RESUMO A introdução de novas tecnologias a bordo das máquinas agrícolas é constante, para maior desempenho energético e eficiência operacional. Recentemente, sistemas de gerenciamento eletrônico são capazes de realizar a seleção da marcha e rotação do motor automaticamente, visando o menor consumo horário de combustível. O objetivo do experimento foi avaliar a eficiência energética e operacional do trator agrícola com gerenciamento automático da transmissão e rotação do motor, submetido a tração de diferentes cargas. O experimento foi conduzido no delineamento de blocos casualizado, em faixas de 50 m, com dois fatores: o sistema de gerenciamento automático da transmissão e rotação do motor (com e sem) e três cargas diferentes aplicadas na barra de tração, com quatro repetições. Os dados coletados foram submetidos a análise de variância e ao teste de Tukey. O sistema de gerenciamento automático da transmissão e rotação do motor proporcionou redução de 20% no patinamento, aumento de 10% na velocidade operacional e economia de 28% no consumo horário de combustível.

HIGHLIGHTS Electronic gear selection and autonomous engine rotation management bring benefits to tractor driving. The electronic management responded positively to the increase in the traction load. The use of electronic management software should be more widespread among farmers and researchers.

ABSTRACT Studies on the longitudinal distribution of seeds in the sowing row seek to improve crop homogeneity, thus generating high productivity. In this context, seed tubes must be analyzed for their angular curvature. Thus, this study aimed to evaluate the influence of the seed tube curvature on the longitudinal distribution of corn and soybean seeds at different speeds. Two experiments were conducted completely randomized in a double factorial design. The first factor consisted of the seed tube curvature (straight and curved) and the second factor consisted of sowing speeds (1.11, 1.39, and 1.67 m s−1 for corn and 1.39, 1.67, 1.94, and 2.22 m s−1 for soybean), with five replications. The parameters analyzed to measure the longitudinal distribution were the number of seeds per meter, average spacing, double, flawed, and acceptable spacings, coefficient of variation, and precision index. The results were subjected to normality and homogeneity tests of residuals, followed by an analysis of variance and Tukey test, when significant. The curved seed tube showed the highest efficiency in the measured parameters for both corn and soybean. The increase in sowing speed had a negative influence on the evaluated parameters, especially in the soybean crop.

RESUMO A resistência à penetração do solo (RSP) é empregada como indicadora da compactação, por estar relacionada a importantes atributos do solo e das plantas, e por ser uma medida de fácil obtenção. Sua determinação com o uso do penetrômetro orienta para as melhores estratégias de manejo do solo, favorecendo assim o desenvolvimento das culturas. O objetivo deste estudo foi desenvolver e validar o penetrômetro eletrônico de acionamento hidráulico georreferenciado, facilitando a obtenção da RSP. Para tanto foram realizadas 36 leituras de 0 a 0,60 m de profundidade da RSP com os penetrômetros manual e hidráulico em duas áreas. Os resultados de RSP foram analisados estabelecendo-se os intervalos de confiança pelo teste t (p ≤ 0,10), a cada 0,05 m de profundidade, e o georreferenciamento através da raiz do erro quadrático médio (RSME). Constatou-se que ambos penetrômetros apresentaram similaridade na mensuração da RSP e do georreferenciamento dos pontos.

ABSTRACT Soil penetration resistance (SPR) is used as an indicator of compaction, as it is related to important soil and plant attributes and is an easily obtainable measure. Its determination with the use of the penetrometer guides to the best soil management strategies, thus favoring crop development. The objective of this study was to develop and validate the georeferenced hydraulic driven electronic penetrometer, making it easier to obtain SPR. For this, 36 SPR readings from 0 to 0.60 m depth were performed with the manual and hydraulic penetrometers in two areas. The SPR results were analyzed by establishing the confidence intervals by the t-test (p ≤ 0.10) at each 0.05 m depth and the georeferencing was analyzed through the root mean square error (RMSE). It was found that both penetrometers showed similarity in SPR measurement and in the georeferencing of the points.

ABSTRACT The operational performance of the agricultural tractor can be increased by adjusting parameters such as tire inflation pressure, axle mass distribution and gauge opening, which is a very divergent factor in controlled-traffic production. The objective of the experiment was to measure the energy performance of a 93 kW agricultural tractor in intermediate grading operation in two slopes (flat and sloping) and three gauge configurations (closed, intermediate and open) in mobilized soil. Energy performance was determined from the following parameters: slip, engine speed, actual effective speed, hourly and specific fuel consumption; strength, power and performance on the drawbar. Turbo pressure and temperature monitoring was also performed at six different engine points. The experiment was conducted in double factorial arrangement (2 slopes and 3 gauges), with four replications, totaling 24 plots. Data were analyzed for normality and homoscedasticity of the residues, after ANOVA and when significant, the means test. Tilts and tire gauges did not differ statistically, so it can be concluded that depending on the operation do not interfere with operating performance.