Each experimental soil condition was trafficked with only one
pass by the tractors with their rear tyres travelling over the tracks
of the front wheels. This was done to recreate the conditions of the
soil following primary and secondary tillage work. The tractors
used in the field trial had all of the basic design characteristics
common to vehicles currently on the market in Argentina (Table 2).
The model John Deere 7515 (FWA) is identified as TR1 and the
Zanello 500 (4WD) as TR2. The John Deere 3530 tractor was only
used to tow TR1 and TR2 to measure the motion resistance force.