Evaluation of the chemical properties of an eutrophic Red Latosol (oxisol) treated with sewage sludge for two consecutive years

Abstract

The disposal of sewage sludge has been one of the most relevant urban environmental problems nowadays. This work evaluated the effects of sewage sludge application on the chemical properties of an eutrophic red latosol, for two consecutive years. The soil samples were obtained from an experiment conducted on the Universidade Estadual de Londrina School Farm, Paraná, Brazil. The experiment was carried out in the field, using a randomized block design with 3 replications, with the following treatments: without fertilizers, with mineral fertilizers and with organic fertilizers containing sewage sludge in increasing doses: 6, 12, 18, 24 and 36 t.ha^-1,on a dry base. The pH, Ca⁺⁺, Mg⁺⁺, P, K⁺, C.T.C., V%, organic carbon and productivity of the maize, were determined during the evaluations. The correction of the soil acidity remained the same once the sewage sludge/ mud application was stopped. The results showed that soil acidity, CTC, V%, Ca⁺⁺, Mg⁺⁺ e P contents in the soil as well as organic carbon and maize productivity increased according to the sewage sludge doses applied to the soil. The best results were achieved in the area which received 36 t.ha^-1 / year