How saving excess rainfall can benefit your operation

Focusing on continually improving their fourth-generation farm, Kellie and A.J. Blair added a center pivot to one of their Iowa operations last year. But rather than a traditional setup, the couple installed a drainage water recycling (DWR) system to help them better use excess rainfall from the spring to water crops during the dry summer. The Midwest is forecast to face increasingly wetter winters and springs, and hotter summers with longer dry spells, according to the federal Environmental Protection Agency (EPA). 

Besides having a steady water supply throughout the growing season to maximize yield, the Blairs also focus on stewarding the land. “To slow down the nutrients and keep them on the farm or slow down the water and reduce potential flooding — trying to protect the environment and leaving things better than how we found them — is part of who we are,” Kellie says. “But if this will increase our yield and profitability, then it’s a good thing for everyone.”

For years, Midwest farmers have used drainage tile and open ditches to remove excess water from poorly drained soil. However, these are also major pathways for nitrogen and phosphorus loss from fields to sensitive bodies of water such as the Great Lakes and the Gulf of Mexico. 

One solution is to store excess spring rainwater, to use in summer, via storage ponds, storage ditches, and controlled drainage systems. “We can get [water] off for field operations and hold it in such a way that we can utilize it later without damaging or compromising the river systems,” says Shaun Casteel, Purdue Extension soybean specialist. “That’s the ideal world.”

Types of DWR systems

Drainage water recycling (DWR) is just an intensified form of water management, says Chris Hay, an agricultural water management consultant in Iowa. “There’s a number of different configurations a DWR system can take,” he points out. “It’s going to vary on what system makes the most sense, depending on site-specific conditions, particularly topography.” 

Purdue University has a prototype drainage water recycling system at its Agronomy Center for Research and Education. Agronomy professor Laura Bowling and her team have taken a wetland, in a corner of the farm too wet for crop production, and use it to store water captured from about 175 acres. 

“The tile drainage comes into the wetland through two really well-defined mains, and then there’s one channel where it leaves, so we can monitor the flow rate and water quality leaving the wetland,” Bowling explains. “We added an outlet control structure to the wetland to let us control the timing of water storage and water leaving.”

The Precision Planting research farm in Tremont, Illinois, southeast of Peoria, utilizes DWR with subsurface drip irrigation. It was designed as a true sustainability project. “When we’re too wet, we’re going to get rid of the water through drainage tile and fill up the reservoir,” says Jason Webster, the lead commercial agronomist. “Then we recycle that rainwater in the form of irrigation. We are learning how to ‘fertigate’ [simultaneously fertilize and irrigate], how to give the crop what it needs, and how we can push yield.” 

Blair Farm’s DWR system uses a center pivot to irrigate 130 acres, formerly 160 acres, with a low spot in the southeast corner. “Even with tile, that corner never produced well,” Kellie shares. “We dug out a pond, and we pump water from the tile main into our pond.” 

Mark Schleisman farms near Lake City, Iowa, east of Sioux City. His DWR system includes a reservoir created with an embankment in a waterway that receives outflow from an upstream drainage district. The water passes through a wetland before entering the deeper water storage, which he uses to irrigate about 55 acres, with a center pivot. 

“We built a dam, [collected] the water in a pond, and the pond [ended] up being a wetland to help reduce nitrogen in the water,” Schleisman explains. “We also use water out of that pond to directly irrigate the field.”

Yield benefits

The benefits to yield come from applying supplemental irrigation during parts of the season when water may be lacking. Research from Iowa State University and Iowa Soybean Association found that irrigated fields produce consistently greater yields than rainfed fields. At one site, the overall yield increase over six years was 35 bushels per acre (bpa) for tiled irrigated corn compared with tiled rainfed corn. 

“In addition to increased yield, the other thing we saw was reduced yield variability,” Hay says. “We saw more consistent crop production by having DWR as opposed to just free drainage.” 

Schleisman also has seen yield benefits since installing his system three years ago. “Our field is closer to the river and the ground is a little bit sandy, so it benefits from irrigation,” he says. “The last two years we’ve seen close to a 50% yield increase. It’s been very dry, and there would have been crop failures on those sandy fields.”

Webster, of Precision Planting, has also documented yield benefits. “In 2023,” he reports, “our highest [corn] yield was 403 bpa under irrigation, and average dryland corn was about 240 bpa. Soybeans have averaged a 23 bpa yield increase by [the farm] being able to irrigate and fertigate. At $13 soybeans, that does add up quickly.”

Water quality benefits

Another major benefit of storing water in the field is that nutrients, such as nitrogen, can be put back in rather than running off into streams, eventually causing problems such as algal blooms and oxygen deficiency. 

Purdue University has researched the water quality benefits of storing water. “The wetland itself is very effective at reducing nitrate load,” the university’s Bowling says. “The nitrate coming in from those tile lines is close to our drinking water limit, around 10 milligrams per liter. The load leaving, even without irrigation, is about 40% less, just by spreading across the wetland, being taken up by vegetation, and denitrification. By reducing how much water goes downstream and applying it to the field, we’re reducing the downstream nitrate load by about another 20%.”

Iowa found reductions in nitrogen and phosphorus runoff. “We’ve gotten anywhere from 60% to 90% reduction in downstream nitrogen export of the water that goes into one of the reservoirs,” says Matt Helmers, an Iowa State University professor and director of the university’s Iowa Nutrient Research Center. 

 At Precision Planting, the ability to fertigate through drip irrigation has led to a reduction in nitrates. “Since we are able to spoon-feed the nitrogen with the weekly irrigation, we don’t see very high nitrates in our water,” Webster says. “I can just put little amounts of fertilizer in the irrigation on a daily or weekly basis rather than putting one large amount in a dry fertilizer mix in the fall that’s supposed to last all year long.”

Additional benefits

“We do a lot of conservation on our farm to help improve water and soil quality,” Schleisman says. “This project was the right thing to do from a nutrient standpoint. But it also made us some money, because we were able to utilize the water to irrigate the field and increase our yields.”

Hay is thinking about how storage components could benefit drainage district infrastructure. “It helps the capacity of that drainage district, and if we have enough of these reservoirs in the landscape, there’s potential to reduce some downstream flood impacts and provide benefits to farmers in that drainage district.”

Funding opportunities and planning tools

Drainage water recycling systems are not inexpensive; costs vary, depending on infrastructure. Webster invested about $4,000 per acre in an 80-acre field. This included installing drainage tile, adding subsurface drip irrigation, and excavating the pond. “With the yield increases we’ve received from drainage and irrigation components, we’re on a 10-year payoff,” he says. Funding opportunities vary among states.

To recognize the new scope of subsurface drainage water recovery, USDA in 2020 revised its NRCS Conservation Practice Standard (CPS) code 447 and renamed it “irrigation and drainage tailwater recovery.” The standard exists nationally, and the states have to accept it. “Once accepted at the state level, they can start to provide incentives for farmers,” says Jane Frankenberger, professor of agricultural and biological engineering at Purdue and project director for the Transforming Drainage project. ​​

Three Midwest states — Illinois, Indiana, and Kansas — offer CPS 447 and related funding through the NRCS Environmental Quality Incentives Program (EQIP), says Scott Wagner, an agricultural engineer for NRCS in Indiana. 

In Iowa, the Department of Ag and Land Stewardship (IDALS) has shown interest in this practice for potential cost share. “IDALS put together a proposal to the EPA through their Gulf of Mexico program that gave us funding to do these couple of pilot sites,” Hay says. “With the positve water quality results we’ve seen — if we have farmer interest — I think there will be continued interest to fund these going forward.”

The Transforming Drainage project, an eight-state consortium of experts in varied ag disciplines, offers additional resources. “One of the tools that we’ve developed is called Evaluating Drainage Water Recycling Decisions (EDWRD),” says Frankenberger. “It offers an opportunity to explore what a system might look like and give an idea of what kind and size of reservoir and irrigation capacity.” 

Learn more

To access more tools to help plan DWR systems on your farm, visit transformingdrainage.org.

In addition to funding varying by state, DWR may require a permit or even face restrictions in some states. Check with your state and local water authorities before starting a project.