Certified Landscape Irrigation Auditor

What condition describes field capacity?

1. Soil that is too dry for plants

2. Soil that has been saturated and allowed to drain by gravity

3. Soil that holds excess water

4. Soil that is compacted

The correct answer is: Soil that has been saturated and allowed to drain by gravity

Field capacity refers to the condition of soil when it has been saturated with water and then allowed to drain under the force of gravity. At this point, the soil has reached a state where the voids between soil particles are filled with water, but gravitational forces have drained away the excess water, leaving behind the moisture that is readily available to plants. This moisture level is optimal for plant growth, as it balances water availability without waterlogging the roots. In contrast, soil that is too dry for plants would not support healthy growth, while soil that holds excess water can lead to poor aeration and root rot. Compacted soil can negatively impact root growth and water infiltration, leading to inefficient water use by plants. Thus, the definition of field capacity accurately captures the state of the soil that is most beneficial for plant health and growth.