The issue of soil compaction in row crops is an interesting one.  Most farmers dealing with soil compaction have the option of either trying to choose a different path for each pass and spread pressures out evenly, or drive the same path for every pass, effectively sacrificing the path of the wheel tracks in order to keep the rest of the field in the best shape possible. farmers with row crops have no choice, they must travel the same path, and with each pass they run the risk of compacting the soil beneath into a inhospitable place for growth, some of the ill effects of soil compaction are:

Aeration – roots need air! if the soil above the roots becomes compacted, the spaces required to transport air down to the root structure will be destroyed

Water retention – the same space that allow air to pass, also allow for water to move through to the root system, and can hold water long after the rain has stopped falling, compacted soil reduces these qualities

Erosion – if the water cannot go into the soil, it has to travel somewhere, so it runs off, carrying valuable topsoil with it!

Reduced root growth – the areas that are compacted become very hard, the plant has to then force its roots through this hard packed material, wasting energy and resulting in reduced overall growth rates and ultimately reduced yields.

The news is not all bad, some studies suggest that within 7 seasons the compaction effects level out. and with some compaction reduction techniques the ill effects can be controlled.
The biggest of these techniques is to stay out of the field when it is wet, this is the single biggest cause of compaction and while it is sometimes an unavoidable scenario, some forethought can keep you on dry land and not sinking into the earth.
The next thing farmers can do is to use low compaction tires or tracks to reduce the amount 0f pressure the equipment places on the ground, tracks are becoming more and more common on orchard tractors and low pressure (ie. “balloon tires”) are a good option as the amount of weight exerted is a function of the amount of PSI in the tire.