Researchers improve environment with innovative irrigation system

COLUMBUS – New technology can improve Ohio farm drainage and irrigation while increasing crop production and protecting water quality.

Bill Shininger, one of the first Ohioans to test the new Wetland Reservoir Subirrigation System, likes it well enough to recommend the set-up to any farmer who is thinking about installing a new system. The Shininger farm in Delta, Ohio, Fulton County, is one of three test sites created in 1996.

“Even if we had to fund the whole system ourselves, I think we would do it again,” said Shininger. “We had substantial yield increases each year, improved drainage, but most of all it’s very environmentally friendly.”

Research continues to test the economic and environmental viability of the WRSIS at the three test sites in the Maumee River Basin in northwestern Ohio.

Barry Allred, USDA agricultural engineer, said researchers continue to monitor the system and are working to improve yields to counter the start-up costs of installing the system.

WRSIS is comprised of a subsurface drainage pipe network, a constructed wetland and a water storage reservoir. The system applies irrigation water through the pipes to the roots, captures and treats subsurface and surface drainage and stores the water for reuse.

It operates in a closed loop, minimizing runoff of sediment, nutrients and pesticides into the Maumee River.

“Initial costs can be reduced substantially by installing these systems at locations that already have subsurface drains,” said Allred. “The costs at each site included the labor and materials needed for system installation, as well as the income lost by removing some of the agricultural land from production.”

The project team installed systems at three demonstration sites in the Ohio portion of the Maumee River Basin – one each in Defiance, Fulton and Van Wert counties. At each site, crop yields from subirrigated fields are compared against those of control plots with drainage pipes but no irrigation.

Overall system design varies depending on site conditions, such as topography, soil type, supplemental water supply and subirrigated acreage.

NRCS engineers used a computer program (DRAINMOD) to design the subirrigation system and estimate the size of the storage reservoirs needed. Wetlands were designed to receive surface runoff and subsurface drainage from a 3-inch rainfall over a 24-hour period.

To prepare for rainfall events exceeding system storage capacity, managers also incorporated off-site effluent release mechanisms from both the wetlands and the reservoirs that allow water to overflow either directly into a local stream or into a drainage ditch that leads to a stream.

For the Fulton and Van Wert locations, the project team installed additional irrigation/drainage pipes between pre-existing drain lines and equipped the whole network with irrigation capabilities.

At the Fulton County site, Bill Shininger and his father, Fred, are responsible for running the system and daily monitoring.

“The system is pretty easy to run, but it does require daily monitoring,” said Shininger. “We had to run electric to the system and provide the electric, and we paid for half of the installation of the wetland.”

Based on the typical maximum yields during a good farming year in northwest Ohio, the WRSIS project team set a crop yield goal of 200 bushels per acre for corn and 70 bushels per acre for soybeans. Although the Shiningers have come close to that goal, with a four-year average total yield of 194 bushels per acre of corn and 66.4 bushels per acre of soybeans, the other two sites posted considerably lower yields (a corn and soybean average of 152 and 45.7 bushels per acre, respectively).

“We test new varieties to see which reacts the best with the system,” said Shininger. “I believe our increase in yield is mostly due to better drainage rather than the better irrigation.”

The low numbers in Defiance and Van Wert counties are partly because of a combination of wet years and poor drainage in certain areas. As the project team continues to learn about and correct these problems, the averages should increase.

“At this point, the increased yields seen are probably not great enough to offset the start-up and operational costs. However, costs will decrease as we gain more experience with design, construction, and management of these innovative systems,” said Allred.

But, Allred emphasized, “there are other benefits that are difficult to put a price on, such as reduced sediment and nutrient inputs into the river and increased wetland wildlife habitat.”

Future designs may include combining the wetland and reservoir, said Allred.

A monitoring program will provide information documenting WRSIS benefits to water quality, wildlife habitat, and crop yield at all three sites. They are currently gathering data on the quality of water being released offsite, the quality of the recycled irrigation water, and wetland treatment efficiencies.

“We’ll have to collect data for a number of years before we can draw firm conclusions about WRSIS sediment and nutrient removal effectiveness,” Allred said. “However, since they’re mostly a closed-loop system, we’re confident that offsite escape of sediment, nitrate, phosphate, and pesticides will be greatly reduced.”

This technology is already being transferred to other places. Many of the design components from the first three WRSIS test sites have been incorporated at a new location presently operational on the Yocom family farm in the Big Darby Creek Watershed in Champaign County. This new location uses no pumps and is totally driven by gravity.

“There are two wetlands used in this system. There was a natural wetland that we enhanced, and we created a new wetland from prior converted crop land,” said Larry Brown, of OSU’s Food, Agricultural, and Biological Engineering Department. “Because it is gravity driven, there is zero energy cost to the farmer.”

The upland natural wetland, fed by surface runoff and subsurface drainage, provides subirrigation water for lower elevation agricultural fields. Subsurface drainage from these fields is then routed to a down-gradient constructed wetland for treatment before water is released offsite into a local stream.

Other potential sites are now being evaluated in Indiana and Ontario, Canada. WRSIS construction and management concepts have recently been included in the Overholt Drainage School (http://www.ag.ohio-state.edu/~ohioline/aex-fact/0321.html), an annual short course offered to consultants, farmers, and drainage contractors that is coordinated by Brown.

“Each system has to be specifically designed for the area. One of the most important components to the system is that we’re enhancing natural wetlands and also increasing the number of wetlands,” said Brown. “We are creating environmentally sound farming.”