YIELD OF Stylosantes guianensis cv. MINEIRÃO AS A RESPONSE TO THE RESIDUAL EFFECT OF BIOSOLIDS IN DEGRADED AREA

Abstract

The present study evaluated the residual effect of sewer sludge produced in the ‘Estação de Tratamento de Esgoto’ (ETE), in Goiânia, Goiás State, Brazil, treated with 50% (v/v) of CaO and a bio-stimulator on the Stylosanthes guianensis cv. Mineirão fitomass yield, at two harvest dates. The first cut occurred 150 days after sowing, and the second, 273 days after the first harvest (423 days old). Eight treatments were evaluated: control; mineral fertilization; 20 Mg ha-1 biosolid; 20 Mg ha-1 biosolid + bio-stimulator; 40 Mg ha-1 biosolid; 40 Mg ha-1 biosolid + bio-stimulator; 60 Mg ha-1 biosolid; 60 Mg ha-1 biosolid + bio-stimulator. The experimental design was randomized complete blocks, with four replications. In the first harvest, the yield did not show significant differences between the mineral fertilization treatments and the treatments with increasing biosolid doses without bio-stimulator. All treatments with bio-stimulator showed negative effects on S. guianensis yield. In the second harvest, it was noticed a tendency to increasing yields for all treatments, except for the treatment that received chemical fertilization. The yield obtained in the treatments that received bio-stimulator were similar to the control and significantly lower than for other treatments. The results suggest the existence of a biosolid residual effect.

KEY-WORDS: Sewer sludge; biosolid; degraded areas; bio-stimulator.