Diego Weslly Ferreira Do Nascimento Santos

CURVA DE RETENÇÃO DE ÁGUA NO SOLO EM FUNÇÃO DO TIPO DE MANEJO MECANIZADO DO SOLO E TEMPO DE PREPARO JULIANA PINHEIRO DADALTO¹; HAROLDO CARLOS FERNANDES2; IGOR RODRIGUES DE ASSIS3; DANIELLA DE MOURA BEZERRA AMORIM4; VALDEIR EUSTÁQUIO JUNIOR5 E DIEGO WESLEY FERREIRA DO NASCIMENTO SANTOS6 1Departamento de engenharia agrícola, Universidade Federal Rural de Pernambuco, Rua Dom Manuel de Medeiros, s/n, Dois Irmãos - CEP: 52171-900, Recife, Pernambuco, Brasil, juliana.dadalto@ufrpe.br 2Departamento de engenharia agrícola, Universidade Federal de Viçosa, Av. Peter Henry Rolfs, s/n, CEP: 36570-900, Viçosa, Minas Gerais, Brasil, haroldo@ufv.br 3Departamento de solos, Universidade Federal de Viçosa, Av. Peter Henry Rolfs, s/n, CEP: 36570-900, Viçosa, Minas Gerais, Brasil, igor.assis@ufv.br 4Departamento de engenharia agrícola, Universidade Federal Rural de Pernambuco, Rua Dom Manuel de Medeiros, s/n, Dois Irmãos - CEP: 52171-900, Recife, Pernambuco, Brasil, daniella.amorim@ufrpe.br 5Instituto Federal Fluminense, Estrada Cambuci-Três Irmãos, Km 05, Zona Rural – Cambuci/RJ CEP: 28430-000, vejunior@yahoo.com.br 6Doutor em engenharia agrícola pela Universidade Federal de Viçosa, Departamento de engenharia agrícola, Universidade Federal de Viçosa, Av. Peter Henry Rolfs, s/n, CEP: 36570-900, Viçosa, Minas Gerais, Brasil, diegoweslley89@gmail.com 1 RESUMO A prática agrícola onde são efetuadas o plantio direto continuamente podem acarretar mudanças na estrutura do solo, como o aumento da densidade, principalmente em solos argilosos. Essas alterações, relacionadas ao manejo do solo, podem ser avaliadas por meio de atributos físicos e hídricos. Com a curva de retenção de água no solo (CRA) é possível ter informações sobre a capacidade de água disponível (AD), água que não está disponível (AND) e da capacidade máxima de água (CMA), além da distribuição dos poros ao longo do perfil de solo. Este trabalho teve como objetivo avaliar a curva de retenção de água no solo de um solo submetido a diferentes sistemas de preparo mecanizado em função do tempo de preparo. O experimento foi composto de três sistemas de preparo do solo, preparo convencional (PC), cultivo mínimo (CM) e plantio direto (PD). As curvas de retenção de água no solo foram ajustadas por meio da equação de Van Genuchten. É possível observar na CRA que o PD, um mês após o preparo do solo, apresentou melhor curvatura da CRA e consequentemente melhor qualidade do solo. Palavras-chave: plantio direto; argissolo; água disponível DADALTO, J. P.; FERNANDES, H. C.; ASSIS, I. R. DE; AMORIM, D. DE M. B.; EUSTÁQUIO JUNIOR, V. E SANTOS, D. W. F. DO N. SOIL-WATER RETENTION CURVE AS A FUNCTION OF THE TYPE OF MECHANIZED SOIL MANAGEMENT 2 ABSTRACT The agricultural practice where no-tillage is carried out continuously can lead to changes in soil structure, such as increased density, especially in clayey soils. These changes, related to soil management, can be evaluated through physical and water attributes. With the soil‒water retention curve, it is possible to obtain information about the available water capacity, the water that is not available and the maximum water capacity, in addition to the distribution of pores along the soil profile. This information is essential for water management, allowing the provision of the ideal amount of water for the development of crops and the rates of water infiltration into the soil. The experiment consisted of three soil tillage systems: conventional tillage, minimum tillage and no tillage. The soil‒water retention curves were fitted using the van Genuchten equation. It is possible to observe in the soil‒water retention curve that no-tillage had a better curvature of the soil‒water retention curve and, consequently, better soil quality. Keywords: No-tillage; ultisol; available water.

Forest machine operators work on a long scale of work, which causes physical and psychological wear and consequently reduced productivity and increased fuel consumption. The objective of this research was to verify the influence of the number of days of the work schedule of harvester and forwarder operators in low-volume forest on technical, economic, environmental and ergonomic parameters. The research was performed in forest stands with an average wood volume of 0.10 m³ tree-1. In the first, second, third and fourth day of the work schedule, productivity, energy demand, production cost, carbon dioxide emission and the occurrence of fatigue in the operators were determined. The productivity values ??of harvester operators on the third and fourth days of the work schedule decreased by 2.62 and 7.74%, respectively, in relation to the average value of the first and second days. The productivity of forwarder operators was similar in the first three days of the work schedule, with a more marked reduction in the fourth day. The reduction in the number of days in the forest machine operators’ work schedule makes the operation more sustainable from a technical, economic, environmental and ergonomic point of view.

The introduction of the forwarder for wood extraction has provided significant improvements in forest harvesting operations. However, these machines have a high energy demand due to the high engine speed and hydraulic system pressure. Such circumstances increase the operational cost and the emission of polluting gases. Therefore, the objective of this research was to quantify technical, economic, and environmental forwarder parameters as a function of hydraulic pump pressure and engine speed. The research was carried out in the northeastern part of Brazil. The machine operations were analyzed in forest stands with average individual volumes of 0.10 and 0.29 m³ trees⁻¹. During the experiment, the machine was configured to operate with pump pressures of 240, 235, and 230 bar and engine speeds of 1550, 1475, and 1400 rpm, totaling 9 combinations. The technical analysis included the study of times and movements, productivity, and fuel consumption per cubic meter. Regarding the economic parameters, the production costs of the machine were determined. Environmental impact was measured by determining the amount of carbon dioxide and methane emitted. The results were analyzed by regression analysis. For the volume of 0.10 m³ tree⁻¹, the combination of pump pressure of 230 bar and engine speed of 1400 rpm showed the best results. For the volume of 0.29 m³ tree⁻¹, the combination of pump flow of 240 bar and engine speed of 1550 rpm provided the best results.

Excavators-based harvesters are self-propelled forestry tractors that normally operate at maximum engine speed. This results in maximum hydraulic pump flow regardless of operating conditions. The objective of this work was to quantitatively investigate the technical performance, as well was the economic and environmental outcomes, of excavators-based harvester as a function of engine speed and hydraulic pump flow. Machine operations were analyzed in forest stands with an individual average volume of 0.08 or 0.16 m3 tree–1. The machine was operated with engine speeds of 2060, 2000, 1950, or 1900 rpm and hydraulic pump flow rates of 300, 295, or 290 L min–1. This resulted in 12 different excavator-based harvester configurations. With regards to the technical performance of the machine, a study of times and movements, productivity, hourly fuel consumption, and fuel consumption was performed. Economic outcomes were considered in terms of the operational costs, while environmental impact was determined by carbon dioxide and methane emissions. Optimal excavator-based harvester operating conditions with an average volume of 0.08 m3 tree–1 were determined to be with an engine speed of 2000 rpm and a hydraulic pump flow rate of 295 L min–1. With the 0.16 m3 tree–1 volume, the best results were obtained with an engine speed of 2000 rpm and a hydraulic pump flow of 300 L min–1.

Reducing engine speed and pressure of forest machine hydraulic pumps may be a strategy to achieve a reduction in fuel costs. However, this approach can positively or negatively affect the ergonomic parameters of the operators, in particular, the whole-body vibration and repetitive movements of the operators. The objective of this research was to evaluate the acceleration force resulting from normalized exposure (Aren) and the Real Occupancy Rate and Maximum Occupancy Rate considering Repetitive Activities (ROR-MORCRA) of forwarder operating at different pump pressures, engine speed, and volume of trees. The research was carried out in forest stands with an individual average volume of 0.10, 0.14, and 0.29 m³ tree-1. For each volume, the machine was configured to operate at hydraulic pump pressures of 240, 235, and 230 bar and engine speed of 1550, 1475, and 1400 rpm, totaling 9 combinations. The values were measured in the 9 combinations and also in each phase of the machine operational cycle, using a triaxial accelerometer of the 01dB brand, model Vib 008. To determine ROR, percentage of rest due to regular breaks, percentage of time with low demand activities, percentage of usual irregular breaks, and percentage of very short breaks were calculated. To estimate MORCRA, the repetition, strength, and static effort factors were calculated. In volumes of 0.10, 0.14, and 0.29 m³ tree-1, the highest Aren values were 0.82, 0.88, and 0.99 m s-2, respectively, being obtained at the 1550 rpm engine speed. The forwarder logging operation is characterized as an ergonomic risk, which can cause discomfort, fatigue, and injuries to operators.

Análise técnica e econômica de dois subsistemas de colheita de madeira de toras curtas - DOI:10.5039/agraria.v13i2a5516

A alteração do ângulo de pontas hidráulicas pode provocar uma má aplicação de defensivos agrícolas, porém não existe uma maneira simples e rápida para mensurar tal caraterística. O presente trabalho tem como objetivo calcular o ângulo do jorro produzido por pontas hidráulicas, em diferentes pressões de trabalho, por meio de dois métodos convencionais (goniômetro e mesa de perfil de distribuição) e por processamento digital de imagens em distintas resoluções. Para o primeiro método foi utilizado um goniômetro da marca Mitutoyo. A mesa de perfil de distribuição era constituída por canaletas equidistantes em 0,05 m, que conduziam o líquido até as provetas graduadas. Para determinação do ângulo do jorro por meio do processamento de imagens foi capturado fotos nas resoluções de 20; 10; 5 MP e VGA, sendo as mesmas processadas no software MATLAB®. Os resultados obtidos mediante a mesa de perfil de distribuição foram estaticamente superiores aos demais métodos. O aumento da pressão de trabalho provocou acréscimos significativos no ângulo do jorro da ponta Hypro, no entanto para a ponta Jacto só ocorreu acréscimo significativo quando o ângulo foi calculado com a mesa de perfil de distribuição. A determinação do ângulo do jorro de pontas hidráulicas por processamento digitais de imagens demonstra-se como uma ferramenta eficiente.Palavras-chave: aplicação de defensivos, resolução digital, programação, jato de pulverização. DETERMINATION OF THE ANGLE OF THE SPOUT OF HYDRAULIC TIPS USING CONVENTIONAL METHODS AND DIGITAL IMAGE PROCESSING ABSTRACTChanging the angle of hydraulic tips can lead to poor application of pesticides, but there is no simple and quick way to measure this. The objective of the present work is to calculate the angle of the spurt produced by hydraulic tips, in different working pressures, by means of two conventional methods (goniometer and table of distribution profile) and digital processing of images in different resolutions. For the first method a goniometer of the Mitutoyo brand was used. The distribution profile table consisted of channels equidistant at 0.05 m, which led the liquid to the graduated test tubes. To determine the angle of the spurt by means of the image processing was captured photos in the resolutions of 20; 10; 5 MP and VGA, being processed in MATLAB® software. The results obtained through the distribution profile table were statically superior to the other methods. The increase in working pressure caused significant increases in the jet angle of the Hypro tip, however for the Jet tip only significant increase occurred when the angle was calculated with the distribution profile table. The determination of the angle of the spout of hydraulic tips by digital image processing proves to be an efficient tool.Keywords: application of pesticides, digital resolution, programming, spray jet. DOI: http://dx.doi.org/10.5935/2318-7670.v05n03a07

A alteração do ângulo de pontas hidráulicas pode provocar uma má aplicação de defensivos agrícolas, porém não existe uma maneira simples e rápida para mensurar tal caraterística. O presente trabalho tem como objetivo calcular o ângulo do jorro produzido por pontas hidráulicas, em diferentes pressões de trabalho, por meio de dois métodos convencionais (goniômetro e mesa de perfil de distribuição) e por processamento digital de imagens em distintas resoluções. Para o primeiro método foi utilizado um goniômetro da marca Mitutoyo. A mesa de perfil de distribuição era constituída por canaletas equidistantes em 0,05 m, que conduziam o líquido até as provetas graduadas.