Cristiano Márcio Alves de Souza

Intervalo hídrico ótimo em um latossolo vermelho distroférrico sob diferentes sistemas de produção

The objective of this work was to characterize the growing systems related to the structural soil quality for plants development by the Least Limiting Water Range (LLWR). The study was developed using soil samples with preserved structure of a Distroferric Red Latossol under the conventional, no tillage and integrated growing systems in de county of Dourados-MS, Brazil. In each system 28 points were sampled, in 0-0.05, 0.05-0.10 and 0.10-0.20 m deep layers, ending up with 84 samples by system which was used to adjust the water retention curve in the soil, soil resistance to penetration curve and porosity determination, all of them necessary to the LLWR determination. In the conventional and no-tillage systems the smallest restriction to de roots development was in the 0-0.05 m layer, while in the integration system the smallest limiting was in 0.10-0.20 m layer. In the conventional system, in the 0-0.05 m layer, the LLWR was equal to the available water capacity, in the direct and integrated systems the resistance to penetration was the limiting factor. The resistance to penetration was the major limiting factor in most of the studied situations.

Variabilidade espacial de atributos do solo em sistema de semeadura direta com rotação de culturas no cerrado brasileiro

This study aimed to analyze the spatial variability of the chemical attributes and texture of a red latosol. The study was carried out on a property in the town of Sidrolândia, Matto Grosso do Sul, which produces soybeans, corn and cotton, using crop rotation and a no-tillage system. In an experimental area of approximately 90 hectares, samples were taken of the soil at 181 geo-referenced points. The samples were each composed of four single samples, representing depths of from 0 to 0.2 m. The chemical and texture of the soil were measured. Initially a discrepancy analysis was performed followed by descriptive and geostatistical analyses, to characterize the samples and identify the spatial dependence of the attributes studied. No spatial dependence was detected for the attributes: active water acidity, aluminum, potential acidity, base saturation and organic matter. The best estimates of values for non-sampled locations were observed for the physical properties of the soil, which presented parameters which best fit the variograms and cross-validation. The geostatistical techniques used allowed adjustment of the theoretical models that best represented the experimental semivariance, thus enabling the construction of thematic maps of spatial distribution for the values of the attributes of the studied soil.

Infiltração de água no solo em áreas cultivadas com cana-de-açúcar sob diferentes sistemas de colheita e modelos de ajustes de equações de infiltração

As tecnicas de colheita da cultura de cana nem sempre seguem preceitos conservacionistas, fato que pode influenciar atributos fisicos do solo com consequente alteracao da velocidade de infiltracao de agua no solo. O trabalho realizado teve como objetivo avaliar o efeito de diferentes sistemas de colheita (manual e mecanizada) da cana-de-acucar (crua e queimada), sobre as caracteristicas de infiltracao e verificar a adequacao de modelos matematicos para a estimativa da taxa de infiltracao de agua no solo. Foi utilizado um simulador de chuva portatil calibrado para aplicar uma precipitacao de 60 mm h-1. Os testes de infiltracao de agua no solo foram realizados em tres sistemas de colheita: colheita manual de cana queimada, colheita mecanizada de cana crua e colheita mecanizada de cana queimada. A qualidade do ajuste dos modelos foi avaliada por meio de regressoes nao lineares entre os valores estimados e os valores medios observados em cada tratamento estudado. Nos tratamentos onde foi empregada a colheita mecânica, observou-se uma reducao da taxa de infiltracao final em relacao a area sob colheita manual de cana queimada. A equacao de Horton foi a mais adequada para a estimativa da taxa de infiltracao de agua no solo estudado.

Rugosidade da superfície do solo sob diferentes sistemas de manejo e influenciada por chuva artificial

Soil roughness is influenced by soil management, particularly by soil tillage and mainly reduced by rainfall action. This study aimed to evaluate the influence of different systems of soil management and artificial rainfall application on soil surface roughness. The treatments were a result of the combination of three systems: no-tillage, conventional tillage and minimum tillage, with three levels of dry soybean (Glycine max L. Merrill): residue: 0; 2; and 4 Mg ha-1. Experimental units received artificial rain (seven rains), at an intensity of 60 mm h-1 and during 60 min each, amounting to 420 mm rain. Roughness was evaluated immediately before and after tilling and immediately after the rainfalls. Roughness values between 1.88 and 5.41 mm were found under no-tillage, 3.88 and 8.30 mm under conventional tillage, and 3.31 and 17.45 mm under minimum tillage. It was concluded that soil tillage operations generally increased surface roughness. Values of random roughness were highest under minimum tillage; rain did not deteriorate the soil microrelief in the no-tillage treatments with soil cover.

Anatomia radicular de milho em solo compactado

O objetivo deste trabalho foi avaliar a relacao entre a estrutura anatomica das raizes de milho e os atributos fisicos de solo submetido a diferentes graus de compactacao. O estudo foi realizado em campo, no Municipio de Dourados, MS, em Latossolo Vermelho distroferrico, textura muito argilosa. O delineamento experimental foi o de blocos ao acaso, com cinco repeticoes. O solo utilizado apresentava historico de oito anos com plantio direto. A compactacao adicional do solo foi realizada por meio de trafego com trator, com uma (PDc1), duas (PDc2), quatro (PDc4) e seis passadas (PDc6) sucessivas, sobre toda a area da parcela. Houve aumento na razao entre o cortex e o cilindro vascular da raiz com o aumento na compactacao do solo. Essa razao correlacionou-se negativamente com a macroporosidade e positivamente com a densidade do solo e com a resistencia do solo a penetracao. O grau de compactacao afeta a anatomia radicular do milho, e a resistencia do solo a penetracao e o indicador fisico que melhor expressa esse efeito.

Derriçadora portátil na colheita total e seletiva de frutos do cafeeiro

The objective of this work was to evaluate the performance of a portable coffee harvester to mountain areas. Two procedures were tested: harvesting all fruits in only one operation, and the selective harvesting. Coffee yield, harvesting capacity, index of leaves taken during harvesting process, harvesting efficiency, noise level and fuel consumption were measured. The harvesting system with two portable harvester presented better performance than with only one machine. Selective harvesting was highly influenced by the percentage of ripen fruits and by coffee yield.

Avaliação de perdas em uma colhedora de fluxo axial para feijão

The evaluation performance of a harvester should include the energy needed for its operation, the harvesting capacity and the quantitative loss in the process. The objective of this work was to evaluate the performance of a bean harvester. Field tests were done in different operational conditions. Based on the collected data, it was concluded that the harvester header causes the greatest quantitative loss, responsible for 49.30% of the total loss. In the separation and cleaning systems the losses were 43.61 and 7.09%, respectively. The maximum harvesting capacity of the machine was 6.56 t h-1 of grains.

Simulação do processo de secagem de sementes de milho em camada fixa

Artificial drying is one of the main problems of seed production, hence it affects quality of grains, and can decrease considerably their market value. This work aimed to develop a mathematical model to simulate a corn seed drying process. Simulation results were validated by comparison to experimental results. The drying method consisted of a fixed-bed, pre-drying of corn (Zea mays L.) ears, which were then kept on rest for 12 hours. After that the product was threshed and kernels were submitted to a final drying process on a fixed bed dryer: bins with radial air distribution. Air temperature was 42°C; specific air rate of the ear corn dryer was 44.8 m3 min-1 m-2 and of the drying bin 5.9 m3 min-1 m-2. The error of the average simulation model was 10.88%, which was considered satisfactory.

Oxisol resistence to penetration in no-till system after sowing

If inappropriately conducted, management and sowing practices may compromise the environment and the profitability of the agricultural activity. The aim of this study was to analyze the furrow opener mechanisms action and the level of load applied to soil firming mechanism in no-till, on the Oxisol resistance to penetration during soybean sowing, under three soil moistures. The experiment was arranged in split-split plot design, in which the plots were composed by three soil moistures (23.8; 25.5 and 27.5% b.s.), two furrow opener mechanisms sub-plots (double disks and furrow plough) and the split-split plot of three levels of load applied to soil firming mechanism (12.2; 18.5 and 24.1 kPa), according to randomized blocks design, with three replications. The soil moisture provided different resistance behavior to penetration with the depth, on the seedbed, independently of the furrow opener and the level of load applied to soil firming mechanism. The furrow plough use provided less soil resistance to penetration when compared to the double disk furrow opener, on the seedbed, independently of the soil moisture and the level of load applied to soil firming mechanism. The pressure applied by soil firming mechanism of 18.5 kPa provided the lower resistance to penetration, when the furrow plough was used. The soil resistance to penetration was less on the sowing line than on between rows, with 20 cm deep.

Simulation of the stability of 2wd agricultural tractors

O objetivo do trabalho foi simular computacionalmente a estabilidade de tratores agricolas 4x2. Experimentos de simulacao foram realizados visando analisar o comportamento dinâmico de um trator agricola 4x2 trabalhando em diferentes condicoes de operacao e de terreno. Nas simulacoes em que se variaram as posicoes do trator sobre uma pista inclinada ate o tombamento lateral, o ângulo de posicao igual a 60o foi o de pior situacao, o que corresponde ao trator descer por uma diagonal em pista inclinada para a esquerda. A bitola e a localizacao do centro de gravidade na vertical foram os fatores que mais afetaram a estabilidade do trator em tombamentos laterais. Ja, a localizacao do centro de gravidade na longitudinal e a distância entre eixos afetaram mais a estabilidade do trator em tombamentos para tras. O trator deslizou os rodados do lado do tombamento ou perdeu a dirigibilidade dos pneus frontais com ângulos inferiores aos limites de estabilidade para tombamento.