Field Capacity and Soil Tension

Field capacity refers to the maximum amount of water that a soil can hold against the force of gravity. It is the point where excess water drains off and the soil holds only the water that is available for plants. The soil tension at field capacity is the amount of force or pressure required to extract water from the soil once it has reached its maximum saturation point.

Soil Tension at Field Capacity

At field capacity, the soil tension is typically around 1/3 atmosphere. This means that there is a relatively low amount of force required to extract water from the soil compared to other soil moisture levels. This tension level is ideal for plant growth as it allows the roots to extract water easily without the risk of drowning.

Other Soil Moisture Tension Levels

There are several other levels of soil moisture tension that are important to understand for agriculture and engineering purposes. These include:

- Wilting point: the point at which plants can no longer extract water from the soil, typically around 15 atmospheres of tension.
- Permanent wilting point: the point at which plants die due to lack of water, typically around 1500 kilopascals of tension.
- Saturation: the point at which all soil pores are filled with water and no air is present.

Understanding these different soil moisture tension levels is important for managing irrigation, drainage, and soil health.