Heavy metals production and content in lettuce fertilized with urban waste compost

Abstract

The objective of this work was to evaluate the effect of urban waste compost period of incorporation on soil pH changes and on heavy metals production and leaf content in lettuce grown in different soils. The experiment was set up in a complete randomized block design. The treatments were arranged in a factorial scheme 3 x 2 x 3, with three replications, corresponding to the samples of three soils (a sandy clay loam Red-Yellow Oxysol - LVA_FAA; a sandy loam Red-Yellow Oxysol - LVA_FA; and a loamy sand Quartzipsamment - RQ), two periods of incorporation of urban waste compost (1 and 2 months) and three levels of soil pH (original pH and pH adjusted for 6.0 and 7.0). Fresh and dry matter weights of the shoots were measured as well as soil pH and
Cd, Cu, Ni, Pb e Zn concentrations in soil and plant. The addition of urban waste compost increased soil pH, with the largest incorporation time, promoting the largest pH increases. Fertilization with urban waste compost did not make lettuce inappropriate for human consumption.