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Underground irrigation

Bob Meiners has developed and patented an underground irrigation system that literally can go where no system has gone before.

Under the company name Agrem, Meiners developed software that accurately maps soil profiles and field typography and integrated it with state-of-the-art tile machines to design and install subirrigation systems that work as well on the contours of hillsides as they do on level ground.

Crop farmers and livestock producers alike benefit from the system's ability to spoon-feed nitrogen at the roots of a growing crop throughout the growing season to improve fertilizer efficiency and crop yield. Because Meiners designs closed-loop systems, it's almost impossible for nitrogen fertilizer to wash away from fields and end up in the Gulf of Mexico. The Agrem systems won't eliminate the hypoxia problem, but neither will they add to it.

“The system also works to drain fields in the spring and fall when farmers want to reduce water levels in the field,” Meiners says. “With improved drainage, farmers can plant fields a day or two earlier in the spring and avoid cutting ruts and creating compaction at harvest.”

The system's biggest bonus, however, might be for confinement livestock producers who can use Meiners' system to pump effluent to fields 365 days a year regardless of the weather and without the neighbors smelling any odor.

How it works

It takes a number of new technologies to make the Agrem system viable. “Three things had to come together,” Meiners explains. “We needed a tile machine that could keep an accurate grade of 1 ft. per 1,000 ft. knife-cut tile that won't silt in and the highly defined topo maps.”

Meiners, whose company is in Anchor, IL, wrote the software. RWF Bron's self-propelled tile plows, manufactured and certified in Canada, provide the necessary tiling accuracy. And Advanced Drainage Systems, Hilliard, OH, provides the tile.

Irrigation water for Meiners' subirrigation system comes from reservoirs that require an area that's 2 to 3% of the acreage to be irrigated. The reservoir collects rain and field runoff and prevents nitrogen and other farm chemicals from moving downstream. A wetland below the reservoir helps filter reservoir water if the reservoir level needs to be lowered.

It takes 20 to 60 hp to pump water through the buried 6- to 8-in. main lines and 3-in. laterals. Control gates, placed along field edges, direct water flow from the main tile line to each zone of the subirrigation system. The control gates can be operated manually or remotely by computer.

“You can choose an individual zone you want to irrigate or irrigate the entire system,” Meiners says. “Depending on the size of the pump, it takes 24 to 36 hours to apply an acre inch of water. The subirrigation system uses about one-third the water that a center pivot uses. We bury the lines 2 to 3 ft. deep, and our data so far show that yield doesn't vary across the field, either over the top of the lines or in between them.”

Yield and safety

Meiners' system isn't just theory. He partnered with The Nature Conservancy to test its yield and environmental safety potential on a 20-acre project, near Colfax, IL. The Agrem system was installed in the fall of 2005 and produced its first crop in 2006.

Testing the Agrem system is just part of a much larger project that The Nature Conservancy has managed since the late 1990s in the Bray Creek and Frog Alley watersheds that drain into the Mackinaw River watershed, according to Maria Lemke, aquatic ecologist for the Illinois Chapter of The Nature Conservancy.

“It's a paired watershed project [each drains about 10,000 acres] where we apply best management practices [BMPs] in one and then compare the results of the treatment watershed to the reference one,” she explains. “We've got monitoring equipment set up throughout each watershed to test if the applications impact the system the way we think they do.”

Initial research showed that BMPs such as conservation tillage, grass waterways and filter strips didn't significantly change the amount of nitrogen and phosphorus leaving the farm fields and entering the watershed.

“Most the fields in the watersheds are tiled for drainage and the water was moving right underneath all the improvements we'd made on the surface,” Lemke says. “So we've started to look at practices that intercept the water from the drainage tile before it enters the watershed. That's how we met Bob.”

The Nature Conservancy, Ducks Unlimited, two McClean County conservation agencies and a number of area universities are all involved in the continuing project.

In addition to the Agrem system, the project is evaluating constructed wetlands as an alternative way to intercept drainage water from field tiles. “We want eventually to be able to give farmers a number of options,” Lemke says. “We want to be able to say, ‘This is what works. This is how well it works. And this is what it costs.’

“The preliminary results are encouraging,” Lemke continues. “There are too many variables to be able to come to any conclusions at this point. We need a few more years of data. But there are a lot of potential benefits.”

From a farmer's viewpoint, the initial data from the project look good, according to Meiners. “From the fall of 2005 through the spring of 2006, the field received just 3 in. of rainfall,” he says. “Then, from May through the first week of August, only 2.4 in. more rain fell on the field. Through the growing season we applied 3.65 in. of water through subirrigation and made three applications of nitrogen fertilizer (46 lbs. actual nitrogen each application) in addition to the 45 lbs. of nitrogen surface applied at planting. We applied approximately 1 gal. of 28% liquid fertilizer per 200 gal. of irrigation water.”

Yield checks at harvest showed the highest-yielding areas of the field averaged 285 bu./acre with the lowest-yielding area of the field coming in at 197 bu., according to Meiners. “In adjacent farm fields, yields averaged from 45 to 113 bu./acre,” he says.

The yield differential was less dramatic in 2007 under more normal rainfall conditions. Yields in the test field ranged from 236.4 to 329 bu./acre, while adjacent fields ranged from 175 to 224 bu./acre.

Farm application

John Leonard, a farmer from Gibson City, IL, considered subirrigation good risk management for the acres where he grows hybrid seed corn. “We put in a system on 200 acres,” he says. “I looked at center pivot irrigation, but I didn't have enough water to run a system.”

The Agrem system cost Leonard approximately $800/acre installed because Meiners was able to adapt the existing tile system into his plan. A new system costs $1,700 to $2,200/acre, depending on the design criteria, according to Meiners.

The price tag doesn't worry financial institutions. Wells Fargo will finance the purchase of an Agrem system, or it can be leased through SCI Leasing Group, according to Meiners.

“It seems like a good option,” Leonard says. “The reservoir covers about one acre in a part of the field that was difficult to farm anyway. With the improved efficiency of the drainage, we actually got in the field two days earlier and it was the first field we planted.”

No yield data are available from Leonard's 2007 crop, his first subirrigated crop, which was harvested as hybrid seed. “But the seed company was happy and that makes me happy,” he says. “The system raises production and returns higher gross dollars per acre.”

While subirrigation systems are a significant investment, land prices without a top in sight may give growers second thoughts about which one is the better deal. “When you compare the costs, investing in a subirrigation system on land you already own may be more attractive than buying additional land,” Leonard says.

New research project

A research project under way at Illinois State University will take a close look at the economics of the Agrem system. Rob Rhykerd, an associate professor in agronomy specializing in soil science, and Paul Walker, professor of animal science, are working together on the project.

“We installed an Agrem system in 2007 on 18 acres of rolling ground about one-fourth mile from the one-million-gallon storage tank we use for the 200-sow farrow-to-finish hog operation on our research farm at Lexington, IL,” Rhykerd says. “In 2008 we'll compare the yield performance, environmental protection and economics of the Agrem system with effluent applied through a center pivot system, applying raw slurry and applying composted manure.”

The scientists will test for nutrients and pathogens in field runoff and nutrient and pathogen levels in ground water and will give each system a subjective sniff test for odor. “We've already pumped effluent through the center pivot system and could barely detect any odor,” Rhykerd says. “I'm anticipating that with the tile lines buried 20 in., we won't have any odor with the subirrigation system.”

The ISU scientists have installed a mechanical separator at the hog buildings that removes roughly 95% of the solids (and about 50% of the nitrogen and 90% of the phosphorus) from slurry pumped out of the building's manure pits. The solids are composted and spread on research farm fields or sold.

The resulting effluent is stored until it's used as irrigation water. “It's dirty water,” Rhykerd says. “It has enough nitrogen, phosphorus and pathogens in it that you wouldn't want to put it directly in a creek.

“It was fascinating to watch the subirrigation system installed,” he says. “The tile machine lifts the soil, sets the tile underneath and lays the soil back down. You don't get much mixing of the subsoil with the surface. The system was installed by the end of May and we were able to disk the field lightly and plant soybeans. The crop ended up yielding close to 60 bu./acre with no effluent applied. It's really unique.”

To learn more about Agrem subirrigation systems, visit Or contact Agrem LLC, Dept. FIN, 17120 N. 3800 East Rd., Anchor, IL 61720, 309/723-3231, visit, or circle 109.

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