Soybean yield and chemical attributes in soil after five-year surface application of slag, aqueous lime and sewage sludge

Abstract

The agricultural use of industrial residues and sewage sludge in order to provide essential nutrients to a plant and soil liming, will be one of the most promising alternative options of soil fertilization and liming management in a very near future, as far as these applications follow the prevailing technical norms to prevent eventual environmental contamination. The aim of this study was to evaluate the effect of slag, aqueous lime, sewage sludge and limestone, under surface application, on soil chemical attributes and soybean yield during a 5-year cultivation period. The experiment was carried out in dystrophic Clayey Rhodic Hapludox in no-till system from 2002 to 2007. The experiment had a 4x4+1 factorial random block design and 4 replications. The treatments consisted of centrifuged sewage sludge (CS), biodigestor sewage sludge (BS), aqueous lime (AL) and slag (SL) doses of zero (control), 2, 4 and 8 Mg ha-1 and one additional treatment of dolomitic limestone of 2 Mg ha-1. All treatments were applied on soil surface in 2002 and reapplied in 2005. CS, AL and SL wastes can be used as alternative materials of limestone in soil liming, presenting effects on pH and base saturation. Superficial application of wastes and limestone on soybean crop increased uptake of N and P in 2003, 2004 and 2005; K in 2003, 2004 and 2006; Ca in all studied years; Zn in 2003, 2004, 2005 and 2006, where applied the sewage BS. Superficial application of wastes increased soybean yield in 2003, 2004, 2005 and 2006; however, in 2007, this increase occurred only with the application of CS. Exchangeable heavy metals available in soil were insignificant and that contributed to the bioavailability absence of these toxic elements in soybean plants during all experimental years.