Retention of metals in agricultural soils after amending with MSW and MSW-biosolids compost

The goal of this study was to measure the As; Cu, Fe, Pb and Zn contents of soils amended with municipal solid waste (MSW) and MSW-biosolids compost and to determine the long-term transport of these metals to lower soil horizons. Lead, Cu, Cd and Zn contents in the composts were 3-20 times more concentrated in the compost compared to the soil at the Calverton, NY, U.S.A. farm. As a result, Pb, Cd, Cu and Zn were elevated in the upper 5 cm soil layer following compost application and the metal enrichment was proportional to the amount of compost applied (21-62 Mg ha(-1)). In addition, Pb, As and Cu contents of the non-compost amended Calverton soils were enriched above the tillage depth (20-25 cm). Cu, Pb and As enrichment was attributed to the historical use of sodium arsenite, lead arsenate and copper sulfate insecticides and fungicides. Results of the metal analyses of soil cores collected 16 and 52 months following compost application showed that Cu, Zn and Pb remained confined to the upper 5 cm soil layer. The low water extractable fraction of these metals in MSW and MSW-biosolids compost was a major factor limiting the transport of these metals to lower soil horizons. In contrast, Cd leaching from the upper 0-5 and 5-10 cm soil layers was continuous over the 52 month study period and was attributed primarily to the presence of soluble Cd in phosphate fertilizer initially applied to the Calverton farm soil.