LODO DE ESGOTO ESTABILIZADO APRESENTA CONDIÇÕES FITOTÓXICAS ADEQUADAS PARA A GERMINAÇÃO DO FALSO PAU-BRASIL

Abstract

Adenanthera pavonina L. is a forest species used for wood production, gardening, and recovery of degraded areas. The use of sewage sludge during the production of seedlings can collaborate to reduce costs, as long as the residue does not cause phytotoxicity to the species. Therefore, the objective was to evaluate the phytotoxicity of the stabilized sewage sludge with cultivation of Urochloa brizantha and, subsequently, composted in the germination and initial growth of A. pavonina, in concentrated extracts of 0, 2, 4, 6, 8, and 10% (v: v). The stabilization processes were efficient in establishing the initial seedling development. Germination and seedling growth were decreased by increasing the concentrations of both biosolids. The germination speed and efficiency were reduced mainly in concentrations above 6% of both residues. Despite this, between the stabilization methods, the composted sewage sludge had the lowest phytotoxicity, with a higher relative percentage of germination and root lengthening, compared to the cultivated sewage sludge. The germination index of the composted and cultivated sewage sludge was higher than 90% in concentrations of 2 and 4%, however, the composted sewage sludge was less phytotoxic, mainly in more concentrated extracts, of 8 and 10%. Thus, it is concluded that the concentrations between 2 and 4% of cultivated or composted sludge were more adequate for the germination and development of the seedlings.