The Inorganic Composition of Tachigali vulgaris Wood: Implications for Bioenergy and Nutrient Balances of Planted Forests in the Amazonia

Scientific information on the ash quality of Tachigalis vulgaris wood may reveal nutrient export mechanisms in energy forests and also insights into the wood quality for thermochemical conversions. This study aimed to evaluate the nutrient export and technological implications of ashes in the combustion of T. vulgaris grown in different planting spacings (4.5 m 2 ;6.0 m 2 ; 7.5 m 2 ; 9 m 2 ; 10.5 m 2 ; 12.0 m 2 ). The levels of inorganic elements were determined for 7-year-old trees cultivated in experimental plantations across the eastern Amazonia region. The element contents were used to obtain the export of nutrients and to calculate the fouling index (FI), basic to acidic compound ratio (B/A), sintering index (SI), slag viscosity index (SR), bed agglomeration index (BAI), and alkali index (AI). The most exported nutrients were Ca (18.7 kg/ha), P (13.9 kg/ha), and K (6.6 kg/ha). The FI, B/A, SI, and SR indices suggested deposition problems in the boilers for all planting spacings. However, BAI and AI indicated a low propensity to form fouling and slag. The spacing significantly influenced the P export. Planting spacing of 12 m 2 demands increased P fertilization to maintain plantation productivity. The low ratio between alkaline earth and alkaline elements and high P 2 O 5 values in the ash of T. vulgaris are disadvantageous. However, the high Al 2 O 3 level and low ash content may contribute to the increase in the melting temperature of the ash. The study revealed that Tachigali vulgaris is a suitable species for wood production in energy forests. Graphical Abstract