Fertilidade do solo, eficiência de utilização de nutrientes e produção de plantios de Eucalipto em função de diferentes espaçamentos, em Dom Eliseu, Pará.

Abstract

Growth, biomass production and nutrient use efficiency in E. grandis, E. grandis x E. urograndis and E. platyphylla clones, based on different plantation spacing of 18 months of age, in Dom Eliseu city, Pará, they were evaluated in a delineation of random blocks with factorial arrangement 3 x 4. In each experimental plot, were measured total height and diameter at breast height (DBH) of all individual on the useful area and, subsequently, was removed a tree with representative average diameter, in which it was proceeded with the quantifying biomass above the ground (leaves, dry and green twigs, wood and bark), with a subsequent sampling to determine the dry weight and chemical analysis. The nutrient use efficiency was determined through the comparison between biomass produced (kg) and nutrient content (kg). The highest average height (8,38m), was found in areas with higher density plantation, which was not observed significant differences between clones. The diameter was higher in less dense plantations (7.86 cm), and E. grandis represented a lower development of diameter compared to the others (6.74 cm). In general, the biomass allocation followed the order wood green twigs> leaves> bark> dry twigs with the best production founded in plantations with smaller spacing. E. urograndis produced more biomass of dry twigs and wood. E. platyphylla had the lowest dry material production of leaves and the three genetic material was not different related to production of bark biomass. In general, phosphorus and calcium nutrients were used, respectively, with greater efficiency and less efficiency independently of clone and spacing considered, except in the leaves where the lowest value of nutricional efficiency was observed to the nitrogen. In most assessments, the greater nutrient use efficiency was found in areas with the less planting space. Genetic materials were different in efficiency of utilization of different nutrients according to the length that was valued and the established spacing.