EFECT OF IRRIGATION AND USE OF ORGANIC URBAN RESIDUES ON GROWING EUCALYPTUS SEEDLINGS

Abstract

Even if not specifically for agricultural areas, the disposal of organic residues seldom occurs according to adequate specifications. In this context, the search for safer parameters for the use of these residues in order to allow the sustainability of ecosystems is increasingly important. The use of Urban Organic Solid Residue (UOSR) shortly after collection without the practice of composting techniques, submitted to desiccation, grinding and applied in soil, may be the solution to avoid contamination of the ground water caused by the concentrated and localized accumulation of this material either in the open or through the practice of composting techniques. Studies in Brazil and the world on the characteristics and possibilities of using Urban Solid Residue (USR), and more specifically UOSR, have not yet yielded information that would result in sufficient knowledge for making decisions, which are necessary to respond to immediate demands due to the increasing volume of residues produced. With the intention of contributing more information, the aim of this study was to examine the effects of irrigation associated with the use of UOSR on growing eucalyptus seedlings. This research was developed in the School of Agricultural and Veterinary Sciences - UNESP (Universidade Estadual de São Paulo) Campus of Jaboticabal. The statistical delineation used was fully random in a factorial design. Eleven substrata were formulated using two types of soil, a purple latossol and a dark red latossol, with and without chemical fertilization, six soil mixtures containing UOSR, and UOSR alone. In direct seeding in soil blocks, Citriodora Hooker eucalyptus seeds were used, using two water quantification methods to be applied through irrigation, class "A" tank methods and through weighing the substrata in four levels (50%, 75%, 100% and 130% of evapotranspiration). The data collected were statistically analyzed and show that mixtures with 20% or more of UOSR presented harmful effects on plant development, being more evident in doses above 20%, and irrigation based on the weighting method was more efficient in the production of eucalyptus seedlings through direct seeding.