Representative elementary area (REA) in soil bulk density measurements through gamma ray computed tomography

Soil sample physical properties can be greatly affected during soil sampling procedures. Improper procedures can impose modifications on soil sample structure and consequently lead to wrong measurements of soil properties. The objective of this work was to evaluate the damage caused by soil samplers to soil structure through the analysis of computed tomography (CT) images. A first generation tomograph was used, having a 241Am source and a 7.62 × 7.62 cm NaI(Tl) scintillation crystal detector coupled to a photomultiplier tube. Results confirm the effect of soil sampler devices on the structure of soil samples, and that the compaction caused during sampling causes significant alterations to soil bulk density. Through the use of CT it was possible to determine the level of compaction and to make a detailed analysis of the soil bulk density distribution within the soil sample.

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Representative elementary area for soil bulk density measurements of samples collected in volumetric rings by CT image analyses

Soil and Tillage Research ◽

10.1016/j.still.2015.03.007 ◽

2015 ◽

Vol 152 ◽

pp. 74-84 ◽

Cited By ~ 5

Author(s):

Talita R. Ferreira ◽

Jaqueline A.R. Borges ◽

Luiz F. Pires

Keyword(s):

Bulk Density ◽

Soil Bulk Density ◽

Ct Image ◽

Density Measurements ◽

Image Analyses ◽

Elementary Area

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Soil bulk density evaluation by conventional and nuclear methods

Soil Research ◽

10.1071/sr04054 ◽

2005 ◽

Vol 43 (1) ◽

pp. 97 ◽

Cited By ~ 29

Author(s):

L. C. Timm ◽

L. F. Pires ◽

K. Reichardt ◽

R. Roveratti ◽

J. C. M. Oliveira ◽

...

Keyword(s):

Bulk Density ◽

Gamma Ray ◽

Soil Bulk Density ◽

Soil Samples ◽

Soil Science ◽

Tukey Test ◽

Nuclear Methods ◽

Density Values ◽

Density Evaluation ◽

Gamma Ray Computed Tomography

Among the methods used to measure soil bulk density, the following have been prominent: paraffin sealed clod (PS), volumetric ring (VR), and the modern methods like gamma ray computed tomography (GCT) and the neutron/gamma surface gauge (SG). The objective of this work was to compare soil bulk density values obtained through these methods, with the aim of assisting researchers on the choice of the more appropriate method. For this, a 200-m spatial transect was chosen in an experimental area cultivated with coffee, belonging to ESALQ/USP, Piracicaba, SP, Brazil. The SG readings were first taken in the field and thereafter soil samples were collected at 8 different points, spaced at 25 m, for the other methods. The lowest values of soil bulk density were obtained for the SG method (average 1.468 g/cm3) and the highest for the PS (average 1.685 g/cm3), which was similar to the GCT method (average 1.684 g/cm3). The average soil bulk density for the VR method, which has been used in soil science as a standard method, was 1.544 g/cm3. The Tukey test indicates that the PS and GCT methods do not differ significantly (P > 0.05). They do differ in comparison with VR and SG, which also do not differ among themselves.

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Soil porosity distribution representative elementary area analyzed through gamma-ray computed tomography

International Agrophysics ◽

10.1515/intag-2016-0016 ◽

2016 ◽

Vol 30 (4) ◽

pp. 447-456 ◽

Cited By ~ 3

Author(s):

Talita Rosas Ferreira ◽

Luiz Fernando Pires

Keyword(s):

Computed Tomography ◽

Gamma Ray ◽

Soil Porosity ◽

Porosity Distribution ◽

Tomography System ◽

Computed Tomography Images ◽

Γ Ray ◽

Computed Tomography Image ◽

Gamma Ray Computed Tomography ◽

Elementary Area

Abstract This study aims to use γ-ray computed tomography images to define the representative elementary area of the soil porosity distribution. Different textured soils from Southeast Brazil and different schemes of areas were analyzed. The image acquisition was performed in 2006 using a first generation γ-ray computed tomography system equipped with 241Am radioactive source. Consecutive increasing areas located at the center (scheme 1), the inferior (scheme 2) and superior (scheme 3) borders of the sample computed tomography image, with size areas ranging from 1.2 to 678.8 mm², were selected. The full width at a half maximum parameter was used to describe the samples soil porosity distribution and mathematical analysis concepts were adopted to define the representative elementary area. The representative elementary areas found for the sandy soil (Geric Ferralsol) and clayey soils (Rhodic Ferralsol and Eutric Nitosol) were respectively: 514.3, 514.3 and 555.4 mm² (scheme 1); 279.5, 393.3 and 457.4 mm² (scheme 2); and 457.4, 457.4 and 457.4 mm² (scheme 3). The results confirmed that the representative elementary area were influenced by the soil texture and management. Different schemes were noticed to provide different representative elementary areas for the same soil, which suggests that this procedure was efficient to detect the heterogeneity inside the soil samples.

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