Which condition illustrates the need for subsurface drainage?

The need for subsurface drainage is best illustrated by somewhat poorly drained, poorly drained, and very poorly drained soils. These soil conditions typically retain excess moisture, which can lead to problems such as waterlogging, poor aeration, and reduced root development for plants. Subsurface drainage systems help to remove excess water from the soil profile, improving soil aeration and creating a more favorable environment for root growth and microbial activity.

In contrast, well-drained soils have a sufficient natural drainage capacity, making additional drainage unnecessary. Excessively drained soils typically do not retain enough moisture for optimal plant growth, and therefore do not require subsurface drainage. Dry and sandy soils, while they may have low water retention, are also not indicative of a need for subsurface drainage. Instead, they may require water retention measures due to their capacity to drain too rapidly.