The culture of açaí (Euterpe oleraceae M.), originating from floodplain areas, was planted on dry land in many properties in Pará, Brazil, making necessary the use of irrigation. To irrigate adequately with less waste, it is necessary that studies aim at increasing efficiency in the use of water in this sector, and one of the ways to do so is to estimate evapotranspiration (ET). The objective of this study was to estimate the actual daily evapotranspiration using the Surface Energy Balance Algorithm for Land (SEBAL) in eastern Amazonia. Six images from the Landsat 8 satellite were used, and the estimates of evapotranspiration with the SEBAL algorithm showed good agreement with the results obtained by the Bowen ratio method in the area of açaí planting, including the mean absolute error (MAE), mean relative error (MRE), root of mean square error (RMSE), and the concordance index (d index) equal to 0.45 mm day−1, 4.23%, 0.52 mm day−1, and 0.80, respectively. SEBAL showed the ability to distinguish the soil cover, demonstrating the sensitivity of the model, which provided the mapping of the components analyzed. The use of the algorithm helps in decision making regarding irrigation management and reducing costs and water losses.

Cowpeas are of high socioeconomic importance in the North and Northeast regions of Brazil, whereby the search for alternatives that offer increased productivity with financial returns has become an important challenge. Thus, the objective of this study was to estimate and evaluate the economic indicators of cowpea production in 2015 and 2016 when applying drip irrigation to different depths. Irrigation treatments were based on crop evapotranspiration (ETc). The experiment was laid in a randomized complete blocks design with four treatments (0, 25, 50, and 100% ETc) and six replications. For economic analysis, the results were extrapolated to an area of one hectare. Productivity in 2015 was lower than that in 2016; however, in all treatments, it was always higher when plants were grown under adequate water supply. In both years, the total operating costs were higher under irrigation than under rainfed conditions. The 100% ETc treatment resulted in a greater number of cowpea bags (60 kg) produced and a higher gross revenue than the rainfed treatment by 17 bags ha-1, equivalent to 1,020 kg ha-1 (gross revenue US$ 711.48) and 16 bags ha-1, equivalent to 960 kg ha-1 (gross revenue US$ 867.12), in 2015 and 2016, respectively. Water deficit limited cowpea yield in both years but made cultivation economically unfeasible only in 2015.

Direitos para esta edição cedidos à Atena Editora pelos autores. Todo o conteúdo deste livro está licenciado sob uma Licença de Atribuição Creative Commons. Atribuição-Não-Comercial-NãoDerivativos 4.0 Internacional (CC BY-NC-ND 4.0).O conteúdo dos artigos e seus dados em sua forma, correção e confiabilidade são de responsabilidade exclusiva dos autores, inclusive não representam necessariamente a posição oficial da Atena Editora. Permitido o download da obra e o compartilhamento desde que sejam atribuídos créditos aos autores, mas sem a possibilidade de alterá-la de nenhuma forma ou utilizá-la para fins comerciais. Todos os manuscritos foram previamente submetidos à avaliação cega pelos pares, membros do Conselho Editorial desta Editora, tendo sido aprovados para a publicação com base em critérios de neutralidade e imparcialidade acadêmica.A Atena Editora é comprometida em garantir a integridade editorial em todas as etapas do processo de publicação, evitando plágio, dados ou resultados fraudulentos e impedindo que interesses financeiros comprometam os padrões éticos da publicação. Situações suspeitas de má conduta científica serão investigadas sob o mais alto padrão de rigor acadêmico e ético.

No abstract