Do the values of field capacity and permanent wilting point change over time in a given soil? If so, what causes these changes?

The permanent wilting point is primarily dependent on the soil components, such as the minerals and the textural distribution. As these soil components are of geological origin, the time scale of change is much longer than changes we may expect to measure in permanent wilting point. Simply put, the permanent wilting point is hard to change and can be considered unchangeable by common uses of soil.

Field capacity, however, is dependent on soil structure, organic matter and density of the soil. Soil management practices which cause changes in soil structure, amount of organic matter and bulk density can result in changes in field capacity.