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Spring nitrogen management for corn

Published April 27, 2016

URBANA, Ill. – Although the price of nitrogen fertilizer has fallen in the past year, the lower price of corn means that decisions about nitrogen management need to be made carefully, with an eye towards maximizing the return on investment for this important input.

The first question on nitrogen management is rate: How much nitrogen will the crop need, and how much of this will need to come from fertilizer?

“The generally accepted rule of thumb is that the crop will take up a total of about one pound of nitrogen for each bushel of yield. We’ve found a similar number in a few studies we’ve done,” says University of Illinois crop scientist Emerson Nafziger.

Not all of the nitrogen needed for the crop has to come from fertilizer, though; some of it will come from soil organic matter. How much the soil provides is related to soil depth and amount of organic matter, but it also varies by year, depending on weather and crop conditions. That makes the amount difficult to predict.

“In the deeper, higher organic matter soils in Illinois, we might see amounts of up to 200 pounds of nitrogen per acre available to the crop in a good year, while in shallower and lower organic-matter soils or in a year with cool, dry soil conditions this could be as little as 20 or 30 pounds,” Nafziger notes.

At current corn and nitrogen prices, studies over recent years have shown that corn following soybean in southern and central Illinois should be fertilized with about 175 pounds of nitrogen per acre, while in northern Illinois, where more nitrogen is present in the soil, this rate is about 150 pounds of nitrogen. For corn following corn, the rate that provides the maximum return to nitrogen is about 200 pounds of nitrogen per acre everywhere, but perhaps slightly less in southern Illinois.

Form, timing, and placement of nitrogen fertilizer can affect nitrogen availability to the crop.

“Knowing the basics of how different fertilizer materials behave can only take us so far,” Nafziger says. “What happens to nitrogen in the soil that affects it availability to the crop is heavily dependent on weather. This means that our predictions regarding nitrogen form and timing are only about as good as our ability to predict the weather before the season starts.”

Still, nitrogen management can be improved with research over a range of sites and years. Nafziger and his research team initiated a large study in 2014 to look at the effect of nitrogen form, timing, and placement on corn yield. There were a total of 15 treatment variables in the study, but the nitrogen application rate was held constant at 150 pounds per acre.

Yield varied somewhat with the form of nitrogen applied. Dry forms of urea with Agrotain® and SuperU® applied at planting produced the highest yields, but yields obtained with urea ammonium nitrate (UAN) injected at planting and of anhydrous ammonia with N-Serve were also high.

The team also experimented with non-traditional application methods and timing, such as surface-banding UAN at planting and holding some of the nitrogen back until tasseling. 

“While we saw some small differences among treatments, commonly used timing and forms of nitrogen all produced similar yields, even under what we would consider high-loss conditions with all the rain in June 2015,” Nafziger says.

Their results showed that both the risk of nitrogen loss and the benefit from delaying nitrogen application or using inhibitors were less substantial than expected.

“That provides some confidence that most of the nitrogen management systems in use today have good potential to provide the crop with adequate nitrogen. Adding costs by changing nitrogen management, for example by making another trip over the field to apply late nitrogen, may not provide a positive return compared to applying all of the nitrogen in one or two earlier trips,” Nafziger says.

Nafziger’s research is sponsored by the Nutrient Research and Education Council. More details and data can be found at

Three NRES Students Achieve Bronze Tablet Honors for 2016

Published April 26, 2016
Three NRES students will receive Bronze Tablet recognition.
Three NRES students will receive Bronze Tablet recognition.

Congratulations to NRES students Catherine Kemp, Abigail Petersen, and Erik Stanek, recipients of 2016 Bronze Tablet honors!

The University of Illinois began the tradition of inscribing the Bronze Tablets with the names of students receiving University Honors in 1925. A new tablet is hung in the Main Library each year. Inscription on the Bronze Tablets recognizes sustained academic achievement by undergraduate students at the University of Illinois at Urbana-Champaign. According to the Student Code, students must have at least a 3.5 cumulative grade point-average through the academic term prior to graduation, and rank in the top three percent of the students in their graduating class.

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College of ACES

Six ACES graduate students receive 2015 Borlaug Fellowships for work in developing countries

Published April 26, 2016
Anna Fairbairn collects a fertilizer sample in Tanzania.

The six ACES graduate students named as 2015 U.S. Borlaug Fellows in Global Food Security were awarded an opportunity of a lifetime to develop their graduate research in developing countries.

“The fact that students from the University of Illinois College of ACES won four of these 22 prestigious awards in the fall and two of the 14 awards in the spring, picked from applicants across the United States, is a testament to the strength of the work we are doing in the area of food security,” said Alex Winter-Nelson, director of the ACES Office of International Programs.

You may view all of the Bourlaug Fellows here:

For Anna Fairbairn, a M.S. student in agricultural and consumer economics advised by Dr. Hope Michelson, the Bourlaug Fellowship helped fund her work in Tanzania to study the implications of mineral fertilizer quality on markets and small farmers.

For nearly two years, Fairbairn has worked long days in Tanzania conducting surveys and collecting samples.

“We surveyed 225 agro-dealers and collected 370 samples of fertilizer. Of the eight districts in Morogoro region where we surveyed and collected fertilizer, we re-visited all of the agro-dealers and purchased additional samples of fertilizer. We have just started a survey with farmers and will also collect fertilizer samples from them,” she said. 

From this work, she has developed evidence on the quality of fertilizers for sale. Her resulting research is the first assessment of market-available fertilizer quality in Sub-Saharan Africa linked with details about the fertilizer supply chain, as well as the first analysis of relationships between actual quality and purchase quantities. The results will be fundamental to designing effective policy to increase agricultural production and food security in the region.  

Seth Morgan, a M.S. student in agricultural and consumer economics advised by Dr. Kathy Baylis, traveled to western Kenya over spring break to begin studying the impacts of agroforestry on soil health and farmer livelihoods. The project is collaboration between Illinois and The International Centre for Research in Agroforestry in Kenya. He will return to Kenya in June to finalize a survey and conduct the data collection.

“Our study uses remote sensing data to identify tree cover, erosion and soil organic carbon impacts due to agroforestry implementation, which is a great opportunity for me to learn spatial analysis methods along with survey data analysis,” said Morgan.

Thanks to the Bourlaug Fellowship, Liana Acevedo-Siaca, a Ph.D. student in Crop Science/Plant Breeding and Genetics advised by Dr. Steve Long, will be taking her experience working on the Realizing Increased Photosynthetic Efficiency (RIPE) project to the International Rice Research Institute (IRRI) based in Los Baños, Philippines. 

Going to IRRI will give Acevedo-Siaca the freedom to cultivate rice in more ideal conditions than Illinois and allow her to work with leaders in rice research.

Marlee Labroo, a M.S. student in Crop Sciences-Plant Breeding, will also be working in The Philippines as part of her Bourlaug Fellowship.

Another Bourlaug fellow, Elizabeth Sloffer, a Ph.D. in Food Science advised by Dr. Juan Andrade, will be in Honduras from June through December to study linkages among gender, nutrition, and agriculture. Using a combination of surveys, interviews, and biomedical data, she will work towards understanding the Honduran woman’s role as a food utilizer. Specifically she will look at how participating in extension services at the Horticulture Innovation Lab Regional Center at Zamorano University contributes to performing that role.

Marshaun Montgomery, M.S. in Agricultural and Applied Economics advised by Dr. Kathy Baylis, traveled to Zambia in February to meet with local partners and government officials to lay the groundwork for household and market to be conducted in June. The goal of his Bourlaug fellowship is improve drought risk by understanding cross-scale interactions of trade and food policy.

“The Government of Zambia has been a great partner in providing extensive secondary data, spatial shapefiles, and logistical support. We are working directly with the Zambian Agricultural Research Institute to ensure that our research is in-line with the national agricultural and economic development agenda with input from local stakeholders,” said Montgomery.

The U.S. Borlaug Fellows in Global Food Security Program awards are awarded each semester through the Center for Global Food Security at Purdue University. The awards are funded by the United States Agency for International Development (USAID) to expand the pool of U.S. food security professionals who have the scientific base needed to effectively study and manage the global landscapes in support of sustainable food systems. For more information and posting dates, visit:




Planting date: Corn or soybean first?

Published April 26, 2016
corn seedlings

URBANA, Ill. – Many Illinois corn and soybean growers are busy planting their crops, with 42 percent of the corn and two percent of the soybean crop planted as of April 24. However, those producers who are just getting started or are still waiting for dry fields may not see a large yield penalty, according to University of Illinois crop scientist Emerson Nafziger.

“We’ve run 35 corn planting-date trials in central and northern Illinois over the past nine years, with four planting dates at each site beginning in early April and going through late May or early June,” Nafziger says.

Nafziger’s data indicated the planting date that gave the highest corn yield was April 17, but that date was not substantially different compared to April as a whole. For example, yields were within 1 percentage point (about 2 bushels per acre) of the maximum between April 5 and April 30.

“Beyond April, we predict yield losses of about 4 percent (8 bushels per acre) by May 10, 8 percent (17 bushels) by May 20, and 14 percent (29 bushels) if planting is delayed until May 30,” Nafziger states. “We don’t have a lot of data for June planting, but the yield loss going into June is at about 2 bushels per day of delay, and it’s accelerating.”

Nafziger’s research team has also gathered 23 site-years of planting-date data for soybeans in the same sites as their corn studies. The earliest planting date for soybeans was in the second week in April, with the latest dates in mid-June.

The data for soybeans showed that the maximum yield was obtained in mid-April, and that yield loss by the end of April was about 4 percentage points, or about 2.5 bushels. After April, losses totaled 7 percent (4 bushels per acre) by May 10; 10 percent (7 bushels) by May 20; 16 percent (11 bushels) by May 30; 21 percent (14 bushels) by June 10; and 29 percent (19 bushels) if planting was delayed to June 20.

“On a percentage basis, these loss numbers are slightly greater than those from planting delays in corn, but some of this is due to planting soybeans a little later in April than we started planting corn. Both crops lost yield at about the same rate as planting was delayed into late May,” Nafziger notes. “That runs counter to the earlier findings that corn loses yield faster when planting is delayed, and therefore needs to be planted earlier.”

Given that neither crop suffers dramatically from planting through early May, farmers might assume that planting priorities for both crops are similar. But because corn seedlings tend to emerge better than soybeans under soil conditions typical of early spring, Nafziger still suggests starting with corn, at least until soils warm up, to allow faster soybean emergence.

“While letting both crops planted on time is beneficial, we shouldn’t lose sight of the fact that yield losses for delays into and even past mid-May are not so large that we need to give up hopes for a good crop if we aren’t done planting by the end of April,” Nafziger says.

More details and data from field studies are available at:

Veterans and their partners see reduced trauma and distress symptoms after intensive retreat

Published April 26, 2016
  • Military veterans face higher risk of posttraumatic stress disorder (PTSD) after returning from combat situations.
  • Veterans experiencing PTSD may be less likely to seek treatment if it means taking time away from their families.
  • Model of a brief, intensive retreat for veterans and their partners shows success in decreasing PTSD symptoms for veterans and distress for their partners.

URBANA, Ill. – Military veterans returning from combat situations face a higher risk—above most other populations—of developing posttraumatic stress disorder (PTSD). Symptoms, which may include flashbacks, night terrors, and intense emotional reactions, affect not only veterans, but also the partners of veterans. Previous studies have shown a significant association between PTSD and intimate relationship problems.  

Although services exist to help veterans who are experiencing trauma symptoms, they are often underutilized. Family studies researchers at the University of Illinois would like to see that change. They recently assessed an existing weeklong, intensive retreat model for veterans and their romantic partners that includes therapeutic group and couple counseling, as well as relaxation activities. They determined that this model is successful in helping to reduce symptoms and distress for the participants.

Kale Monk, a graduate research assistant in the Department of Human Development and Family Studies at the U of I and lead author of the study said that many veterans with PTSD may not seek help because of the stigma associated with mental illness.

“After veterans complete their service, they may be reluctant to report some of these symptoms because they feel a sense of shame or that others would think less of them if they sought therapy,” he explains. “Many service members fear that seeking treatment will have negative consequences for their career or that their security clearance will even be revoked.”

He adds that another important reason veterans may not seek treatment is that they don’t want to take time away from their families for long-term counseling and most services don’t incorporate the partner or family. “Therapy could take anywhere from 8 sessions to months of treatment and that takes time away from service members reuniting with their families, and most people just want to go back to their lives after a long deployment. Service members and veterans indicate that they would be more willing to engage in treatment if it was brief and family focused.”

Monk says this has prompted service providers to seek out brief workshops or retreats for veterans that also include their support systems.

In a recent study, Monk and colleagues assessed what they call the Veteran Couples Integrative Retreat (VCIIR) model—seeking to evaluate a specific, inclusive treatment for those who had served and may still suffer from trauma, and their partners. The model uses a holistic treatment approach including traditional therapeutic couple sessions and group psychoeducation, as well as yoga, massage, hiking, equine-assisted therapy, and other recreational wellness activities to promote relaxation.

For the current study, veterans must have had a diagnosis of PTSD or be experiencing PTSD symptoms, as well as a referral from a physician or VA clinic staff member in order to participate in the retreat.

During the weeklong retreat, participants engage in general psychoeducation, where they are given information about trauma, how it manifests, and what it looks like. Facilitators also share coping strategies for the veteran and the partner, such as how to handle stressors or identify triggers.

“In addition to the couple sessions, participants learn as a group about these different symptoms and ways of managing stress. They break into groups and talk about issues that are really salient to them with others who will understand their situation because they are coming from similar experiences. This experience sharing and sense of camaraderie seems to be really important, validating, and normalizing. When participants are not in session, they are involved in different relaxation activities and things to get them back into nature to hopefully induce a relaxing state.”

The model intentionally includes veterans from a variety of generations or combat eras to allow for interaction between older and younger veterans.

Using data collected from the National Veterans Wellness and Healing Center, a total of 149 veteran couples (298 individuals) completed assessments before and immediately after the retreat as well as assessments at a 6-month follow-up to determine the effectiveness of the model. Assessments included military and civilian versions of the PTSD checklist.

The results showed a significant reduction in trauma symptoms for veterans and a significant decrease in distress for partners after the retreat.

“Obviously we wanted trauma symptoms to decline for veterans, but what’s additionally encouraging is that we also saw a reduction in distress for partners. Many times you see an initial boost or benefit from a treatment and then people go back to where they started at baseline. But this was really encouraging because at 6 months out, we noticed that these benefits seemed to be maintained for both couple members. That’s one of the strengths of this retreat.”

Monk stressed that not all veterans returning from combat experience PTSD symptoms and not all veteran couples experience relational difficulties. However, in the United States, the lifetime risk for all people of experiencing PTSD is 8.7 percent. Scholars estimate that the risk for veterans is 18 to 54 percent for Vietnam veterans and 16 to 30 percent for veterans of the recent conflicts in Iraq and Afghanistan, which illustrates that a significant proportion struggle even if most are doing well.

Sometimes partners may notice changes right away, but not all changes are indicators of PTSD. “Flat affect and a service member wanting to sleep right when they get home might be more indicative of exhaustion after a long deployment,” he adds. “It can also take some time to notice some of the effects of combat. For some in our study, they struggled with symptoms for years. One Vietnam veteran indicated that he had been struggling for 40 years, but these retreats helped him identify where the distress was coming from.”

Because of the model’s potential success, the researchers are now replicating the study as 4-day retreats. “We are still finding similar outcomes as we did in the weeklong retreat study,” Monk says. “In the new project we are also assessing relationship functioning in those that attend. Looking at the preliminary data, we’re finding that the retreats may also improve relationship quality.”

The retreats are currently free to veterans through grant funding and the contributions of communities where the retreats are held.  

For more information on assisting with or attending a retreat go to or

In addition to veterans, Monk is also involved in research for current military-affiliated service members. For service members who are soon-to-be returning from deployment and their romantic partners who are interested in participating in a survey, go to Participants will receive a $15 e-gift card in exchange for filling out the brief survey.

“Veteran couples integrative intensive retreat model: An intervention for military veterans and their relational partners,” is published in the Journal of Couple & Relationship Therapy and is available online at Co Authors include J. Kale Monk and Brian Ogolsky, of the University of Illinois, and Victoria Bruner, clinical consultant, Chicago, Ill.

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J. Kale Monk

Bioreactors ready for the big time

Published April 26, 2016
Bioreactor construction
Bioreactor construction on a dairy farm. Photo courtesy of Brandon C. Goeller, University of Canterbury, New Zealand.
  • Bioreactors are passive filtration systems that can reduce nitrate losses from farm fields.
  • Most bioreactors are simple pits filled with wood chips; bacteria on the wood chips remove 25 to 45 percent of the nitrate in runoff water.
  • Research summarized in a special issue of the Journal of Environmental Quality highlights their potential applications and provides insight into design options.

URBANA, Ill. – Last summer, the Gulf of Mexico’s “dead zone” spanned more than 6,400 square miles, more than three times the size it should have been, according to the Gulf Hypoxia Task Force. Nitrogen runoff from farms along the Mississippi River winds up in the Gulf, feeding algae but depriving other marine life of oxygen when the algae decomposes. The 12 states that border the Mississippi have been mandated to develop nutrient reduction strategies, but one especially effective strategy has not been adopted widely: bioreactors.

Bioreactors are passive filtration systems that capitalize on a bacterial process known as denitrification to remove from 25 to 45 percent of the nitrate in water draining from farm fields. Research on and installation of bioreactors has accelerated in the past decade, but University of Illinois assistant professor of water quality Laura Christianson and her colleagues are urging a move past proof-of-concept toward large-scale deployment.

“Bioreactors are one of the most effective edge-of-field practices, but until now, they haven’t been rolled out on a large scale,” Christianson says.

Designs vary, but the typical arrangement for a 40- to 80-acre field is a large (100 x 20 foot) pit situated just ahead of where drainage pipes flow into ditches or streams. The pit is filled with carbon-rich organic material: usually wood chips, but sometimes corn cobs, biochar, or other matter. Denitrifying bacteria make their homes in the organic material and utilize its carbon as an energy source to convert nitrate in the water to the harmless nitrogen gas that makes up 78 percent of our atmosphere. 

A benefit of bioreactors as a nitrogen management strategy is their cost-benefit ratio. Bioreactors can cost approximately $10,000 to install, but cost-sharing is available through the USDA’s Natural Resources Conservation Service for approximately half of that. Importantly, bioreactors typically operate for 10 years before wood chips need to be replaced.

“It’s a big up-front cost compared to a cover crop, but then you’re ‘one and done’ for 10 years,” Christianson notes.

Christianson put together a special issue of the Journal of Environmental Quality focusing on bioreactors. Fifteen articles in the issue summarize the state-of-the-art of bioreactor technology, confirming that bioreactors could be an effective part of an integrated approach to nitrate management.

A large component to bioreactor efficiency is design.

According to Christianson and other experts contributing to the special issue, flow rates can significantly affect the efficiency of bioreactors. During low-flow periods, water can be held in bioreactors for too long, setting up conditions for different bacteria that create noxious hydrogen sulfide gas. Likewise, in high-flow periods, water may move through too quickly for efficient nitrogen removal.

“Tile drainage systems never flow at a consistent rate,” Christianson explains. “Bioreactors have to be designed strategically to optimize retention time and maximize nitrate removal without undesirable byproducts.”   

Temperature and seasonal changes also affect how well bioreactors work.

“The critical period for nitrate loss is early spring, before plants are growing and taking up nitrogen,” Christianson says. “Snowmelt puts a significant amount of water through a bioreactor, depending on where you are. And because snowmelt and early spring drainage water is cooler, the bacteria aren’t as efficient.”  

Christianson and her colleagues are calling for more field-scale research to optimize design for the set of conditions unique to each field.

“That’s where my interest is for research: coming up with better designs. But on the other side of that coin, we don’t want to become so advanced in the design that it becomes really complicated. There’s a beauty in the simplicity of a trench full of woodchips,” Christianson says.

The article introducing the special issue, “Moving denitrifying bioreactors beyond proof of concept: Introduction to the special section,” appears in the Journal of Environmental Quality along with 14 additional articles on the topic. Christianson co-authored the introductory article with Louis Schipper of the University of Waikato in New Zealand.

Links to the articles, several of which can be read in full without a subscription, can be found at: