Plantios de pau-rosa (Aniba Rosaedora Ducke) estabelecidos em áreas com histórico de degradação por atividades agrícolas e pecuárias

Abstract

This study aimed to evaluate the soil-plant relations of commercial plantations of rosewood (Aniba rosaeodora Ducke) aged 4, 10 and 20 years, implanted over an area with a history of degradation by agricultural activities and cattle raising, located in Maués, Amazonas State, Brazil. We studied physical and chemical characteristics of soil and the nutritional status of the plant, the biomass of branches and leaves and the yield and quality of extracted oil. Plantings of 4 and 10 years are spaced at 3.0 m x 4.0 m, having 334 trees, and planting of 20 years having 200 trees, organized as 5.0 m x 5.0 m. For soil evaluation, it has been outlined five treatments: Soil poultry, planting of 4 years, 10 years of planting, planting of 20 years and a late secondary forest. Chemical analysis of soil samples were collected in five replicates for each treatment at four depths (0-10 cm and 10-20 cm and 20-30 cm and 30- 40 cm) and physical analysis of soil were taken in two depths (0-10 cm and 10-20 cm). To determine the biomass of the crown, were pruned to 100% of the canopy of 10 trees of each age, totaling 30 individuals. At the time of biomass collection, leaves samples were collected for the survey of nutritional status. The extraction of essential oil of biomass collected was made by steam distillation in the distillery in Maués and by hydrodistillation in the laboratory of Amazonia biomolecules, belonging to UFAM. The oil yield was determined from the weight of dry mass of twigs and leaves of rosewood and the weight of the oil extracted from this mass, as in Maués distillery, as in the laboratorial method. Oil quality was determined by gas chromatography and the analysis of chromatograms generated with observation of the levels of linalool. The results of soil analysis showed that the area which includes the planting of 4 years is distinguished from the other, especially regarding to the composition of particle size, higher clay content, higher levels of macro and micronutrients, lower soil density values and higher total soil porosity. Concerning other areas, the soil of the rosewood plantations is matched to the conditions found in fallow and secondary forest late. Due to the effects of spacing, the highest total biomass of the canopy of the rosewood trees per hectare was obtained in the planting of 10 years of age, with 35.15 ton ha-1, followed by the planting of 20 years with 24.73 ton ha-1, while the planting of 4 years has produced the lowest quantity, with about 17.92 ton ha-1. There were no statistically significant differences in oil yield, and on average were obtained in the laboratory and in the distillery 1.34% and 1.15% respectively. The content of linalool found was higher in the oil extracted from trees of 10 years, obtained from the distillery (88.05%), followed by the oil obtained from the planting of 20 years in the laboratory (83.87%). The lowest content of linalool was found in the oil extracted from the planting of 4 years of age in the oil obtained in the laboratory (73.19%). The content of essential oil and linalool on the branches and leaves, showed that it is profitable to extract oil from the pruning. In addition, the raw material of oil can be obtained from commercial homogeneous plantations on degraded areas and/or idle.