Measuring Conservation and Nutrient Reduction in Iowa

Written by: Laurie Nowatzke and Jamie Benning

To address Iowa’s nutrient contributions to the Gulf hypoxic zone, the Iowa Nutrient Reduction Strategy (INRS) established goals for reducing N and P loss from agricultural nonpoint sources by 41% and 29%, respectively. The INRS Science Assessment identified a number of conservation practices that reduce N and P loss including in-field fertilizer and soil management practices, edge-of-field nitrate and phosphorus reduction structures, and strategic conversion of row crop acres to pasture, small grains, or perennial crops.

The current status of conservation in Iowa

The Iowa Nutrient Reduction Strategy Annual Report is published each year to document the change in statewide education and outreach efforts, practice implementation and changes in water quality.  Some of the highlights of this report include:

  • Cover crops planted in Iowa increased from 379,000 acres in fall 2011 to 973,000 in fall 2016, according to the newly available 2017 United States Department of Agriculture (USDA) Census of Agriculture.
  • Based on the USDA Census of Agriculture, annual corn and soybean planted acres have remained relatively consistent since the 1980s, with some fluctuation. Preliminary analyses of the USDA Cropland Data Layer suggest that perennial agricultural acres – including pasture, hay, and acres enrolled in CRP – have decreased over time, with approximately 4.3 million acres in 2018.
  • No-till acreage increased from 6.9 million acres in 2012 to 8.2 million in 2017, according to the Census of Agriculture.
  • By the end of the 2018 calendar year, there were an estimated 27 bioreactors and 13 saturated buffers installed through cost-share programs, treating an estimated 2,000 acres or more.
  • Iowa has 86 nitrate-removal (i.e., CREP) wetlands that treat 107,000 acres. An additional 30 wetlands are currently under development for completion in the coming years.
  • Since 2011, approximately 22.5 million feet of terraces have been constructed using state cost-share funds. These terraces treated 174,000 acres of land and reduced P losses by 40 tons in 2018.

Moving forward

Meeting the goals of the INRS will require changes on every acre of Iowa farmland. One example scenario calls for an estimated 10.5 million acres of no-till and strip-till, 12.5 million acres of cover crops, 7,600 nutrient removal wetlands, and 120,000 bioreactors and saturated buffers. In comparing these numbers to the 2019 assessment of practices, we have a lot of work ahead us to reach the goals. Numerous resources and technical and financial assistance programs are available to assist farmers, landowners, and their advisers select, implement and manage conservation practices successfully.

Tools for getting started

With a range of conservation practice options to choose from, it can be difficult to decide which practice(s) is right for you and where to start. The Conservation Systems Best Practices Manual and decision support tools were developed with these challenges in mind to help new practice adopters and their advisers make sound decisions and have successful conservation practice implementation experiences. The manual outlines recommendations for in-field and edge-of-field practices including cover crops, no-till, strip-till, multi-year crop rotations, prairie strips, bioreactors, saturated buffers, and nutrient removal wetlands. The manual was developed using a cropping systems approach and includes planting, nutrient management, pest and disease management, and harvest tips and considerations for the in-field practices. Download the free manual from the ISU Extension Store website.

Financial incentives

To help offset the cost of getting started, the statewide cost-share program through the  Iowa Department of Agriculture and Land Stewardship Water Quality Initiative Program is offering $25 per acre for first time cover crop farmers and $15 per acre for farmers who have tried cover crops in the past. First time no-till or strip-till adopters are eligible for $10 per acre and farmers using nitrapyrin nitrification inhibitor with fall fertilizer are eligible for $3 per acre. Funding is limited to a maximum of 160 acres per farmer or landowner. Applications can be submitted through your local Soil and Water Conservation District office.

For information on other conservation and water quality programs call your local USDA Service Center office.

Laurie Nowatzke (Measurement Coordinator for the Iowa Nutrient Reduction Strategy)

Jamie Benning (Assistant Director for Agriculture and Natural Resources Extension)

Iowa’s CREP Wetlands Provide Opportunity to Measure Delivery Scale Impacts

The Iowa Conservation Reserve Enhancement Program (CREP) is a state, federal, local, and private partnership that provides incentives to landowners who voluntarily establish wetlands for water quality improvement.

The goal is to reduce nitrogen loads from croplands to streams and rivers, while also providing wildlife habitat and increased recreational opportunities. Over the past 15 years, about 90 CREP sites have been constructed in a 37 county region in north central Iowa.

For over 10 years Dr. William Crumpton, Iowa State University professor in the department of Ecology, Evolution and Organismal Biology, has been leading the monitoring of 10-15 of the CREP sites to measure their performance.

In a new video released by the Iowa Learning Farms, Dr. Crumpton discusses how CREP wetlands function and the need for long-term delivery scale monitoring with Dr. Matt Helmers, Director of the Iowa Nutrient Research Center.

Here’s a sneak peak of their conversation:

How do CREP wetlands go about removing nitrate?

The primary process is denitrification. Denitrification is carried out by anaerobic bacteria. They use carbon as an energy source and nitrate as an electron receptor instead of oxygen. They denitrify nitrate into N2 gas -which is 80% of our atmosphere.

What factors influence their performance in removing nitrate?

1. The amount of water that goes into the wetland, also known as hydraulic loading rate. This factor is the easiest to adjust to control overall performance. If the wetland is larger, the hydraulic loading rate is smaller and the higher percentage of nitrate that entered the system is removed.

2. Temperature. Denitrification increases with warmer temperatures and slows during the cooler times of the year.

3. Incoming nitrate concentrations. If the incoming concentration is higher more mass of nitrate is removed by the wetland.

What are the habitat benefits of these sites?

The buffer area is about 3x the pool area. For example, a 10 acre CREP pool has a 30+ acre buffer around it. The buffers are seeded with native prairies mixes of grasses and forbs. Because CREP sites are designed to be wet, even in drought years these sites have not gone dry. They provide critical habitat during drought conditions.

These CREP sites are being used for projects like the Conservation Learning Labs led by the Iowa Learning Farms. Why is delivery scale level of monitoring important to helping meet the Iowa Nutrient Reduction Strategy Goals?

Delivery scale monitoring helps determine if plot scale performance results on nitrate and phosphorus reductions from various practices is what can be expected at field-level implementation.

For the CLL sites at least 50% of each watershed has been seeded to cover crops for 3 years. However, the water quality data has not yet shown a significant response. What are some factors that are contributing to the lack of response?

Scale and weather both play a role in the results. The larger system has a longer lag time compared to plot scale research. Continued long term monitoring at the delivery scale is extremely important as weather influences nutrient loading and management decisions. Both 2017 and 2018 weather limited the amount of cover crop growth, likely reducing their nutrient reduction performance. Dr. Crumpton recommends at least 10 years of monitoring to average out the weather influences on the practices performances and account for lag time in the system.

For more information on nitrate reduction wetlands in Iowa and cost-share opportunities for your farm, be sure to check out our recent virtual field day with Susan Kozak, IDALS Soil Conservation & Water Quality Division Director, and Shane Wulf, IDALS Water Resources Bureau Environmental Specialist.

Liz Ripley

June 24 Webinar: Environmental Performance of Wetlands Receiving Non-Point Source Nutrient Loads: Benefits and Limitations of Targeted Wetland Restorations

Iowa Learning Farms will host a webinar on Wednesday, June 24 at noon about the potential targeted wetland restorations have to reduce agricultural nutrient loads.

William Crumpton speaks to a water quality field day group at a CREP wetland in Pocahontas County

Over the past 15 years, over 90 wetlands have been restored through the Iowa Conservation Reserve Enhancement Program (CREP) with the explicit goal of intercepting and reducing non-point source nitrate loads. William Crumpton, Professor at Iowa State University, will summarize results from 15 years of work on Iowa CREP wetlands, including nutrient removal, GHG emissions, and hydrology. The research presented in this webinar is one of the largest and longest running projects of its kind and helps to clarify the potential benefits and limitations of targeted wetland restorations. The research methods are also being used to monitor the impact of in-field practice changes through the Conservation Learning Lab project.

“The Iowa Nutrient Reduction Strategy includes a wide range of in-field and off-field practices, but will likely require restoring thousands of wetlands targeted to intercept and reduce nitrate loads from cultivated cropland,” said Crumpton, who studies wetland processes and functions, including the dynamics of energy flow and nutrient transformation in wetlands, the fate and effects of agricultural contaminants in wetlands, and the role of restored and constructed wetlands in watershed hydrology and water quality.

Wetland restored to intercept and reduce nonpoint source nutrient loads from approximately 950 hectares of cultivated cropland in Palo Alto County, Iowa

“I hope participants will better understand the effects of targeted wetland restorations on water quality and hydrology and thus appreciate the potential benefits and limitations of this practice in Iowa’s agricultural landscapes,” Crumpton said about Wednesday’s webinar.  

To participate in the live webinar, shortly before 12:00 pm CDT on June 24:

Click this URL, or type this web address into your internet browser:

    Or, go to and enter meeting ID: 364 284 172 

Or, join from a dial-in phone line:

    Dial: +1 312 626 6799 or +1 646 876 9923

    Meeting ID: 364 284 172

The webinar will also be recorded and archived on the ILF website, so that it can be watched at any time. Archived webinars are available at

A Certified Crop Adviser board-approved continuing education unit (CEU) has been applied for, for those who are able to participate in the live webinar. Information about how to apply to receive the credit (if approved) will be provided at the end of the live webinar.

Hilary Pierce

Edge-of-Field Conservation Practices that Work

Whole farm conservation best practices aren’t limited to in-field practices like no-tillage, strip-tillage, cover crops and extended rotations. A suite of edge-of-field conservation practices, like those pictured below, can help improve water quality in the state by managing the loss of nitrogen from cropland.

Based on 2012 and 2017 United States Department of Agriculture Census of Agriculture data, approximately 50% of Iowa cropland has subsurface drainage. While this drainage makes it possible to farm previously wet soils, it also carries dissolved nitrogen from farm fields to the streams, rivers, lakes, wetlands, and other surface waters of the state.

Excess nitrogen in water leads to local, regional, and national-level alterations to aquatic ecosystems resulting in decreased water clarity, increased algal growth, and oxygen shortages that cause fish kills and reduce diversity. Excess nitrogen also harms drinkable water supplies. Concentrations above the 10 mg/L NO3-N drinking-water standard established by the United States Environmental Protection Agency are not uncommon in Iowa.

Edge-of-field practices such as treatment wetlands, bioreactors, saturated buffers, and controlled drainage can significantly reduce the amount of nitrate-nitrogen that leaves drainage networks. On average, nitrate-nitrogen is reduced by:

  • 52% with treatment wetlands
  • 53% with saturated buffers
  • 43% with bioreactors
  • 32% with controlled drainage

While edge-of-field practices have the potential to remove large amounts of nitrate-nitrogen, there is no one practice that works well at all sites. A combination of appropriate practice implementation and high adoption rates is needed to meet the nitrogen reduction goals of the Iowa Nutrient Reduction Strategy that calls for the reduction of nutrient loadings to the Gulf of Mexico by 45% over the coming decades.

Over the next five weeks, we’ll be exploring different edge-of-field practices and the decision trees to help identify which practice(s) will work best for your system.

-Liz (Juchems) Ripley

Iowa’s Water Quality Challenge

On Wednesday, Iowa Learning Farms hosted a webinar about the efforts and progress being made toward reducing agricultural losses of nitrogen and phosphorus.

Laurie Nowatzke, Measurement Coordinator for the Iowa Nutrient Reduction Strategy at Iowa State University, explained:

  1. How does nutrient loss occur in Iowa agriculture?
  2. Which practices reduce nutrient loss?
  3. Are these practices being adopted?

Nowatzke explained that agricultural losses of nitrogen and phosphorus mainly occur in two different ways: soil and phosphorus loss through erosion from surface runoff and loss of nitrate-nitrogen and some dissolved phosphorus through subsurface drainage. In-field and edge-of-field practices have been designed and are being adopted by farmers and landowners to reduce these losses.

These practices can be used to meet the nutrient reduction goals set forth in the Iowa Nutrient Reduction Strategy. The Strategy lays out several different scenarios in which the goals can be reached through different combinations of practices and the necessary adoption rate for each scenario. One of these scenarios is shown in the figure below, with the current estimated adoption rate also shown.

More widespread adoption of these practices (in this combination of practices or in the other scenarios) will be needed to reach the nutrient reduction goals of the Iowa Nutrient Reduction Strategy.

Nowatzke shared the following resources for more information:

More information about the progress toward Iowa’s water quality goals can be found in the forthcoming 2018-19 Annual Progress Report of the Iowa Nutrient Reduction Strategy. Last year’s report can be found here.

Watch the full webinar here!

Be sure to join us next week, on May 6, when  Ross Evelsizer, Watershed Planner & GIS Specialist at Northeast Iowa RC&D, will present a webinar titled: “Multi-Cropping as a Profitable Soil Health Solution“.

Hilary Pierce

Iowa’s Water Quality Challenge: Efforts and Progress in Reducing Agricultural Nitrogen and Phosphorus Loss

Iowa Learning Farms will host a webinar on Wednesday, April 29 at noon about the work that is being done in Iowa to reduce losses of agricultural nitrogen and phosphorus, as well as the progress that has been made.  

What are the drivers of nutrient loss and water quality impacts in Iowa? To what extent are agricultural conservation practices being used in Iowa to address these concerns? This webinar will explore these questions, describe the wide variety of data sources available, and present findings from the forthcoming Annual Progress Report of the Iowa Nutrient Reduction Strategy. Laurie Nowatzke, Measurement Coordinator for the Iowa Nutrient Reduction Strategy at Iowa State University, will share how Iowa’s water quality efforts are tracked, the latest findings, and where participants can find additional resources about these efforts.

“There are many programs and initiatives working toward reducing nutrient loss in Iowa. This project uses data to show the current status and outcomes of those efforts, and it aims to provide Iowans with timely information regarding water quality improvement,” said Nowatzke. She works for the College of Agriculture and Life Sciences to evaluate Iowa’s progress in meeting water quality goals, research Iowa farmers’ conservation practice adoption, and track statewide use of water quality improvement practices in agriculture.

To participate in the live webinar, shortly before 12:00 pm on April 29:

Click this URL, or type this web address into your internet browser:

    Or, go to and enter meeting ID: 364 284 172 

Or, join from a dial-in phone line:

    Dial: +1 312 626 6799 or +1 646 876 9923

    Meeting ID: 364 284 172

The webinar will also be recorded and archived on the ILF website, so that it can be watched at any time. Archived webinars are available at

A Certified Crop Adviser board-approved continuing education unit (CEU) has been applied for, for those who are able to participate in the live webinar. Information about how to apply to receive the credit (if approved) will be provided at the end of the live webinar.

Hilary Pierce

Chatting with Secretary Mike Naig

If you missed our February webinar with Iowa Secretary of Agriculture Mike Naig, you are in luck! You can listen to the conservation with Dr. Jacqueline Comito on Episode 52 of the Conservation Chat.

The newest episode offers a shorter version that highlights discussion topics like the challenge of scaling up to meet the Iowa Nutrient Reduction Strategy Goals and the need for federal, state and private partnerships to reach the goals.

Be sure to subscribe today and catch up on all the great episodes on your favorite device. You can also stream the podcast and webinar from our website.

Liz (Juchems) Ripley

February 5 Webinar: A Conservation Chat with Secretary Naig


Sec. Naig headshot 19

Iowa Learning Farms will host a webinar on Wednesday, February 5th at 12:00 p.m. with Iowa Secretary of Agriculture Mike Naig.

The webinar will feature Dr. Jacqueline Comito, Iowa Learning Farms Program Director, and Secretary Naig discussing conservation, water quality and the Secretary’s vision for Iowa.  They will also discuss the Iowa Nutrient Reduction Strategy and how Iowans are working to meet the nitrogen and phosphorus loss reductions outlined in the Strategy. Webinar participants will be able to submit questions for Secretary Naig during the webinar through the Zoom Webinar software.

Don’t miss this webinar!
DATE: Wednesday, February 5, 2020
TIME: 12:00 p.m.
HOW TO PARTICIPATE: visit and click the link to join the webinar

More information about this webinar is available at our website. If you can’t watch the webinar live, an archived version will be available on our website:

Hilary Pierce

Overview of the Iowa Nutrient Research Center


Are you curious about the role of the Iowa Nutrient Research Center (INRC) and the projects that the INRC has supported and is currently involved with?

Kay Stefanik, Assistant Director of the INRC, discussed the Center and some of the impacts from research projects funded by the INRC, as well as its current activities, in a short webinar on Wednesday. Watch the webinar here!INRC Graphic

Be sure to also check out the upcoming seminar series that is being launched by the INRC! The first seminar will be next Wednesday, January 22 – see below for more information.

INRC Seminar

And  join us next month, on February 5, when Jacqueline Comito will sit down with Mike Naig, Iowa Secretary of Agriculture, for a Conservation Chat!

Hilary Pierce

Saturated Buffer Helping Improve Water Quality Near Walcott

ILFHeaderIMG_0035Mike Paustian returned to the family’s heritage farm in 2008 which encompasses nearly 1,400 acres and a 1,200 sow farrow-to-finish hog operation. In addition to using no-till and minimum tillage, the Paustian’s began adding cover crops to hold soil in place, while scavenging nutrients from the soil and fall applied manure. Their goal is to build long term soil health and organic matter in their fields and improve water quality. They have used primarily cereal rye and oats on about 600 acres for over seven years.

Taking the next step to reduce nitrate loss from their farm, the Paustians installed a saturated buffer just north of their home in the summer of 2018 and are using drone technology to monitor the performance of their farm and conservation practices.

These practices were on full display at our field day last night as the Paustians shared their experiences and efforts to help improve water quality and soil health.

IMG_0003Kay Stefanik, assistant director of the Iowa Nutrient Research Center, set the stage with an overview of the Iowa Nutrient Reduction Strategy and demonstrated how nitrate test strips can be used by farmers and landowners to check their local water quality. These test strips can provide a nitrate and nitrite concentration result in just 30 seconds and should be used multiple times throughout the year to provide a more accurate representation of the system. These strips are available through ISU County Extension offices or by contacting Jamie Benning, Iowa State Water Quality Manager.

After a short walk to the saturated buffer, Keith Schilling and Matthew Streeter, Iowa Geologic Survey, guided us through the installation process and ongoing monitoring of the site. Supported by an Iowa Department of Agriculture and Land Stewardship grant, they are collected data through 2020.

Results from the first year of data indicate that the nitrate concentration leaving the saturated buffer is <2 mg/l whereas the control is measuring an average of over 20 mg/l. With good infield management of nutrients and the addition of cover crops, there is little nitrate entering the buffer and the soil microorganisms are then able to efficiently remove nitrate that does enter the system and release it as N2 gas.

IMG_0029Using their sampling gear, we were able to use a nitrate test strip and take a quick measurement during the field day. The strip revealed about 2 mg/l – consistent with the results from the on-going monitoring.

Back at the shop, Mike provided a quick demonstration of how he is using drone technology to monitor crop and conservation practice performance to help guide management choices for their operation. Using software to analyze the imagery, he was able to observe how his cereal rye cover crop fared during the very wet spring.

IMG_0041“It is clear on this map (lower left corner) where we ran out of manure two years ago. There is less rye growth in that area and we can now adjust our management decisions to help improve our system,” noted Mike. “Another result of using the drones, is our decision to use a tractor with tracks next spring on a field that showed signs of compaction.”

Whether you have access to drone technology or pick up some nitrate test strips from your local Extension office, you can use these tools on your farm to better inform your decisions and seek technical help from your NRCS office to help make some changes to your system to help improve the long term productivity of your farm.

If you are interested in hosting or attended an upcoming field day, feel free to reach out at 515-294-5429 or

Liz Juchems