SOIL FERTILITY, NUTRITIONAL STATUS, AND YIELD OF SUNFLOWER FERTILIZED WITH SEWAGE SLUDGE

The disposal of sewage sludge in agricultural soils is of great concern. It can substitute mineral fertilizers, after a proper potassium supplementation, especially in crops such as the sunflower one. This study aimed to evaluate the grain yield and mineral nutrition of the sunflower cv. CATISSOL 01, as well as the fertility of an Oxisol fertilized with sewage sludge, in comparison to mineral fertilization, for two consecutive years. A randomized blocks design, with 4 treatments (control - mineral fertilization, 5 t ha-1 year-1, 10 t ha-1 year-1, and 20 t ha-1 year-1 of sewage sludge) and five replicates, was used. Grain yield, macro and micronutrients contents (in diagnostic leaves) and soil fertility were evaluated. The sunflower seeds yield was similar, in all doses, for both the sewage sludge and mineral fertilization, and macro and micronutrients contents in leaves were within the adequate range. The use of sewage sludge enriched with K showed to be effective for replacing totally or partially mineral fertilization, without affecting the sunflower yield.