Soil Drainage & Irrigation

Role of Drainage in Your Garden

• Soil drainage is determined by the size of its particles and the amount of space between them. Soils that have large particles and pores tend to drain very quickly, whereas those with fine particles and small amounts of space drain slowly. Because water carries nutrients to plant roots, plants may not receive enough nutrients in fast-draining soils, which can produce conditions that are similar to drought without regular watering. On the other hand, soil with a high level of water retention may cause roots to become waterlogged, which reduces oxygen levels and increases the chance of developing disease or becoming infested with insect pests.

Amending Your Soil

• In addition to proper irrigation and watering, soil drainage can be improved by amending your soil. Organic matter such as peat moss, compost or manure can improve soil tilth by either increasing the amount of space between soil pores or filling in very large pores. This makes it a versatile amendment that can be used both in clay soils and in sandy soils. You can also use mulch to decrease runoff and help the soil to better retain water.

Drip Irrigation Systems

• Some irrigation systems produce more runoff than others. The term "runoff" refers to the water that is not absorbed by the soil due to excessive water amounts or inadequate soil drainage. According to the Colorado State University Extension, drip irrigation is the best system for gardeners who need to reduce runoff and overall water waste. Drip irrigation provides small amounts of water to plant root zones through small underground pipes. According to the Texas A&M University Extension, drip irrigation is the most water-efficient irrigation system, with a 97 percent application efficiency.

Other Types of Irrigation Systems

• Sprinklers are another common irrigation system, especially for landscape use. Although sprinklers can be effective, careful placement and operation will maximize their effectiveness. As noted by Colorado State University, you should be especially vigilant of water use if you have clay soil in your lawn or garden, since sprinkler systems may overapply water if not properly adjusted. If you find that your soil does not absorb water, which causes pooling or excessive runoff, consider cycling your sprinkler watering sessions. This entails splitting your watering into two or three sessions, allowing the water to completely soak into the soil before watering again.