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

Gamma ray computed tomography (CT) has recently become a useful tool for non-invasive characterization of soil physical parameters. Such technique is interesting because it can be used, for instance, in measurements of representative elementary area or volume (REA or REV) of soil samples used to assess soil physical properties. Soil scientists are aware that a sample has to be of a certain size in order to represent certain physical property of that soil in the field. In this study, CT was used to measure REA of samples of a Brazilian soil of clay texture. The objective of using this technique was to verify the minimum volume of soil to be collected for bulk density measurements (ρs) through the paraffin sealed clod method (PSC). Results revealed that samples with volumes from 50 to 100 cm3, with minimum cross section 640.1 mm2 are enough to produce representative ρs values.