Heavy traffic of tractors causes changes in soil physical quality triggering compaction and erosion. This study aimed to evaluate the influence of tire inner pressure and travelling speed of a 4x2 FWA (front wheel assist) farm tractor on soil physical properties, using the parameters of soil compaction evaluation, and tractor operating parameters related to the machine performance. For these purposes, soil bulk density, total porosity and cone index were determined from soil samples collected before and after tractor passage. Moreover, it was also analyzed tractor kinematic advance, wheel slipping, ground-tire interface and soil surface pressure beneath the tires. Varied inner pressure and travelling speed sets did not change both soil wheel slipping and cone index. On the other hand, soil density was affected only by travelling speed changes. A greater reduction in total porosity was observed by applying 124 and 110 kPa pressure in tractor front and rear tires, respectively, in combination with 1.51 m s-1 travelling speed.
compaction; soil bulk density; wheel slipping; total porosity
