RESUMO As energias renováveis são alternativas para substituição dos combustíveis fósseis sendo crucial para a sustentabilidade do setor agrícola, e importante alternativa para o bombeamento de água na irrigação. Assim, a compreensão das receitas e despesas são fundamentais na viabilidade econômica. Com isso, o objetivo do presente estudo foi verificar o comportamento dos indicadores econômicos em sistema de energia solar off-grid para irrigação com base em diferentes cenários. Foram desenvolvidos projetos fotovoltaicos para diferentes potências de irrigação variando de 0,736 até 22,1 kW, e avaliado os custos para implantação e operação, a ocorrência de economia de escala e verificado o custo nivelado de energia para cada potência analisada. Além disso, foram realizadas análises de sensibilidade, considerando a variação do preço de produto e custo de investimento, para demonstrar as respostas em relação aos indicadores econômicos. Portanto, os projetos de energia fotovoltaicos apresentaram custos crescentes com aumento da potência, e o custo normalizado por kW seguiu uma economia de escala, já o custo nivelado de energia demonstrou viabilidade, exceto para a potência de 22,1 kW. As análises de sensibilidade demonstraram a rentabilidade para as configurações analisadas.

ABSTRACT Renewable energies are alternatives to replace fossil fuels and are crucial for the sustainability of the agricultural sector, besides being an important alternative for pumping water in irrigation. Thus, understanding revenues and expenses is fundamental in economic feasibility. Therefore, the aim of this study was to assess the behavior of economic indicators in off-grid solar energy system for irrigation based on different scenarios. Photovoltaic projects were developed for different irrigation powers ranging from 0.736 to 22.1 kW, and the costs for implementation and operation, as well as the occurrence of economy of scale were evaluated, and the levelized cost of energy for each power analyzed was determined. In addition, sensitivity analyses were performed, considering the variation in product price and investment cost, to demonstrate the responses in relation to economic indicators. Photovoltaic energy projects showed increasing costs with the increase in power, and the normalized cost per kW followed an economy of scale, while the levelized cost of energy showed feasibility, except for the power of 22.1 kW. The sensitivity analyses showed profitability for the analyzed configurations.

ABSTRACT The present work aims to evaluate grain productivity, water productivity, and economic water productivity of three soybean cultivars under supplementary irrigation. Two experiments were conducted during the 2018 and 2019 harvests in Santa Maria/RS, Brazil. The experimental design consisted of a random bifactorial block design with six irrigation depths as the first factor and three soybean cultivars (Glycine max L.) as the second. The irrigation system used was the conventional fixed sprinkler, with a fixed irrigation shift of seven days. Crop productivity, water productivity, and economic water productivity were evaluated. The highest productivity was for 100% of reference evapotranspiration (ETo) in both harvests. Maximum technical efficiency was obtained for depths of 73.03% (Harvest 1) and 77.94% (Harvest 2) of ETo. Both harvests presented higher water productivity and economic water productivity in the 50% and 25% ETo depths respectively. Productivity is increased with irrigation, and the economic water productivity is maximized with reduction of depth.

RESUMO: O presente trabalho teve como objetivo avaliar o rendimento, produtividade da água e produtividade econômica da água para o teor de óleo de três cultivares de soja sob diferentes condições hídricas. Os experimentos foram conduzidos nas safras 2017/2018 e 2018/2019. O delineamento experimental constou de um bifatorial em blocos ao acaso, com o primeiro fator de cinco lâminas de irrigação, com base na evapotranspiração de referência (ETO), mais o tratamento sem irrigação e o segundo fator foram três cultivares de soja. Os resultados para o rendimento e produtividade de óleo foram maiores para as lâminas de 75% (safra 1) e 100% da ETO (safra 2). Nas avaliações de produtividade da água e produtividade econômica da água os maiores resultados foram obtidos na lâmina de 50% na safra 1 e 25% e 50% na safra 2. A cultivar BRASMAX Ponta apresentou os maiores valores para produção de óleo e a BRASMAX Valente para produtividade de óleo, em ambas as safras. Na safra 1, a BRASMAX Valente obteve os maiores resultados na produtividade de água e produtividade econômica da água e, na Safra 2, foi a BRASMAX Ponta que apresentou maiores valores. A irrigação suplementar favoreceu o incremento na produção de óleo e a produtividade de óleo. Para o uso mais eficiente e econômico da água é necessário a utilização de menores lâminas.

ABSTRACT: This research evaluated the yield, water productivity, and economic water productivity for the oil content of three soybean cultivars under different water conditions. The experiments were conducted in the 2017/2018 and 2018/2019 harvests. The experimental design consisted of a two-factor randomized block, with the first factor of 5 irrigation depths, based on the reference evapotranspiration (ETO), plus the treatment without irrigation and the second factor was 3 soybean cultivars. Results reported oil yield and productivity were higher for the depths of 75% (crop 1) and 100% of ETO (crop 2). For the evaluations of water productivity and economic water productivity, the highest results were obtained at the level of 50% in crop 1 and 25% and 50% in crop 2. Cultivar BRASMAX Ponta had the highest values for oil production and BRASMAX Valente for oil yield, in both crops. In Crop 1, the BRASMAX Valente cultivar had the highest results in water productivity and economic water productivity, and in Crop 2, the BRASMAX Ponta cultivar had the highest values. Supplemental irrigation favored the increase in oil production and oil productivity. For a more efficient and economical use of water, it is necessary to use smaller irrigation depths.

ABSTRACT In rural areas, the electricity supply is affected by problems such as low quality and limited access in some regions. The use of renewable sources, with decentralized generation, can offer an alternative to the existing scenario. The objective of this work is to perform a technical and economic analysis of off-grid photovoltaic systems, without energy storage, intended for irrigation. Photovoltaic systems from different irrigation systems were sized, with power ratings from 0.736 to 29.44 kW. Their technical feasibility was determined based on the energy supply period and the availability of solar radiation as restriction variables. Economic feasibility was determined by the indicators of net present value (NPV), internal rate of return (IRR), benefit/cost ratio (B/C) and profitability index (PI). Feasible operation was found for irrigation systems with motors up to 11.04 kW; however, for systems that required higher powers, the number of operating hours available was less than the minimum required. NPV, IRR, B/C and PI showed increasing values as a function of increasing power. Thus, off-grid photovoltaic systems without energy storage are technically and economically feasible for systems with power of up to 11.04 kW.

RESUMO O estudo visa quantificar os custos de produção das culturas de milho e sorgo em condições de sequeiro e irrigado para a geração de etanol, e avaliar a viabilidade econômica em diferentes cenários de preço de comercialização. Foram realizados dois experimentos nos anos de 2019/2020 e 2020/2021, em área experimental da Universidade Federal de Santa Maria, Santa Maria, RS. O delineamento experimental foi em faixas, com blocos ao acaso e quatro repetições. Foram avaliadas três lâminas de irrigação: 0, 50 e 100% da evapotranspiração de referência (ETo) como o primeiro fator, e duas cultivares de milho e uma de sorgo granífero como o segundo fator, sendo utilizados 45 cenários. O uso da irrigação plena (100% de ETo) reduz os custos de produção do litro de etanol em 15 e 17,89% e aumenta a produção de etanol em 44,18 e 48,25% para as culturas de milho e sorgo, respectivamente. Para o preço de mercado de R$ 2,00 L-1, o sorgo granífero não apresenta bom desempenho, com valor presente líquido (NPV) e taxa interna de retorno (IRR) negativos. O preço de venda de R$ 4,00 L-1 e irrigação plena é o melhor cenário econômico, com valores de NPV de R$ 90.356,93, IRR de 33,83%, relação benefício/custo (B/C) de 2,28, índice de rentabilidade (PI) de 3,99 e payback de três anos. O milho é economicamente viável para a produção de etanol em todos os cenários, sendo a irrigação plena e preço de comercialização de R$ 4,00 L-1, o que apresentou o melhor cenário econômico, com valores médios para o NPV de R$ 204.381,68, IRR de 63,35%, B/C de 2,96, IR 8,67 e payback de 1,58 anos, entre as cultivares.

ABSTRACT The study aims to quantify the production costs of maize and sorghum crops under rainfed and irrigated conditions for the generation of ethanol and to evaluate the economic feasibility in different scenarios of marketing price. Two experiments were carried out in the years 2019/2020 and 2020/2021, in an experimental area at the Federal University of Santa Maria, Santa Maria, RS, Brazil. The experiment was in strip plots, in a randomized block design and four replicates. Three irrigation depths, 0, 50 and 100% of the reference evapotranspiration (ETo), as first factor, and two maize cultivars and one grain sorghum cultivar as second factor, using 45 scenarios. The use of full irrigation (100% of ETo) reduces the production costs of the liter of ethanol by 15 and 17.89% and increases ethanol production by 44.18 and 48.25% for maize and grain sorghum crops, respectively. For the market price of R$ 2.00 L-1, the grain sorghum does not show good performance, with negative net present value (NPV) and internal rate of return (IRR). The sale price of R$ 4.00 L-1 and full irrigation is the best economic scenario, with values of NPV of R$ 90,356.93, IRR of 33.83%, benefit/cost ratio (B/C) of 2.28, profitability index (PI) of 3.99 and payback of three years. Maize is economically viable for ethanol production in all scenarios. Full irrigation and market price of R$ 4.00 L-1 represent the best economic scenario, with mean values for NPV of R$ 204,381.68, IRR of 63.35%, B/C of 2.96, PI of 8.67 and payback of 1.58 years, among the cultivars.

RESUMO O cultivo do feijão apresenta importância mundial, tanto no que se refere ao desenvolvimento econômico, quanto ao caráter social. O trabalho foi realizado com o objetivo de avaliar a produção de grãos e a lâmina ótima econômica que reflete a máxima eficiência técnica da cultura do feijão. O experimento foi conduzido em casa de vegetação, em Alegrete – RS, no período de fevereiro a maio de 2016. Utilizou-se um delineamento inteiramente casualizado, composto por cinco tratamentos de reposição de água (25, 50, 75, 100 e 125% da evapotranspiração da cultura) e quatro repetições. Através dos resultados obtidos, permitiu-se observar que tanto o déficit hídrico, quanto o excesso de água, afetaram diretamente na produção final de grãos da cultura. A máxima produção de grãos foi de 3554,1 kg ha-1, aplicando-se 492,72 mm (100% da evapotranspiração da cultura). Em contrapartida, a lâmina ótima econômica foi estimada em 91,2% de reposição da ETc, indicando que lâminas acima desse valor não são adequadas visando à máxima eficiência econômica da irrigação, para a cultura do feijoeiro. Deste modo, conclui-se que a lâmina que representa 100% da evapotranspiração da cultura maximiza a produção de grãos para a região de Alegrete, RS, sendo a prática da irrigação considerada uma solução no suprimento de água para a cultura do feijão, nos períodos críticos.

ABSTRACT Common bean crop plays an important role in the world, not only in economic aspects but also in social development. The objective of this study was to evaluate the grain yield and the economically optimal water depth which reflects the maximum technical efficiency of the common bean crop. The experiment was conducted in greenhouse, in Alegrete - RS, from February to May 2016. A completely randomized design was used, consisting of five water replacement treatments (25, 50, 75, 100 and 125% crop evapotranspiration - ETc) and four replicates. Based on the obtained results, both water deficit and water excess directly affected the final grain yield of the crop. Maximum grain yield was 3,554.1 kg ha-1, obtained by applying 492.72 mm (100% ETc). On the other hand, the economically optimal water depth was estimated at 91.2% ETc, indicating that water depths above this value are not suitable for maximum technical efficiency in the common bean crop under these conditions. It was concluded that the water depth equivalent to 100% ETc maximizes grain yield for the region of Alegrete-RS, and irrigation is considered a solution in the water supply to the common bean crop during critical periods.

ABSTRACT The aim of this study was to present and to evaluate methodologies for the estimation of soil resistance to penetration (RP) using artificial intelligence prediction techniques. In order to do so, a data base with values of physical-water characteristics of the soils available in the literature was used, and the performances of Artificial Neural Networks (ANN) and Support Vector Machines (SVM) were evaluated. The models generated from the ANNs were implemented through the multilayer perceptron with backpropagation algorithm of Matlab software, varying the number of neurons in the input and intermediate layers. For the procedure from SVM, the RapidMiner software was used, varying input variables, the kernel function and the coefficients of these functions. The efficiency of the techniques was analyzed by the ratio 1:1, and later, compared to the Busscher non-linear model (Busscher, 1990). The results showed that the artificial intelligence models (ANN and SVM) are efficient and have predictive capacity superior to the Busscher model, under data conditions of soils with textural classes and different, and similar managements, although with higher performance index values for conditions of soils of the same textural class exposed to the same management.