In Brazil, several municipalities are building waste treatment plants and in the future thousands of tons of sewage sludge will be generated. Sewage sludge is the waste left over after wastewater treatment and its disposal needs to be well planned, considering sanitary, environmental, economic and social implications. Sewage sludge (biosolids) is high in organic content and plant nutrient and could be applied as fertilizer in forest plantations. The aim of this research, conducted at the Experimental Station of Itatinga (University of São Paulo) was to evaluate the effects of increasing doses (10, 20 and 30 tons ha-1) of wet and dry biosolids(pellets), complemented with K and B, and applied to planting rows in experimental Eucalyptus grandis plots 1.5 years after seedling plantation. Trunk volume increased significantly regarding the eucalypt trees that received wet and dry sewage sludge, compared to the control treatment (no fertilization), and a similar growth of eucalypt trees that received full mineral fertilization. Regarding mineral nutrition, a positive correlation was observed between doses of biosolids and P, Ca, and Zn concentrations in the leaves, but a negative effect for Mn and biosolid dose. The foliar concentration of all the nutrients in the biosolid-treated eucalypt trees remained within the limits observed in commercial plantations, with no signs of nutritional imbalance.
Sewage sludge; biosolids; foliar nutrition
