Nerilson Terra Santos

Definition of management zones in coffee production fields based on apparent soil electrical conductivity

Fertilizer application at variable rates requires dense sampling to determine the resulting field spatial variability. Defining management zones is a technique that facilitates the variable-rate application of agricultural inputs. The apparent electrical conductivity of the soil is an important factor in explaining the variability of soil physical-chemical properties. Thus, the objective of this study was to define management zones for coffee (Coffea Arabica L.) production fields based on spatial variability of the apparent electrical conductivity of the soil. The resistivity method was used to measure the apparent soil electrical conductivity. Soil samples were collected to measure the chemical and physical soil properties. The maps of spatial variability were generated using ordinary kriging method. The fuzzy k-means algorithm was used to delimit the management zones. To analyze the agreement between the management zones and the soil properties, the kappa coefficients were calculated. The best results were obtained for the management zones defined using the apparent electrical conductivity of the soil and the digital elevation model. In this case, the kappa coefficient was 0.45 for potassium, which is an element that is associated with quality coffee. The other variable that had a high kappa coefficient was remaining phosphorous; the coefficient obtained was 0.49. The remaining phosphorus is an important parameter for determining which fertilizers and soil types to study.

The relationship between apparent soil electrical conductivity and soil properties

Precision agriculture that is based on the physical and chemical properties of soil requires a dense sampling to evaluate spatial variability in the field. This dense sampling is often expensive and time consuming. One technique to reduce the number of samples is to define management zones based on information that is collected in the field. Some researchers have demonstrated the importance of the electrical properties of soil in defining management zones. Thus, the objective of this study was to evaluate the relationship between the apparent soil electrical conductivity and soil properties in mountainous areas of coffee production. The electrical conductivity of soil was evaluated at soil depths ranging from 0.00-0.20 m (EC20) and 0.00-0.40 m (EC40) using a portable meter. The mean values of EC20 and EC40 were 1.80 mS m-1 and 1.22 mS m-1, respectively. Both EC20 and EC40 exhibited comparatively low correlations with the soil properties, whereas higher correlations were obtained for measurements of remaining phosphorus, wherein values of 0.427 and 0.465, respectively, were obtained.

Geração de zonas de manejo para cafeicultura empregando-se sensor SPAD e análise foliar

The objective of this work was to define management zones for fertilizer application in coffee crop by using the K-means and the Fuzzy C-Means methods. The data used to define management zones were the chlorophyll index measured by SPAD sensor and the nutritional coffee leaf analysis performed in laboratory. The study was conducted in Jatoba Farm, located in Paula Candido, Minas Gerais state, Brazil. The data was collected in November, 2007 when the coffee fruits were starting their development. The coffee variety was Coffea arabica Catuai, and the total analyzed area was 2.1 ha. The management zones were generated using different set of data: the SPAD values; the N, P and K leaf concentrations; the N and Ca leaf concentrations; the N, Zn and B leaf concentrations; the N, P, K, Ca and S leaf concentrations; and the N, Ca and S leaf concentrations. The management zones generated by using K-means and Fuzzy C-Means did not present difference in management zone delimitation. The management zones defined by using the SPAD values were different from the ones generated by using leaf analysis.

Análise discriminante paramétrica para reconhecimento de defeitos em tábuas de eucalipto utilizando imagens digitais

The lumber industry has given special attention for lumber grading and selection stages. Machine Vision Systems have been proposed as a technological solution for automation of these stages. The proper feature selection for discriminating defect and clear wood is one of the most challenging in the development of such technology. The objective of this work was to evaluate, using multivariate analysis, the discriminating power of color images percents. In this work, linear and quadratic discriminant analysis were accomplished for classification of defects and clear wood in digital images of eucalyptus lumber. The percent features of the histogram for the red, green and blue bands, from two sizes of image blocks were used for developing and testing the discriminant functions. 492 blocks were used, containing the 12 studied defects and clear wood, derived from images of 40 lumbers randomly sampled. The features were analyzed with their original values, scores of the principal components and scores of the canonical variables. The smallest global misclassification errors were 19% and 24% for linear discriminant function with the canonical variable scores using block sizes of 64x64 and 32x32 pixels, respectively. The percent features were considered appropriate to discriminate defects and clear wood in digital images.

Characterization and delimitation of the terroir coffee in plantations in the municipal district of Araponga, Minas Gerais, Brazil

Differentiating coffees through the notion of terroirs allows us to determine potential areas for specialty coffee production and to characterize the type of coffee in these areas, exploring their potential. The objective of this work was to study spatial variability quality and to characterize and delimit terroirs in coffee crop production in Araponga municipality, Minas Gerais State, Brazil, using sensorial evaluation. The data were collected from four crops, from altitudes ranging from 770 to 1270 m, with the extract increasing from low to high. In each plot of crops, samples of cherry fruits were collected, dried, benefited, subjected to sensorial analysis and given grades ranging from 0 to 100 points for the global drink quality and relative characteristics of honey, body, acidity, flavor and equilibrium. The spatial variability of the quality was analyzed using the Moran Index. To define coffee production terroirs, average quality grades were compared through separation tests and the individual values of the plots were subjected to an analysis of groupings. The study was efficient in identifying terroirs for mountain coffee culture, therefore allowing coffees to be differentiated as a function of their production locations. Araponga has more than one coffee production terroir characterized by two distinct altitude extracts.

Discriminação entre estágios nutricionais na cultura do trigo com técnicas de visão artificial e medidor portátil de clorofila

Sidedress nitrogen fertilization is currently discussed throughout the world due to its economical and environmental implications. The cereal crops strongly respond to N application and there is a lack of current methods to determine N availability on the soil. The aim of this work was to evaluate the discrimination among three nutritional levels in wheat crop using digital images and a portable chlorophyll meter. Data were collected in plots with three levels of N (0; 30 and 60 kha-1) in three dates (8; 14 and 20 days after sidedress fertilization). The images were processed using nine spectral indices and elaborated multivariate classifiers based on the mean pixel values. The chlorophyll data and leaf nitrogen concentration were used in univariate classifiers. The classification using the machine vision techniques were better than the chlorophyll meter (SPAD) at 8 DAF, since the Kappa coefficient was better than a random classification. At 14 and 20 DAF there were no statistical differences between this type of data and the data from images. Using digital images it was possible discriminate the nutritional levels eight days after sidedress fertilization.

Avaliação ergonômica da cabine de um trator florestal

Studies conducted by anthropometric and ergonomic assessments contribute to aid for new projects based on the design of machines and equipment. The objective of the present work was to perform an anthropometric analysis of workers who operate forest harvest machines and an ergonomic assessment of the operator cabin of a Feller-Buncher, in order to gather information needed for future modifications. Analyses were performed at CENIBRA forestry company in Minas Gerais. The anthropometric evaluation of the operators was conducted by two sets of measures, while standing and sitting. During the ergonomic assessments and measurement of controls positioning and field of view, distances were determined from the seat reference point (ARP) in three dimensions (x, y and z). The results showed that there is need for ergonomic improvements in the seat, controls, control panel, symbology commands, dials and warning lights.

Determination of nitrogen and chlorophyll levels in bean-plant leaves by using spectral vegetation bands and indices

Objetivou-se desenvolver classificadores com base em diferentes combinacoes de bandas e indices de vegetacao espectrais de imagens originais, segmentadas e reflectâncias, para discriminacao de teores de nitrogenio e clorofila foliares do feijoeiro, definindo a melhor epoca e as melhores variaveis. Foi utilizado um sistema de sensoriamento remoto constituido por um balao a gas helio e duas câmeras digitais de pequeno formato. Alem das bandas isoladamente, foram testados quatro indices de vegetacao: da razao simples, da diferenca normalizada, da diferenca normalizada utilizando a banda do verde e o da absorcao de clorofila modificado. Os classificadores demonstraram serem eficientes na discriminacao de teores de nitrogenio e clorofila foliares. A melhor epoca para discriminar teor de nitrogenio foliar foi aos 13 DAE (estadio V4). Os melhores classificadores para esta epoca utilizaram como entrada dois indices em imagens reflectância segmentada, um indice relacionado com a estrutura do dossel e outro relacionado com a clorofila, com Kappa variando entre 0,26 a 0,31. Para discriminar teor de clorofila foliar, a melhor epoca foi aos 21 DAE (estadio V4). O melhor classificador utilizou como entrada duas imagens originais, uma da banda vermelha e outra da banda azul, com Kappa de 0,47.

Vegetation spectral indices to discriminate nitrogen rates in tanzania grass

The objective of this study was to determine, among five vegetation indices, calculated based on spectral reflectance data, the one that best discriminated nitrogen rates, and presented highest correlation with chlorophyll readings and tanzania grass (Panicum maximum Jacq.) dry matter. The tested vegetation indices were NDVI (normalized difference vegetation index), VARI (visible atmospherically resistant index using red edge and green bands), WDRVI (wide dynamic range vegetation index using three weighted coefficients, 0.05, 0.1 and 0.2). Four nitrogen levels (0, 80, 160 and 320 kg/ha) were evaluated in a randomized complete block design with three replications and three subsamplings per block. The indices VARI, using red edge band, and WDRVI, using weighted coefficients 0.05 and 0.1, were the best indices to discriminate nitrogen rates. The index that presented the highest correlation with chlorophyll readings and dry matter was the VARI using red edge band.

Spatial variability of the physical attributes of soil under pasture

O objetivo desse trabalho foi avaliar a variabilidade espacial de atributos fisicos do solo para areas de Latossolo, Argissolo e Cambissolo ocupadas por pastagens. O conhecimento dessa variabilidade e importante, pois ela influencia a qualidade das pastagens e a recarga de agua subterrânea. Foram coletadas 154 amostras georreferenciadas para cada area de estudo. Para analisar os dados foi usada a estatistica descritiva e a geoestatistica. A dependencia espacial ocorreu para a maioria dos atributos fisicos: condutividade hidraulica em solo saturado e densidade do solo para as tres classes de solos; microporosidade, macroporosidade e porosidade total para as areas de Cambissolo e Latossolo. Os resultados da estatistica descritiva e o fato do padrao da dependencia espacial nao ter se mantido constante indicam que as classes de solo, juntamente com a declividade e o uso da terra influenciaram a variabilidade espacial dos atributos fisicos do solo analisadas e que a media nao e suficiente para representar a distribuicao espacial das variaveis analisadas. A malha de amostragem usada e adequada, pois permitiu captar a dependencia espacial da maioria das variaveis analisadas.