in Illinois and Minnesota on soils receiving massive loadings of biosolids. Corn uptake of Mo was low or, in many cases, non-existent even at high soil Mo loads. Hence, molybdenosis risk to ruminants is small as corn Cu:Mo ratios exceeded 2:1, which avoids molybdenosis problems. This extensive data set and findings will be used by USEPA as they establish rules for beneficial agricultural utilization of biosolids.
Technical Abstract: This study was part of a larger effort to generate field data appropriate to the assessment of biosolids-Mo risk to ruminants. Corn (grain and silage) is an important component of cattle diet, and is a logical crop for biosolids amendment owing to its high N requirement. Paired soil and corn stover samples were collected from two unique field experiments to quantify ythe relationship (uptake coefficient, UC) between stover-Mo and soil-Mo load. Both studies utilized biosolids with total Mo concentrations typical of modern materials. Data from long-term (continuous corn) plots in Fulton County, IL confirm expected low Mo accumulation by corn stover, even at very high biosolids loads and soil Mo leads near 18 kg Mo ha**-1. Uptake slopes were actually negative, but UC values of 0.001 were assigned following EPA protocol. Data from plots in Minnesota yielded similarly low UC values for continuous corn, but greater Mo accumulation in corn grown following soybeans suggesting enhanced Mo bioavailability to corn in corn- soybean rotations. Nevertheless, molybdenosis risk to cattle consuming corn stover produced on biosolids-amended land is small as stover Mo concentrations were always low and stover Cu:Mo ratios exceeded 2:1, which avoids molybdenosis problems.