Swiss Chard and Alfalfa Responses to Soils Amended with Municipal Solid Waste Incinerator Ash: Growth and Elemental Composition

The effects of three municipal solid waste (MSW) incinerator ashes on soil chemical properties, plant growth, and elemental composition of Swiss chard (Beta vulgaris L.) and alfalfa (Medicago sativa L.) were investigated in greenhouse pot experiments. Ash rates of 13.1,16.2, and 26.7 g kg^-1 of soil, based on their available K content, were compared with K fertilizer, P fertilizer, P + K fertilizer, and nonamended controls. Plant dry matter production in ash-amended soil was similar to or greater than that in fertilized soil. Responses varied with crop and ash type, but increases occurred in MSW ash treatments for soil pH, soluble salts, extractable soil P, K, Ca, Na, Cu, Zn, Mo, Cd, and Pb, and plant tissue (leaf plus stem) concentrations of P, K, Ca, Mg, Na, B, Cu, Zn, Mo, and Cd. No phytotoxic effects were observed, but some alfalfa treatments exceeded livestock dietary tolerances for Mo (>5 mg kg^-1) and Cd (>0.5 mg kg^-1)·.