Numlock Sunday: Joy Mazur on the unexpected consequences of an agriculture breakthrough

Photo by Ashwini Chaudhary(Monty) on Unsplash

By Walt Hickey

Welcome to the Numlock Sunday edition.

This week, I spoke to Joy Mazur, who wrote “‘We should have a sense of urgency’: Drainage tile drives nutrient pollution” for The Lens. Here's what I wrote about it:

To increase crop yields, many farmers use agricultural drainage tile, a pipe system that is present across 50 million acres in the U.S., the vast majority of which (84 percent) are in the upper Midwest. The reason for their installation — at $1,850 to $3,700 per acre — is that annual crop yields go up between 5 percent and 25 percent as a result, diverting excess water out from the soil. The problem, though, is that it speeds up the movement of water that’s contaminated with fertilizers into waterways, without giving it time to filter through soil en route to a culvert. As it stands, 98 percent of drainage tile is in watersheds with excess nitrate and phosphorus levels, as a raindrop that would take a decade to get to a waterway can now be swiftly diverted there, contaminants and all, within hours.

This story was fascinating, highlighting a somewhat obscure-to-many agricultural practice and the unintended side effect it can have thousands of miles away. It’s a fascinating look at how complex water systems can be, and how a clever drainage solution can have deeply unexpected consequences

We spoke about the pros and cons of drainage tile systems, some conservation drainage alternatives, and the current lack of regulation.

Mazur can be found on X and LinkedIn.

This interview has been condensed and edited.

Joy, thank you so much for coming on.

Absolutely, thank you for having me.

I was really, really into your story. It was a fascinating look into a very underground issue, quite literally. I'll just take a few steps back here and ask you, what is agricultural drainage tile and why should folks care about it?

Agricultural drainage tile is essentially this subsurface river system. It's a pipe system that farmers generally implement because it increases crop yields by keeping crops from getting waterlogged, especially when it rains. It takes out all of that excess water, brings it down into the soil, and brings it out through the pipes into a nearby waterway or stream. We kind of imagined it as this metaphor, this subsurface river system, that we used a lot, my editors and I, in writing and editing the story.

The reason people should care about it is because we have a huge nutrient pollution problem, especially in the Mississippi River Basin, which is where our outlet is centered. Nutrient pollution, specifically excess nitrogen and phosphorus, in our waterways can cause water quality issues for drinking water as well as just for the environment. It also creates a huge dead zone in the Gulf of Mexico, because the nutrient pollution goes through the Mississippi River down into the Gulf of Mexico, and creates this essentially massive area where there's little to no oxygen in the water. A lot of animals and organisms either leave the area or sometimes die, if there's not enough oxygen.

This just creates huge problems for everything that relies on water in our environment, and drainage tile helps shoot all that excess — all those excess nutrients, nitrogen, phosphorus — and basically streamline it directly into our waterways faster than would happen normally.

This was such an interesting side effect of a fairly basic mod to the territory of a farm. What are the incentives for farmers here? There seems to be a pretty substantial cost that you wrote about for getting this stuff in, so why do farmers do this in the first place? What does it help them?

Absolutely. Like I said, it helps significantly improve crop yields, especially in areas where there might be extra rainfall or extra water clogging up the plants and the soil. One farmer that I talked to used this analogy that before he put in drainage tile, his field looked like it had chicken pox, because there would just be these little puddles of water everywhere and in those areas the crops could not grow, they would die.

So one of the main drivers is that they do increase crop yields by taking out that excess water, allowing the plants and their roots to breathe, and obviously that's a super big incentive. Farmers are, just like the rest of us, trying to make money, and it helps them put a little more in the ground sometimes. I think some of the estimates were that they can increase annual crop yields by 5 percent to 25 percent, and they're generally not super expensive per acre, so those are pretty much the main incentives.

There are also some different kinds of incentives depending on the drainage tile system. It could sometimes help with soil erosion, that sort of thing. But the main thing is that they increase crop yields very significantly.

And 5 percent to 25 percent is not nothing, right? That's a pretty substantial increase.

Yeah. I know if that was my income, hey, I get it.

You had an amazing stat in here that said a raindrop that would ordinarily take a decade to get to a waterway can be delivered within hours.

Right. One of my sources, and one that the desk talks to a lot, is Chris Jones. He is a retired hydrologist, worked at the University of Iowa, and just really knows his stuff. He shed some great light on that issue, and yeah, it just goes straight into the waterway. I know one of the sources I talked to from the USGS said that it's basically a direct shot into our streams now.

So that basically gets in the way of the natural filtering properties of soil? How does that work?

It does change the natural hydrology. Not being a scientist myself, I can't get too much into the nitty-gritty, but it does change the natural hydrology of an environment when you input a tile like that. Essentially, it would usually take longer for some of that excess water to soak into the soil, or it would just remain in the same place and be a puddle of standing water, perhaps. Or it would just take much longer to go over the surface or under the surface into waterways and streams nearby.

You can imagine it’s like — well, I don't want to use the analogy of like a toilet, but if you're flushing water down the toilet, or you're putting water down your sink, it's kind of like that. It's just sucking the water right out and then directly into the waterway.

Fascinating. So clearly it's a bit of an issue; is there a solution here? Is there a way to address this? What are the hopes of some of the folks that you spoke to about this?

That's where things get quite tricky. Some people do propose conservation drainage. A lot of researchers are turning their eye toward researching how conservation drainage can help, in what ways it can help, how we can implement it, and so on.

There are different technologies that can be used. One is a bioreactor, which is kind of this trench filled with wood chips that take nitrogen out of water from drainage tile. People also sometimes plant these vegetation buffers around their fields, so the water filters through shrubbery that takes out the extra nitrate going into streams. There have been studies that suggest conservation methods are the best way to reduce excess runoff. A lot of research indicates that you should, for the best results, be stacking conservation methods.

There's no silver bullet. You just have to look at what you have, look at your different geography and ecology, see what's best for that and use different methods on different fields, and that sort of thing.

However, other places aren't as sold on conservation. There are a lot of other people that think the farming system as a whole just needs to be changed, what we farm needs to be changed, and we should be having more diverse cropping. A lot of people are concerned with the resources and the costs, especially of conservation methods. They're more costly. They also take a while to implement. I know one source I talked to said that through the NRCS, which is what farmers would have to go through to get some of these conservation methods, it would take about a year to implement these things.

Sometimes that's not what farmers want to pursue when you have those barriers. It makes it hard to want to do that. So, there are some conservation methods, but there's a lot of nuance behind that, basically, as far as solutions go.

Fascinating. Anything else that you learned over the course of reporting the story that you think people ought to know?

Oh, there are a lot of other things that I didn't even include. The original story ended up being super long and I had to cut back.

There was a lot of regulation nuance behind this story. There's really no federal regulation that manages drainage tile in any way. Most states don't really have the resources to manage drainage tile, and they don't have laws surrounding it. Drainage tile is just put in; it's not really monitored.

It was really interesting to me in this current climate we have. The EPA has goals to reduce nutrient pollution in our river basin and in the Gulf of Mexico, and they want to reduce the dead zone, but this thing that is a big contributor to putting extra nitrogen and phosphorus into our waterways is not really regulated or kept track of super precisely. That was a really interesting part.

Obviously, it would be very hard to keep track of. That was also a challenge to writing the story, was trying to figure out if states regulate it, how they regulate it. The answer largely being that they don’t.

It’s always so interesting to see the classic butterfly effect, when a decision made at a farm in Wisconsin can have drastic effects by the time the water gets to Louisiana.

Right. And it's a whole amalgamation, when everybody is doing that and drainage tile is increasing. Obviously there are a lot of other factors that come into play. Synthetic fertilizer, for example, introduces a lot of excess nitrogen and phosphorus into our waterways as well, and then if it goes through the drainage tile, it just gets shot into the streams. It's a huge stack up of factors.

All right. Thank you so much for your time. I really appreciate it.

Where can folks find you and where can they find your work? This seemed to be a bit of a one-off piece that you did with these folks, but where can people find your journalism?

That's a great question. I'm pretty early in my career, so it’s a transitory period of my life. But on Twitter, my handle is @JoyAMazur, and my name is Joy Mazur on LinkedIn. That's where I promote a lot of my work currently, but I'm not officially with any outlet as of this moment.

Excellent. I look forward to reading more from you.

Thank you.

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Edited by Susie Stark.

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