Rev. Bras. Ciênc. Solo.2002;26(4):835-42.

ISSUE Cover

Computed tomography for the soil density evaluation of samples of semi-arid brazilian soils

L. Fante Junior, J. C. M. Oliveira, L. H. Bassoi, C. M. P. Vaz, A. Macedo, O. O. S. Bacchi, K. Reichardt, A. C. Cavalcanti, F. H. B. B. Silva

01/Dec/2002

DOI: 10.1590/S0100-06832002000400001

The soil bulk density of undisturbed samples was evaluated using computed tomography and paraffin-sealed soil clod techniques, with the objective of identifying soil compaction processes and to compare the applied methodologies. Data were also used to complement a soil classification survey for irrigation purposes. Samples were collected from soil profiles of the semi-arid region of Petrolina (PE), Brazil, from the soil surface down to a depth of 1 m, in 10 cm layers. Two distinct areas were chosen: (1) native vegetation (“caatinga”), and (2) cultivated area under central pivot irrigation. Tomographies were obtained by a first generation tomograph, using a ¹³⁷Cs gamma source, a NaI (Tl) scintillation crystal, and a standard electronic counting system linked to a sample moving system, controlled by a specific computational interface. Results suggest a density increase at greater depths (below 0.4 m) for the “caatinga” area. In the central pivot area, a compacted soil layer was detected between approximately 0 and 0.4 m, consisting of natural and/or dense layers, possibly due to machinery action during soil tillage.