The Truth About Tile Drainage, Prairie, and Iowa's Nitrate Problem: A Conversation with Dr. Matt Helmers

If you've ever heard someone blame tile drainage for Iowa's water quality problems, Dr. Matt Helmers has some news for you: it's more complicated than that.

Dr. Helmers is a professor of agricultural and biosystems engineering at Iowa State University and director of the Iowa Nutrient Research Center. On a recent episode of the Prairie Farm Podcast, he sat down with Kent Boucher and Nicolas Lirio to talk about nitrate loss, soil conservation, and why the data on prairie restoration might surprise you.

The conversation covered a lot of ground—literally. From the mechanics of how nitrogen moves through soil to why Iowa needs to think bigger about conservation, here's what we learned.

Tile Drainage: Delivery System, Not Root Cause

One of the biggest misconceptions about Iowa's nitrate problem? That tile drainage is the culprit.

"We often hear that tile drainage causes nitrate loss," Dr. Helmers explained. "It definitely delivers nitrate. So it intercepts that water that's moving through the soil profile and delivers it to downstream waters."

But here's the thing: tile isn't creating the nitrate problem. It's just exposing it.

Think about it this way—the Central Platte Valley of Nebraska has heavy annual row crop production and a serious nitrate problem in their shallow groundwater. But they don't have tile drainage. The issue isn't the tile. It's the annual cropping system itself.

"I think tile drainage definitely delivers nitrate to downstream water bodies, but we also lose nitrate from non-tiled soils," Dr. Helmers said. "It's not just on the tile soils that we need to be concerned about nitrate, really non-tiled soils too."

Most studies on nitrate loss have focused on tiled soils because researchers can actually capture and measure the water coming through the tiles. But when they've looked at nitrate concentrations in leachate moving through the plant root zone, it's relatively similar in both tiled and non-tiled soils.

And if you want proof that non-tiled acres have nitrate issues? Look at Iowa's rural private wells. Many of them are testing high in nitrate, and they're not being fed by tile lines—they're pulling from that same leachate moving through the soil column.

The takeaway? We need to think about nutrient reduction across all our acres, not just the ones with tile.

Prairie vs. Corn and Beans: The Numbers Are Shocking

Here's where the conversation got really interesting. Dr. Helmers has been running a long-term study on tile-drained plots near Ames. In 2008, they restored prairie on eight of these plots. The others stayed in corn and soybeans.

From 2010 through 2022, those corn and bean plots lost about 120 pounds of nitrogen per acre through nitrate leaching.

The prairie plots? Five pounds per acre.

Let that sink in. Five pounds versus 120 pounds. Even when they fertilized the prairie with about 75 pounds of nitrogen, it still only lost five pounds per acre total.

"Prairie is one of the best for reducing nitrate loss," Dr. Helmers said. "That nitrate concentration, it's almost at the detection limit for nitrate nitrogen from that prairie system."

Why is prairie so effective? It starts growing earlier in the year, taking up nitrate that might otherwise be lost. It has a tighter nutrient cycle. The diverse root systems—some of them going six, eight, even ten feet deep—create this incredibly efficient system for capturing and using nitrogen.

The prairie they used wasn't just a big bluestem monoculture either. It was a local ecotype mix with maybe 30 species. And in the fertilized plots, they saw the C4 grasses—switchgrass, big bluestem, Indian grass—really take off.

The Real Crisis: We're Losing Our Soil

While nitrate loss gets a lot of attention, Dr. Helmers thinks we're not talking enough about soil erosion.

"We lose on average in the state of Iowa, about five tons of soil per acre per year. We generate about a half a ton per acre per year," he explained. "So we're mining our most important natural resource by a factor of ten to one."

Think about that ratio. We're losing soil ten times faster than nature can build it.

Sure, we've gotten really good at compensating for that loss. Genetics, inputs, technology—we've managed to maintain or even increase yields despite degraded soils. But at some point, that math doesn't work anymore.

"This is a pretty important natural resource that we have in the state of Iowa," Dr. Helmers said. "We could think about it a little more and have a bit more reverence for it because it's made Iowa what it is today."

And here's the beautiful thing: if you focus on practices that keep your soil in place, you're automatically addressing a lot of other issues. Biodiversity, water quality, even things like the nutrient density of the food we grow—it all starts with protecting the soil.

How Nitrogen Actually Moves Through the System

For anyone wondering how this all works mechanically, Dr. Helmers broke down the process.

When you knife in anhydrous ammonia in November, it sits in the soil as ammonium. As long as the soil is frozen, that nitrogen isn't going anywhere—frozen soil prevents water movement through the soil column.

But as soon as soils warm up, even when they're pretty cold, that ammonium starts converting to nitrate. The rate slows below 50 degrees, but it's still happening. Then when spring hits and soils get warm and moist, you see a lot of conversion from organic nitrogen into nitrate form.

If it gets wet, you can get denitrification—but only if the conditions are right. You need microbes and carbon. That's the whole concept behind saturated buffers: routing water through carbon-rich subsoil where denitrification can happen.

Cover crops help too. They actively take up nitrate in both fall and spring, reducing what's available to leach through the soil profile.

But row crops? They're what Dr. Helmers called "a leaky system." There's a mistiming between when nitrate is available in the soil and when the crop can actually use it. That window of vulnerability is when we lose nitrogen.

The Conservation Gap: We Need to Do More

Dr. Helmers was honest about where things stand. Cover crop adoption has grown—that's a success. But is it enough? Not even close.

"We wanna do more," he said. "We want more wetlands. We wanna do more prairie stuff. We need to do more of it."

The scale of change needed for Iowa's nutrient reduction strategy is "orders of magnitude" beyond what we're currently doing. It's going to take time. It's going to take dedication. And it's going to require people willing to work on it constantly.

But here's where the conversation took a hopeful turn.

Nicolas brought up something their boss Carol used to say: if you're going to be in the conservation business, you have to be an optimist. You have to celebrate the victories along the way, even when the overall goal feels overwhelming.

Dr. Helmers agreed. "I'm a believer that we can celebrate the good things that are happening while challenging that we need to do so much more."

He pointed to examples like the comeback of bald eagles in Iowa. Growing up in northwest Iowa, he never saw a bald eagle. Now they're common. Change is possible—it just takes time and dedicated effort.

And this year? Over 30 elk sightings in Iowa. Nobody's restocking elk—they're finding their way here because something is attracting them. The landscape is changing, bit by bit.

Practical Implications for Landowners

So what does all this mean if you're managing land in Iowa or the broader Midwest?

First, understand that tile drainage isn't the enemy. The issue is the cropping system and how we manage nutrients. You need to think about nutrient management across all your acres—tiled or not.

Second, consider what prairie can do. Those numbers don't lie: five pounds of nitrogen loss per acre versus 120 pounds is a massive difference. Even small prairie plantings, prairie strips, or restored corners of fields can make a real impact.

Third, focus on keeping your soil in place. The practices that prevent erosion—diverse rotations, cover crops, perennial systems—also address water quality, biodiversity, and long-term productivity.

At Hoksey Native Seeds, we've seen firsthand how prairie restoration can transform both the landscape and water quality. If you're thinking about adding prairie to your operation—whether as strips along waterways, around field edges, or as full restorations—we have locally-adapted seed mixes that can help you get started.

We're All in This Together

At the end of the podcast, Kent and Nicolas asked Dr. Helmers their traditional closing question: if you could snap your fingers and change one thing about the world, what would it be?

His answer got right to the heart of what conservation really requires.

"I think it's that we all realize we're in this together," he said. "People want to live in a state that they are proud of and enjoy. And I think there are more things that bring us together than tear us apart."

He's right. Most Iowans want cleaner water. Most farmers want to see thriving wildlife and healthy soils. We might have different views on how to get there, but we have more common ground than we realize.

"We need to focus on the need for agriculture and the need for more natural spaces," Dr. Helmers continued. "I think the better off we'd all be."

It's a both/and situation, not either/or. Iowa needs productive agriculture. Iowa also needs prairie, wetlands, and wild spaces. We can have both—but it's going to require some serious changes in how we think about land use.

The Path Forward

This conversation with Dr. Helmers reinforced something we talk about a lot on the Prairie Farm Podcast: conservation happens one mind at a time.

The data is clear. Prairie works. Cover crops help. We're losing soil at an unsustainable rate. The nitrate problem isn't just about tile—it's about the fundamental mismatch between annual cropping systems and nutrient cycling.

But we're also seeing progress. More farmers experimenting with different practices. More people asking questions. More willingness to try something new.

As Dr. Helmers said, we can celebrate what's happening while recognizing we need to do so much more. Those aren't contradictory positions—they're both necessary for the long game of conservation.

If you're a landowner, a farmer, or just someone who cares about Iowa's future, the question isn't whether we need to change. The question is: what role will you play in making it happen?

This blog post was inspired by an episode of the Prairie Farm Podcast featuring Dr. Matt Helmers. Listen to the full conversation for more insights on water quality, soil health, and conservation practices that actually work.

Ready to add prairie to your land? Whether you're looking at prairie strips for water quality or full restorations for wildlife habitat, Hoksey Native Seeds has the locally-adapted seed mixes and expertise to help you succeed.