Good Soil Structure:
The picture above shows a light, limestone-based soil in a moist state after harvest, having aggregates of reasonable structure with cracks and open pores occurring throughout the profile. The profile can be readily broken apart by hand. The presence of stones assists maintaining a free drained and open structure.
Poor Soil Structure Due to Heavy Traffic:
This is the same soil pictured above, in the same state of moisture, where compaction through heavy traffic has occurred. Here, the structure has few cracks, few open pores, and cannot be easily broken apart. Visible cracks mainly run horizontally, as opposed to vertically, or in a random fashion throughout. This structure will not allow easy water and root movement. Corrective action is needed to ensure the next crop can grow to its full potential. Provided the problems are limited to the clearly visible wheel marks, soil loosening can be limited to these areas as opposed to across the full field (for example, only sub-soiling the tramlines).
Poor Soil Structure Due to Tillage in Moist Conditions:
Tillage in moist conditions, as pictured here, can create a smeared layer in the soil. If left uncorrected, the layer can worsen, as fine soil particles wash down to this barrier, then build up and increase its thickness through time. While the problem is clearly visible in the base of the rut during tillage, this problem is covered as the field is worked, and cannot then be easily seen without digging.
Additionally, as the profile is loose to depth, it can take considerable time for smeared layers to become apparent, and generally occurs during the growth of the next crop. Sub-soiling to below the depth of the tillage pan is the solution to this issue.