Wet spots – losing more than just crop yields


With all the rain these last few weeks, Dr. Steven Hall’s webinar on understanding and managing nitrogen losses from prairie potholes provides great insight as to what is happening in those ponded areas in our cropping landscape.


When discussing nitrogen loss in Iowa and across the Corn Belt, the focus is often on the nitrate that is leached to local waterbodies and the Gulf of Mexico. However, the Corn Belt is also the leading source of nitrous oxide – the third most important greenhouse gas!

As a neglected pollutant, nitrous oxide is now the most important ozone-depleting substance. Local estimates of emissions are 3-4% of nitrogen inputs applied to agricultural land. Due to the concentration of agricultural production, the Corn Belt nitrous oxide emission from soil and water are a leading cause of climate change.

N20 map

Here in Iowa, the majority of the pothole wetlands are found in the Des Moines lobe region of central and north central Iowa. Pothole depressions comprise about 9% of the Des Moines lobe with the majority of them partially drained and cropped. These farmed wet spots become hot spots for nitrogen loss and contribute a disproportionate amount of nitrous oxide and nitrate to our environment.

As Emily Heaton pointed out her recent post, there are management alternatives for the pothole depressions that can help reduce these losses and potentially improve the bottom line for landowners.

Check out the full webinar here to learn more about these alternatives and the case studies Dr. Hall and his team are exploring here in Iowa.

You can catch up on all of our webinars by visiting our website.  While you are there, be sure to check out our Conservation Chat podcast series!

Liz Juchems

Water in the Public Domain

Public domain: a concept that evokes thoughts of music, photographs, paintings, and other creative works of art … and their relationships with copyright policy. From another perspective, public domain is all about shared availability, the common good …  much like our natural resources.

As nearly 40 people gathered for a conservation field day at Paustian Family Farm just outside Walcott, IA this past week, this idea of water in the public domain was an ever-present undercurrent in the conversations among area farmers, landowners, rural and urban residents alike.

In addition to in-field conservation practices like reduced tillage, cover crops, and a close eye on nutrient management, host farmer Mike Paustian is now taking conservation to the edge of the field as well. In fall 2017, the Paustians installed a saturated buffer on their land to specifically address the challenge of nitrates in tile drainage water.

Saturated buffers are a field-scale practice, treating subsurface tile drainage water from 30-80 acres of cropland. The presence of an existing streamside vegetative buffer is a great first step, and makes the installation a breeze. In order to “saturate” the existing buffer, a flow control structure and lateral tile line running parallel to the stream (700’ long, in this case) are installed.

Quite a bit of the water then moves through that new perforated tile line parallel to the stream, slowly trickling out of the tile, working its way through the soil. On this journey to the stream, the water is in direct contact with plant roots and the soil itself – where the biological process of denitrification occurs. Under saturated, anaerobic conditions, naturally occurring bacteria breathe in the nitrate, and then transform it to atmospheric N2 gas, sending cleaner water to the stream (to the tune of 40-50% nitrate reduction).

As folks got to see the saturated buffer firsthand, one of the attendees asked Paustian, “As a city person, why should somebody from Davenport, Pleasant Valley, etc. care about what’s going on out here?”

Paustian responded, “We’re all in this together, using the same water. It’s a limited resource. We’ve got to find common ground – urban and rural – being good stewards of our land and water. That’s why saturated buffers matter out here.”

Washington Co. farmer Steve Berger, an early adopter and long-term user of cover crops, emphasized the benefits of cover crops for water quality, promoting infiltration and likewise minimizing soil erosion.  Berger added, “Anything that comes off this field ends up in the public domain somewhere … long-term no-till and cover crops are working together to keep soil and nutrients in place in the field!”

As Iowa’s water quality continues to garner attention locally, statewide, and even on the national level, that concept of water in the public domain resonates strongly. Bringing urban and rural people together to see how we can work for positive improvements in water quality is a step in the right direction. This field day was an excellent example of the engaging conversations and positive dialogue we at Iowa Learning Farms hope to facilitate surrounding water quality, soil health, and our agricultural production systems across the state of Iowa.

Ann Staudt

Webinar highlights cover crop, water quality connections

In case you missed it, this past week’s Iowa Learning Farms webinar offered an excellent overview of the research findings related to the potential of winter cover crops to reduce nitrate leaching in corn and soybean cropping systems. Dr. Tom Kaspar, plant physiologist with the USDA-Agricultural Research Service, shared results from numerous studies that show the ability of cover crops to reduce nitrate concentrations and loads in tile drainage water.

The press headlines about nitrates and water quality are seemingly ubiquitous, and Kaspar provided solid data that help to paint a complete picture of the challenges and opportunities. Our land uses have changed dramatically, and over the past 60-70 years, our cropping systems have likewise changed dramatically with significant reductions in small grains, hay and perennial vegetation.  With corn and soybeans having a 7-month brown gap when they are not actively uptaking nutrients, that leaves a significant amount of time with nutrients vulnerable to leaching.

However, Kaspar’s research clearly demonstrates that cover crops help transition that brown gap to a green gap, providing the ability to “capture” nutrients in the soil that would otherwise be vulnerable to leaching loss. One of Kaspar’s long-term research studies in central Iowa found that rye cover crops in a corn-soybean cropping system reduced nitrate concentrations in tile drainage water by 57%. Additional studies by Kaspar and collaborators around the state found nitrate reductions of anywhere from 20% to 40%. This variability is expected, with different amounts of cover crop growth, weather, rainfall, soil types, tile systems, and field histories.

Kaspar also pointed out that it takes quite some time for nitrate to move through the system – there is a noticeable lag effect.  For instance, Kaspar and collaborators found that nitrate concentrations in subsurface tile drainage continued to decrease through the summer, long after spring cover crop termination.

Check out the full webinar, Lessons Learned from Using Cover Crops to Reduce Losses of Nitrate for 15 Years, on the Iowa Learning Farms webinar archives page.  And to hear more perspectives from Dr. Kaspar, tune in to Episode 06 of the Conservation Chat podcast!

Ann Staudt

retaiN: Putting the Power of Data in the Hands of Farmers

One piece of the puzzle in encouraging farmers to adopt practices that reduce nitrogen loss is to show them how much nitrate is being lost through their tile lines, and if some fields have higher loss than others. Most water monitoring methods are expensive or labor-intensive and it is impractical now to professionally test every farm. We needed to come up with an idea that was effective, inexpensive, and easily done by farmers. The result was the retaiN project.

ILF Juchems 068The seeds for retaiN came from conversations Clare Lindahl and I had with farmers that had participated in tile monitoring. The farmers told us that it was an eye-opening experience. They found that while they were using practices that minimized soil loss and improved soil health, those practices weren’t addressing nitrate loss through their tile.

Afterwards, Clare (at the time Executive Director of Conservation Districts of Iowa) and I were trying to figure out how to make the tile monitoring process easier and accessible to a larger number of farmers. Building on the idea of citizen science, we decided that we could create less expensive testing kits that farmers could use privately on their land to help answer these questions. To get the funds we needed, we applied for and received a grant through the State Soil Conservation Committee.


Oct_2017_Retain2This seed money enabled us to develop simple kits to make testing tile water for nitrate easy and to also provide farmers with solutions for retaining nitrogen on the farm. In two years, the project has distributed over 1,200 retaiN kits to farmers and landowners individually and through watershed project coordinators, ISU Extension field specialists and county offices, Iowa Corn Growers Association (ICGA) and agribusinesses.


Oct_2017_Retain1The test kit provides an opportunity to collect on-farm nitrate concentration data and further engages farmers in water quality issues. Participants are encouraged to discuss their results with a specialist but there are no requirements to submit data. A new partnership with Iowa Corn Growers Association saw significant growth this year with ICGA distributing over 400 kits at Crop Fairs, Soil Health Partnership events, and watershed education and outreach events across the state.

The evaluation of the kits from farmers, agribusiness and organization partners, watershed coordinators, and ISU Extension and Outreach specialists has been overwhelmingly positive. In some cases, it has led to expanded on-farm water sampling to gather additional or more precise data, ongoing monitoring to gather baseline results, and changes in nitrogen management and practice adoption. Thanks to our funding partners, we are still able to offer farmers their first retaiN kit at no cost.  Additional kits can be purchased for $39 and can be requested through the project website www.retainiowa.com/.

The retaiN project demonstrates the power of information when it comes to reducing the amount of nitrate that leaves a farmer’s land through their tile lines. The more farmers learn about the quality of the water leaving their land, the closer we will get to achieving our Nutrient Reduction Strategy goals, one retaiN kit at a time.


Jamie Benning

retaiN is a collaboration between Conservation Districts of Iowa, Iowa State University Extension and Outreach and Iowa Learning Farms with support from the Iowa Department of Agriculture and Land Stewardship, Division of Soil Conservation and Water Quality. Jamie Benning is an Iowa Learning Farms team member and Water Quality Program Manager at Iowa State University.

Lessons Learned from Farmer Interviews of the Lyons Creek Watershed Project

Today’s guest post was provided by Steve Hopkins, Nonpoint Source Coordinator with the Iowa DNR’s Watershed Improvement Section.

The University of Northern Iowa’s Center for Social and Behavioral Research recently completed a study of farmers and stakeholders involved with the Lyons Creek Watershed Project about the farmers’ participation in the project and their attitudes toward adopting conservation practices.  The study was a post-project evaluation done at the end of the Lyons Creek Watershed Project, administered through the Hamilton County SWCD in north central Iowa.

The primary goal of the watershed project was to reduce nitrate levels in Lyons Creek, which has the highest nitrate levels of all of the tributaries of the Boone River.  The Boone River is a tributary of the Des Moines River, which is a source of drinking water for the city of Des Moines.


Despite the fact that the primary goal of the project was to reduce nitrate levels, and that the project coincided with the release of the Iowa Nutrient Reduction Strategy, the project fell short of its goals due to a lack farmer participation and adoption of nitrate-reducing practices.  The purpose of the study was to find out why.

The study, based on in-depth interviews with farmers and project stakeholders, found both positive and negative factors related to farmer participation in the watershed project:



The study included recommendations for future watershed projects, including providing funding for a full-time project coordinator, involving farmers early on in project planning, and making project goals clearer.

UNI will be presenting the results of the study at the 2017 Iowa Water Conference in March.

This study, funded by Iowa DNR with EPA Section 319 funds, is available on the DNR Watershed Improvement webpage under “Watershed News” at  http://www.iowadnr.gov/Environmental-Protection/Water-Quality/Watershed-Improvement.

Steve Hopkins


Cover crops key to N retention + soil health, especially before soybeans

How can we increase nitrogen retention and soil health in Iowa’s corn and soybean cropping systems? There is not just one single quick fix, but Dr. Mike Castellano, William T. Frankenberger Professor of Soil Science and Associate Professor in the Department of Agronomy at Iowa State University, made the strong case for cover crops in last week’s Iowa Learning Farms webinar.

Castellano framed the webinar with a discussion of nitrogen budgets. As he put it, we don’t typically think about financial management without a budget – nutrient management is the same way! He then explored the potential of cover crops, especially cereal rye, to aid farmers in retaining nitrogen (via the cover crop plant biomass) and building soil organic matter. Watch the full archived webinar on the Iowa Learning Farms website: https://connect.extension.iastate.edu/p6kfk1qr4te/.

OR, if you’d like the CliffsNotes version, here are the Top 5 key take home points that jumped out at me…

cc-top5takehomepoints-iiAgain, you can check out the full presentation on the Webinar Archives page of the Iowa Learning Farms website.

Save the date…
The next Iowa Learning Farms webinar will be Wednesday, October 19 at 1:00 p.m., featuring our own Dr. Matt Helmers. He will be addressing common questions and misconceptions regarding cover crops, drainage, and more … think Mythbusters meets water quality! It’s sure to be a lively conversation.

Ann Staudt


Dirty Hands, Fertile Land: Late Spring Nitrate Testing

My name is Hannah Corey, and I am a sophomore in Agronomy at Iowa State. I was raised on a farm near Lake City, Iowa along with my brothers, some cattle, and a whole lot of corn and soybeans.

MeetTheInterns-HannahI am a soils nerd. I like to read about it, talk about it, and think about it, but most of all I like to get my hands dirty and work with the soil. Thankfully, as an intern for Water Rocks! and the Iowa Learning Farms, I get to do all four! I spent this past week traveling to the Iowa State University Research Farms and collecting soil samples for the Late Spring Nitrate Test. Here’s what I learned…

The Late Spring Nitrate Test is used to determine the amount of nitrate in the soil available to corn plants in late spring when the corn is 6-12 inches tall (we sampled statewide this past week, June 6-10). It’s a straightforward process designed so that farmers can do it in their own fields without much hassle.

The tools of the trade are simple: a soil probe, a clean bucket, and a bag to put the sample in.

Our plots on the research farms are no-till and alternate between single-species cover crop, mixed-species cover crop, and no cover crops. In each plot we pull eight different soil cores and mix them together to form one composite sample. Each core is a standard 12 inches deep and ¾ inch in diameter. We pull cores in a diagonal line across the plot to get a sample that accurately represents the area.


Added bonus: it’s also a great arm workout!

After the samples are bagged and labeled, they are sent to the lab to be analyzed for the nitrate content of the soil. The Iowa Learning Farms team uses this data for research, but with data from their own fields, farmers can also use the Late Spring Nitrate Test in their operations.


A composite sample from the Nashua Research Farm bagged, labeled, and ready to go!

A Late Spring Nitrate Test can tell a farmer how much nitrate is available to their corn, and whether or not they need to apply additional nitrogen fertilizer. If the soil is low on nitrate, farmers can help their corn by supplying the additional nitrogen it needs to grow. If the soil has adequate or high nitrate levels, they can save money and keep nitrates out of the water by refraining from adding excess fertilizer.

To me, the Late Spring Nitrate Test is a win-win-win situation. Proper use of the data collected can help boost corn growth, save money, and improve water quality.

HC-SoilSo dig in, get your hands dirty, and learn about your soil. The more we know about our soil, the more we can do to improve its fertility. After you’ve dug in and your hands are covered in soil, remember, “Dirty hands, fertile land!”

Follow our new #dirtyhandsfertileland series on Facebook and Twitter throughout the summer to learn more about what you can do to improve soil health and fertility!

Interested in learning more about the Late Spring Nitrate Test or having your soil tested? Click on these links to learn more…

Nitrogen Fertilizer Recommendations for Corn in Iowa
(free PDF download from ISU Extension Store)
ISU Extension Specialist Suggests Late Spring N Test For Corn
ISU Soil and Plant Analysis Laboratory

Hannah Corey