Soil drainage refers to the soil’s natural ability to allow water to pass through it. Dense soil will hold water, while loose soil will allow water to pass through quickly. Soil drainage may determine which types of plants grow well in it.
Clay soil is a very dense type of soil. Its particles are closely packed together and clay generally does not allow water to drain through. This type of soil slowly releases air and allows water to seep down into it. Clay soil generally sits on top of a solid rock bed.
Once water draining slowly through clay reaches the rock bed, it no longer has an outlet and pools within the soil. Plants that grow in it are at risk for root rot. Roots that sit in standing water for long periods of time will become prone to disease and fungus and may wilt and die.
Sandy soil is very loose. Its particles allow for the passage of both water and air. This soil drains water very quickly, which allows air to circulate around the plants within it. This can also cause the plants to dry out and some varieties grown in sandy soil may need to be watered more frequently for this reason.
Dense clay soil is typically acidic and loose, while sandy soil is typically basic and holds a low amount of nutrition for plants. A well-balanced soil with good soil drainage will contain a mixture of both clay and sand, allowing for a gradual passage of both water and air to circulate around plant roots. It will also add a valuable amount of nutrition to the soil to feed new plants.
To determine the quality of the soil in a garden, gardeners may wish to perform a pH test. Soil testing kits may be purchased in many home improvement stores and plant nurseries. A variety of sites within the lawn or garden should be tested.
Organic compost is a common additive used to improve soil quality and drainage. It generally consists of lawn clippings, shredded leaves, and kitchen food scraps, not including dairy or meat. Organic compost neutralizes the pH balance of soil, bringing either acidic or basic soils to a medium pH. It also incorporates loose particles into dense clay, and adds solidity to sandy soils.
Extremely dense soils that continue to hold water after the addition of organic compost may need to be manually drained. Drainage pipes and ditches may be dug around the garden area or site of poor soil drainage. These pipes and ditches will direct water flow away from the problem area and allow air to move through the soil.