Daniel M. de Queiroz

Alteração de atributos químicos do solo e estado nutricional e características agronômicas de plantas de milho, considerando as modalidades de calagem em plantio direto

Lime application on the soil surface in no-tillage systems, without incorporation, has not been effective in certain edaphic and climatic conditions for the correction of acidity or for calcium and magnesium supply to plants. Searching alternatives for limestone application without the conventional tilling and harrowing operations, this study tried to evaluate the efficiency of different lime application forms for the chemical soil attributes, nutritional state, and agronomic characteristics of corn crop. A randomized block design with split-plots and three replications was used. The treatments applied on the plots were: double hybrid corn Z 8447; corn variety AL 25; and double hybrid AG 122; and on the split-plots: control without liming; lime applied along the soil profile in the planting furrow; lime applied by spreading on soil surface; lime applied along the soil profile into the planting furrow plus more lime spread on the soil surface. Where lime was applied in the furrows, maize was sown in the furrows that had received lime. Soils were sampled 30 and 150 days after liming, from the sowing line to a distance of 25 cm from the sowing line, and at five depths. The pH was determined in the water and exchangeable Ca, Mg and Al in the samples. The nutritional state of foliar tissue was evaluated for the three cultivars, as well as some agronomic crop characteristics. Results showed that the lime applied into the planting furrow was distributed efficiently along the soil profile down to a depth of 20 cm, in a 10 cm wide strip. Surface lime application only had an effect on the chemical soil characteristics down to a depth of 5 cm. The concurrent application along the soil profile into the planting furrow plus more lime on the surface was the most efficient, with higher values of pH, exchangeable Ca and Mg, and lower levels of exchangeable Al. No effect of the lime application mode was observed on the nutritional state of the tested cultivars or the agronomic characteristics of the corn crop.

Avaliação dos níveis de vibração vertical no assento de um trator agrícola de pneus utilizando um sistema de aquisição automática de dados

A study was carried out at the Faculdade de Engenharia de Guaratingueta - FEG-UNESP, SP, in the acoustic and vibration laboratory as well as in an experimental area, to: a) determine the levels of vertical vibration in both the seat and seat base of an agricultural tire tractor under operation (harrowing) at different forward speeds; b) characterize the frequency range presenting the highest vertical vibration peaks in the tractor operator seat; c) analyze ride comfort for tractor operators by comparing the actual level of vibration with that of the main effective norms. The data acquisition system consisted of some vibration sensors, conditioners, amplifiers, and a digital-analogical converter plugged to a microcomputer and connected to the tested tractor. Later, the data were treated by the program ORIGIN 50. Based on the results, it was concluded that the acceleration levels obtained at the upper part of the seat were much lower than those in the seat base at the three operational speeds, whereas the third gear presented the highest vibration levels; the frequency range from 2 to 4 Hz presented the highest peaks of vertical vibration; the values of the total weighted acceleration were found to be much above the limits determined by the norm ISO 2631 for an 8-working hour period; the vibration levels increased as the forward speed of the tractor-implement system increased.

Algoritmo para classificação de plantas de milho atacadas pela lagarta do cartucho (Spodoptera frugiperda, Smith) em imagens digitais

An image processing and analysis algorithm was developed to identify the fall armyworm damage on corn plants. The developed program segmented the larvae damage on the image in two stages: a coarse and fine classification. The coarse stage applied a threshold technique on image blocks of 60 x 60 pixels. The fine stage was based on a neural network classifier which classifies image blocks of 3 x 3 pixels. The algorithm accuracy was accessed by evaluating the error matrix based on 80 and 75 image blocks of the coarse and fine stages, respectively. The algorithm presented an overall accuracy of 80.74%.

Variação das dimensões características e da forma dos frutos de café durante o processo de secagem

The present work had as objective to evaluate the effect of moisture content variation on dimensions and physical properties (sphericity and roundness) of coffee fruit of the arabica and canephora species, for different varieties. The obtained results show that the reduction of moisture content affects in an accentuated way the physical characteristics of coffee fruit of the studied species and varieties, indicating that the variations of dimensions of the fruit along the drying process are important. Further, the mathematical expressions adjusted to the data were satisfactory for the studied phenomena.

Módulo de elasticidade de grãos de milho submetidos a impactos mecânicos

Neste trabalho investigou-se a viabilidade de se obter o modulo de compressao de graos de milho, utilizando-se dados experimentais de forca versus tempo, provenientes de testes de impacto, juntamente com uma analise estrutural elastica do processo. Os modulos de elasticidade foram determinados para graos, a diferentes teores de umidade, submetidos a impactos de diferentes velocidades, e obtidos por um processo de otimizacao por meio da tecnica de elementos finitos. Dois tipos de modulo foram avaliados: (a) um modulo efetivo para todo o grao e (b) um modulo para cada uma das tres regioes, com diferentes caracteristicas, segundo as quais o grao foi dividido. O teor de umidade e a velocidade de impacto influenciaram nos valores dos modulos. Modulos para graos a 13,4% base umida (b.u.) foram maiores do que para aqueles a 20,0% b.u. A analise realizada (elastica) mostrou-se ser mais adequada na obtencao de modulos de elasticidade de graos a 13,4% b.u.; neste teor, os graos apresentam caracteristicas elasticas mais pronunciadas que quando a 20,0% b.u. e, nos graos com altos teores de umidade, as caracteristicas viscoelasticas tornam-se predominantes.

Qualidade dos grãos de milho em função da umidade de colheita e da temperatura de secagem

Com este trabalho, objetivou-se avaliar o efeito imediato e latente de quatro teores de umidade de colheita, associados a quatro niveis de temperatura do ar de secagem sobre a qualidade do milho, colhido com 25, 22, 16,5 e 15% b.u. e secado nas temperaturas de 40, 60, 80 e 100 oC, ate a umidade final de 13% b.u. Os graos foram submetidos as analises de teor de impureza e materia estranha, massa especifica aparente, indice de danos, indice de trincas e susceptibilidade a quebra. De modo geral, pode-se inferir que os graos colhidos com os teores de umidade de 15 e 16,5% e secos nas temperaturas do ar de secagem de 40 e 60 oC, foram os tratamentos que menos afetaram a qualidade do milho.

Detecção do efeito da adubação nitrogenada em Brachiaria decumbens Stapf. utilizando um sistema de sensoriamento remoto

The objective of the present work was the detection of different nutritional statuses in Brachiaria decumbens pasture using remote sensing techniques. The area was treated with five rates of nitrogen fertilizer (0, 50, 100, 150 and, 200 kg ha-1) with six repetitions and evaluated in a completely randomized statistical design. A remote sensing system composed of digital cameras, cables, a framegrabber and a computer was used with a three meter metallic support to position the cameras. The system acquired images in two spectral bands simultaneously in two phases. The first phase occurred from February to March 2006 at 15, 21 and, 32 days after fertilization and the second from March to May of 2006 at 28, 36, 45 and, 53 days after reapplication of the same N rates. Vegetation indices were evaluated from the original images, and the data was submitted to regression and correlation analyses. Estimate values of chlorophyll content using the chlorophyll meter SPAD 502 and values of the leaf N content were also acquired. First or second degree models were adjusted to the experimental data for all periods. The indices using the green band proved more efficient to detect the relationship with the estimated chlorophyll values, the leaf N content and the dry mass yield than the red band in all studied periods. Thus, the used remote sensing system technique allowed for the identification of different effects of nitrogen fertilization in the forage.

Multivariate Classifiers Using Image Texture Features for Nitrogen Doses Discrimination in Wheat

Sidedress nitrogen fertilization is currently discussed all over the world due to its economical and environmental implications and the lack of current methods to determine N availability on the soil. The aim of this work was to study the nitrogen doses discrimination from the spectral response of the wheat dossel on visible and near infrared images, associated or not with texture features. The classification results were compared to that obtained with a portable chlorophyll meter and leaf nitrogen concentration. Data were collected in plots with three levels of N in three dates (8, 14 and 20 days after sidedress fertilization). The images were processed using nine spectral indices and elaborated multivariate classifiers with the different features. From each index image were extracted the pixel’s mean value and five texture measurements (2nd, 3rd, 4th, 5th and 6th moments of the histogram), so that a vector of features was created from each original image. The chlorophyll data and leaf nitrogen concentration were used in univariate classifiers. Statistical classifiers were developed to discriminate the classes defined by the N doses using combinations of the nine indices. The classifiers were evaluated using the leaving one out cross validation technique, creating the error matrix and the overall accuracy and the kappa index calculation. Using the images, it was possible to discriminate the N doses eight days after sidedress fertilization with no benefit of the use of texture features.

Potência necessária para acionamento de uma colhedora de fluxo axial para feijão

The objective of this work was to find the power requirement for operating an axial flow bean harvester. Experimental tests were performed, the torque and angular velocity in the power take-off (PTO), the drawbar force, the machine speed and harvesting capacity were measured. To analyze the effect of the variables on the power needed, regression analysis were done. The drawbar power for the maximum grain bin capacity was 7.90 kW. The maximum PTO power to operate the machine was found to be 45.28 kW. The maximum harvesting capacity was 6.56 t h-1. The minimum specific energy consumption was 2.46 kWh t-1.