Níveis de fertilização e seus efeitos no crescimento, nas características da madeira e do carvão em clone de híbrido de Eucalyptus grandis x Eucalyptus urophylla

Abstract

This work was developed with the aim to evaluate the effect of mineral nutrition on growth characteristics, wood and charcoal quality of a hybrid clone of Eucalyptus grandis x Eucalyptus urophilla planted experimentally in fertilization essays. In this study, 264 six years old trees were used, planted in a spacement of 3 x 3 m, which came from the company APERAM Bioenergia, located in the upper Vale do Jequitinhonha, municipality of Itamarandiba, Minas Gerais state. Three experiments were evaluated: Experiment 1, called nitrogen fertilization, containing five treatments; Experiment 2, called phosphate fertilization, with nine treatments; Experiment 3, called potential fertilization, with five treatments. Experiments were evaluated considering a randomized blocks design in four repetitions (blocks). In the experiments, two trees were sampled per treatment in each block. Experiments were implanted in June 2005. On experiments 2 and 3 in November 2008 a complementary fertilization was made. Thus, treatments were evaluated considering initial fertilization, the effect of complementary fertilization, and a general assessment, in which all treatments were evaluated simultaneously before and after complementary fertilization. The assessment of experiments considered growth characteristics like basic density and estimate of dry mass, besides analysis of chemical and energetic composition and dimensions of wood fibers. Wood was carbonized and the produced charcoal was evaluated quantitatively and qualitatively. Results allow concluding that, in general, there was not effect of the fertilization on the wood and charcoal quality for the experiment with nitrogen, phosphorous and potential fertilization, although for growth characteristics of wood the effect of fertilization tended to increase in all experiments. For some characteristics, especially basic density, there was a tendency to reduction as nutrients content increased, and consequently a reduction on the estimate of dry mass. The content of total extractive and lignin tended to increase with nitrogen and potential fertilization. For charcoal there was no significant differences for the analyzed characteristics, however, complementary fertilization presented a slight reduction for characteristics of yield, apparent relative density, chemical and energetics of charcoal. However, applying complementary fertilization to evaluate wood and charcoal properties is not justifiable when considering the high cost of nutrients.