Master of Science / Department of Biological & Agricultural Engineering / Ajay Sharda / In recent years, the technology employed on precision row-crop planters has rapidly advanced. These new technologies include automatic downforce control systems and electronic drive singulation seed meters. These new technologies offer producers higher productivity through high speed planting and increased yield potentials through accurate seed spacing and placement. To begin to understand the benefits and performance of these new technologies, research must be conducted that specifically targets these new systems. With this research, producers would be able to better select equipment for their operation and have a deeper understanding of proper system operation and settings. A test stand, of a scissor-lift type design, was developed to evaluate row crop planter automatic downforce systems. Evaluation of a planter’s automatic downforce system is important for understanding the planter’s capability of maintaining target seeding depth throughout varying field conditions. The test stand consists of a horizontal platform that can raise and lower to simulate terrain changes as well as a mechanism to load the planter row unit’s opening discs to simulate varying soil texture. The vertical height of the test stand and the disc load can be varied in real-time based on utilizing real-world scenarios under simulated conditions to evaluate downforce system response. The stand incorporated several sensors to obtain the overall applied downforce, applied disc load, applied gauge wheel load, and hydraulic pressure. The test stand’s capabilities were evaluated and found to be satisfactory for planter downforce system testing. The test stand was then used to evaluate a commercial automatic downforce system when operating under simulated field conditions. Field data was used to create simulations representing soil type changes, planter operating speed changes, and extreme conditions such as a hard, packed clay or rocky soil type. It was found that the evaluated downforce system was able to maintain target gauge wheel load to within ±223 N for at least 94% of the time during all simulations. This would suggest that the planter would be able to maintain target seeding depth for at least 94% of field operations. Another key aspect for precision agricultural planters is to achieve accurate seed spacing at varying speeds. An electronic drive singulation seed metering system was evaluated to gather the meter’s effectiveness for high speed planting during straight and contour farming mode using simulated field conditions. The simulated conditions were used to gather the meter’s response when encountering high planting speeds, accelerations, decelerations, point-rows, and contours. These meters were found to be highly accurate, with less than 1.5% error in target seed meter speed during all simulated conditions. The meters were also found to have a response time that was always 0.34 seconds or less for all simulated conditions.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / To evaluate the performance of precision sowing, it is necessary to collect a sample of seed spacing to be classified in accordance with current standards, thus demonstrating the performance of the machine as its quality that is expressed in regularity distribution . Generally, how much higher percentage of acceptable spacing between seeds, will be better the performance of the feeder. Due to the great heterogeneity of sample sizes used in these evaluations, the objective of this study was to estimate the sample size for laboratory experiments with horizontal plate and pneumatic seed meters, under the conditions described in rules, still evaluating the regularity of distribution of seeds of corn and soybeans. Experiments were conducted under laboratory conditions, according to the international standards ISO, UNE and design of ABNT, with four different seed feeders, two pneumatic and two horizontal plate. In test 1, the treatments comprised the combination of the four metering mechanisms with three seeding rates of 2.5, 5.0 and 7.5 km h-1. In test 2, were combined the four metering mechanisms and four peripheral speeds of the plate, 0.09, 0.18, 0.28 and 0.38 m s-1, both in a factorial design with three replications. We used three methods for determining the sample size: sampling intensity, bootstrap adapted and practical method. Regarding the distribution of maize seeds, the meter mechanism studied showed no differences in the regularity of seed distribution and response to elevated peripheral speed was negatively linear for the percentage of acceptable spacing. For soybean, the meter mechanism valued tires perform better mechanisms for horizontal plate, no direct correlation with the regularity of the peripheral speed of the plate. About the sample size, it is possible to reduce both cultures, but in a more pronounced for maize, the reduction of which can reach 73% of the value above the standard. For soybean, it is possible to reduce by 27% the sample size for testing in the laboratory with a high level of accuracy. / Para avaliar o desempenho de semeadoras de precisão, torna-se necessária a coleta de uma amostra de espaçamentos entre sementes, para que estes sejam classificados de acordo com as normas vigentes, denotando assim, o desempenho da máquina quanto a sua qualidade, expressa na regularidade de distribuição. De uma maneira geral, quanto maior o percentual de espaçamentos aceitáveis entre sementes, melhor o desempenho de um dosador. Devido à grande heterogeneidade de tamanhos amostrais empregados nestas avaliações, o objetivo deste trabalho foi estimar o tamanho de amostra para experimentos em laboratório, com dosadores de sementes tipo disco alveolado horizontal e pneumático, nas condições estabelecidas em normas, avaliando ainda na regularidade de distribuição de sementes das culturas de milho e soja. Para isso, foram conduzidos experimentos em condições de laboratório, conforme as normas internacionais ISO, UNE e o projeto de norma da ABNT, com quatro diferentes dosadores de sementes, sendo dois pneumáticos e dois de disco alveolado horizontal. No ensaio 1, os tratamentos compreenderam a combinação dos quatro mecanismos dosadores com três velocidades de semeadura, de 2,5, 5,0 e 7,5 km h-1. No ensaio 2, foram combinados os quatro mecanismos dosadores com quatro velocidades periféricas do disco dosador, de 0,09, 0,18, 0,28 e 0,38 m s-1, ambos em esquema fatorial com três repetições. Foram utilizados três métodos de determinação do tamanho de amostra: intensidade de amostragem, bootstrap adaptado e método prático. Quanto à distribuição de sementes de milho, os mecanismos dosadores estudados não apresentaram diferenças na regularidade de distribuição de sementes e a resposta à elevação da velocidade periférica foi negativamente linear para o percentual de espaçamentos aceitáveis. Para a cultura da soja, os mecanismos dosadores pneumáticos avaliados apresentam desempenho superior aos mecanismos de disco alveolado, sem correlação direta da regularidade com a velocidade periférica do disco. No que se refere ao tamanho da amostra, é possível reduzir para ambas as culturas, porém de maneira mais acentuada para a cultura do milho, cuja redução pode chegar a 73% do valor referido em norma. Para a cultura da soja, é possível reduzir em 27% o tamanho de amostra para ensaios em laboratório com um nível de precisão elevado.