Cadmium, Copper, Lead, Nickel and Zinc Concentrations In Tomato and Squash Grown In MSW Compost-amended Calcareous Soil

Abstract

Vegetables grown in compost containing cadmium, copper, lead, nickel, and zinc in low concentrations should be safe for human consumption unless the crop acts as a bioaccumulator. The effects of amending soil with compost products made from municipal solid waste (MSW) on cadmium, copper, lead, nickel, and zinc concentrations in tomato and squash were investigated. For each crop, three inorganic nitrogen treatments were applied 1) 72, 2) 143, or 221 kg N ha−1 for tomato 1991 and 1992 and 40, 80, or 120 kg N. ha−1 for squash 1991 and 1992. Each fertilizer treatment was subdivided into three MSW compost treatments. For the compost treatments, the following products were incorporated into calcareous limestone soil at rates suggested by the manufacturers: 1) Agrisoil compost, a processed MSW, at 48 t. ha−1, 2) Eweson co-composted MSW and biosolids at 24 t. ha−1, or 3) no MSW compost. The experimental design, strip-split plot with four replications was conducted in 1991 and repeated in 1992. Compost treatments were applied annually prior to tomato transplanting in the winter. After the tomato crop was harvested, squash was grown on the same plots with no further addition of compost. Soil amended with Agrisoil had the highest concentration of Cd, Cu, Pb, Ni and Zn in tomato and squash, except for Cd in squash 1992 and Cu in tomato and squash 1992, as compared with the control. Although extractable metals in the soil increased with higher loading rates, there was no significant changes in fruit concentrations due to compost treatments. Therefore, neither tomato nor squash acted as metal bioaccumulators. Use of these compost sources at the manufacturers recommended rates should be suitable for producing vegetables for human consumption.