Pollinator Week: Its History & Why it Still Matters

by Katelyn Rinicker | May 28, 2026

History

Pollinator Week was started by and is managed by Pollinator Partnership. In 2008, the U.S. Senate’s unanimous approval and designation of a week in June as “National Pollinator Week” marked an essential step forward in pollinator conservation.

Pollinator Week has now grown into an international celebration, including Canada, Mexico, and some countries in Europe! This event promotes the valuable ecosystem services, like pollinating the 87% of flowers that require assistance, provided by bees, birds, butterflies, bats, beetles, moths, wasps, and flies.

People can participate and help raise awareness about the importance of pollinators by hosting an activity during Pollinator Week. Many have already pledged to Pollinator Partnership to continue promoting pollinator health.

“Through the numerous virtual and in-person gatherings, webinars, planting sessions, garden and farm walks, and monument lightings, Pollinator Week 2026 is geared to be the busiest and best one yet!” – Pollinator Partnership

Why it’s Still Important

Pollinator Week is still incredibly important to pollinator conservation. It highlights the role that bees, butterflies, and other insects play in our food systems and everyday lives. Not only are they beautiful creatures, they also contribute 100s of billions of dollars globally every year by pollinating our food crops. This week is filled with educational events and is full of advocating for wildlife.

Historic Youngville Cafe Along Lincoln Highway National Heritage Byway

There are many ways to get involved!

Many of these events and activities are family-friendly and made for young and old alike. Everyone is invited to participate.

Online

Vote for pollinator-friendly policies
Tell your pollinator stories on social media using #PollinatorWeek
Highlight pollinators on your blog
Register your pollinator habitat
Attend an educational webinar
Screen a pollinator film
- Pollinators Under Pressure

At Home

Plant native plants
- Pollinator Friendly Ames has some great resources for planning
Sign the Pesticide Pledge by Good Neighbor Iowa
Provide clean water sources
- How to Guide
Host/Join a nature walk
Build a bee house
- Guide by Michigan State
Turn off your outdoor lights at night for nocturnal polliantors
Leave your leaves for overwintering pollinators

Use Your Dollars

Prairie Rivers of Iowa
- Donation
- Store
Xerces Society
- Donation
- Store
Pollinator Partnership
- Donation
- Store
Monarch Joint Venture
- Donation
- Store

Frequent Fliers: Birds on the Move

by Kristine Micheletti | May 7, 2026

This is perhaps my favorite time of year! Flowers are blooming. Trees are getting their leaves back. The weather is getting nicer. Animals are emerging. And one of my favorite things…the birds are back! I absolutely love waking up in the morning to the birds chirping.

Millions of birds are making the lengthy journey from their wintering areas to their summer nesting grounds. Some may choose to stop here and make Iowa their summer home. Others though, may be traveling as far as northern Canada and the subarctic! Sometimes they may even be flying from as far away as South America!

This is an exciting time of year for anyone who is interested in our avian friends. The Cornell Lab BirdCast estimated nearly 1.5 million birds flew over Iowa in a single night, and nearly 207 million flew over the United States on the same night, April 29-30!

Iowa is located along the Mississippi River flyway, a migration highway for birds that extends from Canada to the Gulf of Mexico. Iowa’s variety of habitats, including forests, wetlands, prairies, and agricultural land provide an array of resources for the migrating birds to rest and refuel. Saylorville Reservoir, Rathbun Lake, and Neal Smith National Wildlife Refuge are all major stopovers along the route. You may have noticed American White Pelicans along the waterways or songbirds like Baltimore Orioles near homes and parks recently. These are just two of the hundreds of species that either migrate through or call Iowa home every year.

(American White Pelican, Cornell Lab)

(Baltimore Oriole, Cornell Lab)

Migration is not only exciting, but also important. Birds play an essential role in pollination, seed dispersal, and pest control. Without birds, our ecosystems would not be the same. The Ruby-throated Hummingbird is Iowa’s only bird pollinator, and you might even be able to catch a glimpse flitting around your feeders and flower gardens. The Northern Cardinal, perhaps one of Iowa’s most recognizable birds, is just one of many avian species that eat fruit and seeds and help disperse those seeds by passing them through their digestive system intact. Other birds, like the Black-capped Chickadee, may cache seeds for later. Some birds, like Northern House Wrens, eat insects, which can help control pest populations.

(Ruby-throated Hummingbird, Cornell Lab)

Despite the beauty and importance of our avian friends, bird populations across North America are declining rapidly, with reports of up to 3 billion birds lost since 1970. Some contributing factors include habitat loss, outdoor cats, collisions with windows, and pesticides. Many of these same factors are also contributing to the decline of other species, like pollinators.

There is hope though! You can help birds in several ways. One way is by enhancing bird habitat through acts like establishing a Conservation Reserve Program (CRP), creating a habitat for pollinators, or
planting or keeping trees. Planting native plants and trees will not only help our pollinator friends like butterflies, bees, and other insects, but will also help provide food and shelter for birds that rely on those
resources. If you have ever experienced a bird hitting your window, they might be seeing the reflections of vegetation or the sky, or they might be seeing house plants through the glass. Installing mosquito screens on the outside of the window or putting decals, stickers, sun catchers, or even sticky notes on your window can help reduce bird collisions.

There are many resources available for those of us that are interested in birds, and if you’re anything like me, they might be some of your favorite apps or resources, especially this time of year.

Check out a few of them below!

Iowa Women In Conservation

by Katelyn Rinicker | Mar 30, 2026

March is not only Iowa History Month, but also Women’s History Month!

While women have not always had recognition for their efforts, they have been involved.

Ada Hayden, 1884 – 1950

Photo from the Ada Hayden Collection, Iowa State University Library Digital Collections

One of the most well-known women in Iowa Conservation, Ada Hayden, was born in 1884 and grew up on a farm as an only child. Her home was in Franklin Township in Story County. She attended Iowa State College, which was later renamed Iowa State University. In 1908, she received a bachelor’s degree in botany. After receiving her master’s in botany from Washington University in 1910, she moved back home and worked toward getting her Ph.D from Iowa State College. In 1918, she was the 1st woman and 4th person overall to recieve a doctorate from ISU.

This was only the beginning of her passion for prairie. After her Ph.D, she worked as an assistant botany professor at ISU. In 1934, she became the curator of the herbarium on campus. She concentrated on prairie plants and is said to have created “possibly the best published native flora survey… of any part of Iowa”. She added over 14,000 specimens to the herbarium, many of which were from her family land.

In the 1940’s she began focusing more on prairie preservation. This however, is far from the first time that she thought about saving prairie. In 1919, she wrote an article about the importance of setting aside prairie for permanent preservation and research. She believed that prairie preserves serve as a living museum and field lab for scientists. In 1944 she helped write a report identifying areas of perservable prairie in Iowa.

In 1950, at the age of 65, she died of cancer. Today, there is a beautiful prairie and park in Ames, IA, named after her.

Herma Albertson Baggley, 1896 – 1981

Herma was born in Inwood, Iowa, on October 11th, 1896. She attended the University of Idaho and, while there, received her bachelor’s in botany with a minor in philosophy in 1921 and a master’s in botany in 1929. Over the summer in 1929 and 1930, she worked at Yellowstone National Park, giving talks about Old Faithful. Her entertaining and informative talks would draw in hundreds of people. Because of these talks, in 1931, she became the first woman to become a full-time naturalist with the National Parks Service. She helped design the first trail to Old Faithful, and in her 7 years as a naturalist, she wrote over 20 articles and coauthored Plants of Yellowstone National Park with Walter B McDougal. She also advocated for better living conditions for Park empluees and their families. She argued that improved housing and more benefits would help recruit better-qualified staff.

Kathryn “Kitty” Hach-Darrow, 1922 – 2020

Kathryn_Hach-Darrow_by science history institute under CC SA 3.0

While not Iowa-born, Kitty did a lot of good work in Iowa. While attending Iowa State University, she met her husband, Clifford C. Hach, and they married in 1943. While working in a water treatment plant, Clifford had the idea for a simplified method of analysis that would allow workers to treat water with powdered formulas rather than the heavy chemical solutions they were using. In 1947, they co-founded the Hach Chemical Company based on this idea. They bought an acre of land in Ames, IA, to build their plant on. They also lived in an apartment on the plant with their 3 children.

As municipal standards for drinking water evolved, Kitty recognized the importance of water plant operators as a market and the need to work closely with them to provide long-term customer service. This drive for excellent service led to her creating a direct mail marketing campaign where she flew a plane with product directly to municipalities of all sizes. While operating this campaign, she flew over 7,000 hrs and became a part of the Ninety-Nines, an international group of women pilots.

In 1957, the Hachs won the American Water Works George Warren Fuller Award for distinguished service in the water supply field. In 1978, they moved their headquarters to Loveland, CO.

Kitty was known as an accomplished pilot and one of the top women business owners. She was also the first woman director of an international non-profit focused on better water quality, the American Water Works Association. Afterward she served on many AWWA committees, including the President’s Advisory Council.

These are only a handful of intelligent, caring, and passionate women who have helped shape today’s conservation. Without them and many others, we may not be where we are today. So thank you to the women of the past, who have paved the way for others. Without your struggle, roughly half of the population would not have the choice to be naturalists or conservationists.

The 2026 Impaired Waters List

by Dan Haug | Mar 2, 2026

Cyanobacteria bloom in Lake Darling, July 2024

Updated March 26

A draft of Iowa’s 2026 impaired waters list was released for public comments in March. In our comments, we raised some concerns about how data gets ignored or misinterpreted.

On St. Patrick’s Day, I gave a talk for the Izaak Walton League explaining why lakes and rivers turn green and how the assessment process works and why so many waters get stuck on the impaired list. Here is a recording.

Update on nitrate and drinking water

The last time the Iowa DNR submitted a list of impaired waters to the EPA, there was a dispute about six stretches of river that supply drinking water to Des Moines, Cedar Rapids, Iowa City, and Ottumwa, and used to supply water to Oskaloosa. The DNR claimed that the drinking water standard for nitrate should be evaluated using a 10% threshold, but even with this interpretation, two of the rivers failed to meet the standard this time. This chart shows what all the fuss is about.

The Goose Excuse Bill

Ioway Creek in Ames and West Indian Creek in Nevada have very high levels of E. coli, but aren’t on the impaired list because of a state law which limits how the DNR can use our data. They would have been joined on the Waters in Need of Further Investigation list by hundreds more rivers if the legislature passed House File 2530:

An Act requiring the Department of Natural Resources to identify specific animal sources of pollutants to a water of the state when determining the water’s inclusion on a list of impaired waters.

Thankfully, the bill did not make it through the second funnel. While it’s useful to know where bacteria is coming from, DNA testing is expensive and should be done after a problem has been identified.

Finding clean waters

I am sometimes asked where to go in Iowa to find clean water for paddling, swimming, floating in an inner tube, or just letting the kids splash and catch crayfish in the creek. A map or list of impaired waters is not very helpful for this, because the waters that aren’t included might be clean, or they might not have been assessed. So I made an interactive map, color-coded to show which lakes and rivers met or exceeded the primary and secondary contact recreation standards, in the last four recreational seasons.

The Fine Print

If you explore the Impaired Waters List and the rest of the assessment database, you will likely run across some things that don’t make sense. I share your frustration! This pair of short videos from our “Clean Water Act: 50 Years, 50 Facts” series contrasts how Section 305(b) and 303(d) of the Clean Water Act should work in theory, and how it can go wrong in practice. However, I continue to see improvements in the assessment database (ADBNet) and water quality database (AQuIA) and want to express my appreciation to IDNR for the data they collect and their efforts to be make it available to the public.

Lost Lakes and Found Lakes

by Dan Haug | Mar 2, 2026

March is Iowa history month and that’s a good opportunity to dust off some material from the archives to share the history of lakes in Iowa, some lost and some found.

Iowa has just 34 natural lakes remaining, most of them located in northern and central Iowa, which was covered by the last advance of ice sheets 12,000 to 14,000 years ago. The examples I will use are from Hamilton County, where naturalist Thomas MacBride had this to say:

“None of the lakes hereabout are very deep. They are all marsh-like, only distinguished from a thousand marshes by the courtesy of the pioneer who called them lakes to suit his fancy, recognizing their greater width and possibly, in some cases their bluffy shores.”
-Thomas H. MacBride, Geology of Hamilton and Wright Counties (1910)

1875 Andreas atlas, showing lakes in Hamilton County

Residents of Hamilton County should recognize one of the lakes on this 1875 map. Little Wall Lake is a popular spot for swimming, fishing, and motor-boating. At 249 acres, it’s plenty big enough to call a lake but only deeper than a marsh because of regular dredging. The lovely cabins for rent from Hamilton County Conservation were built from Iowa-sourced white oak logs as part of a Prairie Rivers of Iowa forestry and economic development project in 2013!

water sports on Little Wall lake in 2014

However, the 1,300 acre Lake Cairo and 870 acre Iowa Lake disappeared shortly after A.T. Andreas’s atlas was made. You can still see the shoreline of Lake Cairo on LiDAR, as well as the ditches (Rahto Branch and Ditch 71) built to drain it. Lost Lake Farm, a dairy located on the north “shore”, is named as a nod to that history. They employ rotationally managed grazing practices that build soils and protect water. I got to see this in action as part of Watershed Management Authority field trip in 2018; here’s a photo of the cows making a beeline for the tall grass after the fences are moved!

The scale of the drainage work is impressive, especially given the technology available at the time, and was just one of many such alterations that built up Iowa’s agricultural economy. In this case it made farmable over 1000 acres of Blue Earth muck loams with a corn suitability rating of 63 to 66. However, even at the time, there were disputes about how to balance public and private interests. To learn more about the history of drainage, I recommend a presentation by Joe Otto, recorded on Iowa Learning Farms.

The balance shifted as cropland became abundant and natural areas became scarce. In 1920 (partly at the urging of Thomas MacBride, quoted above) Backbone was dedicated as Iowa’s first state park. The Civilian Conservation Corps built a low dam on the Maquoketa River to form Backbone Lake in the 1930s and since then over 100 other lakes have been created in Iowa for public use by damming streams or by digging quarries and borrow pits.

In 1919, Iowa’s first county park was established in Hamilton County, not far from Lake Cairo, and Briggs’ Woods Lake was created sometime in the late ’60s by damming Terwilliger Creek. There are some more log cabins at this park, also built with the help of my former colleague Mike Brandrup. The porch is a good place to watch the lake and reflect on the complicated history of Iowa’s land and water!

A boy catches a bass at Briggs Woods Lake.

Mike Brandrup at a wetland restoration field day

Nitrate testing tips for cold weather

by Dan Haug | Feb 25, 2026

For the past few months, Rick and Dan have been dipping nitrate test strips when we collect water samples for the lab. We have confirmed that the reaction is temperature-sensitive, causing nitrate test strips to under-estimate nitrate concentrations in winter.

Accuracy can be improved by testing a water sample in a warm car, or by allowing an extra 30-60 seconds for the color change, but for best results, follow Heather Wilson’s advice, reprinted below:

“Hach (the manufacturer of the test strips included in your Nitrate Watch kit) says that sampling will be most accurate when the sample temperature is between 20 and 25° C (68 to 77° F). These ideal temperatures are easy to obtain indoors, but much more uncommon outside.

If you are concerned about cold weather impacting your nitrate readings, we recommend collecting your sample in a clean container and allowing the water to come to room temperature before taking your nitrate reading. Make sure to rinse the container three times with water from the water source you are sampling to ensure that no residual water from past samples remains.”

-Heather Wilson, Midwest Save Our Streams Coordinator, Izaak Walton League

End the No Swim Era

by Dan Haug | Jan 28, 2026

Warning sign posted at beach for water quality advisory

The Driftless Water Defenders launched a social media campaign last summer calling for the end of Iowa’s #NoSwimEra. It’s a catchy slogan, and timely. 2025 was an especially bad year for recreational water quality. The Iowa DNR tests for E. coli (an indicator of poop in the water) and microcystin (a toxin produced by algae) at 41 beaches at state parks, every week between Memorial Day and Labor Day. If you had picked a beach and weekend at random for a family outing, there is a 1 in 4 chance you would have encountered a “Swimming Not Recommended” sign when you got there. Over the past 25 years, the number of microcystin advisories has fallen but the number of E. coli advisories and the number of beaches affected has increased.

Iowa’s water quality problems aren’t unique, but they are a lot worse than some of our neighbors. I analyzed 2025 E. coli data from Wisconsin beaches and found that 11% of the water samples had high enough E. coli levels to trigger an advisory (235 CFU/100mL), versus 24% in Iowa. 3% of Wisconsin beaches had average E. coli levels high enough to violate water quality standards (a seasonal geometric mean of at least 126 CFU/100mL), versus 25% of Iowa beaches.

Some of the advisories are posted at lakes where there has already been a lot of public funding invested in lake restoration and in voluntary soil conservation projects in the watershed, so don’t think we can solve this problem with more of the same. At Lake Darling, the work seems to have been undone by an expansion of the hog industry. At the Lake of Three Fires, the work seems to have been undone by conversion of pasture to cropland, motivated by the Renewable Fuel Standard. We need to take a hard look at how state and federal policies allow or even encourage farming practices that foul our lakes.

However, I follow the data where it leads, and it doesn’t always lead to a hog barn. Here is my latest summary of E. coli data collected by the water monitoring program in Story County. Hickory Grove Lake has been well-studied by the DNR, and both DNA markers and transects point to Canada geese on the beach, not livestock in the watershed. College Creek is usually our worst stream on days when it’s flowing, and it has an urban watershed. A large fraction of the bacteria in West Indian Creek came from an old sewage treatment plant that was just replaced this year. DNA testing of water from Ioway Creek showed that human waste is present. We’ll be doing more testing in 2026 to confirm this and narrow down the sources, including a volunteer event in early summer. Donations also help support our monitoring and education efforts!

2 page handout summarizing E. coli in Story County

Some people are afraid to dip a toe in any lake or river in Iowa, and their No Swim Era goes back decades. That’s a shame. Even in a bad year, it’s possible to find clean water for recreation. For example, I took my daughter and her friend swimming and paddleboarding at Peterson Park, a Story County-owned beach where E. coli counts never exceeded the double digits. I joined Iowa Project A.W.A.R.E. to canoe and clean up trash on some scenic stretches of the Upper Cedar and Shell Rock Rivers, which averaged 69 and 45 CFU/100mL for the season–the standard is 126. I’ve updated this interactive map to help you find others.

The new Currents of Change report has some good tips for minimizing your risk of a waterborne illness when recreating in waters of poor or unknown quality. I regularly go in Ioway Creek, which I know to have poor water quality, but pack hand sanitizer and do my best to keep my head above water. I dunked my head in the Winnebago River (which was muddy and hadn’t been tested recently) multiple times during a whitewater kayaking class, but wore nose clips. I stay out of green water but otherwise am comfortable with a certain amount of risk to be able to enjoy the outdoors. But that’s just making the best of a bad situation. No Swim advisories have gotten way too common, and we need to work together to clean up our water and end that era!

Infographic from CISWRA report with recreational safety tips

How bad was nitrate in 2025?

by Dan Haug | Jan 6, 2026

When the ball dropped on New Year’s Eve, nitrate in the Raccoon River was once again above the drinking water standard, closing out a bad year for water quality in Iowa. Below, I’ve compared this year’s nitrate levels to long-term averages at sites in Iowa DNR’s Ambient Stream Network with at least 20 years of data to get a sense for where and when nitrate was highest and what was unusual about 2025.

To understand these patterns, it’s important to remember that 2025 was not a uniformly wet year. Heavy rains in July broke or came near to breaking some records and caused flash flooding in many communities. These rains also raised the water table enough to keep drainage tiles flowing into into the fall. However, most of the state received less than average rainfall from January through May and from August through December. In a band from Ames to Charles City, that works out to a much wetter year than normal. In other parts of the state, like Dubuque, Ottumwa, and Red Oak, that works out to a much drier year than normal.

Nitrate was much higher than normal in the Boone River, Skunk River, and many others in northern and central Iowa, especially in July and August. Nitrate was within 1 mg/L of the long-term average for the Nishnabotna and other rivers in southern Iowa and for the Rock and Floyd Rivers in northwest Iowa. In the table below, red indicates nitrate was higher than average, blue is lower than average, and white is close to the long-term average.

There are some unusually high readings (25 mg/L in the South Skunk River in January) and unusually low readings (3.3 mg/L at Beaver Creek In July) that may have been collected during a storm or other event that is not representative. This is a limitation of monthly grab samples and one reason why maintaining Iowa’s network of real-time nitrate sensors is important. The Ioway Creek sensor was removed at the end of 2024, but the pattern I documented here here (a quick flush of low nitrate surface runoff followed by a gradual release of high nitrate drainage water) happened over and over, in many places in 2025. These kinds of leaks can be avoided with changes in cropping systems and land use, reduced with better nutrient management and cover crops, or intercepted and treated with saturated buffers and wetlands, but we’ll need a lot more of them to prevent another bad year like 2025.

A Year Later, Where Does the Monarch Butterfly Stand with its Listing Under the Endangered Species Act?

by Katelyn Rinicker | Jan 5, 2026

In December of 2024, the U.S. Fish and Wildlife Service (USFWS) proposed adding the monarch butterfly (Danaus plexippus) to the threatened species list under the Endangered Species Act (ESA). You can read their press release here. As part of the proposal, the agency also introduced a proposed 4(d) rule and a critical habitat designation focused on key overwintering sites in California. Typically, the U.S. Department of the Interior finalizes ESA listing decisions within one year of a proposal. However, a year later, no final ruling has been issued. Instead, we have less than that, we have a promise that maybe someday they will decide on it, keeping this incredibly important species in regulatory limbo, along with many other species awaiting listing or delisting decisions under the ESA.

This delay is only the latest chapter in a long and complex history surrounding efforts to protect the monarch butterfly. In fact, this iconic pollinator has been under consideration for ESA listing for more than a decade.

This is a flow chart from the US Fish and Wildlife Service showing the process for getting listed under the Endangered Species Act.

The saga actually started in August 2014 when a petition was filed with the USFWS from several reputable organizations, including Xerces Society, the Center for Biological Diversity, Center for Food Safety, and Dr. Lincoln Brower. They requested that the Monarch be listed as a threatened species with a 4(d) rule. Essentially, a 4(d) rule allows for continued conservation activities like monitoring, tagging, and rearing for educational purposes while still having protective actions in place.

In December 2014 the USFWS released a 90-day finding on the proposal . They “found the petition presented substantial scientific or commercial information that indicated listing the monarch may be warranted (79 FR 78775) and initiated a range-wide status review.” They proceeded to issue 12-month findings on the petitions.

You would think that would lead to a decision in 2015, however more research was requested and they actually took 5 years to create an assessment of population trends, threats, and consult with stakeholders. Granted, collecting data takes time and isn’t always the easiest to sort through or coordinate. While the research was being done, the Monarch was flying its way into the hearts of millions. Classrooms, communities, and Non-Governmental Organizations (NGOs) were banding together to create habitat for the beloved butterfly. Many concerned individuals were planting milkweed, reducing pesticide use, tagging Monarchs, and planting flowering native plants.

Over the next five years, USFWS conducted extensive analyses while monarch conservation gained widespread public attention.

Finally in September of 2020, the USFWS published their findings in the Monarch Species Status Assessment (SSA) Report. In this report they assessed the historical and current (2020) distribution of monarch populations, their status and health, identified key drivers of their health/decline, and their resiliency. Three months later, in December 2020, the USFWS announced their decision on listing the Monarch Butterfly under the ESA. They determined that the monarch should be listed as an endangered species, HOWEVER it was precluded due to higher-priority listing actions for other species that were in greater danger of extinction. The Monarch was categorized as a candidate species and the USFWS will review its status each year until it is finalized and published as a notice in the Federal Register, assuming it was still warranted.

In December of 2024, just a little over a year ago, the Monarch Butterfly was once again proposed as threatened under the ESA, along with a 4(d) rule and a critical habitat designation. This would have been a significant step in protecting the monarch butterfly. For 90 days following this proposal (Dec 12, 2024 – Mar 12, 2025) a comment period was open to the general public. Then the comment period was extended for another 60 days, meaning it ended in May 2025. Comments are essential to the proposal process and allows invested parties, such as scientists, organizations, individuals, and volunteer groups. Prairie Rivers, as well as many other conservation organizations, sent in a comment in favor of listing the Monarch as Threatened. The USFWS received more than 186,000 comments during this period.

Monarch Caterpillar on Whorled Milkweed by Katelyn Rinicker

USFWS generally has up to one year after a proposal to review comments and data before issuing a final rule. That rule may modify the original proposal or finalize the listing as proposed, after which it is published in the Federal Register and takes effect within 60 days. This listing would ensure the development of a recovery plan and provide clearer guidance for conservation actions.

As of December 15, 2025, roughly one year after the proposal, no final decision has been made. Recently, the Department of the Interior updated an agency rule list suggesting delays in the timeline for monarchs and other species awaiting listing/delisting actions to the ESA. The final rule for listing the monarch is now categorized as “Long-term Actions”. This means that the agency does not expect to act within the next year. Now, at the earliest, a final decision for the monarch would be the fall of 2026, at the earliest.

This is a bar graph from Monarch Watch showing the overwintering populations of eastern monarchs. 6 hectares are needed to have a sustainable population.

To say that this is a disappointment is an understatement. More than ever, monarchs need our help. Their populations have steadily declined and have been under stable repopulation numbers for the past few years. The Eastern population of monarchs (those in Iowa fall in this group) have declined by 80% since the 1990s. “According to the most recent monarch Species Status Assessment, by 2080 the probability of extinction for eastern monarchs ranges from 56 to 74% and the probability of extinction for western monarchs is greater than 95%.” (USFWS).

Without timely and decisive action, monarch butterflies could disappear within this generation.

The economics of nitrogen have changed. Has our thinking?

by Dan Haug | Dec 4, 2025

Revised December 10

It sounds too good to be true, wrote Neil Hamilton in a 2021 opinion piece. Reducing nitrogen fertilizer application rates to the Maximum Return to Nitrogen (MRTN) recommended by Iowa State University promised to save farmers money while keeping nitrate out of the rivers and greenhouse gases out of the atmosphere. In retrospect, it was too good to be true.

Reducing fertilizer rates will cut into profits (for most farmers)

Early this year, ISU researchers published a study in Nature Communications showing that the amount of nitrogen fertilizer required to maximize yield (the agronomic optimum) and maximize profits (the economic optimum) have been steadily increasing, driven partly by corn genetics and partly by weather. The economic optimum is always lower than the agronomic optimum (the revenue from those last few bushels isn’t enough to pay for the fertilizer) but the difference between the two is getting smaller. I wrote about this in July, but since then I’ve had a chance to download and explore the data used in the study. Here are the trends in optimal nitrogen application rates for just the sites in Iowa, compared to actual nitrogen application rates, which I estimated using a combination on IDALS fertilizer sales data and INREC survey data. For more details on the data I used to estimate actual nitrogen application, read this attachment.

The scenarios in the Iowa Nutrient Reduction Strategy were based on data from 2006-2010. At that time, it would have been possible for farmers to reduce nitrogen application rates on corn following soybeans from 151 lbs/acre to 133 lbs/acre while increasing profits, on average. However, those figures were already out of date when the Iowa Nutrient Reduction Strategy was released in 2013, and in the decade since, fertilizer application rates have levelled off while the amount of nitrogen needed to maximize yields or profit has continued to increase. A minority of farmers may still find opportunities to boost profits by reducing nitrogen application, but average rates are now below the economic optimum.

This part of the study looks solid and matches what I’ve seen from other sources. Practical Farmers of Iowa have done their own trials and found that a majority of their participants were able to save money by reducing nitrogen rates in an especially dry year, but in a more typical year only 41% of farmers saw potential for savings.

Reducing fertilizer rates could still have significant water quality benefits

Farmers no longer have an economic incentive to reduce rates (on average) but it’s not hard to imagine policies that could shift the incentives by making it cheaper or less risky to apply at low rates, or more expensive to apply at high rates.

The ISU study includes an “environmental optimum nitrogen rate” that hints at that. The authors used a crop systems model to estimate nitrous oxide emissions and nitrate leaching for different scenarios, assigned a price to the pollution, and calculated the nitrogen application rate that would be economically optimal if those costs were reflected in the marketplace. Instead of evaluating the environmental benefits of reducing rates from current levels, they estimate the impacts of reducing rates (for corn after soybeans) from an economic optimum of 143 lbs/acre to an environmental optimum of 116 lbs/acre. Those are averages for the entire 20 year period and not at all relevant today. Oops! Because of this mistake, they conclude that “a reduction in N fertilizer rate towards improving sustainability will not have the anticipated reduction in environmental N losses because of the nonlinear relationship between N rate and N loss.”

Actually, the non-linear (curved) relationship between nitrogen application rates and nitrate pollution implies that rate reduction will have bigger benefits now than it did when rates were lower. The figures below contrast some outdated assumptions with new reality.

The increase in fertilizer rates has been bad for water quality

In most presentations and interviews about the Iowa Nutrient Reduction Strategy, ISU faculty correctly point out that fertilizer management alone is not enough to meet our water quality goals and emphasize the need for a variety of conservation practices. However, every scenario in the INRS assumed that fertilizer application rates would go down. It may not be possible to meet our goals now that fertilizer rates have gone up.

Based on the increase in fertilizer rates for corn after soybeans (from 151 lbs/acre in 2007 to 173 lbs/acre since 2017), we would expect a 16% increase in nitrate concentration in drainage water. The 3.8 million acres of cover crops reported in recent INREC aren’t enough to undo the damage. Nitrate in streams is also affected by weather, changes in land use, and other practices not modeled here, but fertilizer rates and cover crops do help to explain why nitrate concentrations in many streams peaked between 2013 and 2015 and have fallen since.

What about continuous corn?

Nitrogen application rates for corn after soybeans have gone up, but application rates for continuous corn may actually have gone down. I say “may” because we didn’t have good baseline data. Because corn stover ties up a lot of nitrogen as it decomposes, growing corn after corn requires higher nitrogen application rates to achieve the same yield. The confusing Figure 5 in the Nature Communications paper looks at the yield penalty for reducing nitrogen rates from the economic optimum to the “environmental optimum,” which is what it would make economic sense for farmers to apply if the societal costs of pollution were reflected in the marketplace. The authors concluded that reducing nitrogen application rates past the economic optimum would have unacceptable consequences for grain markets and food security, especially for continuous corn. I looked at the same figure and concluded that growing corn after corn would not be commercially viable in a society that valued clean water, a stable climate, and public health.

Your mileage may vary

My biggest takeaways from both the Iowa State University research and the Practical Farmers of Iowa research are how much the optimum nitrogen rate varies from year to year and place to place. One farmer in the PFI study saved money by reducing rates from 150 to 100 lbs/acre, while another lost money by reducing rates to 246 to 200 lbs/acre.

The ISU study includes nitrogen rate trials for seven sites in Iowa and six years since the Iowa Nutrient Reduction Strategy was released. If you had followed the recommendations from the old nitrogen rate calculator and applied 140 lbs/acre to corn after soybeans, 62% of the trials would been at least 10 lbs/acre below the economic optimum. But even in the most recent year, there were 2 sites where that would have been at least 10 lbs/acre above the economic optimum!

The Iowa Nitrogen Initiative addresses this problem through an expanded program of nitrogen rate trials and a decision support tool that can provide customized recommendations by county given assumptions about rainfall, planting date, and residual soil nitrate. Using the new information, some farmers will find an opportunity to increase profits while reducing nitrogen rates. A larger group of farmers will find opportunities to increase profits by increasing nitrogen rates. Dr. Castellano has made a complicated argument for how the water quality benefits of bringing down the high rates can be greater than the water quality penalties of bringing up the low rates. Great. Please apply that logic to manure.

What about manure?

Since 2017, the INREC survey report has asked farmers what percent of fields receive manure application (about 20%), how much commercial fertilizer is applied to fields that do not (174 lbs/acre for corn in rotation and 199 lbs/acre for continuous corn), and what proportion of cropland is planted to continuous corn (about 12%). Manure expert Dan Anderson recently did some algebra to see what that implies about nitrogen application rates for fields that do receive manure, and came up with 342 lb N/acre on corn-after-soybean and 391 lb N/acre on continuous corn. I used slightly different assumptions and came up with lower numbers, but they’re still much higher than needed to maximize yield. If you’ve read anything by Chris Jones, this won’t come as a surprise.

I’m showing the agronomic optimum rate rather than economic optimum because the economics of manure aren’t the same as commercial fertilizer. Manure has much lower nutrient content and is much more expensive to haul. Manure pits fill up and there’s often a time and labor crunch to get it applied. Manure has highly variable nutrient content, which adds to the uncertainty and makes a supplemental application of commercial fertilizer seem like cheap insurance. If farmers had a strong economic incentive to make the most of manure nitrogen, nobody would be applying it in early fall and we wouldn’t have a cloud of ammonia hanging over the Midwest. There are also some farmers who are doing an exceptional job of conserving soil and water by feeding cover crops, small grains, or forage to livestock, and we should figure out how to level the playing field to make it easier to replicate their model.

Are these changes in nitrogen management good or bad?

It’s a mixed bag. I had to puzzle over this for quite a while!

The increase in the economic optimum nitrogen rate is partly due to good things (improved corn yield response) and partly due to bad things (increasing nitrogen losses to the air and water).

It’s good that nitrogen fertilizer use has gotten more efficient. Farmers can grow more bushels per pound of nitrogen than they used to. It’s bad that manure management plans still allow nitrogen to be applied at a rate of 1.2 lbs per bushel of potential yield.

It’s good that fertilizer rates for corn following soybeans have levelled off recently. It’s bad that nitrogen fertilizer rates went up in the early 2000s.

It’s good that nitrogen application rates for continuous corn have fallen. It’s bad that farmers are planting corn after corn.

It’s good that farmers are now applying less commercial fertilizer (on average) than required to maximize yield. It’s bad that farmers are over-applying manure.

It’s bad that we don’t have a plan to reach the goals of the Iowa Nutrient Reduction Strategy without rate reduction, and it’s bad that the price tag of reducing rates (either to farmers, the public, or both) is higher than we previously assumed. However, it might still be a better deal than other conservation practices. It’s bad than more people aren’t talking about this.

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