Evaluation of Low Inflation Tire Technologies on Soil Compaction

Abstract

Evaluation of recent advances in tire technologies such as advanced deflection agricultural tires (Firestone IF and VF) and precision tire inflation technologies on soil compaction, traction, fuel economy and crop yield responses are important. The purpose of the study was to investigate the effects of field and transport (road) tire inflation pressure settings of row-crop agricultural tractor and planter tires on soil compaction. A randomized complete block design experiment was conducted at Iowa State University farm in Boone, Iowa for two tire inflation pressure levels on Dual Front (Firestone IF 420/85R34) and Dual Rear (Firestone IF 480/80R50) tires on a John Deere 8310R MFWD tractor, and transport tires (Super single 445/50R22.5) on a John Deere DB60 planter. Soil compaction was measured using Stress State Transducers (SST) buried at 15-cm and 30-cm depths beneath the untrafficked soil surface. Cone index depth profile was measured at tire- centerline, tire-edge and 20 cm laterally outboard of the tire edge before and after tractor-planter tire passes. Peak Octahedral Normal Soil Stress (ONSS) and the corresponding Octahedral Shear Soil Stress (OSSS) values were calculated from the SST data. The peak ONSS and OSSS values from the road tire pressure settings were statistically higher (p-value < 0.01). The maximum ONSS was observed at 15 cm soil depth from the road tire inflation pressure setting of the rear tractor tires (179 kPa tire inflation pressure and 25 kN load per tire). The ONSS from the front tractor tires (138 kPa tire inflation pressure and 17 kN load per tire) and planter transportation tires (620 kPa tire inflation pressure and 16.5 kN load per tire) were similar. Cone index data also showed significant differences, comparing before and after tires passes, at the tire- centerline. The peak cone index values were 1.3 MPa and 1.2 MPa from the road and field tire inflation pressure settings, respectively.