Abstract: The aim of this study was to find potential ways of immobilization or remediation of molybdenum (Mo) contaminated agricultural soils. We employed industrial by-products including include biosolid and manure as amendments for Mo contaminated soils in the mining area. We evaluated the effectiveness efficiency of the two amendments on Mo immobilization by measuring the amount of extractable Mo in soils and Mo uptake by plants. The results demonstrated that, after 60 days of incubation, both amendments decreased the extractability of Mo in contaminated soils and demonstrated Mo immobilization efficacy. The decrease, however, was not significant compared to the control treatment, with manure performing better than biosolid. Both biosolid and manure could decrease Mo uptake by the shoots of alfalfa and ryegrass while increase their biomass at the same time. Therefore, we recommended that, for Mo contaminated soils remediation, the two by-products used in this study can each be applied alone or used in combination with other inorganic amendments to treat light to moderately Mo-contaminated soils.

Key words: soil, molybdenum, immobilization, biosolid, manure