ABSTRACT The generation of sewage sludge and the concern with their fate has greatly increased. The objective of this study was to assess the effects of using in natura (SS) or composted sewage sludge (SSC) in comparison with mineral fertilizer (MF) application and a control (CT) treatment on the nutritional status of Guanandi (Calophyllum brasiliense Cambess.) seedlings in a typical Red Oxisol in Brazil. The leaf-level nutritional responses of the Guanandi seedlings to these three different fertilizers and the control were evaluated at 90 and 180 days after planting. Nutritional data of leaf variables were compared between the treatments by means of one-way analysis of variance using the F test and a pair-wise comparison of means done by Tukey’s test. The seedlings that received SS or SSC showed deficiencies in Ca, Mg, and Mn, which were confirmed by a visual diagnosis of their leaf symptoms. However, at 180 days after planting there were significant differences (p < 0.05) for K that was greater for MF, SS and SSC than CT, Mg, with SSC larger than SS, and for S that was greater with SS and SSC uses relative to MF. The results highlight the potential for using SS and SSC, after adding KCl and lime, although the Guanandi was highly demanding of Ca, Mg, and Mn. However, they were able to nutritionally supply seedlings, although the short-term cannot be conclusive as regards the exclusive use of them in place of mineral fertilizers.

The large volume of sewage sludge (SS) generated with high carbon (C) and nutrient content suggests that its agricultural use may represent an important alternative to soil carbon sequestration and provides a potential substitute for synthetic fertilizers. However, emissions of CH4 and N2O could neutralize benefits with increases in soil C or saving fertilizer production because these gases have a Global Warming Potential (GWP) 25 and 298 times greater than CO2, respectively. Thus, this study aimed to determine C and N content as well as greenhouse gases (GHG) fluxes from soils historically amended with SS. Sewage sludge was applied between 2001 and 2007, and maize (Zea mays L.) was sowed in every year between 2001 and 2009. We evaluated three treatments: Control (mineral fertilizer), 1SS (recommended rate) and 2SS (double rate). Carbon stocks (0-40 cm) were 58.8, 72.5 and 83.1 Mg ha–1in the Control, 1SS and 2SS, respectively, whereas N stocks after two years without SS treatment were 4.8, 5.8, and 6.8 Mg ha–1, respectively. Soil CO2 flux was highly responsive to soil temperature in SS treatments, and soil water content greatly impacted gas flux in the Control. Soil N2O flux increased under the residual effects of SS, but in 1SS, the flux was similar to that found in moist tropical forests. Soil remained as a CH4sink. Large stores of carbon following historical SS application indicate that its use could be used as a method for carbon sequestration, even under tropical conditions.

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 CO2 e N2O das amostras dos filmes contendo 4% lignossulfonato do tipo Vixil S, em comparação com as amostras sem lignossulfonato.

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 Vixil Tan). With some displacement of the main maximum peak temperatures for the films containing lignosulfonate (4% Vixil S), thermal analysis similarities between the two main types of polymer films (starch and starch with lignosulfonate) were observed. All materials are biodegradable, but higher CO2 and N2O emissions were observed for samples of the films containing 4% lignosulfonate type, Vixil S, compared to the samples without lignosulfonate.

O 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 CO2 do solo. O CLE foi o tratamento de apresentou os maiores fluxos de CO2, 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 CO2 de 6,35±1,17 C m- 2 dia- 1 (p<0,005), já o tratamento AM (4,96±1,61 g C m- 2 dia- 1) apresentou o mesmo efeito estatístico que o T0 (5,33±0,49 g C m- 2 dia- 1). Os fluxos de CO2 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 CO2 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.

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 CO2 emissions from soil. The CLE exhibited the highest CO2 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 CO2 flux of 6.35±1.17 C m- 2 day- 1 (p<0.005). The AM treatment (4.96±1.61 g C m- 2 day- 1) had the same statistical effect as T0 (5.33±0.49 g C m- 2 day- 1). CO2 fluxes were correlated with soil temperature in all treatments. However, considering the period of 172 days of evaluation, the total loss of C as CO2 was 2.7% for sewage sludge and 0.7% for the sewage sludge compost of the total C added with the application on soil.