Long Term Monitoring of Vegetative Response and Microbial Activity Upon the Addition of Amendments to a Metal Contaminated Mine Waste.

One of the method for stabilizing Pb and Zn contaminated waste materials is to establishing vegetative cover upon application of large quantities of organic matter with or without other soil amendments to improve all characteristics that enhances biogeochemical cycling of nutrients and help sustaining vegetative cover. A field study was set-up in Galena, Kansas covered with Pb and Zn contaminated mine waste materials. Beef manure compost was applied to the plots at two different rates (45 and 269 Mg ha-1) with and without lime and bentonite to investigate the changes in microbial activity. Switchgrass (Panicum virgatum) was seeded into plots to establish a vegetative cover. Enzyme activities measurements were used to monitor nutrient cycles upon amendment addition. Results from earlier investigations of the study indicated that large additions of beef manure compost improved microbial activity, and a healthy vegetative cover. Further monitoring was done to observe if the amended plots did sustain for a long period. The results showed the high compost treatment resulted the greatest increase in Switchgrass biomass. Treatments with high compost had much higher arylsulfatase and alkaline phosphatase activities compared to all other treatments, β-glucosidase activity was also high in high compost treatment when compared to other treatments. From the investigations it seems that the high compost treatments were successful in supporting higher biological activity and vegetative response as compared to the contaminated control and low compost treatments. Thus, use of high rate manure compost appeared to be an effective treatment for the long term stabilization of metal contaminated mine waste. Further monitoring may be needed to find if the amendments can support the sustainability of microbial ecology and plant cover for longer than four years.