Uso do lodo de esgoto (biossólido) como fertilizante em eucaliptos: demanda potencial, produção e crescimento das árvores e viabilidade econômica / Use of sewage sludge (biosolids) as a fertilizer in eucalypts forest plantations: potential demand, production and growth of the trees and economic viability

AUTOR(ES)
DATA DE PUBLICAÇÃO

2007

RESUMO

This work evaluates the use of the residual sludge (biosolids) produced by sewage treatment units located in the Metropolitan Region of the City of São Paulo (MRSP) as a fertilizer in Eucalyptus grandis forest plantations. The aspects studied were potential demand, wood production response to the fertilization, trees growth and economic viability. A high level of potential demand was observed for the biosolids on forest eucalyptus plantations located at short ground transportation distances in the MRSP. It was also observed that biosolids, complemented by phosphorous and potassium at the planting stage, increased the growth rate of the trees, resulted in more wood output and reduced the rotation age at levels similar to those observed for conventional mineral fertilization. When evaluated 99 months after planting, it was observed that the highest dosage of biosolids did not result on the highest wood production output. The adjusted models can be separated in only two groups according to the statistical differences among them: (i) control and dosage 10 Mg ha-1; and (ii) all other treatments. The economic analysis (annualized net present value at 12% return rate) recommended dosage 5 Mg ha-1 complemented with K, for rotation lengths defined by the age that maximizes mean annual increment. The use of biosolids does not substitute totally the use of mineral fertilizers. Economically, it was confirmed that the highest biosolid dosages were not viable, due mainly to its high levels of water content and consequently high transportation cost.

ASSUNTO(S)

biosolids potential demand eucalyptus spp economic evaluation florestas biossólidos nonlinear models wood production eucalipto – viabilidade econômica modelos não lineares sewage sludge fertilizante orgânico eucalypts stands lodo de esgoto madeira – produção analysis of the growth crescimento vegetal – análise organic fertilizer

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