Eucalyptus plantations play an important role in capturing and storing atmospheric carbon, mitigating global climate change. Forest management policies encouraging integrated livestock-forestry systems require quantitative estimates of temporal and spatial patterns of carbon storage for these agricultural systems. This study quantified the effects of eucalyptus management and arrangement on carbon stock dynamics in integrated livestock-forestry (ILF) systems versus monoculture eucalyptus plantings. Arrangement and management resulted in equal storage of carbon in both monoculture and ILF systems (34.7 kg per tree). Both factors are important to better understand how forest species in integrated systems stock carbon and how this can compensate for other agricultural system components, such as cattle. The extent to which ILF systems offset beef cattle (Nellore) emissions was determined by estimating changes in carbon stock over time for Eucalyptus urophylla × E. grandis, clone H13, under three scenarios (S) of wood use. These scenarios were (S1) tree growth without thinning, (S2) trees used for biomass energy without thinning, and (S3) 50% of trees used for biomass energy at five years old and 50% of trees used for both timber and energy after eight years, considering the full life cycle of eucalyptus. The S1 and S3 systems can stock 510 and 73 metric tons (t) of CO₂ ha⁻¹, respectively, while S2 emits 115 t CO₂ ha⁻¹ of biogenic carbon.

Leaching and nitrous oxide (N₂O) emissions can represent substantial nitrogen (N) losses from chemical fertilizers, and slow-release fertilizers (SRFs) can mitigate these effects. Thus, biochar can be an alternative from an agronomic and environmental point of view to synthesize SRFs due to its physicochemical characteristics. We investigated the effect of nitrogenous organomineral fertilizers (OMF-N) formulated based on activated biochar on N losses by leaching and N₂O emissions. The OMF-N were developed from a dry mechanical pelleting process with different biochar and urea proportions (2:1; 1:2, and 1:4). Three experiments were conducted using four fertilizer sources (urea, OMF-N 2:1, OMF-N 1:2, and OMF-N 1:4): i. to analyze the kinetics of N release from OMF-N at times: 5, 15, 30, 60, 90, and 120 min; ii. for N₂O emission analysis determined at 3, 6, 10, 14, 24, 44, 54, 64, 74, 84, 104, and 118 days after application to the soil; and iii. for a double factorial design that was adopted to analyze N leaching, consisting of the combination of applying 160 kg N ha⁻¹ of fertilizers in PVC columns at different depths (20, 40, 60, and 80 cm) and analyzed at five times (1, 7, 14, 21, and 28 days). FTIR spectroscopic analysis, specific surface area, porosity, and surface morphology showed physicochemical interactions of N of the OMF with biochar; the N from the OMF interacts physically and chemically binds to the functional surfaces of biochar, delaying the dissolution flow. The OMF-N proved capable of retaining 48% to 60% more NH₄⁺ and reduced the release of N_total from urea from 27% to 60%, as well as reduced N₂O emissions from 47% to 66%. Although absolute CO₂ emissions intensified with the application of OMF-N, its use provides C sequestration in the soil to due to the recalcitrant C of the biochar, which results in a positive input-output balance in the system. The NO₃⁻ concentration profiles revealed that the OMF-N application was able to reduce leaching in the soil to a depth of 80 cm. These studies enabled better understanding of the processes involved in the biochar:urea interaction and revealed that biochar can be used as an organic matrix in the synthesis of SRF.

The objective of this work was to evaluate the development and quality of clonal seedlings of teak (Tectona grandis) grown in substrate with two types of biochar. The assay was carried out in a randomized complete block design, with ten treatments and four replicates: CS, commercial substrate, composed of pine bark and vermiculite at a ratio of 4:1; NS, nursery substrate composed of carbonized rice husk and coconut fiber at 1:1; and the remaining treatments were composed of the inclusions of biochar (BC) or activated biochar (BCA) in the CS, at the proportions of 25, 50, 75, and 100%. The development and quality parameters of seedlings were evaluated 90 days after striking the minicuttings in the substrates. BCA substrate additions at 25, 50, and 100% allowed for a development of height and stem diameter comparable to that of the NS. Biochar without the activation procedure does not improve quality parameters of seedlings, in comparison with the commercial substrate. The use of 25% activated biochar added to the commercial substrate is enough to improve seedling growth performance to the same level as that provided by the already validated NS.

Alternative biomass for energy can reduce fossil fuel use and environmental impacts, providing energy security in semi-arid areas with shallow soils that are not ideal for agro-forestry. The densification of sorghum biomass (SB) brings its energetic characteristics closer those of wood. Higher heating value (HHV) represents the heat produced by a given quantity of fuel. This Brazilian research tested different mixtures of SB, eucalyptus wood (W), and eucalyptus bio-oil (Bo) as briquettes for HHV and least ash. Compressed mixtures of SB+B were compared to W+Bo and SB+W+Bo. The concentrations of bio-oil added to SB/W were 1%, 3%, 4%, and 5%. SB+W+Bo composites’ W content was 0%, 25%, 50%, 75%, and 100%, with Bo as 3% of the weight. Sorghum biomass’ HHV is equivalent to W at 3%Bo. Bo doses of 4% and 5% had the same HHV as 3%. Eucalyptus wood did not have a significantly greater HHV with any amount of Bo. SB+W+3%Bo had the same HHV as W when W was at least 50% of the mixture. At greater than 36%W, the ash content was lower than 3%, meeting the EN-B international standard. The optimal composite mixture was 64%SB+36%W+3%Bo for HHV and ash content. SB briquettes can be more widely adopted given sorghum’s prevalence in semi-arid environments.

Wood vinegar has been used for over a century as a fertilizer and antimicrobial agent, but its impacts on ecosystems are poorly understood; further research is necessary to understand its chemical characteristics and avoid negative impacts. This study assessed the chemical characteristics, phytotoxicity, potential cytotoxicity, and greenhouse gas emissions of wood vinegar made from slow pyrolysis in a hot-tail kiln using cambara wood (Qualea sp.). Incubation experiments with varying concentrations of wood vinegar were established in samples of clayey, loamy, and sandy tropical soils, measuring CO₂, N₂O, and CH₄ over a 120-day period. Toxic effects on the germination, root tips, and meristematic cells of Lactuca sativa were also assessed. The findings confirmed that wood vinegar can function as a chemical fertilizer and pesticide, as well as a co-solvent for chemicals, particularly in agricultural and pharmaceutical applications, while the phytotoxicity indicated that this substance must be diluted for agricultural uses. Wood vinegar was seen to inhibit CO₂ and N₂O emissions from loamy and clayey soils, but this effect was not observed in sandy soil. Wood vinegar also blocked cell division in some dilutions, but at concentrations of less than 0.5% it did not present a potential risk to the environment or plants in general. Keywords: pyroligneous acid; biomass; pyrolysis; residues; cytotoxicity. Vinagre de madeira: características químicas, efeitos fitotóxicos e impactos nas emissões de gases   RESUMO: O vinagre de madeira é usado há mais de um século como fertilizante e agente antimicrobiano, mas seus impactos nos ecossistemas são pouco conhecidos; pesquisas são necessárias para entender suas características e evitar impactos negativos. Este estudo avaliou as características químicas, fitotoxicidade, potencial citotoxicidade e emissões de gases do vinagre de madeira obtido a partir de pirólise lenta em forno de cauda quente utilizando madeira de cambará (Qualea sp.). Experimentos de incubação com concentrações variadas do vinagre foram estabelecidos em amostras de solos tropicais argilosos, textura média e arenosos, medindo CO₂, N₂O e CH₄ durante 120 dias. Efeitos tóxicos no modelo Lactuca sativa também foram avaliados. Os resultados confirmaram que o vinagre de madeira pode funcionar como fertilizante químico e pesticida, bem como um co-solvente para produtos químicos, principalmente em aplicações agrícolas e farmacêuticas, enquanto a fitotoxicidade indicou que essa substância deve ser diluída para uso agrícola. O vinagre de madeira parece inibir as emissões de CO₂ e N₂O de solos argilosos e argilosos, mas esse efeito não foi observado em solo arenoso. O vinagre de madeira também bloqueou a divisão celular em algumas diluições, mas em concentrações inferiores a 0,5% não apresentou risco potencial ao meio ambiente ou às plantas em geral. Palavras-chave: ácido pirolenhoso; biomassa; pirólise; resíduos; citotoxicidade.