João de Mendonça Naime

Soil particle size fractions determined by gamma-ray attenuation

Soil texture-or the particle size fractions of sand, silt and clay-is an important characteristic of soils and is used for their characterization and classification. Textural analysis also helps agronomists and farmers in the recommendation of herbicide and fertilizer applications. Soil particle siz

Automated soil particle size analyzer based on gamma-ray attenuation

Abstract Application of gamma-ray attenuation principles permits the determination of density and water content of a material. Moreover, this technique also allows one to determine particle size distribution, when particles are falling in a liquid medium according to Stokes’ law. Based on these principles, computerized equipment was developed to perform a fully automatic analysis of soil particle size distribution. This equipments main advantage is the capability to analyze ten soil samples automatically, each one in 18 min, the resulting output is a complete curve of soil particle size distribution, ranging from 2 μm to 2 mm. Another feature of this equipment is its fast soil granulometric fraction analysis (at ten samples per h), which determines the fractions of clay, silt, and sand. Results obtained with the gamma-ray technique showed an excellent correlation with the pipette method.

X-ray microtomography to characterize the physical properties of soil and particulate systems

Abstract Since many of the phenomena occurring in soil are related to grain and pore sizes and their distribution, investigation on a micrometric scale is of great importance. Also, the investigation should be non-invasive in order to avoid disturbing the region of interest of the sample. Many techniques from various areas of science have been adapted to make such investigations, but most of them are invasive or can only analyze global soil properties. Thus an X-ray tomograph was developed at Embrapa—Agricultural Instrumentation, to scan images of soil samples on a micrometric scale. A microtomographic image of a sieved soil sample, presenting aggregates from 212 μm to 250 μm and pores of 100 μm, is shown. Pores of the same size can also be seen in a microtomograph of a sand column, composed of two layers with granulometries of 106 μm to 149 μm and 297 μm to 500 μm. A microtomograph of a column composed of three layers of an orthoclasius powder is also presented. A slight variation in density along the column height can be observed.

Planosol soil sample size for computerized tomography measurement of physical parameters

Computerized tomography (CT) is an important tool in Soil Science for noninvasive measurement of density and water content of soil samples. This work aims to describe the aspects of sample size adequacy for Planosol (Albaqualf) and to evaluate procedures for statistical analysis, using a CT scanner with a 241Am source. Density errors attributed to the equipment are 0.051 and 0.046 Mg m-3 for horizons A and B, respectively. The theoretical value for sample thickness for the Planosol, using this equipment, is 4.0 cm for the horizons A and B. The ideal thickness of samples is approximately 6.0 cm, being smaller for samples of the horizon B in relation to A. Alternatives for the improvement of the efficiency analysis and the reliability of the results obtained by CT are also discussed, and indicate good precision and adaptability of the application of this technology in Planosol (Albaqualf) studies.

Detection of beetle damage in forests by X-ray CT image processing

Algumas especies de besouros tem elevado impacto economico em florestas e industrias de moveis. Exemplo recente e aquele produzido pelo besouro Anophophora glabripennis, uma especie conhecida nos Estados Unidos como Asian Longhorn, que tem produzido danos significativos em varias florestas americanas, representando uma ameaca que podera encontrar transporte nao-intencional para paises da America do Sul, inclusive para o Brasil. Neste trabalho e apresentado um novo metodo com base no uso de tomografia de raios X computadorizada (CT) e processamento de imagens digitais para deteccao de injurias causadas por besouros em florestas. Os resultados mostram a correta identificacao da localizacao de besouros em arvores vivas, como tambem fornecem uma avaliacao do estrago temporal causado.

Prerequisite Study for the Development of Embedded Instrumentation for Plant Phenotyping Using Computational Vision

This paper sought to investigate the most relevant criteria for determination of an embedded stereo vision system, both in the choice of the cameras and in terms of the processing platform to be used for plant phenotyping. Since this paper is a result of a preliminary study of the real implementation itself, the main motivation was to evaluate the accuracy of the low-cost visual systems field of view and its viability for the proposed application. In addition, the real agricultural scenario was presented and studied, showing how the stereo system should be modeled to meet the accuracy and the portability requirements for using in situ machine vision in agricultural decision-making processes.