Influência da aplicação do lodo de esgoto (Biossólido) sobre a concentração e o estoque de nutrientes na biomassa do sub-bosque, na serapilheira e no solo de um talhão de E. grandis. / Influence of sewage sludge application (biosolids) on the concentration and stock of nutrients in the understory biomass, litter and soil in a stand of Eucalyptus grandis.

AUTOR(ES)
DATA DE PUBLICAÇÃO

2005

RESUMO

The increasing of urban population generates the need for an ecological and social acceptable disposal of sewage sludge produced by waste treatment plants. Therefore, the use of the sewage sludge (biosolid) as fertilizer and soil conditioner in forests plantations may be a suitable solution, becoming possible the increment of renewable wood production. However, previous studies are necessary to evaluate eventual impacts on environmental, such as the possible dissemination of pathogens in the ecosystem and the accumulation of heavy metals in soil and plants tissues, mainly in the understory species, that supplies foods and nutrients to herbivores. This paper had as objective to study the influence of the sewage sludge, 68 months after its application, in the stocks of nutrients of the "soil-litter- understory " system in experimental plots of Eucalyptus grandis located in the Experimental Station of Forest Sciences of Itatinga - SP (Cwa climate, according to Köeppen classification) and planted on Red-Dark Latossol, sandy clay loam texture. The stocks of nutrients were quantified in the soil, up to 60 cm of depth, also in aerial biomass of the understory vegetation and in the biomass of litter accumulated on the upper layer of the soil in the following treatments: T1 - control, T2 - application of chemical fertilizer and T3 - superficial application of 20 t/ha of sewage sludge + K (produced in the ETE of Barueri - SABESP) between the lines of eucalypts. It was been evaluated also, comparatively, concentrations of macro and micronutrients and heavy metals in grass/shrub species of the understory growing in the different treatments. Results showed that sewage sludge increased soil fertility manly for P, Ca, Zn and for pH and increased also the stocks of all soil nutrients, but the concentration of total heavy metals Cu, Ni and Zn had been similar to the treatment control. Also concentrations and stocks of N, P, Ca and Zn increased in the litter accumulated on the soil. Sewage sludge promoted the increment of understory aerial biomass and also increased concentrations and stocks of N, P, Ca, S and Cu in the monocotyledoneous species and K, Ca, B and Cu in the leaves of dicotyledoneous. Comparing the understory plants growing in the control, chemical fertilizer and sewage sludge treatments, it were not observed significant differences for macro end micronutrients and also for heavy metals concentrations between the species Piper aduncum, Cenchrus ciliaris, Urena lobata and Solanum palinacanthum. In general, addition of chemical fertilizer and sewage sludge to the soil did not affect significantly concentrations of heavy metals in understory vegetation, assuring for the herbivores the nutritional quality of the biomass, that integrate the food chain in the ecosystem. However, heavy metals monitoring in vegetal components of each species (mainly leaves and fruits), during its cycle of life, would be important to plan the adjusted forest management to avoid or attenuate futures impacts in the ecosystem.

ASSUNTO(S)

soils biomassa lodo de esgoto solos serapilheira biosolid-influnce biomass litter metals eucalyptus metais sewage sludge biossólido – influência eucalipto

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