ABSTRACT The automatic control of section shut-off in seed drills minimizes seeding overlap and can reduce productivity losses, especially in responsive crops such as corn. In that context, this study evaluated the effect of sowing overlap on the grain yield and productivity of three corn hybrids. A DB-50 precision seed drill, with 33 rows equipped with a 16-row automatic section control, was used in this experiment. A randomized block design was applied to test three corn hybrids under two sowing conditions (without sowing overlap - WOSO; and with sowing overlap - WSO), with four replications. The analyzed variables were the number of plants per hectare, the number of cobs per hectare, cob length, the number of grains per cob, the thousand grain weight, and productivity. WOSO areas presented cobs that were larger and had more grains, as well as a higher thousand grain weight, resulting in a productivity 13% higher than that of WSO areas. Therefore, the use of automatic section control is a technically feasible alternative to reduce seed costs and avoid productivity losses in corn crops.

RESUMO No momento da aquisição e utilização de um trator agrícola, o consumo de combustível pelo motor deve ser levado em conta pelo usuário, tendo em vista sua origem não renovável e o preço de comercialização. Estratégias adequadas de condução de tratores podem auxiliar os usuários a reduzirem os custos de produção. Nesse contexto, objetivou-se avaliar o consumo de combustível de um trator agrícola utilizando diferentes estratégias de condução. Cargas parciais foram impostas, seguindo instruções contidas no Código 2 da Organização para a Cooperação e Desenvolvimento Econômico, utilizando carro dinamométrico instrumentado, em pista de concreto. Foram aplicadas seis cargas parciais (30; 40; 50; 60; 70 e 80% de Q0) e três velocidades de deslocamento (5,16; 7,29 e 10,48 km h-1), para as estratégias utilizadas (Aceleração Máxima; e Marcha Longa - Aceleração Reduzida), onde Q0 é a força de tração correspondente à potência máxima na barra de tração, para cada marcha selecionada. Foram realizadas três repetições, que totalizaram 108 unidades experimentais (2 x 3 x 6 x 3), em um delineamento experimental inteiramente casualizado. O modo Marcha Longa - Aceleração Reduzida deve ser utilizado como uma estratégia de condução do trator, pois pode-se economizar até 29,39% de combustível em relação ao modo Aceleração Máxima, normalmente utilizado pelos usuários.

ABSTRACT During the acquisition and use of an agricultural tractor, the consumption of fuel by the engine must be taken into account by the user, considering its nonrenewable origin and the marketing price. Appropriate strategies in driving tractors can help users to reduce production costs. In this context, the objective of this study was to evaluate the fuel consumption of an agricultural tractor using different driving strategies. Load levels were imposed, following the instructions from Organization for Economic Co-operation and Development Code 2, using an instrumented dynamometer car, in a concrete test track. Six load levels (30, 40, 50, 60, 70, and 80% of Q0) and three travel speeds (5.16, 7.29, and 10.48 km h-1) were applied for the strategies used (Full Throttle and Shifted Up - Throttle Back), where Q0 is the traction force corresponding to the maximum power in the drawbar for each gear selected. Three repetitions were made, which totaled 108 experimental units (2 × 3 × 6 × 3), in a completely randomized experimental design. Shifted Up - Throttle Back mode should be used as a strategy of tractor driving, because it can save up to 29.39% of fuel in relation to the Full Throttle mode, typically used by users.

ABSTRACT Farming operations are usually performed implements driven by a power take-off (PTO) from tractors. Some manufacturers offer PTO settings named as economic (540E). Such configuration drives implements at lower tractor’s engine rotation, thus providing lower fuel consumption. An engine performance using standard (540) or 540E settings are different and poorly studied. The amounts of pollutants emitted by engines vary mainly with the applied load and rotation. The aim of this study was to compare the performance and exhaust emissions of a farming tractor engine under different PTO loads, using both standard (540) and 540E settings. Specific fuel consumption using 540E was an average 14.7% less than the standard setting. However, 540E promoted increasing levels of gas opacity, CO, CO2, NOx, and HC for the highest PTO power demands.

RESUMO Na semeadura do arroz irrigado, é necessária a boa drenagem da área, sendo realizados drenos cortando as taipas transversalmente. Para o estabelecimento da lâmina de irrigação definitiva, é necessário o fechamento destes drenos realizado pelos agricultores por meio de diversas maneiras. O estudo de tempos e movimentos de diferentes operações agrícolas é uma importante ferramenta para a obtenção de dados que reflitam o desempenho das mesmas. Dessa forma, o presente trabalho objetivou avaliar o desempenho de cinco equipamentos utilizados na lavoura orizícola, na operação de fechamento de taipas abertas para drenagem (entaipadora de base larga, braço valetador, caçamba "scraper", pá de corte e um protótipo desenvolvido para realizar esta operação), em duas diferentes áreas (coxilha e várzea). Após a avaliação, verificou-se que há diferenças entre os equipamentos utilizados, sendo o protótipo superior aos demais para as variáveis tempo total de operação, eficiência de tempo sem tempo gasto com deslocamento entre taipas, capacidade efetiva de campo e consumo de combustível por taipa.

ABSTRACT A good drainage system is critical during irrigated rice sowing; therefore, earth dikes are built to control water flows. Therefore, irrigation depths can be regulated by these dikes' openings, being performed in a variety of ways. Studying time and motion of different agricultural practices consists of a meaningful tool to gather data on the performance of these mechanisms. Given that, we aimed to test the performance of five equipment used in paddies to close earth dikes opened for drainage purposes (rice-dike plow, ditcher, bucket scraper, cutting shovel and a prototype developed for this operation) in two different areas (hills and lowland). After evaluation, we concluded that there are differences among the assessed equipment and, the developed prototype had the best results for total time of operation, time efficiency, effective field capacity and fuel consumption by dike.