Fábio Moreira da Silva

Variabilidade espacial de atributos químicos e de produtividade na cultura do café

The knowledge of determined attributes of the soil associated to the reply of productivity of the coffee can make the application rational, located and individualized of the farm input, with guaranteed ambient economic results possible. Therefore, this work was aimed at evaluating the spatial variability of soil chemical attributes and the productivity of coffee cropping in an Oxisol. Soil samples were collected in a depth of 0-0.2m, at the crossing points of a regular grid with 25m-intervals, comprising a total of 68 points in an area of 6.2ha. Fruits of four coffee plants around the soil sampling points were collected and the average production per plant was calculated. The variables presented a spatial dependence structure, allowing their mapping by geostatistics techniques. Chemical attributes presented low range values, with exception of the phosphorus and potassium variables, evidencing the low soil continuity spatial under the coffee crop. The wide variation range of chemical attributes shows the necessity of point fertilizer application for coffee cropping.

Variabilidade espacial de atributos químicos e produtividade da cultura do café em duas safras agrícolas

O emprego da Agricultura de Precisao pode ser uma das alternativas para o pais continuar com a lideranca mundial de cafe, por meio da competitividade nos custos e na qualidade do produto. Objetiva-se com este trabalho, avaliar a variabilidade espacial dos atributos quimicos do solo e da produtividade da cultura do cafeeiro em duas safras agricolas. Amostras de solo foram coletadas na profundidade de 0,0-0,2 m, nos pontos de cruzamento de uma malha com intervalos regulares de 25 m, perfazendo um total de 68 pontos em uma area de 6,2 ha. Os frutos de quatro plantas, em torno dos pontos de cruzamento da malha, foram coletados para o calculo da produtividade media por planta. A dependencia espacial encontrada para os atributos quimicos e produtividade da cultura do cafe, bem como a semelhanca de comportamento dos atributos estudados nas diferentes safras, permite inferir que o efeito de bianuidade nao interferiu na variabilidade espacial da cultura do cafe. A grande amplitude nos atributos quimicos justifica o estudo da aplicacao diferenciada e localizada de fertilizantes na lavoura cafeeira. A regressao linear espacial mostrou comportamento semelhante da variabilidade espacial dos atributos quimicos e produtividade da cultura do cafe nas duas safras estudadas.

Desempenho comparativo de um motor de ciclo diesel utilizando diesel e misturas de biodiesel

Os atuais elevados precos do barril de petroleo no mercado internacional, a possibilidade de geracao de postos de trabalho e renda com a consequente fixacao do homem no campo, as excelentes e variadas condicoes climaticas e os tipos de relevo fazem com que o Brasil, com suas extensas areas agricultaveis, destaque-se no cenario mundial em relacao a sua grande potencialidade de geracao de combustiveis alternativos. A situacao ambiental faz com que o ser humano trabalhe no desenvolvimento de alternativas energeticas, destacando-se aquelas oriundas de fontes renovaveis e biodegradaveis de carater eminentemente sustentavel. Assim, objetivou-se com este trabalho avaliar o desempenho de um motor ciclo diesel, funcionando em momentos distintos com diesel mineral e misturas deste com biodiesel nas proporcoes equivalentes a B2 (98% de diesel mineral e 2% de biodiesel), B5 (95% de diesel mineral e 5% de biodiesel), B20 (80% de diesel mineral e 20% de biodiesel) e B100 (100% de biodiesel). Para a realizacao dos ensaios, foi utilizado um motor ciclo diesel de um trator VALMET 85 id, de 58,2kW (78 cv), de acordo com metodologia estabelecida pela norma NBR 5484 da ABNT (1985) que se refere ao ensaio dinamometrico de motores de ciclo Otto e Diesel. Concluiu-se que a potencia do motor ao se utilizar biodiesel foi inferior aquela quando se utilizou diesel mineral. Observou-se que, em algumas rotacoes, as misturas B5 e B20 apresentaram potencia igual ou ate superior, em algumas situacoes, aquela quando se utilizou diesel mineral. A melhor eficiencia termica do motor foi verificada na rotacao de 540 rpm da TDP equivalente a 1720 rpm do motor.

Influência da vibração das hastes e da velocidade de deslocamento da colhedora no processo de colheita mecanizada do café

Nowadays, there are many studies about the efficiency of the mechanized coffee harvest but not much is known about the influence of the sticks vibration and the speed of the harvester machine on the mechanized coffee harvest process. The goal of this paper was to evaluate this influence. The study was conducted at the Capetinga Farm, south of the state of Minas Gerais. For the experiments, it was utilized the randomized design with four repetitions in aleatory portions having, on average, 40 plants in each line. The experiments were done with two runs of the harvester considering the green coffee berries rate. The first run was done having 30% of green coffee berries and, on the second one, about 10% of green coffee berries. It was concluded that, on the first run, the volume of coffee berries harvested, the leaf loss and the seed dropping efficiencies were 29.25%, 31.12% and 31.85%, respectively, having better results when operating with the highest vibration. On the second run, with the highest operational speed, the volume of coffee berry that fell on the ground varied 61.2% in relation to the lowest speed and the reduction on the harvested volume and in the harvest efficiency varied 14.28% from the lowest to the highest operational speed.

Geostatistical analysis of fruit yield and detachment force in coffee

The aim of this study was to use geostatistical analysis to evaluate the spatial variation in the detachment force of coffee fruit and coffee yield by variograms and kriging for precision agriculture. This study was conducted at Brejão farm, Três Pontas, Minas Gerais, Brazil. The detachment force of green and mature coffee fruit was measured with a prototype dynamometer and georeferenced. The yield data were obtained from manual harvesting and were georeferenced. The data were evaluated by variograms estimated by residual maximum likelihood (REML), which provided a satisfactory approach for modeling all the variables with a small sample size. Spherical and exponential models were fitted, the first provided the better fit to mature fruit detachment force and the latter provided the better fit to coffee yield and green fruit detachment force. They were used to describe the structure and magnitude of spatial variation in the variables studied. Kriged estimates were obtained with the best fitting variogram models and mapped. The statistical and geostatistical analyses enabled us to characterize the spatial variation of the detachment force of green and mature coffee fruit and coffee yield and to visualize the spatial relations among these variables. The precision agriculture techniques used in this paper to collect, map and analyze the variables studied will help coffee farmers to manage their fields. Maps of coffee yield will enable farmers to apply nutrients site-specifically and manage harvesting either manually or mechanically. In addition, maps of detachment force of coffee fruit can enable farmers to harvest coffee selectively by choosing the appropriate places and the right time to start. This will improve the quality of the final product and also increase profits.

Avaliação do desempenho de um aquecedor para aves adaptado para utilizar biogás como combustível

It was carried out a trial to evaluate the adaptation (injector diameter) and performance (biogas consumption and heating efficiency) of a heating adapted to burn biogas. It was tried a common heater, burning liquefied petroleum gas (LPG), operating with low gas pressure (28 cm water column), with calorific capacity of 5024 kJ/h and recommended for 500 birds. The heater was evaluated with the original fuel (LPG) without any modification in the gas injector and after adapting to biogas burning. Five injectors were evaluated with drillings of 1,0053; 1,5080; 1,5708; 1,7672 and 1,980 mm2. It also was varied the biogas pressures in the heater entrance of 10, 12, 15, 17 and 20 cm of water column. Results showed that expressions for theoretical calculation and proposed parameters in the literature can be used for aviaries heaters adaptation. The adaptation is simple, indicating the viability for utilization of existing heaters in farms and in the market. Air temperatures were similar to the obtained with the original fuel (LPG).

Efeitos da colheita manual na bienalidade do cafeeiro em Ijaci, Minas Gerais

Analisou-se, neste trabalho, a relacao entre a produtividade e a desfolha do cafeeiro durante o processo de colheita manual nas safras agricolas de 2005, 2006 e 2007. O experimento foi desenvolvido na fazenda Cafua, localizada no municipio de Ijaci, sul de Minas Gerais, em uma area de 6,5ha de lavoura de cafeeiro (Coffea arabica L.) da variedade cultivada Catuai Vermelho IAC-99. Foi demarcada na area uma malha irregular na distância de 25x25 e 50x50m, num total de 67 pontos amostrais, nos quais foram avaliados a producao de cafe (L.planta-1) obtida por meio da colheita no pano e a desfolha das plantas, quantificada com base no peso de folhas (kg. planta-1) apos a colheita manual. Procedeu-se a analise de correlacao de Pearson para verificar a relacao linear entre a produtividade e a desfolha nos diferentes periodos avaliados. A dependencia espacial dos dados tambem foi analisada por meio de ajustes de semivariogramas e interpolacao por krigagem. Constatou-se que a colheita manual desfolhou mais em locais de maior produtividade, e apresentou reducao da produtividade de cafe na lavoura no ano subsequente, pelo aumento da desfolha em plantas de maior produtividade e consequente reducao da radiacao fotossinteticamente ativa interceptada pelo dossel dessas plantas, ocasionando bienalidade da producao.

Influência da colheita mecanizada na produção cafeeira

A colheita mecanizada de cafe no sul de Minas Gerais tem promovido uma melhor qualidade do produto e reducao de perdas, aumentando os lucros dos cafeicultores. Porem, a lavoura cafeeira ainda necessita de estudos sobre o efeito da mecanizacao na produtividade da cultura ao longo dos anos, uma vez que a colheita mecanizada malconduzida pode causar danos na planta. O objetivo deste trabalho foi avaliar o efeito da colheita mecanizada na produtividade da cultura cafeeira, ao longo dos anos, comparativamente com colheita no sistema manual. O delineamento utilizado foi o inteiramente casualizado, com 8 tratamentos e 3 repeticoes, em parcelas aleatorias contendo em media 40 plantas nas safras de 2000 a 2004, realizando a colheita tanto de forma mecanizada quanto manual. A produtividade da lavoura cafeeira nao foi influenciada pela colheita mecanizada ao longo dos anos, passando a colhedora uma ou duas vezes na lavoura. O aumento de vibracao das hastes promoveu uma maior quantidade de graos colhidos, porem a desfolha aumentou proporcionalmente ao aumento de vibracao. Com duas passadas da colhedora, a desfolha foi maior que a colheita manual em todas as safras agricolas estudadas.

Variabilidade espacial e temporal do fósforo, potássio e da produtividade de uma lavoura cafeeira

The Precision Agriculture appears as an important tool to the management of coffee farms where the knowledge of some soil features associated with the coffee production could help specific application of fertilizing with positive environmental and economic results. So the aim of this study was to use precision agriculture and geoestatistics to evaluate the variables phosphorus, potassium and the coffee plant yield, in three different crops, by evaluating the semivariogram and kriging maps and show that these tools are important to the coffee management. This study was conducted on the Brejao farm in Tres Pontas, Minas Gerais, in 2007/2008, 2008/2009 e 2009/2010 crop. As data base were used chemical soil data obtained by sampling in a georreferenced location using a quadricycle with a sampler and a GPS, and the yield data was obtained from manual harvest on the georreferenced location. It was possible to characterize the spatial variability magnitude of the studied attributes, and they presented huge variation on time and space. Adjusts of the best semivariograms enable to produce more accurate maps that contribute to the geostatistics uses on coffee crop.

Agricultura de precisão no estudo de atributos químicos do solo e da produtividade de lavoura cafeeira

Precision agriculture appears as an important tool in the management of coffee farms where the knowledge of some soil fertility characteristics associated with the coffee production could help in specific application of fertilizers with positive environmental and economic results. So the aim of this article was to use precision agriculture and geoestatistics to evaluate the availability of phosphorus, potassium and yield of the coffee plant by evaluating the semivariogram and kriging maps and show that these tools are important for coffee management. This study was conducted on the Brejão farm in Três Pontas, Minas Gerais state, Brazil. As a data base we used soil chemical property data obtained by sampling in a georreferenced location using a quadricycle with a sampler and a GPS, and the yield data was obtained from manual harvest on the georreferenced location. The analysis of these data by using statistics and geostatistics tools allowed to characterize the spatial variability of the phosphorus, potassium, and the coffee yield, and allowed to analyze the relation among these variables. It was possible to observe that spatial dependence exists so it is possible to create maps of spatial distribution of the variables.