January 18, 2021

Transforming drainage: Taking control of rain variability

EAST PEORIA, Ill. — Sometimes too much, sometimes not enough sums up rain events during the growing season.

Obviously, we can’t control the weather, but what if there were better ways to control the water, make it available when needed, while reducing nitrogen and phosphorous losses.

Jane Frankenberger, Purdue Extension agricultural engineer, has served as director of the Transforming Drainage project, a multi-state collaborative effort focused on increasing the resiliency of drained farmland through controlled drainage, saturated buffers and drainage water recycling. She spoke of the project, opportunities and challenges in a recent webinar hosted by the Illinois Sustainable Ag Partnership.

“Managing water is key for successful agriculture in our flat rich soils, and excess water is the most common issue that we deal with. So, we’ve installed subsurface drainage for many years,” Frankenberger said.

“We’ve made drainage infrastructure that’s designed to get rid of the water as quickly as possible. From the point of view of the farmer is that the water goes away, but we know it doesn’t go away, it goes into streams, rivers and the Gulf of Mexico.”

The focus of getting the water off the field as quickly as possible through tiling also creates other issues.

“The first issue is flooding. Now, it’s not drainage that leads to flooding, but it’s that if we don’t take any effort to store some of the water and just getting rid of it, people downstream are receiving it,” Frankenberger explained.

“The second issue and I think it drives a lot of what we do, especially in the conservation community, is that we know that drainage water when we see it doesn’t just have water even if it looks fairly clear it actually always has nitrogen in it. And what we’ve also realized more often is that it also has phosphorous in it. So, the water that looks clean is still leading to substantial water quality issues downstream.

“The third issue that’s not always so obvious because the excess water problem is such an issue is that later in the summer when we sometimes have dry periods we can reduce crop yields and stream flow.”

Weather Extremes

Looking ahead to tomorrow’s challenges, Frankenberger said the bad news is those three issues will become worse, “exacerbated by the changing climate, and will become more extreme."

Winters and springs are becoming wetter and resulting in increased flooding and that will continue to increase nutrient loss. Summers are getting drier and warmer and crops need more moisture to reduce stress.

There also is the financial impact of weather trends. Frankenberger said from 1991 to 2015 the losses paid by crop insurance in Indiana totaled $930 million for flooding and excess moisture and $1.6 billion for drought.

“When we think of too much and too little hopefully the concept that comes to everyone is the idea that we need to think about how we can store drained water in the landscape,” she noted.

Options

Transforming Drainage’s vision is to change the drainage is designed and installed. That would include more water storage and even water recycling through practices such as controlled drainage, saturated buffers and drainage water recycling.

Incorporating one of those practices could increase the sustainability of water for agriculture, producing positive impacts for crop production, as well as the environment.

“Storing rainwater in the landscape is key, but we’ve got these very flat lands and so it’s not always obvious where we are and one practice won’t work everywhere. So, we need to think of all the multiple benefits and identify opportunities where we can store drained water in our landscape,” Frankenberger said.

“Where we have drainage, and that is probably everywhere in our really flat landscapes, we can put controlled drainage or drainage water management. Where there’s a buffer we can make a saturated buffer. Where there’s some kind of opportunity to hold water we can do drainage water recycling. Constructed wetland is another option to retain water in the landscape,” she continued.

“The benefits of storing water in the landscape are it reduces the uncertainty and risk related to water availability and reduces the nutrient losses from agricultural fields.

“As we think about not just today’s agriculture but working towards tomorrow’s agriculture ideally we don’t want the nitrate and phosphorous to go down stream but instead go back to where they’re not only not harmful but they’re actually beneficial. We need those nutrients. They’re important, they’re critical for crop growth and we want them to be taken up by the crop.”