Compaction characteristics of towed wheels on clay loam in a soil bin

Wheel induced soil compaction is an ongoing concern in mechanized agriculture. This experimental study was performed with the aim to evaluate whether soil compaction is related to stresses induced by towed wheels. Soil bin studies were conducted and soil compaction variables were measured under two towed tires, with different tread patterns, commonly used in Turkey. Tests were carried out at three tire loads (3.5, 5.5 and 7.5 kN) and two forward velocities (0.8 and 1.4 m/s) on a clay loam. To determine soil compaction, surface sinkage, subsurface layer deformation, compaction index, penetration resistance and bulk density were measured. With increasing vertical load, average contact pressure of tires increased from 39.3 to 68.5 kPa. In different trials, surface sinkage, compaction index, penetration resistance and bulk density varied from 46 to 86 mm, 0.18 to 0.48, 1472 to 2530 kPa and 1.31 to 1.70 Mg m−3, respectively. The soil contact projected area of tire 2 was approximately 10% greater than tire 1. The greater contact surface reduced the compaction at the soil surface and subsurface, but the tire load was still the dominant factor in the 0–20 cm depth range used in this study. According to the experimental results, decreasing contact duration with increasing forward velocity decreased soil compaction. Tire load and type affected soil deformation characteristics stronger than forward velocity.