Iowa Learning Farms Webinar: Quantifying and Managing Residual Soil Nitrogen

The Iowa Learning Farms (ILF) conservation webinar taking place Feb. 22 at noon CST will feature Greg LaBarge, field specialist, agronomic systems department, The Ohio State University. LaBarge conducts research and outreach on nutrient management and water quality issues through The Ohio State University Extension. His work focuses on the application of 4R (Right Source, Right Time, Right Rate, Right Place) management of nitrogen (N), phosphorus (P) and potassium (K) in row crops, and conservation practices which help limit downstream impacts of nutrients leaving farm fields.

Iowa Learning Farms is an Iowa State University Extension and Outreach conservation and water quality education program.

In the webinar, “Quantifying and Managing Residual Soil N after Corn,” LaBarge will highlight research conducted to help measure residual nitrogen in soil after harvest and discuss management techniques such as cover crops which have proven to limit transport of nutrients to waterways. He will also discuss edge of field losses and additional conservation practices that mitigate nutrient losses.

“Having sufficient nitrogen (N) is critical to supporting maximized crop yields, but our studies are showing a significant amount of residual N in the soil after harvest,” said LaBarge. “Research has shown that the use of cover crops after corn is an effective way to capture residual N as organic matter and improve soils. Identifying and encouraging the deployment of additional practices which keep that N in the field is important to achieving both long-term economic and environmental goals.”

Participants are encouraged to ask questions of the presenters. People from all backgrounds and areas of interest are encouraged to join.

Webinar Access Instructions

To participate in the live webinar, shortly before noon CST Feb. 22:

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. All archived webinars are available on the ILF website, so that they can be watched at any time.

ILF has applied for a Certified Crop Adviser board-approved continuing education unit (CEU) for attending this webinar. Those who participate in the live webinar are eligible. Information about how to apply to receive the credit will be provided at the end of the live webinar.

Upcoming Webinars in the Series:

Up Next: Wednesday, Mar. 1Citizen Scientists and the Community Collaborative Rain, Hail and Snow (CoCoRaHS) Network, with Justin Glisan, Bureau Chief and State Climatologist, Iowa Department of Agriculture and Land Stewardship

March 8: Adam Janke and Kay Stefanik, Iowa State University

March 15: Daniel Kaiser, University of Minnesota

March 22: Seth Watkins, Page County Farmer

Iowa’s Nutrients: Agricultural Inputs and Exports

Iowa soils have given way to 92,000 farms across 48,100 square miles (86% of Iowa’s total land area) that lead the U.S. in two of the most versatile grains; corn and soybean. Meanwhile, Iowa also leads the U.S. in hog meat and egg production. Corn and soybeans, hog meat, and eggs annually produce a multi-billion dollar export industry. However, life vital nutrients from Iowa’s land are also exported in tremendous quantities with these agricultural exports. To sustain Iowa’s agriculture productivity, these nutrients, such as nitrogen (N) and phosphorus (P), must continually be replenished to the soil. To address our question regarding sustaining productivity and our natural resources we need to consider Iowa’s land as a whole including both soil and water.

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What is the Iowa 4R Plus Program?

by Greg Wandrey, Iowa agriculture program director, The Nature Conservancy and 4R Plus program coordinator

The 4R Plus program is a science-based framework designed to increase awareness and provide information about 4R nutrient stewardship and conservation practices to crop advisers and farmers.  These 4R Plus practices can improve soil health, crop yields and water quality.


4R Plus combines the 4Rs of nutrient stewardship – applying the right source of fertilizer at the right rate and right time and in the right place – with the “Plus” conservation practices like cover crops, no-till and edge of field practices like saturated buffers and bioreactors.  These combined practices are needed to achieve the nitrogen and phosphorus loss goals of the Iowa Nutrient Reduction Strategy.  This strategy calls for a 45% reduction in total nitrogen and phosphorus loads going into Iowa waters, with 41% and 29% reductions in nitrogen and phosphorus loads, respectively, from non-point sources, such as agricultural production.

The 4R Plus program began in 2016 by bringing diverse organizations together to create an outreach campaign to help inform Iowa farmers about the suite of conservation practices available to them.  To date, more than 40 organizations have enlisted their support of the Iowa 4R Plus program, including agri-businesses, commodity groups, trade associations, government agencies, conservation organizations, Iowa State University and Iowa Learning Farms.

To kick off the project, market research was conducted with Iowa farmers and Certified Crop Advisers (CCAs) to help understand what practices they were using, key messages that resonated with them, barriers that hindered them from trying new practices and what their plans were for adopting new practices in the future.  The results showed that messages that resonated the strongest with farmers centered on 1) the role of healthy soil in addressing more extreme precipitation patterns, and 2) the importance of passing the farm to the next generation in better shape than they received it.  The market research also verified the importance of CCAs as the trusted adviser to farmers.

With the market research results in hand, 4R Plus coalition members developed 4R Plus informational resources that they could leverage with their internal and external stakeholders, including CCAs and farmers.  The resources include a 4R Plus brochure, 4R Plus Fact Sheet, a website (, 4R Plus Blogs, an adviser module and a Twitter account (@4RPlus).  Most recently, a series of five videos were released that describe Conservation Practices, the 4Rs of Nutrient Stewardship and the Iowa Nutrient Reduction Strategy.  In addition, the five videos were converted into courses for CCAs to take for Continuing Education Units (i.e. credits).  The CCA courses can be found at 4R Plus CCA Courses.

In addition to the 4R Plus resources mentioned above, the 4R Plus program has a communications and outreach component at the state level that includes radio, print and digital media.  In 2018, these media platforms are delivering 4R Plus messages to 85-90% of Iowa farmers.

The 4R Plus program is an exciting new effort to bring information about nutrient management and conservation practices to the Iowa farming community in a straight-forward and factual way.  The partners are committed to helping farmers implement practices that fit their unique individual operations and provide economic, agronomic, environmental and societal benefits on their farm and to their downstream neighbors.

If you are interested in learning more about 4R Plus or want to join the coalition of more than 40 agricultural and conservation organizations that support 4R Plus, please contact me at


gregGreg is a native Iowan who grew up on a crop and livestock near Dyersville, Iowa.  He received his B.S. and M.S. degrees in agronomy from Iowa State University and Ph.D. in agronomy and plant genetics from the University of Minnesota.  Greg joined the Iowa chapter of The Nature Conservancy in 2016 to lead the Iowa 4R Plus program.