Anything, for example tillage and wheel traffic, that reduces pore space results in a dense soil with poor internal drainage and reduced aeration. Soil compaction is becoming a more serious problem for Missouri farmers. Field machines tend to be heavier, and there is motivation for farmers to work the soil when it is too moist. Because compacted soil has smaller pores and fewer natural channels, water infiltration is drastically reduced. This causes greater surface wetness, more runoff, which in turn increases erosion, and longer drying time.
Wet fields delay planting and harvesting and decrease crop yields.
Plant roots don't grow well in dense soil. Inadequate moisture and nutrients reach the plant, and yield is reduced. Compaction is directly affected by field machine weight, tire size and tire inflation pressure. Machines such as combines or manure tanks might weigh up to 30 tons. While lighter loads may cause just as much compaction near the surface, heavy loads cause compaction at depths that cannot be remedied by tillage.