Aplicação de lodo de esgoto em latossolo distrófico: fertilidade e disponibilidade de metais pesados

Abstract

Sludge sewage is the residue obtained in sewage treatment. As sludge sewage usually contains high levels of organic matter and nutrients, its application in soil improve the chemical, physical and biological soil properties. Thus, the sludge can be used sustainably as agricultural fertilizer and soil conditioner of degraded areas. However, the composition of sludge may contain high levels of heavy metals, which can accumulate in the soil and contaminate the food chain. The maximum levels of heavy metals allowed in sewage sludge for agricultural use, as well as the maximum amount that can be accumulated in the soil, are established by CONAMA Resolutions n ° 375 and 380 of 2006. Therefore, an experiment was conducted in pots, with the application of sludge produced in Varginha, South of Minas Gerais state, in dystrophic Red Latosol, dominant in Alfenas. Were applied concentrations equivalent to 0, 60, 120 and 180 t ha-1 in a completely randomized design using lettuce as test plant. The sewage sludge has increased the levels of organic matter, cation exchange capacity, nutrients and the soil and plants is not contaminated with heavy metals. In addition, soil porosity was increased and its density, decreased, , indicating a high potential for recovering degraded soils, and conditioning and fertilizing agricultural ones.