Evolutionary trends in soil bulk density
One of the most direct effects of soil compaction results in an increase on soil bulk density. Increased soil bulk density is known to hinder many soil physical functions such as gas diffusivity and water conductivity. Along with physical processes, increased bulk density also hinders many biological processes.
The following plots in figure 1 show the influence of compaction as well as the influence of plowing.
Figure 1: Evolution of bulk density over time. a) and b) represent measurements taken at 10 and 30 cm depth respectively.
Although plowing reduces the bulk density back to the soils initial (uncompacted) conditions, this is limited to the surface layer of the soil. At the 30 cm depth, the soil compaction effects still remain quite unphased.