What is Field Capacity?

Field capacity is a measurement that has to do with the ability of soil in a given area to absorb water, once all excess and surface water has been drained from the area. Assessing the field capacity of soil is very important in determining the type of crops to grow in a particular section of land, as well as judging the capacity of that land to support buildings of various types. The result of these assessments is usually presented as a percentage.

Calculating field capacity is a process that normally takes a couple of days. The soil is saturated to the point that there is some water left standing on the ground surface. The standing water is removed, then the remaining water is allowed to seep into the soil and eventually drain away. After anywhere from twenty-four to forty-eight hours, the moisture content of the soil is tested. This process makes it possible to get a good idea of how much moisture the soil can retain while still remaining viable for planting or as a site for constructions.

One of the benefits of testing a tract of land using this process is that it can help growers to determine what types of crops to plant in the area. Depending on the actual soil moisture field capacity, it may be advantageous to go with crops that require less water retention in the soil in order to thrive. A high water content will indicate that the soil is better suited for planting crops that require a great deal of moisture in order to grow properly. A calculation of this type is often known as a field capacity wilting point, since the idea is to determine what plants will grow and not wilt and decay due to exposure to the higher moisture content in the soil.

Determining the field capacity is also helpful when planning construction in an area. Soil that can retain a great deal of moisture and still remain solid is often a good choice for construction ranging from storage facilities to multi-story buildings. In this application, the soil analysis helps builders to determine the best approach to laying a foundation and making sure the building with not shift and crack due to the average amount of ground saturation that occurs through the calendar year. Taking the time to run a field capacity test before erecting any kind of building will enhance the chances of the building being safe and useful for many years without the need to shore up a failing foundation.