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.

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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.”
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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.

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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:

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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.

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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.

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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

Getting Dirty and Getting Samples

My name is Mary and I am a high school intern with Water Rocks! this summer. I have always been interested in natural resources, and I will be pursuing a degree in Natural Resources and Environment Science with a concentration on Resource Conservation and Restoration Ecology at the University of Illinois Urbana-Champaign this fall.

MeetTheInterns-Mary

I have had so many great opportunities and experiences with Water Rocks! this summer. I have been able to participate in multiple outreach events at county fairs and farmers markets across Iowa.  I have also had the opportunity to attend a farmer field day discussing everything anyone would want to know about cover crops.

Mary-ConservationStationMost recently I was able to go up to Nashua and collect water samples from lysimeters at the Northeast Research Farm. Our lysimeters are buried 24” deep and collect water from the surrounding soil.  The water samples are then tested to see the nitrate levels in the water at different times during the year and under different cover crop treatments. This research is very important in helping us better understand cover crops – they are one of the key practices in the Iowa Nutrient Reduction Strategy, where the goal is to try and reduce the nitrogen and phosphorus loads in Iowa waters by 45%.

The plots from which we collected water samples were each 6 rows wide – and we have plots that are in both corn and soybeans (rotated every other year). The entrance to the research farm is a couple of buildings, and then it moves straight into the research plots.  We had to drive a little ways to reach our lysimeter plots. There are many other research plots around our lysimeter plots. All of our fields were no till fields – some of them had cover crops in the spring (single species/mixtures) and some did not. We started collecting samples from the soybeans first, and then moved to the corn.

Lysimeters-InGroundCollecting water samples is quite simple, but finding the lysimeters when the crops are large isn’t always a piece of cake!  The lysimeters are buried underground, so all we can see is the PVC cap protecting it … and sometimes they get covered with soil or are hidden by residue.

Lysimeters-SuppliesOnce we have found the lysimeters, we grabbed our equipment which included a plastic beaker with a rubber stopper on top and a long thin tube attached, an air pump, plastic bottles to pour collected samples into, and a clipboard with labels to mark the samples.

Lysimeters-SamplingInProgressWe collected the sample by inserting the thin tube down into the lysimeter, attaching the beaker to the air pump, and applying vacuum to the lysimeter so the water would be sucked out.  After the sample was collected, we would have to apply vaccum to the lysimeter again (60 psi) so it could collect the next batch of samples.

Collecting clean samples is a key component.  If there was soil in the water sample, how would we know that the nitrates in the water weren’t from the soil?  I was out collecting samples the day after a big rainstorm, and of course it was really muddy out, so we had to be extra careful to keep the soil and mud off of the equipment used to collect the samples.  If we collected a dirty sample, then it would have to be filtered in the lab before the nitrate test could be done accurately.  Also, after every sample is collected, the plastic collection beaker must be rinsed out with DI Water (deionized water), so the next sample wouldn’t be contaminated by the previous sample.

Seeing the lysimeters and collecting water samples was very educational for me, and I was glad that I had an opportunity to see what research is being done and how it is done.  I learned how thorough you have to be when conducting research – there can be lots of variables in the field so quality control is really important.  I was also surprised by how dirty I was on the way home after collecting all of the samples!

So now we’ve collected water samples… next they go to the lab for nitrate testing. After that, there are lots of water quality data to analyze. Stay tuned to the blog as Emily, another high school intern, will tell us more about that process!

Mary-ShowingPigsBooneCoAs a fun side note, I wanted to share another one of my projects for this summer. In addition to this internship, I am a member of the Gilbert FFA Chapter and I recently showed pigs at the Boone County Fair (I’m number 344 in the blue shirt). That pig in the picture will be making an appearance at the Iowa State Fair – the show is on August 12th if you’d like to stop by and watch after you visit Farm Bureau Park and check out the Conservation Station!

Mary Marsh

 

Wetlands and Water Quality

Wetlands are often viewed as filters, or kidneys of the landscape, and that’s for good reason as they have great potential for improving water quality!  Today let’s dig in and investigate how wetlands help to improve water quality and the mechanisms at work to make that happen.

Denitrification
Wetlands can be strategically placed to improve water quality through the removal of nutrients, specifically nitrate, like the wetlands in the Conservation Reserve Enhancement Program (CREP). Water enters these nutrient removal wetlands coming from a series of tile drains, often carrying a substantial load of nitrogen in the form of nitrate.

As water moves slowly through the wetland, microbes breathe in and consume nitrate (NO3), the way humans use oxygen when we breathe and respire, converting the nitrate to inert N2 gas (comprising 80% of the atmosphere).  This process is called denitrification. In turn, cleaner water is sent downstream. 

nitrate_wetlands_03

Put simply, these wetlands are strategically designed and placed to allow the natural microbiology to happen – the microbes are doing all of the heavy lifting! These nitrate removal wetlands are ideal locations for denitrification to occur because they provide saturated anaerobic soil conditions, and the system is supplied with a source of nitrate from agricultural drainage water. Aquatic plants and wetland soils provide surfaces on which those microbes live, in addition to providing organic carbon to help maintain growth and metabolism of the denitrifying microbes. Strategically designed and sited wetlands can reduce nitrate loads to downstream water bodies by 40-70%.

Hear more about this process from Dr. Bill Crumpton and others in our award-winning video Incredible Wetlands:

Sediment Capture
Wetlands can also improve water quality by slowing the flow of water and capturing sediment, if the contributing water is coming from overland flow.  When the velocity of water slows down, as in wetlands, sediment is unable to stay suspended.  Think of it like a salad dressing with herbs and spices … when you give it a good shake, it gets well mixed throughout, but after letting it sit for some time, the herbs/spices sink to the bottom.

The same thing happens in wetlands.  When the speed of the water slows down, the suspended sediment (soil) particles gradually settle to the bottom where wetland plants hold the accumulated sediment in place, again sending cleaner water downstream.

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Role of Wetlands in Nutrient Reduction Strategy
Iowa’s Nutrient Reduction Strategy lays out several different scenarios of conservation practices in which the targeted 45% reduction in nitrogen and phosphorus can be achieved.  Wetlands play a really key role in reaching those goals, particularly on the nitrogen side of things!  One of the combined scenarios of practices calls for ~7,600 wetlands strategically placed for nitrate removal.  There are currently 77 CREP wetlands across the state of Iowa, with others in the works.

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The amount of human and financial capital to reach these goals is huge, but we continue to make forward progress in increasing the number of wetlands acres (see last week’s blog post, Wetlands: By the Numbers, for more information about ongoing wetlands restoration efforts).

Check out our previous posts celebrating American Wetlands Month:

Stay tuned next week for the fun tools and techniques we use to help teach young people about the amazing benefits of wetland ecosystems on our landscape!

Ann Staudt