The objective of this work was to define technical and economic parameters for biosolid use as fertilizer for soybean production. The soybean response to humid biosolid at rates 7.5, 15, 30 and 45 Mg ha-1 was compared to equivalent NPK applied as mineral fertilizer, in two crop seasons in a Rhodic Haplustox. Nine treatments were arranged in a randomized block design with three repetitions. Biosolid and mineral fertilizer were incorporated at once before the first crop. At the rate of 30 Mg ha-1 of humid biosolid, grain yields of 3,602 and 3,183 kg ha-1, in the first and second crops, respectively, showed the immediate and residual effects of biosolid application. The same trend was observed at 45 Mg ha-1 of biosolid. In economic terms, the best benefit-cost ratio (1.15) was obtained at 30 Mg ha-1. As for its agronomic fertilizer effect, biosolid was, in average, 18% more efficient than the mineral fertilizer. These results show the agronomic and economic viability of biosolid as a substitute of mineral fertilizer for soybean production.
Glycine max; sewage sludge; nutrients; fertilizer; economic evaluation
