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

Who Owns Any Creek?

“Who owns Cross Creek?”

That is a line from one of my favorite films, Cross Creek. Released in 1983, the film is based on a memoir of the same title by Marjorie Kinnan Rawlings, the author of the classic children’s book The Yearling. The film is about her life as owner of an orange grove in Florida and all the local residents of “the creek.”

“Who owns Cross Creek?”

This line popped into my head when I was talking to Ann about our winter workshops. It was clear from the brainstorming activity that many of the farmers and landowners were more knowledgeable and caring about questions concerning soil health than water quality.

When I pointed that out to Ann, she said, “Soil health happens on the land they own and they directly benefit from it. It’s personal. Water is a part of the common good and is less tangible.”

The common good is often a hard sell economically. No one owns the water. So no one is really responsible. Or everyone is responsible?

Let’s face it: when it comes to water quality, we have been slipping in through the back door, so to speak. As Marty Adkins points out in his previous blog post (Reducing Nutrient Losses While Building Iowa’s Soils and Economy), generally the practices that improve soil health also improve water quality.

That’s true. Cover crops are a good example. They are good for soil health, especially where land is highly erodible or degraded. On the water quality side, they play a major role in reducing both phosphorus and nitrogen loss. It is difficult to show a direct return on investment with cover crops in terms of soil health, and it could cost billions of dollars annually to implement the 12 million acres of cover crops needed every year to improve water quality (The Nutrient Reduction Strategy: Creating A More Resilient Iowa). That kind of investment is going to require a seismic change in attitudes toward water quality if it is going to happen.

In his 2012 book, Navigating Environmental Attitudes, social psychologist Thomas Heberlein argues that the way to change attitudes is by changing social norms. Norms are different than attitudes because they are tied directly to behavior, whereas attitudes are based on values and beliefs. In order for norms to change behavior, they must be focused on and activated by how society shapes what we do—i.e., what shapes the status quo. Norms influencing environmental behaviors do change, but it takes years (decades) for norms to emerge, change and strengthen. For norms to function, individuals must feel responsible for their acts.

I am not saying that farmers are deliberating doing wrong—they are following the norms within our current agricultural system. While many farmers could add more conservation practices to their operations, it is the system itself that needs changing. Policies over the last several decades have intensified row crop agriculture and led us to our current water quality and soil erosion challenges. The long-term vision for Iowa must include policies that more readily allow for a diversity of cropping systems and land use (Expand Beyond a Two Crop System, Clean Up Our Water).

Poor water quality is the unintended consequence of agricultural norms that aren’t sustainable. To change this is going to require a seismic change in attitudes.

As we try to implement Iowa’s Nutrient Reduction Strategy, we need to do a better job of helping farmers see where we are, how we got here, and where we need to go. As we heard from one of the speakers at ISU Extension and Outreach’s Agriculture and Natural Resources spring inservice training earlier this year, “Farmers don’t need any help to stay the same.”

In 1983, I couldn’t have imagined how the answer to a question posed at the end of a loved film would become one of the central questions of my career. It has. Who owns Cross Creek? Or any creek?

Here’s how Rawlings responds to her haunting question:

“Who owns Cross Creek?

The red-birds, I think, more than I, for they will have their nests even in the face of delinquent mortgages…It seems to me that the earth may be borrowed, but not bought. It may be used, but not owned. It gives itself in response to love and tending, offers its seasonal flowering and fruiting. But we are tenants and not possessors, lovers, and not masters. Cross Creek belongs to the wind and the rain, to the sun and the season, to the cosmic secrecy of seed, and beyond all to time…”

Jacqueline Comito


Do cover crops reduce phosphorus loss?

Cover crops are proven to reduce nitrate loss and decrease soil erosion on our agricultural landscape, but field scale studies on phosphorus loss are still in their infancy. Drs. Antonio Mallarino, Matt Helmers, Rick Cruse, John Sawyer with Iowa State University and Dan Jaynes with National Laboratory for Agriculture and the Environment have completed two years of a long-term field study and have released their preliminary results.


The Hermann farm site south of Ames allowed Mallarino’s team to observe the effects of cover crops on phosphorus in the runoff study funded by the Iowa Nutrient Research Center.

The study is located at south of Ames on Iowa State’s Hermann Farm. The study includes replication on 12 areas ranging from one to three acres in a field that tested very high in soil phosphorus and is managed with a corn and soybean rotation. The study compares the use of winter cereal rye cover crops with and without tillage.

After two years, Dr. Mallarino observed:

“It is confirmed that cover crops reduce soil loss with tillage or no-till but mainly with tillage. Results also show that with tillage a cover crop reduces phosphorus loss. But it is not so clear that with no-tillage management a cover crop reduces phosphorus loss,” Mallarino said. “With no-tillage, there seems to be a small reduction in particulate phosphorus loss, but an increase in dissolved phosphorus loss.”

Surface runoff at the testing site is evaluated for total solids and several forms of nutrients.

Why the focus on dissolved phosphorus? The Iowa Nutrient Reduction Strategy is a technical, scientific and voluntary approach to reducing the loss of nitrogen and phosphorus to our waterbodies and the Gulf of Mexico that is home of a large hypoxic or dead zone.  Both particulate and dissolved phosphorus are part of the reduction goal, however dissolved phosphorus is responsible for algae blooms and has a visible impact on aquatic ecosystems.

Caution should be taken when drawing conclusions from only two years of data. Environmental factors play a role in nutrient dynamics with surface runoff, and during the two years of the study, major rain events at the test site had been minimal with very low runoff.

“We can’t make a strong conclusion from these two years of data. There needs to additional data collection from this site and better science-based projecting so we can encourage the addition of cover crops for the right reasons,” Mallarino said.

Click here to read the full article and learn more about project.

Questions about the project contact:

Antonio Mallarino, Agronomy, 515-294-6200, apmallar@iastate.edu


Liz Juchems

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


Help Celebrate Cover Crop Week with #FarmersCoverIowa!

aerial-vs-hagie-plot_-hagie-seedingLed by Iowa Department of Agriculture and Land Stewardship and CleanWaterIowa, we are joining the celebration of Cover Crop Week.

Cover crops are a great way to improve soil health and protect water quality. Many Iowa farmers are adding cover crops to their crop rotations so soil stays covered when the fields are not growing other crops. Cover crops also improve soil organic matter and slow water runoff.

The Iowa Nutrient Reduction Strategy research summary indicated an average 31% reduction in nitrate (N) concentration with use of a rye cover crop and a 28% reduction with an oat cover crop. The living cover crop will reduce soil erosion and phosphate (P) loss by about 29%, when planted in late summer or early fall.

Share your photos and experiences with cover crops with #FarmersCoverIowa!

For more information on adding cover crops to your farmland, visit our resources page today and follow us on Twitter and Facebook.

Liz Juchems

Cover Crop Webinar to Focus on Soil Health and Nitrate Retention

As fall cover crops go into the ground, many farmers have questions about how to best manage cover crops and achieve benefits such as soil health and nitrate retention. Dr. Mike Castellano will share his research on how cover crops can best be managed to maximize benefits during the Iowa Learning Farms’ monthly webinar on Wednesday, September 21 at 1 p.m.

corn_in_rye_small“Future gains in crop production and environmental quality will require a systems approach that integrates many disciplines,” Castellano said. To achieve this vision, Castellano uses expertise in soil science and ecosystem ecology to work with a broad range of scientists, managers and policy makers.

Castellano is the William T. Frankenberger Professor of Soil Science and Associate Professor in the Department of Agronomy at Iowa State University. He has a PhD in Soil Science from The Pennsylvania State University.


Log on as a guest shortly before 1:00 p.m.:https://connect.extension.iastate.edu/ilf/

If you can’t participate live, watch the archive of today’s webinar (along with all of ILF’s past webinars) on our website: https://www.iowalearningfarms.org/page/webinars.

Julie Whitson

PEWI: Sandbox for Creativity, Tool for Real Change

Have you ever wondered how changes in land use could affect nutrient reduction, habitat for pollinators or soil health? In this month’s webinar, Dr. Lisa Schulte Moore showed us how to use a new tool, People in Ecosystems Watershed Integration (PEWI).

Today, we face water quality issues related to soil erosion, nutrient loss, and water runoff in Iowa and beyond. Many of these problems stem from how our landscape has changed over the last two centuries. One way that we can begin to address these problems is to strategically target land use changes at the watershed scale.

runoff combined 2

Left: real-world challenges like erosion and water runoff; Right: PEWI shows how land use changes pay off

Schulte Moore and her team created PEWI because they wanted a tool that could show people how changes in land use could affect the surrounding area without having to make risky or costly decisions. PEWI gives users a chance to test-drive changes in land use in a 6,000 acre watershed. Each cell in the simulation represents ten acres. Users can choose from 15 different land uses and can simulate crop rotations over a three year period.

Topography, soil drainage, and flood frequency can all be altered to the user’s preference. The tool also considers the impacts of weather and provides a random distribution of weather patterns based on 30 year averages of precipitation in Iowa.

combined features

PEWI does not require any specific software licenses or computer skills. To use PEWI, all users need is the internet. Users can compare different landscape designs and learn about how different mixes of landscapes or even weather patterns might affect conditions in the real world. PEWI can provide estimates for nutrient runoff and erosion. The tool can also score landscapes and compare how different designs meet different goals.


You can view an archived version of the webinar here. Other archived webinars from Iowa Learning Farms are available on our website.

For more information about PEWI, visit the PEWI website.  You can try PEWI for yourself here. Lesson plan ideas, user guides, and tutorials are all available at the PEWI website.

Julie Whitson