Tendo em vista a crescente demanda por alimentos e uma agricultura cada vez mais desenvolvida, é importante avaliar os impactos causados pelos agroecossistemas no que se refere à sustentabilidade ambiental. Nesse contexto, o balanço energético constitui uma importante ferramenta para essa avaliação, pois permite contabilizar os "inputs" e "outputs" referentes ao sistema produtivo na forma de energia e determinar a eficiência de cada um. O presente trabalho teve como objetivo avaliar os fluxos de energia do processo de produção do milho para silagem, cultivado em três espaçamentos, 0,90 m, 0,75 m e 0,60 m. A análise foi feita por meio do acompanhamento da cultura em um período de 204 dias (12/11/2013 a 6/6/2014), sendo cada componente envolvido (direta e indiretamente), quantificado e multiplicado por seus respectivos coeficientes energéticos. Em todos os espaçamentos houve a predominância da energia direta sobre a energia indireta. As eficiências para os espaçamentos 0,90 m, 0,75 m e 0,60 m foram respectivamente 9,50%, 9,30% e 9,69%. A análise energética constitui-se em importante instrumental para avaliação da sustentabilidade dos sistemas de produção.

The objective of this study was to evaluate the potential of the practical application of unmanned aerial vehicles and RGB vegetation indices (VIs) in the monitoring of a coffee crop. The study was conducted in an experimental coffee field over a 12-month period. An RGB digital camera coupled to a UAV was used. Nine VIs were evaluated in this study. These VIs were subjected to a Pearson correlation analysis with the leaf area index (LAI), and subsequently, the VIs with higher R2 values were selected. The LAI was estimated by plant height and crown diameter values obtained by imaging, which were correlated with these values measured in the field. Among the VIs evaluated, MPRI (0.31) and GLI (0.41) presented greater correlation with LAI; however, the correlation was weak. Thematic maps of VIs in the evaluated period showed variability present in the crop. The evolution of weeds in the planting rows was noticeable with both VIs, which can help managers to make the decision to start crop management, thus saving resources. The results show that the use of low-cost UAVs and RGB cameras has potential for monitoring the coffee production cycle, providing producers with information in a more accurate, quick and simple way.

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Lignocellulosic material residues in cement composites are a favourable option for new fibre cement formulations in building materials, because they combine good mechanical properties with low density. This study aimed to evaluate the chemical, physical, anatomical, and mechanical properties of five cement panels reinforced with the following lignocellulosic materials: eucalyptus, sugarcane bagasse, coconut shell, coffee husk, and banana pseudostem. Lignocellulosic cement panels were produced with each lignocellulosic material residue, and three replicates of each type of lignocellulosic material were examined (15 panels in total). The lignin, extractives, ash, and holocellulose were examined. After 28 days of composite curing, the following physical properties of the panels were evaluated: density, porosity, water absorption after immersion for 2 and 24 h, and thickness swelling after immersion for 2 and 24 h. Mechanical tests (compression strength, internal bonding, modulus of rupture, and modulus of elasticity) were performed before and after the accelerated ageing test with a universal testing machine. Scanning electron microscopy and supervised image classification were performed to investigate the morphologies of the different materials and the filler/matrix interfaces. Eucalyptus and sugarcane panels had the best results in terms of the evaluated properties and thus, could potentially be used as non-structural walls. However, banana pseudostem, coconut shell, and coffee husk panels had the worst results and therefore, under these conditions, should not be used in building.

Mechanized operations on terrain slopes can still lead to considerable errors in the alignment and distribution of plants. Knowing slope interference in semi-mechanized planting quality can contribute to precision improvement in decision making, mainly in regions with high slope. This study evaluates the quality of semi-mechanized coffee planting in different land slopes using a remotely piloted aircraft (RPA) and statistical process control (SPC). In a commercial coffee plantation, aerial images were collected by a remotely piloted aircraft (RPA) and subsequently transformed into a digital elevation model (DEM) and a slope map. Slope data were subjected to variance analysis and statistical process control (SPC). Dependent variables analyzed were variations in distance between planting lines and between plants in line. The distribution of plants on all the slopes evaluated was below expected; the most impacted was the slope between 20–25%, implementing 7.8% fewer plants than projected. Inferences about the spacing between plants in the planting row showed that in slopes between 30–40%, the spacing was 0.53 m and between 0 and 15% was 0.55 m. This denotes the compensation of the speed of the operation on different slopes. The spacing between the planting lines had unusual variations on steep slopes. The SCP quality graphics are of lower quality in operations between 30–40%, as they have an average spacing of 3.65 m and discrepant points in the graphics. Spacing variations were observed in all slopes as shown in the SCP charts, and possible causes and implications for future management were discussed, contributing to improvements in the culture installation stage.

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Pela praticidade e simplicidade de construção, nos últimos anos, os biodigestores tubulares, também conhecidos como canadense, têm sido utilizados para o manejo e tratamento de resíduos da suinocultura. Contudo, a escassez de informações acerca da composição energética destas estruturas limita a realização de estudos relacionados às análises energéticas nesses biossistemas. O objetivo deste trabalho foi contabilizar a energia empregada na construção de biodigestores anaeróbios de fluxo tubular utilizados para o manejo e tratamento de resíduos da suinocultura. Para tanto, foram quantificados os componentes envolvidos na construção dos biodigestores e, em seguida, para transformação em unidades de energia desses componentes, multiplicou-se a quantidade destes pelos seus respectivos coeficientes energéticos. Os resultados indicaram que a construção dos biodigestores consumiu 490.179,59 MJ de energia, sendo que o componente energético mais expressivo no consumo energético foram as geomembranas flexíveis de PVC (29,33%), seguido pelas tubulações de PVC e lonas de impermeabilização com 28,45% e 21,06% da energia consumida, respectivamente. Considerando o volume útil dos biodigestores, o índice energético determinado foi de 225,89 MJ m-3.