IRRIGATION METHODS Straight from the field
Two top researchers share what you need to know related to current research focused on two different methods of irrigation: mobile drip and subsurface drip.
Subsurface drip irrigation being installed for cotton experiments at Texas A&M AgriLife Research, Halfway, Texas
Mobile drip system used for irrigating corn at a K-State irrigation research plot in Southwest Kansas Photo credit: K-State
MDI: What you need to know T
he concept of mobile drip irrigation, known as MDI, is to combine the high application efficiency of drip irrigation to a versatile and low
maintenance center pivot irrigation system. Instead of sprinkler nozzle packages, a certain length of drip hose corresponding to the design flow rate drags behind the pivot structure.
Although this concept was explored in the early 1980s, several recent design changes have resolved some challenges that have led to an increase in use. The most significant technology that made this concept viable was the availability of pressure compensating emitters with high flow rates. When Kansas State University tested a variant of this technology in 2008, drip hoses did not have pressure compensating emitters. It prevented the system from having a uniform application
10 Irrigation TODAY | Fall 2020
of water when the hoses ride on top of mature corn plants before going back on the ground. That issue and other design flaws have been addressed with the new designs of MDI. There are currently two vendors offering this technology in the market.
Research results
K-State has been conducting research on the latest design of MDI since 2015. Based on field research, we saw about 35% less soil evaporation on MDI compared to low elevation spray application (LESA), with most of that water going into and redistributing across the soil profile. At high well capacities (>600 gpm), there is barely
By Jonathan Aguilar, PhD, PE
any difference in corn yield between MDI and LESA. When well capacity gets into the lower end, which is between 300 to 150 gpm, then corn yield in MDI is significantly higher than LESA. These results indicate that the concept is working.
However, there are some issues and challenges that MDI users must contend with. To maximize efficiency potential, crops, particularly the tall types like corn and sorghum, must be planted in a circular pattern to avoid the hoses from riding the canopy. Management of MDI is more involved than a typical center pivot system, leaning more toward the management of a drip irrigation system. Since MDI utilizes drip hoses,
Utilizing MDI shows potential in increasing irrigation efficiency and solving some issues with center pivot irrigation systems.
irrigationtoday.org
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