By Kellie Potucek
A growing number of ranches bordering urban cities in Texas are being sold off as suburbanized “ranchettes,” and new owners are asking how they can maximize the use of their land. Many owners desire to raise livestock for 4-H or recreational purposes, but do not have the time or labor to manage grazing land with conventional sprinkler irrigation. Dr. David Forbes of the Texas Agricultural Experiment Station in Uvalde is investigating subsurface drip irrigation as an economically feasible alternative.
In subsurface drip irrigation, plants are directly watered at their root zone via buried hoses referred to as drip lines. Drip lines are laid approximately nine inches below the soil surface and precisely distribute water flow. Water is supplied from a central source and serviced by a filtration facility in the system that can also inject fertilizers and pesticides. The technology is traditionally used by crop farmers, but is more recently being adopted for other applications.
During the 2002 season, Forbes installed a subsurface drip irrigation system on a two acre plot and established vegetation using rooted transplants of Tifton 85 bermudagrass. The two acres were subdivided into eight 0.25 acre plots. Based on calculations supplied by the Uvalde Center weather station, Forbes irrigated half of the plots at 25 percent potential evapotranspiration (PET) and the other half at 50 percent PET. “Of the four plots receiving each irrigation treatment, half were designated for hay production and the other two designated for grazing,” explained Forbes.
When comparing outputs from subsurface drip irrigation and sprinkler irrigation, Forbes says his research, though not yet complete, clearly suggests subsurface drip irrigation is a viable method in sustaining a forage-livestock system. He explained the most significant advantage of subsurface drip irrigation is that it completely eliminates evaporative loss, which conserves water and saves money.
Subsurface drip irrigation also has several other benefits over sprinkler irrigation. For example, the system is very successful in atypically shaped areas that are not adequately watered by sprinklers. Farmers value this feature because they can install a system in the corners of their crop fields that are often missed by conventional sprinklers. Because the quality of drip tape has greatly improved, systems have an average life of 10 to 12 years and do not suffer from corrosion as do traditional pipes. Additionally, because there are no sprinkler heads exposed, the system is more aesthetically pleasing and is less prone to vandalism and theft. Home owners and athletic complexes are increasingly adopting the submerged technology for these reasons.
Forbes said, currently, the main obstacle in subsurface drip irrigation is finding someone to install the system. However, once installed, maintenance is relatively simple, but essential. The system has a filter that must be checked at least twice a year, and acids should be injected to clean the lines. Some users have reported fire ant damage to the drip lines, but pesticide application may solve the problem.
Forbes was awarded two Soil and Water Conservation grants from Texas Water Resources Institute in previous years and will continue his research with funds awarded by the Texas Water Development Board.
