Obviously, we won't be getting any new soil overnight, and that's a problem. Erosion is one of the major problems. The most common forms are where water or wind tear at the soil and carry it away. Some types of soils erode more easily. Soil that is disturbed is more vulnerable.
Compaction is another problem.
You see this on school grounds where large numbers of people follow the same route. They cut a path where no grass grows. The still-barren ruts where the Oregon Trial ran are another example of compaction. Compacted soil has lost desirable structural properties, such as the right-sized pores for storing air and water. Heavy equipment, like the kind used in farming, logging and construction, can compact the soil, especially when it's wet.