In recent years, the Midsouth has seen a significant gain in row rice acres. The crop production system, also known as furrow-irrigated rice (FIR), boasts an array of advantages over flood-irrigated rice. Now, patented technology offers additional benefits through a tailwater recovery system developed by researchers at the University of Arkansas System Division of Agriculture. 

With over a decade of research and development, the pit-less tailwater pumping system reduces water use by more than 60% and has reported irrigation efficiencies over 90%. Furthermore, this tailwater recovery technology allows for practices like cover cropping and no-till and has the potential to reduce nitrogen fertilizer applications through the process of fertigation. 

Chris Henry, professor and water management engineer at the Division of Agriculture, is the developer and principal investigator of the pit-less tailwater pumping system. He has worked to improve the efficiencies and simplify installment, and Arkansas farmers are seeing success. 

Henry said, “We have several of these systems placed in fields throughout the Delta. Now we are ready to commercialize them.” 

Gold standard in irrigation efficiency 

This journey began when Henry joined the Division of Ag faculty in 2012. FIR was catching on with Arkansas rice farmers, and Henry saw an opportunity to improve water use in the production system. 

Related:Arkansas Cooperative Extension announces irrigation contest winners

Through collaboration with a colleague and funding by the Department of Energy, the first pit-less tailwater pumping system was engineered and placed at the Rice Research and Extension Center in Stuttgart in 2013. 

By continuously recirculating water from the bottom of the FIR field to the top, the system keeps the soil moisture more consistent across the entire field. Henry said data collected from the pilot project confirmed its success. From there, the technology evolved, and each year since, his research team has tried new methods to improve the system.  

“We’ve compared it by planting different rice varieties. We’ve tried different fertilizer treatments – from time-released fertilizers to different splits. We have also tried no-till, cover crops, and different irrigation strategies to figure out the best way to use this system.” 

Of all advantages, irrigation efficiency stands out as the most substantial. For reference, Henry explained that the average water use on flood-irrigated rice is 32 acre-inches of water. When it comes to zero-grade rice fields, that number improves dramatically at 19 acre-inches of water – which is considered the gold standard. Henry reported that the pit-less tailwater pump measures up to the test. 

Related:Tailwater recovery shows savings

“In all the years of this project, we have never been over 19 acre-inches per acre of irrigation and as low as 10 acre-inches per acre,” Henry reported. “This tailwater pumping system is right there with the gold standard.” 

Technology takes to the field 

The technology was acknowledged by the Arkansas Rice Research and Promotion Board who took interest in Henry’s efforts and provided funding to further support research and development. 

Henry said, “If it was not for the Rice Research and Promotion Board, I probably would have given up on the idea. They funded the project and allowed us to take a deeper look at it. Once we got things figured out, that allowed us to go after NRCS funding to demonstrate the system on farmers’ fields.” 

The USDA Natural Resource Conservation Service (NRCS) of Arkansas contributed additional funding to Henry’s research – making it possible for this technology to take the field and boost FIR to the next level. 

Through improved iterations, Henry has developed a system that includes a lightweight sump constructed of PVC and powered by a small motor. The pumping system is energy efficient at only 3-hoursepower, which is noteworthy compared to the 50 to 75-horsepower irrigation pumps that are traditionally used. 

Henry said the tailwater recovery technology is easy to install and touts portability, allowing it to be moved to new fields according to crop rotation and irrigation needs each season. Once installed, the rice field can be irrigated continuously from the 4-leaf growth stage until R7. 

He explained, “It is a high flow, low-head pump that recirculates the water to irrigate the field. The idea is when the water comes out of the furrow, it is recycled back to the top of the field using polypipe, keeping all the water on the field where it needs to be for the rice plant.  

“The variable flow nature of the pump allows it to run continuously without any intervention. The grower simply shuts it off when adding irrigation water, which keeps the top of the field wet in-between irrigation cycles,” Henry said. 

Over the years, Henry has worked with farmers during the installation process and said it is easy for two men to manhandle the pump system and self-install. The system is made to be taken apart and reassembled if needed. Furthermore, Henry noted the newest design has improved portability and can be picked up with a forklift or forks on a tractor and relocated without complete disassembly. 

Improved nutrient uptake 

Part of Henry’s research with the tailwater recover system is fertigation, or the process of injecting fertilizer applications into the water as it irrigates the rice crop.  

Henry said, “One thing that is really useful about the tailwater recovery pump is that when you are recirculating the water, it is a good time and place to put the fertilizer out. The soil is wet from the recirculated water, so the intake rate of the water into the soil is constant which results in very uniform application of fertilizer.” 

This method also allows for optimized fertilizer application and timing based on the plant’s needs.  

Henry monitors plant health through Normalized Difference Vegetation Index (NDVI) remote sensing and applies fertilizer to the water as needed. Once the crop has had enough, fertilizer injections can be stopped. Henry hypothesizes that this application method could save farmers on fertilizer inputs, and more research is planned to verify this potential savings. 

While Henry is focused on the commercialization of this pit-less tailwater pumping system, this technology is already available to farmers. Those interested should contact their local NRCS office to inquire about installation of this tailwater recovery system. Also ask about cost-share and climate-smart programs available to offset approximately half of the cost.