Bioethanol from sugarcane is becoming an increasingly important alternative energy source worldwide as it is considered to be both economically and environmentally sustainable. Besides being produced from a tropical perennial grass with high photosynthetic efficiency, sugarcane ethanol is commonly associated with low N fertilizer use because sugarcane from Brazil, the world's largest sugarcane producer, has a low N demand. In recent years, several models have predicted that the use of sugarcane ethanol in replacement to fossil fuel could lead to high greenhouse gas (GHG) emission savings. However, empirical data that can be used to validate model predictions and estimates from indirect methodologies are scarce, especially with regard to emissions associated with different fertilization methods and agricultural management practices commonly used in sugarcane agriculture in Brazil. In this study, we provide in situ data on emissions of three GHG (CO 2 , N 2 O, and CH 4 ) from sugarcane soils in Brazil and assess how they vary with fertilization methods and management practices. We measured emissions during the two main phases of the sugarcane crop cycle (plant and ratoon cane), which include different fertilization methods and field conditions. Our results show that N 2 O and CO 2 emissions in plant cane varied significantly depending on the fertilization method and that waste products from ethanol production used as organic fertilizers with mineral fertilizer, as it is the common practice in Brazil, increase emission rates significantly. Cumulatively, the highest emissions were observed for ratoon cane treated with vinasse (liquid waste from ethanol production) especially as the amount of crop trash on the soil surface increased. Emissions of CO 2 and N 2 O were 6.9 kg ha À1 yr À1 and 7.5 kg ha À1 yr À1, respectively, totaling about 3000 kg in CO 2 equivalent ha À1 yr À1 .

Crop residues returned to the soil are important for the preservation of soil quality, health, and biodiversity, and they increase agriculture sustainability by recycling nutrients. Sugarcane is a bioenergy crop that produces huge amounts of straw (also known as trash) every year. In addition to straw, the ethanol industry also generates large volumes of vinasse, a liquid residue of ethanol production, which is recycled in sugarcane fields as fertilizer. However, both straw and vinasse have an impact on N 2 O fluxes from the soil. Nitrous oxide is a greenhouse gas that is a primary concern in biofuel sustainability. Because bacteria and archaea are the main drivers of N redox processes in soil, in this study we propose the identification of taxa related with N 2 O fluxes by combining functional responses (N 2 O release) and the abundance of these microorganisms in soil. Using a large-scale in situ experiment with ten treatments, an intensive gas monitoring approach, high-throughput sequencing of soil microbial 16S rRNA gene and powerful statistical methods, we identified microbes related to N 2 O fluxes in soil with sugarcane crops. In addition to the classical denitrifiers, we identified taxa within the phylum Firmicutes and mostly uncharacterized taxa recently described as important drivers of N 2 O consumption. Treatments with straw and vinasse also allowed the identification of taxa with potential biotechnological properties that might improve the sustainability of bioethanol by increasing C yields and improving N efficiency in sugarcane fields.

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Post‐harvest biomass can be used as feedstock for energy production and alter N2O emissions from the soil, which is among the main issues determining bioethanol sustainability. To assess the effects of sugarcane straw return on gas emissions, we established a field experiment in which 0, 50, 75 or 100% (0, 5.65, 8.47 and 11.30 Mg/ha dry biomass, respectively) of the crop residues (straw) was left in the field during the first two ratoon crops. As fertilizer is applied in bands to sugarcane, we also investigated the contribution of different positions to the N2O emissions within the field. There was an interactive effect between straw and inorganic fertilizer, leading to a nonlinear effect of crop residues on the fertilizer emission factor (EF). However, straw consistently reduced N2O emissions from the field, acting mainly in the unfertilized areas in the field (P < 0.05). We observed that considering the typical EF used in the literature, the N2O‐N emissions attributed to fertilizer ranged from 0.19 to 0.79 kg/ha, while the total emissions ranged from 3.3 to 5.2 kg/ha, from the highest amount of straw to the lowest. We conclude that overall, the fertilizer EF is not as relevant as the total emissions, based on this and other studies. Consequently, management practices might be more effective in improving the GHG balance than changing inorganic fertilizer use. We conclude that keeping up to 11 Mg/ha of straw with a large C:N ratio (>100:1) on site might increase sugarcane production sustainability by reducing the greenhouse gas emissions from the field.

Resumo: Este trabalho envolveu a obtenção de filmes poliméricos a partir de amido de milho e incorporação de lignina na forma de lignossulfonato. A motivação deste trabalho está relacionada à utilização do amido na obtenção de filmes devido ao seu potencial de biodegradação, além do aproveitamento de resíduos de lignossulfonatos provenientes da indústria de celulose e papel. Para a obtenção dos filmes foram utilizados lignossulfonatos em pó e foram realizadas diversas moldagens com variação do tipo e da proporção (1% a 4%) de lignossulfonato utilizado. Algumas análises foram realizadas nos filmes poliméricos para comparar propriedades térmicas por DSC (Calorimetria Exploratória Diferencial), e propriedades de tração, em equipamento de DMTA (Análise Térmica Dinâmico-Mecânica). Neste estudo são destacadas as análises da biodegradação e da emissão dos gases liberados utilizando a técnica de Cromatografia Gasosa. De acordo com os resultados de DMTA, a maioria dos filmes poliméricos contendo lignossulfonatos apresentou resistência à tração inferior quando comparados aos filmes poliméricos sem lignossulfonatos (1,024 MPa). Porém, os filmes contendo lignossulfonato modificado com sódio (Vixil S) apresentaram maiores valores de resistência à tração quando comparado aos outros filmes contendo os lignossulfonatos utilizados (Vixil I e Vixil Tan). Nas análises térmicas foram notadas semelhanças entre os dois tipos principais de filmes poliméricos (amido; e amido com lignossulfonato), com alguns deslocamentos das temperaturas dos principais picos máximos dos filmes contendo lignossulfonato (4%, Vixil S). Na análise de biodegradabilidade foi verificado que os materiais são biodegradáveis e houve uma emissão maior de CO 2 e N 2 O das amostras dos filmes contendo 4% lignossulfonato do tipo Vixil S, em comparação com as amostras sem lignossulfonato. Palavras-chave: Filme polimérico, amido, lignossulfonato, DMTA, DSC, biodegradação. Polymeric Films Based on Starch and lignosulfonates: Preparation, Properties and Evaluation of BiodegradationAbstract: We obtained polymer films from corn starch with lignin incorporation as lignosulfonate. The motivation is the use of starch in obtaining films, due to their potential for biodegradation, and the use of lignosulfonate waste from the pulp and paper industry. To obtain films of lignosulfonates various powders of lignosulfonate were used, varying type and proportion (1% to 4%). Analyses were performed on polymer films to compare thermal properties by Differential Scanning Calorimetry, and tensile properties in Dynamic Mechanical Thermal Analysis, DMTA. We emphasize analyses of biodegradation and gas emission using gas chromatography. According to the results of DMTA, most polymeric films containing lignosulfonates showed lower tensile strength when compared to polymer films without lignosulfonates (1.024 MPa). However, the films containing lignosulfonate modified with sodium (Vixil S) showed higher tensile strength when compared to other films containing lignosulfonates (Vixil I and Vixi...

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This study aimed to quantify the carbon dioxide emissions from an Oxisol under degraded pasture located in Sorocaba, São Paulo State, Brazil. The treatments were: sewage sludge (LE), sewage sludge compost (CLE), mineral fertilizer (AM) and no fertilization (T0). The experiment was conducted in a completely randomized block design with analysis of the effect of the four treatments (CLE, LE, and AM T0) with four replications. The application of sewage sludge, sewage sludge compost, mineral fertilizer and no fertilizer was statistically significant for the variables of height increase and stem height of Guanandi seedlings (Calophyllum brasiliense Cambessèdes -Calophyllaceae). Treatments showed significant differences in terms of CO 2 emissions from soil. The CLE exhibited the highest CO 2 fluxes, reaching a peak of 9.33±0.96 g C m -2 day -1 (p<0.0001), as well as the LE with a maximum CO 2 flux of 6.35±1.17 C m ). CO 2 fluxes were correlated with soil temperature in all treatments. However, considering the period of 172 days of evaluation, the total loss of C as CO 2 was 2.7% for sewage sludge and 0.7% for the sewage sludge compost of the total C added with the application on soil.Key words: GHG, organic waste, carbon.Emissão de CO 2 do solo após reflorestamento e aplicação de lodo de esgoto ResumoO presente estudo teve como objetivo quantificar as emissões de gás carbônico a partir de um Latossolo Vermelho eutroférrico sob pastagem degradada localizada na região de Sorocaba. Os tratamentos avaliados foram: lodo de esgoto (LE), composto de lodo de esgoto (CLE), adubo mineral (AM) e ausência de adubação (T0). O experimento foi conduzido em blocos inteiramente casualizados, sendo analisado o efeito dos quatro tratamentos (CLE, LE, AM e T0) com quatro repetições. A aplicação de lodo de esgoto, composto de lodo de esgoto, fertilizante mineral e ausência de adubação apresentaram efeito estatístico quanto às variáveis de incremento em altura e a altura do coleto das mudas de Guanandi (Calophyllum brasiliense Cambessèdes -Calophyllaceae). Os tratamentos apresentaram diferença significativa quanto às emissões de CO 2 do solo. O CLE foi o tratamento de apresentou os maiores fluxos de CO 2 , atingindo um pico de 9,33±0,96 g C m -2 dia -1 (p<0,0001), assim como o LE, com um fluxo máximo de CO 2 de 6,35±1,17 C m ). Os fluxos de CO 2 apresentaram correlação com a temperatura do solo em todos os tratamentos estudados. No entanto, considerando o período de 172 dias de avaliação do experimento, a perda total de C na forma de CO 2 foi de 2,7% do total de C adicionado com a aplicação dos resíduos no solo para o lodo de esgoto e de 0,7% do total de C adicionado com a aplicação dos resíduos no solo para o composto de lodo de esgoto.Palavras-chave: gases do efeito estufa, resíduos orgânicos, carbono.

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