A q-and-a on 'difficult tradeoffs' of nitrogen pollution

Nitrogen makes up three-fourths of the air around us. It is an essential part of all the proteins in our bodies and in all living organisms.

Food production – the vast gains achieved over the last century, and the still-greater gains needed to feed a growing world population — is dependent on the availability of nitrogen in a chemical form that food grains and other plants can readily use.

Instead of two nitrogen atoms bound together as they are in air, plants need nitrogen in which a single atom is available to bond with other elements.

Paradoxically, the synthetic manufacture and application of that plant-usable, single-atom nitrogen, the increased cultivation of soybeans and other legume plants that capture nitrogen from the air and the release of nitrogen in the burning of fossil fuels cause serious environmental problems.

A 2011 report to the U.S. Environmental Protection Agency said:

“Excess reactive nitrogen compounds in the environment are associated with many large-scale environmental concerns, including eutrophication of surface waters, toxic algae blooms, hypoxia, acid rain, nitrogen saturation in forests, and global warming. In addition, reactive nitrogen is associated with harmful human health effects caused by air pollution and drinking water contamination.”

Otto Doering

On Thursday, Oct. 4, 2012, the Freshwater Society and the University of  Minnesota College of Biological Sciences will sponsor a free public lecture on the excess nitrogen issue.

Otto Doering, a Purdue University agricultural economist who chaired the committee of scientists that wrote the 2011report to the EPA’s Science Advisory Committee, will deliver the lecture. His talk is titled Excess nitrogen: A Confounding Problem for Energy Use, Food Production, the Water We Drink and the Air We Breathe.

The lecture will be at 7 p.m. in the Student Center theater on the University of Minnesota’s St. Paul campus.

In the lecture, Doering will discuss the difficult choices the committee faced and that policy-makers will face for years to come.

“The overarching question,” the EPA committee chaired by Doering wrote, “is how do we protect and sustain ecosystems that provide multiple benefits to society while also providing the interconnected material, food and energy required by society?”

Millions of metric tons of reactive nitrogen introduced into the U.S. each year. The ‘natural’ category is nitrogen from plants on grasslands, rangelands and forests. The ‘cultivation’ category is nitrogen fixed by farmed legumes. Source: ‘Reactive Nitrogen in the United States: An Analysis of Inputs, Flows, Consequences and Management Options.’

The committee concluded that, as a first step, policy-makers and scientists should embark on a variety of agricultural and industrial efficiency measures that the committee said would allow crop production to continue increase while reducing the escape of excess nitrogen into the environment by 25 percent.

The Freshwater Society interviewed Doering about the nitrogen issue and the committee’s recommendations for addressing the water and air pollution problems. A transcript of that interview, edited for clarity and brevity, follows:

Very briefly, what’s your background?  Where did you grow up?  Where did you get your education?

I’m an agricultural economist, an applied economist.  We do a great deal more than just agriculture.  I grew up in the suburbs of New York City but was shipped every summer to Northern Wisconsin, where I lived on a farm while very young in one of the last counties without electricity. It was an unintended sustainable organic farming experience.

I went to Cornell University as an undergraduate.  I worked overseas for the Ford Foundation in their Economic and Agricultural Development programs.  I went back to Cornell, got a doctorate in agricultural economics and took my first job at Purdue University, and have been there ever since.

What kind of teaching and research do you focus on?

My original specialization was agricultural policy, but I’ve gotten involved more and more over the years in resource and environmental policy questions.  I was heavily involved in energy and biofuel concerns at the time of the first Arab oil embargo, during the Carter Administration. Recently I’ve been involved in assessments of cleaning up the Mississippi River in addition to a lot of water quality and environmental concerns and climate issues. I still get involved in farm bill issues, especially the conservation programs.

How did you, as an agricultural economist, come to chair this Integrated Nitrogen Committee?

I was really the token economist on the group. The people involved in the group were chemists, hydrologists, some agricultural specialists, people who worked with air chemistry, combustion engineers, biophysical scientists — particularly people like Jim Galloway, who worry about the nitrogen cascade.  I became chair because as leadership changed the rules required the chair be a member of the EPA’s Science Advisory Board, and I was the member.

Cover of August 2011 report to the EPA’s Science Advisory Board.

As simply as you can, explain the difference between the nitrogen that makes up most of the air we breathe and the reactive nitrogen that your committee’s research explored.

The air that we breathe is two atoms  of nitrogen that are bound together. That nitrogen is pretty happy in that form. It tends to stay in that form and doesn’t really cause much in the way of problems or give us advantages that nitrogen in other forms can give us.  If you apply energy to this combination of two nitrogen units, you can break it up and you could then have nitrogen oxides of various sorts. You can have N2O, you can have forms related to anhydrous. Nitrogen then becomes very active, morphing and combining in different forms.

It can morph into a form that is soluble, it can morph into a form that goes up into the air as a gas.  Reactive nitrogen combines in different ways, and it is very, very slippery to deal with.

Your report quotes the National Academy of Engineering as identifying management of the nitrogen cycle as one of the “grand challenges” facing the U.S. in the 21st Century.  Is that hyperbole, or is it reality?

I think it is reality in the long term.  The earth has absorptive capacity for a whole variety of things. Mother Nature adds nitrogen to the earth’s system through things like legumes that fix nitrogen. It also adds nitrogen when a bolt of lightning goes through the air—that’s energy—and disrupts that bond between the nitrogen atoms and puts nitrogen in a reactive form.

Mother Nature puts a certain amount of nitrogen into the system to help plants and other organisms.  With the Haber-Bosch process, which the Germans invented primarily for munitions and nitrate explosives at the time of the First World War, the United States now puts about five times as much nitrogen into our environment as  Mother Nature would. Other countries—Japan, parts of Europe—they’re putting substantially more in than that.

The real question, then, becomes: The nitrogen that is put into the system, that reactive nitrogen that is not used by plants or animals, what happens to it?  We know in the United States some of it goes down the Mississippi River and causes the Dead Zone. Some of it goes into the air and causes air pollution, which is a health problem. This is why there is that level of concern—we’re putting so much more into the system than Mother Nature does or can deal with.

Do you think scientists, or people generally, share this view that nitrogen is this kind of pressing issue?

No, I think it’s something that is not seen as a pressing problem. I think most people are a little bit weary of nature- related problems but, unfortunately, I think both climate change and nitrogen are, in fact, problems of very large magnitude.

Talk about the sources of this reactive nitrogen in our environment, and try to quantify them a little bit, at least as a percentage.

Most of it comes from the Haber-Bosch process. The big, 800-pound gorilla that we have in terms of nitrogen going into the ecosystem in the United States is agriculture.  Some of that gets into the system through fertilizers, which is obvious. Some of it gets into the system from soybeans, leguminous plants that we plant and cultivate.  More than half is from Haber-Bosch.

What about industry and transportation?
Transportation and industry, between them, make up probably a bit less than a sixth of the total amount, about the same as Mother Nature’s own biological nitrogen fixation.  Stationary power plants–stationary being industry and coal-powered plants, these sorts of things—are about half the magnitude of transportation.

This is sort of a qualitative question–what would this country and the world look like and be like if the Haber-Bosch method of manufacturing nitrogen had never been invented?

What I think we would miss is the level of food production we have now, where we are getting more than half the nitrogen for a corn crop, for example, directly from the Haber-Bosch process.  The main issue in terms of Haber-Bosch today for us is, without it, would we be able to maintain the level of food production we have? I think my answer to that is, no.

So, without it, would we have a dramatically smaller and hungrier world population?

Yes, I believe we would. That is the very, very difficult trade-off we deal with when we talk about trying to better manage or limit excess nitrogen.  The efficiency of our corn plant and the way we apply fertilizer is such that about a quarter to a third of it is actually used by the corn plant. The rest is excess. So how do we cut down the excess without cutting back on what the plant can utilize to produce more grain?

Now that we have this artificial nitrogen, what are the human health impacts?

Health impacts run the gamut, and this depends upon where you are geographically. In the Midwest, the greatest health impact from excess nitrogen probably comes through water pollution and problems with water quality.  If you go to the Chesapeake Bay, the greatest health problem from nitrogen is airborne nitrous oxide and the extent to which nitrogen influences ozone creation and serious respiratory problems that can come from reactive nitrogen in the gaseous form.

I want to ask you about environmental impacts, and please touch on impacts on both surface and ground water.

In terms of groundwater, it is dependent upon what the particular geological structure is where you have excess nitrogen at the surface.  In some cases, the transfer between surface water and groundwater is fast enough that you can, in fact, have groundwater problems as a result of surface excess reactive nitrogen.  Most of the problem is going to appear with respect to water in terms of surface situations.

If you look at a freshwater lake or stream and an algae bloom there, that is probably phosphorous, because our surface water inland is really short of phosphorous. So when they get a little bit of extra phosphorous,  those algae can go to town.  Where excess nitrogen in surface waters really plays is when you’re talking about salt water or estuaries that are nitrogen-limiting for algae and other small forms of life. There  the nitrogen can cause algae blooms and the dead zones that we see in the Gulf of Mexico.

You’ve touched on this a little bit, but your committee’s report says  the “overarching question” about excess nitrogen is:  “How do we protect and sustain ecosystems that provide multiple benefits to society, while also providing the interconnected material, food and energy required by society?”  Explain that, please.

The answer to the question is incredibly difficult because what we’re looking at is trade-offs. Unfortunately, there are all these trade-offs. If we go ahead and say: “All right, we’ve just got to cut down excess nitrogen across the world, across all systems, have less nitrogen coming out of transportation, industry, fertilizer” — that’s fine, we can do that, we can reduce excess nitrogen.

Then the question is: Are we reducing excess nitrogen to the point, for example with fertilizer, where we’re not getting the yields we need to sustain even the world’s current population of 7 billion, let alone 9 billion. If we cut back on fossil fuel combustion, are we then having the amount of transportation or the amount of electricity, or other energy services that we need?

We’re talking about a very difficult management job to do this in a way where we can continue to get needed services from nitrogen — nitrogen gives us services — and cut back on the amount of damage that excess nitrogen does.

Can we say how much human-introduced nitrogen the U.S. can reasonably tolerate and how much we need to reduce?

Well, we can say but I’m not sure we’re right.  The EPA a few years ago put out a report that basically said, in order to make a significant reduction in the Dead  Zone in the Gulf, we would have to reduce the excess nitrogen going down the Mississippi River by 40 percent or more.

My personal judgment is that is not something that is doable in a very short term.  In our EPA report, we suggested we set a goal of reduction of about 25 percent, which we feel we can do with current technology, as a start.  What we need to do is try various things that we think will reduce excess nitrogen and see if these efforts actually work, which ones work best, which ones are least expensive.

What we did was urge that people start the process now; don’t set unrealistic goals.  We feel 25 percent would be realistic over the next decade or so with current technology.

Your recommendations include a lot of changes in the way agriculture is practiced: Restoring wetlands, cutting nitrogen losses releases  from manure by 30 percent and—the biggest change—increasing crop yields while, at the same time, reducing applications of nitrogen fertilizer by 20 percent.  Is that doable?  What would be the costs for farmers and for consumers?

We think it’s doable over the coming decade.  One of the keys here is increasing the nutrient efficiency of the plant and of the cropping system.  We now know that some plants are better than others at pulling in nutrients from the soil. This is something we need to work on a great deal more.

The fertilizer industry is beginning to talk seriously about encapsulating dry fertilizer like a slow-release pill, so that it is released at the time the plant needs it.  We think we can do some of these things.

If you think of an agricultural system, you put nitrogen on a corn plant and some of that nitrogen goes to the animals, and the animals use that nitrogen, and some of that ends up in manure. Can we be sure that a higher proportion of nitrogen we put on the soil for the plant is used by the plant? Can we effectively get most of the nitrogen from that grain into the animal when and where the animal needs it, and then, have an animal that is efficient in utilizing that nitrogen, and beyond that, take the excess nitrogen from the manure and get it back into the cycle again?

The second part of that last question is what would be the cost to farmers, and to consumers?

We don’t really know what the cost would be to farmers or to food prices in terms of increasing nitrogen use efficiency, reducing excess nitrogen.  Our group was fairly well convinced that there is some low-hanging fruit out there that is not terribly high-cost.

There was some work done a little over a decade ago where we looked more specifically at this cost area. We basically determined that we thought we could get a 20-25 percent  reduction in excess nitrogen within the agricultural system.  The impact on crop prices would not be greater than the historic variability that had occurred in crop prices over the previous decade.  Now, in those days we did not have $8 corn and $16-$17 soybeans, so we’re talking a narrower range in variability.

Economically, we think it’s doable and we think it’s something within the normal cycling of food prices and farm income.

You’re saying that we can achieve an overall 25 percent reduction in current nitrogen production without significant changes in people’s lifestyles.  Is that correct, and do we need a bigger reduction?

The answer to the second question is, yes, we probably need a bigger reduction.  One reason we picked the 25 percent  goal is, No. 1, we felt it was attainable, and, No. 2, in the best of our judgment, after spending a lot of time in sessions with people from the agricultural industry, the transportation industry, and the public utility industry, we believe this can be done at a cost level that would not be disruptive to people or to the national economy.

Any final thoughts?

No, that’s about it.

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