Mechanical parameters of a constructed soil under different machinery traffic intensities in South of Brazil

Intense machinery traffic tends to degrade the soil physical quality. With the purpose of finding critical values of physical parameters and viable alternatives to minimize soil degradation, this study aimed to evaluate the effects of different traffic intensities on physical parameters of a constructed soil in Candiota, Rio Grande do Sul state, Brazil. Bulk density (Bd), porosity, saturated soil hydraulic conductivity, penetration resistance (PR) and soil compression parameters were evaluated. Different tra­ffic events (TE) were simulated during the soil construction process of an opencast coal mining area with a crawler tractor: zero (TE0), one (TE1), three (TE3), five (TE5) and eight (TE8) passes of the tractor. Immediately after the topographic recomposition and on the traffic track of the crawler tractor, disturbed and undisturbed soil samples were collected from the 0.00 to 0.10 and 0.10 to 0.20 m layers. Hydraulic conductivity, penetration resistance and soil compressibility parameters were sensitive to detect alterations in the constructed soil under different traffic events. PR values were higher than those considered as the critical limit (2000 kPa) in all layers and traffic intensities. Minimizing the traffic machinery intensities can be an effective alternative to mitigate compaction of constructed soils. More studies are necessary to obtain viable alternatives for adequate crop development in these areas.