INDEXES OF SOIL COVER AND PHYTOMASS OF Stylosanthes guianensis cv. MINEIRÃO ON DEGRADED LAND FERTILIZED WITH MINERAL FERTILIZER AND SEWAGE SLUDGE

Abstract

Sewage sludge, when treated and considered proper to agronomic application, is called biosolid and can be used to recover degraded areas, as an organic material source for soil conditioning and plant nutrition. The objective of this research was to evaluate the potential of sewage sludge produced by the Estação de Tratamento de Esgoto (ETE), in Goiânia, Goiás State, Brazil, enriched with 50% (v/v) of CaO and growth bio-stimulator, for recovering a degraded area. The evaluated variables were soil covering and the Stylosanthes guianensis cv. Mineirão yield. Eight treatments, in randomized complete block design, were evaluated, with four replications. The treatments were: control; mineral fertilizer; 20 Mg ha-1 of biosolid; 20 Mg ha-1 of biosolid + bio-stimulator; 40 Mg ha-1 of biosolid; 40 Mg ha-1 of biosolid + bio-stimulator; 60 Mg ha-1 of biosolid; and 60 Mg ha-1 of biosolid + bio-stimulator. Soil covering and productivity indexes showed no significant differences, if we consider the mineral fertilizing treatments and those with increasing levels of biosolid residues, in the absence of bio-stimulator. All treatments with bio-stimulator showed negative effects over soil recovering and S. guianensis productivity. The research suggests that the biosolid residues produced by ETE present appropriate characteristics for recovering degraded soil, replacing mineral fertilizing, as long as sanitary and environmental quality can be assured.

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