Gravitational water

Definition

Gravitational water is the portion of water in soil that is held under the influence of gravity and drains away from the soil profile. This type of water moves through soil layers, typically downward, due to the force of gravity and is not retained by soil particles. It plays a crucial role in soil water movement and storage as it affects how much water is available for plants and how quickly it can be replenished.

5 Must Know Facts For Your Next Test

1. Gravitational water moves rapidly through the soil profile and is primarily responsible for drainage after heavy rainfall or irrigation.
2. This type of water does not contribute to the moisture available for plants because it quickly moves beyond the root zone.
3. Gravitational water can lead to soil erosion if it carries away topsoil during heavy rainfall events.
4. The presence of gravitational water can affect soil structure and compaction, as saturated soils may become more prone to compaction.
5. Different soil types retain gravitational water differently; sandy soils allow it to drain quickly, while clay soils can retain more for longer periods.

Review Questions

• How does gravitational water influence the availability of moisture for plants?
  • Gravitational water primarily drains away from the soil profile due to gravity, which means that it quickly moves beyond the root zone where plants can access it. As a result, this type of water does not contribute to the moisture that is readily available for plant uptake. Understanding this concept is important for managing irrigation practices, as too much gravitational water can lead to leaching essential nutrients away from the plant roots.
• Discuss the implications of gravitational water on soil erosion and compaction.
  • Gravitational water can significantly impact soil erosion, especially during intense rainfall events when excess water drains quickly through the soil. This rapid movement can carry away topsoil, reducing land productivity and leading to sedimentation in waterways. Additionally, when soils are saturated with gravitational water, they become more susceptible to compaction, which can further reduce pore space and negatively affect root growth and water infiltration rates.
• Evaluate how different soil types manage gravitational water and what that means for agricultural practices.
  • Different soil types exhibit varying capacities for managing gravitational water, with sandy soils allowing rapid drainage while clay soils tend to retain more moisture. For agricultural practices, understanding these differences is crucial; sandy soils may require more frequent irrigation to compensate for quick drainage, while clay soils may hold excess moisture that can lead to root rot or other issues. Thus, farmers must tailor their irrigation and land management strategies based on their specific soil types to optimize crop health and yield.

Related terms

field capacity: The amount of soil moisture retained after excess water has drained away and the rate of downward movement has decreased.

capillary water: Water that is held in the spaces between soil particles by surface tension, which is available for plant uptake.

infiltration:

The process by which water enters the soil surface, allowing it to move down into the soil profile.