Submitted to: Composting and Compost Utilization International Symposium
Publication Type: Abstract only
Publication Acceptance Date: 5/6/2002
Publication Date: 5/4/2002
Citation: Interpretive Summary:
Technical Abstract: This report is an update on risk assessment for metals (Cd, Pb, As, Zn, Cu, Hg) in compost products used in agriculture or horticulture, and progress in our research to develop and demonstrate the use of Tailor- Made Composts to remediate metal phytotoxic soils. Research has increasingly illustrated the role of inorganic adsorption surfaces in composts and biosolids in adsorption of metals in the amendment and in amended soils. In general, hydrous oxides of Fe and Mn with high surface area can persist in amended soils, and limit solubility, phytoavailability, and bioavailability of soil metals including Zn, Cd, Ni, Cu, and Pb. Such products can also be used as effective Zn, Cu, Fe and Mn fertilizers if Fe and Mn are balanced for plant nutrition during addition of adsorption materials to composts. The ability of a Fe and Mn rich compost, biosolids, or manure to adsorb or precipitate soil metals and correct the severe infertility of metal mine wastes or smelter contaminated land can provide comprehensive remediation of a metal phytotoxic site if sufficient limestone or alkaline byproducts are added to keep the site calcareous. The combination of alkalinity, sorption, and plant nutrients reduce solubility of Zn, Cd, Pb, Ni, and Cu, preventing phytotoxicity and reducing bioavailability of soil metals to animals which ingest soil. Highly effective revegetation of long dead smelter or mine waste killed ecosystems was achieved at numerous locations.