What is Sub-Surface Irrigation?
With recent water shortages, you may have heard of drip irrigation systems as an alternate means of watering your landscapes. These systems water straight at the source of the plant for more efficient irrigation. With drip emitters (or emission devices), you can control how much water is released per hour. However, with sub-surface drip irrigation all of this is now below ground and there is no need for drip emitters. It provides more even water movement and keeps roots wet and healthy.
Sub-surface drip irrigation systems contain drip lines (which carry water to the plants or grass roots, also known as “lateral lines”), flushing “submains” (pipes that supply water to the drip or “lateral lines”) and drip emitters. With the right emitters, your drip lines will be free from root intrusion. Some manufacturers, have a chemical that is released from the emitters causing the roots to stay away. The chemical can be placed on rings of a disc filter, such as the Netafim Techfilter, so it is easily accessible to add more.
It is important to bury the lines at either 4, 5, or 6 inches below ground level. To avoid shallow roots, you will need to know your soil type. The following GPH rates are recommended for different types of soils (at 12 inch spacing):
- 0.26 GPH for clay soil
- 0.4 GPH for loam soil
- 0.6 GPH for sandy soil
- 0.9 GPH for coarse sandy soil
Recently, demand for sub-surface irrigation has increased, particularly in Southern California and Texas, according to Mauricio Troche from Netafim as Director of Landscape and Turf. He states, “Sub-surface drip is a solution for an ever-growing problem of diminished water supplies and higher water costs.” Homeowners and city officials are recognizing the need to reduce water more significantly. Traditional methods of irrigation are not quite as efficient as a sub-surface drip system.
When one thinks of water conservation for the landscape, it usually entails removing your lawn. While we recommend reducing the size of your lawn for water efficiency, you don’t need to remove all of it. One of the ways to keep it is by using sub-surface irrigation. Not only does it eliminate water runoff, it offers up to 40% of reduced water use. Studies have found that it results in higher agricultural yields and adapts more easily to difficult soils and terrains.
Additionally, sub-surface drip irrigation allows for more flexible irrigation. For example, it works efficiently for grass strips between hardscapes, steep slopes and green roofs. It only requires about 1-5 inches of soil depth for green roof irrigation. With the aid of capillary action, water from sub-surface drip lines moves up, down and sideways, therefore irrigating more effectively than overhead spray.
If you are a contractor and concerned about the necessary skills to install sub-surface drip irrigation, there are many resources available and visit your local Hydro-Scape to ask all your questions. For the homeowner, this is a highly efficient option to consider when installing your lawn’s irrigation system. Not only does it provide easy access to all parts of your lawn throughout the day, but it offers an increase in water savings and a significant decrease in water usage.