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Subsurface irrigation creates opportunities in Iowa

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More and more farmers are considering subsurface drip irrigation to provide nutrients and water during the growing season. (Photo: Joseph L. Murphy/Iowa Soybean Association)

By Joseph L. Murphy

Are you interested in subsurface drip irrigation (SDI) but think it is only applicable in other parts of the country? You might be surprised to know that SDI is growing and soybean yields in Iowa could benefit.

According to a leading irrigation company, over 3 billion feet of drip tubing was installed in U.S. row crop fields in 1995 alone. Since that time the technology and durability of drip tape have improved to give flexibility to farmers working in different terrains.

“I’m helping mother nature, I’m making sure I get the things I don’t have control over covered," Jeff Jorgenson, an Iowa Soybean Association (ISA) director from Sidney, said of his current pivot irrigation system. "Soybeans need a lot of water from late July to early September, and by irrigating during that time, we can get a quick response to yield."

He spent time last week talking with representatives of Netafim, an irrigation company that has designed and installed subsurface drip tape systems on millions of acres across the U.S, to see if the technology is right for his southwest Iowa farm.

SDI is a series of plastic irrigation tubes that are buried about nine to 18 inches deep in fields to provide a more direct route for water to reach the roots of plants. By moving the tubing to the subsurface, evaporation decreases significantly and provides water and nutrients to the plants at the root level.

The plastic used to produce the irrigation tubes comes in different densities that impact the longevity of the product. Growers in California prefer a product that lasts for a single growing season, but farmers in Nebraska, Kansas and other parts of the country have been using tubing that will last 25 to 50 years.

For Jorgenson, the SDI system is attractive for some of his irregular shaped farm fields where pivot irrigation won't help. He said that SDI systems could help even out the limiting factors that impact his yields during the growing season.

"If you look at trying to achieve 80 bushels an acre yields for soybeans the factors you have limiting you are fertilizer and moisture," he said. "Subsurface irrigation can help with both by adding prescribed amounts of nutrients and water at critical times."

The process of adding dissolved fertilizer through irrigation lines is called fertigation. Fertigation and irrigation through SDI benefits crops by providing nutrients and water at root level while preventing evaporation.

Christopher Hay, senior environmental scientist with ISA, recently authored a proceedings paper titled "Evaluating Drainage Water Recycling Benefits for Crop Production in Iowa" that examined the possibilities of storing subsurface drainage water for reuse as irrigation water. The practice has been gaining more interest as a way to maximize production while minimizing nutrient loss from fields.

"Drainage water recycling captures subsurface drainage water in a storage reservoir for use as irrigation water during periods of inadequate rainfall in the summer," he said.

He went on to say that by capturing the water and reusing it fewer nutrients leave the system.

"Reduced nutrient loading would benefit local water quality and contribute to state nutrient reduction strategies," Hay said.

The major drawback to drainage water recycling and SDI technology at this time is cost according to both Hay and Jorgenson. The average price for SDI is $1,400 to $1,900 an acre according to Kurt Grimm, a grower in Hiawatha Kan., and a speaker during a drip irrigation session at Commodity Classic in San Antonio, Texas.

"The tough part right now is that we are in a downturn in ag," Jorgenson said. "It is hard to look at cash flowing irrigation, but that will change over time. SDI might be something I do in the future that will help my children more than it helps me."

For permission to republish articles or to request high-res photos contact Aaron Putze at aputze@iasoybeans.com.

©2017 Iowa Soybean Association On-Farm Network®. All rights reserved. On-Farm Network® is a registered trademark of the Iowa Soybean Association, Ankeny, IA.Portions of some On-Farm Network trials are paid for in total or in part by the soybean checkoff.

Iowa Soybean Association | On-Farm Network | 1255 SW Prairie Trail Pkwy | Ankeny | IA | 50023 | US

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Iowa Soybean Review

August 2017 Contact Ann Clinton for past publications.