RESUMO Dentre os ajustes fitotécnicos necessários, a correta recomendação da população de plantas de cada cultivar de soja é de suma importância para o sucesso na produção desta cultura. Assim, o objetivo deste estudo foi analisar a distribuição e autocorrelação espacial da população de plantas de soja de acordo com a variabilidade espacial de atributos físicos e químicos de um Latossolo na região do Cerrado brasileiro. Os atributos estudados foram: população de plantas, produtividade de grãos de soja, condutividade elétrica aparente do solo, teor de matéria orgânica do solo, capacidade de troca catiônica, potencial hidrogeniônico e teor de argila no solo. A população de plantas variou inversamente em função da condutividade elétrica aparente do solo. As áreas com os maiores valores de condutividade elétrica aparente do solo, teor de matéria orgânica do solo, capacidade de troca catiônica e teor de argila apresentaram as menores populações de plantas. A produtividade da soja não foi influenciada pelo aumento ou diminuição da população de plantas, por isso é economicamente viável plantar com menor densidade de plantas para melhorar a margem de lucro do agricultor. necessários cultura Assim brasileiro foram solo agricultor

ABSTRACT Among the necessary phytotechnical adjustments, the correct recommendation of the plant population of each soybean cultivar is of paramount importance for success in crop production. Thus, the objective of this study was to analyze the distribution and spatial autocorrelation of the soybean plant population according to the spatial variability of the physical and chemical attributes of Oxisol in the Brazilian Cerrado region. The attributes studied were plant population, soybean grain yield, apparent soil electrical conductivity, soil organic matter content, cation exchange capacity, hydrogenionic potential, and clay content in the soil. The plant population varied inversely as a function of apparent soil electrical conductivity. The areas with the highest values of apparent soil electrical conductivity, soil organic matter content, cation exchange capacity, and clay content had the lowest plant populations. Soybean yield was not influenced by increase or decrease in the plant population. Thus, it is economically viable to plant with lower plant density to improve the farmer’s profit margin. adjustments production Thus region conductivity capacity potential populations farmers farmer s margin

ABSTRACT The wear rate of spray nozzles affects several factors. This study aimed to investigate the influence of spray nozzle wear rate on droplet characteristics, such as droplet size, droplet homogeneity, droplets prone to drift, and flow rate variation. Eight hydraulic nozzles models (AIXR-110-02, JSF-110-02, TT-110-02, DG-110-02, XR-110-02, ADI-110-02, XR-110-02, and AI-110-02) were subject to an accelerated wear test, and their effects were measured at six experimental wear times (0, 10, 20, 30, 40, and 50 hours). The following variables were evaluated: volume median diameter, percentage of spray volume containing droplets smaller than 100 μm (prone to spray drift), flow rate (L min-1), and relative span, which indicates droplet size homogeneity. The droplet population was measured using a laser particle size analyzer. The use of the spray nozzle tip influences the quality of the spray application due to the wear rate. This study revealed a linear increase in the flow rate and volume median diameter as functions of the wear rate increment. The droplet size increased over the wear time, which consequently modified the volume percentage of droplets smaller than 100 μm and significantly increased the relative span.

ABSTRACT The sizing of mechanized agricultural systems depends on the soil and climatic conditions, the crop and the work regime. The aim of this study was to determine the probabilities of time available during an agricultural year for mechanized spraying and sowing in the northeast region of the State of Mato Grosso do Sul and south of Goiás. The meteorological restrictions imposed as unfavorable hours were: ambient temperature above 32°C, relative air humidity below 50%, wind velocity above 15 km h-1 and soil volumetric moisture above 39% (humidity equivalent to 90% of the available water capacity for the studied soil). The mathematical models were elaborated for eight years, based on the historical data of the automatic station of the National Institute of Meteorology installed in the region. It was possible to determine the time available for mechanized sowing and agricultural spraying operations. The available times for every ten days of the agricultural year for mechanized spraying and sowing in the study region were determined. The hourly water balance is used for the restrictive study of soil moisture in determining the time available for mechanized operations. A single self-propelled sprayer (30 m bar) and a single seed drill (48 rows) are not sufficient to meet the operational rate in an area of 3,000 ha in the northeast of the state of Mato Grosso do Sul and south of Goiás.

ABSTRACT: The aim of this study was to evaluate a financial analysis by the use of precision agriculture (PA) techniques on cotton crop. The experiment was carried out in a cotton field of 91 ha and its result compared to another field with similar area, cultivated with the conventional agricultural techniques. The financial analysis was extrapolated to the total farm area of 3,500 ha. All agricultural inputs applied, during the 2013/14 cotton crop season were analyzed, as well as their costs. The use of precision agriculture techniques over the cotton crop reduces production costs in 6.6%, increases the profitability index and operating profit in 3.3% and 7.9% respectively, when compared to conventional agriculture. The fertilizer application in variable rate, using precision agriculture, provides 41% of costs reduction with these inputs. Profitability and investment analysis indicators demonstrate economic feasibility and return over investment to both production systems (precision agriculture and conventional) over the cotton crop production, however, the use of precision agriculture techniques shows higher economic viability and smaller return over investment time, even having higher initial costs with machines, sensors and maps production.

ABSTRACT: The investment in precision agriculture technologies has been growing as well the investment in vegetation index sensors with different types of data collection. This study aimed to evaluate the NDVI potential use obtained from passive and active multispectral sensors as phenological parameters indicator of cotton growth. The experiment was conducted in cultivated cotton fields during the harvest seasons of 2013/14 and 2014/15. The phenological variables analyzed in the field, were cotton plant height and number of branches per sampled cotton plant. The active sensors Crop Circle and Green Seeker were mounted on a manual support. The passive sensor Tetracam was installed on a support positioning the sensor at 4 m height from the ground. NDVI readings are positively correlated with plant height and number of branches per cotton plant. Active sensors present exponential correlations between NDVI and phenological readings. Passive sensor, when installed in a support above the cotton canopy level, presents linear correlation between NDVI and phenological readings. NDVI values obtained by the passive sensor are higher than the active sensors. Filtering the raw NDVI values obtained by passive sensor decreases the adjustment of the regression analyses with cotton height and number of branches per plant.

RESUMO A qualidade física do solo é um dos fatores mais determinantes no desenvolvimento de qualquer cultura. Este trabalho teve, como objetivo, avaliar a representatividade amostral nos mapeamentos da resistência mecânica do solo à penetração nas linhas e entrelinhas no cultivo do algodoeiro, sob duas condições de umidade. Foram amostrados 30 pontos de controle em um talhão de 91 ha cultivado com algodoeiro. Foram realizadas leituras da resistência mecânica do solo à penetração (RP) e de umidade nesses pontos georreferenciados. Independentemente da umidade do solo é indiferente o posicionamento amostral da resistência mecânica do solo à penetração (linha, entrelinha ou em ambas as posições) quando a camada analisada é maior que 0,20 m no cultivo do algodoeiro. A diminuição da umidade do solo ocasiona o aumento dos valores da resistência mecânica do solo à penetração, independentemente do posicionamento amostral.

ABSTRACT The soil physical quality is one of the most determinant factors for the development of any crop. This study aimed to assess the sample representativeness in soil resistance to penetration mappings taken in rows and interrows of the cotton crop, under two soil moisture conditions. Thirty control points were sampled in a cotton field of 91 ha. Soil resistance to penetration and soil moisture were measured at these georeferenced points. Regardless of soil moisture, the sampling position of soil resistance to penetration is indifferent (row, interrow, or in both positions) when the analysed depth is greater than 0.20 m in the cotton crop. The decrease of soil moisture causes the increment of soil resistance to penetration, regardless of the sampling position.

A seleção de uma máquina agrícola pode tornar-se uma tarefa árdua, pois há diversas variáveis que devem ser consideradas. A escolha do equipamento mais adequado para uma propriedade agrícola é uma das etapas mais importantes do processo produtivo. O objetivo deste trabalho foi desenvolver um modelo de computador por programação linear em plataforma web para seleção automatizada de conjuntos mecanizados agrícolas, baseados no menor custo operacional. O programa, desenvolvido em linguagem ASP.NET, pode ser acessado gratuitamente pela Internet (http://www.maquinas.ufms.br). O usuário pode selecionar um conjunto mecanizado agrícola dentro de uma vasta lista de opções que contém suas especificações técnicas ou deixar que o programa lhe retorne automaticamente a melhor opção, pelo menor custo operacional. O programa desenvolvido proporciona ao usuário uma seleção racional via Internet de conjuntos mecanizados, permitindo o estudo econômico do uso das máquinas e implementos, sem a necessidade da instalação de programas dedicados no computador, que dificultariam a manutenção do banco de dados.

The selection of an agricultural machine may become a challenging task, because there are several variables that must be considered. Choosing the more suitable equipment to a farm is one of the most important production process steps. The purpose of this study was to develop a computational model by linear programming based on web platform to select automatically mechanized agricultural systems founded on the lowest operational cost. The software was developed in ASP.NET language and can be accessed for free by the Internet (http://www.maquinas.ufms.br). The user can select a mechanized agricultural system in a list that contains the specifications or let the system returns automatically the best option at the lowest operational cost. The developed software brought to the user via Internet a rational selection of mechanized systems, allowing the economic machinery studies, without any dedicated setup on the user's computer, which would hinder the database maintenance.

Com o crescimento da mecanização da cana-de-açúcar, é necessária uma dinamização dos processos, como no uso de técnicas de agricultura de precisão para uma diminuição do custo de produção. O presente trabalho foi desenvolvido com o objetivo de contrastar a acurácia nas passadas orientadas por dois sistemas de direcionamento, autodirecionamento via satélite versus manual, assim como comparar as capacidades de campo e a eficiência operacional envolvidos no plantio mecanizado da cana-de-açúcar. Foram analisados dois tratamentos: com e sem o auxílio do piloto automático por GPS RTK na operação de plantio mecanizado. As avaliações foram realizadas em condições de campo, na Usina IACO Agrícola S.A., em Chapadão do Sul - MS. De acordo com os resultados obtidos, afirmou-se que o uso do piloto automático na operação de plantio da cana-de-açúcar ofereceu uma acurácia de 0,033 m entre as passadas, sendo cinco vezes maior do que aquela obtida com o direcionamento manual, e que o seu uso não melhorou a eficiência operacional do conjunto mecanizado na operação de plantio, sendo limitada pelo sistema de colheita e transporte da cana muda para a plantadora.

With the growth of mechanization on the sugar cane plantation, the processes need to be speeded up, such as with the use of precision farming techniques to decrease the production cost. The purpose of this study was to compare the accuracy achieved by an auto guidance system driving the passes of a sugar cane planter machine over the field versus the manual system, compare the operational field capacity and compare the operational efficiency. Two treatments were analyzed: auto guidance by RTK GPS and manual guidance on the sugar cane planting operation. The evaluations were conducted under field conditions at IACO Agrícola S/A mill, in Chapadão do Sul-MS. According to the results, it was stated that the use of auto guidance system on sugar cane planting operation gathered an accuracy of 0.033 m pass to pass. This accuracy is five times greater than the obtained by the manual steering system. The use of an auto guidance steering did not increase the operational efficiency of the mechanized system, which is limited by the harvesting and transporting system of the sugar cane seeding to the planter.

A seleção de pulverizadores agrícolas que se adaptem às necessidades da propriedade, é um processo trabalhoso, sendo uma das etapas mais importantes dentro do processo produtivo. O objetivo do presente trabalho foi o de desenvolver e utilizar um modelo de programação linear para auxiliar na seleção de pulverizadores agrícolas de barras, baseado no menor custo horário do equipamento. Foram utilizadas as informações técnicas referentes a 20 modelos de pulverizadores disponíveis no mercado, sendo quatro autopropelidos, oito de arrasto e oito do tipo montado. A análise de sensibilidade dos componentes dos custos operacionais mostrou que as taxas de reparo e depreciação foram os fatores que mais interferiram na variação do custo horário do conjunto trator-pulverizador. O modelo matemático desenvolvido facilitou a realização da análise de sensibilidade que foi processada em um tempo muito pequeno.

The selection process of agricultural machines is one of the most important stages of the productive process. The purpose of the present work was to develop and to test a linear programming model to aid in the decision of agricultural boom sprayer selection based on the cheapest hour-cost. The technical information about 20 sprayer models available in the market was used, where four were self-propelled, eight were trailed and eight were lift mounted sprayer. The sensibility analysis of the operational cost components showed that the repair and depreciation rates are the factors that most contribute to hour-cost variation of the sprayer-tractor group. The developed mathematical model facilitated the accomplishment of the sensibility analysis, which was processed in a very short time.

Alguns equipamentos utilizados na agricultura de precisão têm, por finalidade, a melhoria das condições operacionais. A barra de luz é um equipamento utilizado para a orientação de um veículo em faixas adjacentes, diminuindo a sobreposição da operação agrícola entre passadas consecutivas e otimizando a eficiência da aplicação agrícola. O presente trabalho teve por objetivo a determinação da acurácia da barra de luz em relação ao marcador de espuma e a verificação da adaptação dos operadores à nova tecnologia. Para tanto, foram realizados dois ensaios em locais distintos, com operadores diferentes e foram comparados os erros de sobreposição e falhas nas passadas adjacentes de um pulverizador automotriz. Ocorreu alta adaptação dos operadores à nova tecnologia, devido a uma facilidade operacional maior em relação ao marcador de espuma. Concluiu-se que o marcador de espuma pode ser substituído pela barra de luz na aplicação de defensivos agrícolas.

Some equipments are used in precision farming to improve operational conditions. A light bar is an equipment used to guide a vehicle in adjacent bands, reducing the overlap of the parallel swathing and optimizing the efficiency of the agricultural application. The objective of this work was to determine the accuracy of a light bar compared to a foam marker, and to verify the adaptation of the operators to this new technology. Experiments were conducted at two different places with several operators. The overlap errors and missed applications in the parallel swathing system were compared for both systems. There was a high adaptability of the operators to the light bar since this system was easier to operate than the foam marker. It was concluded that the light bar for the application of agricultural chemicals could replace the foam marker.