The key to success is often rooted in a solid plan, and experts with the University of Arkansas System Division of Agriculture are encouraging Arkansas rice producers to start that plan with the technology known as Multiple Inlet Rice Irrigation, or MIRI.
Chris Henry, an irrigation engineer and assistant professor with the Division of Agriculture, said MIRI technology has been around since the 1990’s, and has many benefits.
“MIRI reduces the cold water effect on the first levee, reduces total water use by 25 percent, allows for the implementation of alternating wetting and drying, and a faster flood time than the traditional cascade system,” he said. “Being able to quickly flood up a field is beneficial for being able to get the flood established for water management as well as weed control and ensuring fertilizer efficiency.”
Henry said both the Division of Agriculture and Delta Plastics have programs designed to promote the implementation of MIRI, as well as support growers throughout the process.
MIRI is a required component of a Natural Resource Conservation Service, Irrigation Water Management plan, which frequently provides financial assistance to growers, including those participating in alternating wetting and drying or carbon credit programs.
MIRI has also been shown to increase yields by five to 10 bushels per acre over cascade fields.
“All in all, there’s more than $100 an acre available through incentive programs, yield advantages and pumping cost savings,” Henry said.
Blue gates — the 2.5-inch gates used in poly-pipe to control water flow — are an essential element to the MIRI system that are sometimes ignored during the installation process. Properly set levee gates are also key to optimum performance of a MIRI system.
“Two-and-a-half inch blue gates and a plan are required to use MIRI successfully,” Henry said. “The blue gates allow for a wide range of flow and for the irrigator to adjust and balance the flow to each levee, so that the field floods up evenly.
“Leave the ‘piranha puncher’ in the truck when you are in a flooded rice field,” he said, referring to the commonly-used hand tool used for punching small holes in poly-pipe. “It may be chewing through your profit. If holes are punched without any way to adjust them, then some levees will cascade over the other.”
Effective implementation of MIRI should only have water going over levee gates when more than an inch of rainfall has occurred, and levee gates should be set higher than they would be for cascade irrigation, because they are essentially overflow devices when MIRI is used. Some MIRI irrigators no longer put in levee gates, instead using a simple overflow, further reducing cost and labor. When properly executed, MIRI eliminates the in-season chore of wading through rice fields to adjust levee spills.
A mobile app developed by the Division of Agriculture in 2015, Rice Irrigation, helps takes the guesswork out of MIRI implementation. Levee files can quickly be created from aerial maps, uploaded from survey programs, or uploaded from the tractor GPS monitor to provide an effective MIRI plan on even the most complicated contour levee fields.
Pipe requirements and blue gate settings are provided and can be shared easily with other mobile devices. Flow rate for the field is also needed, but portable flow meters are available for checkout from your local Cooperative Extension Service office, Conservation District offices, NRCS offices, and even some irrigation dealers.
Funding to develop the mobile app was provided by the Arkansas Rice Research and Promotion Board. Assistance using the app is available through your local Cooperative Extension Service office. Search for “Rice Irrigation” in the Apple App Store or in the Google play store on android devices.