Monitoring and assessment of soil and forage molybdenum near an atmospheric source.
Forage and soil molybdenum (Mo) were measured in the vicinity of a Mo processing plant in southwestern Pennsylvania, USA. Molybdenum concentrations in red clover plants (Trifolium pratense L.), measured at 23 sites, ranged from 1.1 to 56.6 mg kg(-1). Fourteen of the 23 sites sampled had red clover plants with Mo concentrations over the threshold value of 6 mg kg(-1). Red clover Cu:Mo concentration ratios were below the recommended ratio of 4 in 19 of the sites. The low Cu:Mo values, along with high plant Mo concentrations, indicates that there is a potential risk of molybdenosis in ruminant animals in this area. Acid digested (sorbed) soil Mo concentrations, measured at 30 sites, ranged from 7.0 (background level) to 131 mg kg(-1). Using the Baker Soil Test (BST) extract, molybdenum soil concentrations ranged from 0.01 to 3.99 mg kg(-1). Regression equations were developed to predict plant uptake of soil Mo based on the red clover plant, soil extracts and soil pH data. The R-squared values for predicting plant uptake were 81.9% for the BST extract and 81.6% for the acid digestion extract plus soil pH. Based on the above results, a protocol has been implemented for assessing the risk of high soil Mo near this Mo processing plant.
The Soil and Environmental Chemistry Laboratory, Department of Agronomy, The Pennsylvania State University, 104 Research Building A, 16802, University Park, PA, USA.
M R
MR
Murray
D E
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Baker