- 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: https://dl.sciencesocieties.org/publications/jeq/tocs/45/3#h1-SPECIAL%20SECTION:%20MOVING%20DENITRIFYING%20BIOREACTORS%20BEYOND%20PROOF%20OF%20CONCEPT
OIP to host seventh annual summer immersion program that has recruited dozens of grad students to ACES
The Office of International Programs (OIP) will host students from China, Ghana, and possibly Mexico as part of the seventh annual International Summer Immersion Program (ISIP) that begins on July 5.
The award-winning ISIP is a five-week program that includes a research apprenticeship with an ACES faculty member as well as a series of topical seminars, language classes that focus on English for graduate students, and cultural field trips. The program culminates with a poster session, where the students showcase their research experiences.
“This unique program, with more than 120 graduates in the past six years, has served to introduce many potential graduate students to the Urbana-Champaign campus,” said Suzana Palaska, associate director for OIP who coordinates the program.
One such student is Jing Jin, an alum of the 2014 summer program, who joined the ACES Department of Food Science and Human Nutrition as a “3+2” program student this past August. (The “3+2” program consists of three years of undergraduate work at the student’s home institution and two years of graduate study at an institution abroad.) Jin is currently studying under Dr. Nicki Engeseth.
Jin said she certainly had the “3+2” in mind when she first visited the U of I as part of ISIP.
“I wanted to get a feel for the University, see the labs, and meet potential advisors,” Jin said.
Completing the ISIP program and especially the research project in Dr. Keith Cadwallader’s lab was life-changing for Jin and inspired her to apply to the graduate program at Illinois.
“Previously I had only worked with food chemistry, but by working with Dr. Cadwallader, I gained experience in a sensory lab working with aroma and taste. I learned how to use all the machines in this lab, and I met people I am still friends with today. The research project I completed, although relatively small because of the short timeframe of 40 days, is something that has added great value to my resume,” Jin said.
The quality and value of the ISIP program have been recognized by faculty and students at ACES’ key partner universities. At Zhejiang University, the program has repeatedly received the “Best Summer Group Program” award.
In addition to Jin, more than 20 other ISIP alums have matriculated to graduate programs at Illinois. A new component to the ISIP program is to facilitate an alumni network of past students who are now at Illinois.
“Continuing our relationship with former participants of ISIP is of great importance to the ACES Office of International Programs. Our alums are our best recruiters, and their positive experience with the program - our most potent advertisement. In an attempt to further nurture this important network, OIP will strengthen existing ties, plan alumni events, and organize 'mixers' with the new program participants in the coming months,” said Palaska.
The ISIP program is also a great opportunity for ACES faculty to cultivate new international collaborations.
OIP will soon be matching each new student with an ACES faculty mentor. Most of the students are interested in crop sciences, agricultural and biological engineering, and food science and human nutrition. If you are an ACES faculty or staff member interested in serving in a mentoring capacity, please contact Suzana Palaska at email@example.com.
Webinar to look at complex system of local governments in Illinois
URBANA, Ill. – The University of Illinois Extension Local Government Education (LGE) will host a free webinar titled, Illinois Local Government: How do you make essential services more effective and efficient?, on Thurs., May 19 from noon to 1 p.m.
During the webinar, Kent Redfield, a professor emeritus of political studies at the University of Illinois at Springfield (UIS), will describe how the complex system of local government in Illinois came to be, the current constitutional and statutory structure that frames local government, and the barriers and forces that prevent the creation of more efficient and effective ways of providing services to the citizens that local government serve.
Building on that foundation, he will look at the promise and the limitations of intergovernmental cooperation, single unit and multi-function consolidation, and mandate relief as ways of achieving benefits for citizens who play multiple roles as funders, consumers, and providers of essential local government services.
Redfield has research appointments with the Center for State Policy and Leadership at UIS and the University of Illinois’s Institute of Government and Public Affairs. Prior to joining UIS in 1979, he worked for four years as a member of the research/appropriations staff for the Speaker of the Illinois General Assembly. His primary assignment with the legislature was staffing the House’s local government committees.
Redfield served as a member of the Sangamon County Citizens Efficiency Commission, which was created by a countywide referendum in November 2010. The commission studied the structure and performance of local government units in Sangamon County and recommended a series of reforms and initiatives aimed at improving the effectiveness and efficiency of the services that local governments provide to the citizens of Sangamon County.
There is no cost to attend the webinars, however pre-registration is required. Register online at https://web.extension.illinois.edu/registration/?RegistrationID=14370. For more information, contact Kathie Brown, community and economic development educator, University of Illinois Extension at firstname.lastname@example.org.
Are large corn and soybean price swings finished or just beginning?
URBANA, Ill. – Corn and soybean prices have traded in a wide range since last summer. July 2016 corn futures traded to near $4.70 in early July 2015, declined into harvest, and then bottomed at $3.51 following the release of the recent USDA Prospective Plantings report. July 2016 soybean futures traded near $10.31 in early July 2015, dropped sharply into harvest, and traded between about $8.60 and $9.30 from harvest through early April 2016.
According to University of Illinois agricultural economist Darrel Good, the price of both crops experienced a sharp rally this month. July 2016 soybean futures moved to a high of $10.43 on April 21 before finishing last week at $9.96. July 2016 corn futures experienced a more modest rally, trading to a high of $4.07 and finishing the week at about $3.75.
“A number of factors contributed to the rally that was led by soybeans,” Good says. “Excessive rainfall in parts of Argentina likely resulted in a measurable, but unknown, reduction in the size of the soybean crop due to flooding. Heat and dryness in Brazil has threatened the size of the corn crop in those areas that produced bumper crops the past two years. A weaker U.S. dollar also raised expectations for increased export demand for U.S. corn and soybeans. Large producer sales of corn and soybeans contributed to a weaker basis in many areas as futures prices increased. Forecasts for more favorable weather in parts of both Argentina and Brazil helped fuel the sharp reversal in prices on Friday of last week.”
So where do prices go from here?
“In the short term, much will depend on how much corn and soybean production potential has been reduced in Brazil and Argentina,” Good says. “The magnitude of the reduction will not be known for a while, but some evidence of the market’s expectation about South American crop size will likely be revealed in the pace of U.S. export sales. For corn, weekly sales have been generally strong since early January and are currently well above the pace needed to reach the USDA’s projection of 1.65 billion bushels of exports for the year.
“Recognizing that some sales for delivery this marketing year may be cancelled or rolled into the next marketing year, sales may need to reach 1.725 billion bushels in order for exports to reach 1.65 billion bushels. New sales of only about 16 million bushels per week are needed during the last 20 weeks of the marketing year to reach that goal. New sales averaged 46 million bushels per week for the two weeks ended on April 14, and 38 million bushels per week since the beginning of the calendar year.”
For soybeans, Good says export sales may need to reach about 1.75 billion bushels if actual exports by the end of the marketing year are to reach the USDA projection of 1.69 billion bushels. That goal would require weekly sales averaging 2 million bushels over the last 20 weeks of the marketing year.
“Although new sales are typically very small from April forward, sales averaged 14.5 million bushels per week for the two weeks that ended April 14,” Good says. “It appears likely that both corn and soybean exports will exceed the current USDA projection, with the magnitude of new sales over the next few weeks to give an indication of how big the margin might be.
“The pace of domestic consumption of corn and soybeans will also have some influence on prices through the end of the marketing year,” Good adds. “Corn used to produce ethanol and co-products during the last half of the year will have to be about equal to that of last year for use to reach the USDA projection of 5.25 billion bushels. The pace of ethanol production in March and early April suggests that the projection will be exceeded. Feed and residual use of corn during the last half of the year needs to be only 97 percent of last year’s use in order for the marketing-year total to reach the USDA projection of 5.25 billion bushels. The current level of livestock and poultry inventories suggests that the projection could be exceeded as well. The soybean crush during the remainder of the marketing year will have to be about equal to that of a year ago to reach the USDA projection of 1.87 billion bushels.”
According to Good, the pace of export sales of soybean meal, along with the monthly USDA soybean crush estimates, will provide some indication of the likelihood of the domestic soybean crush meeting that projection. The year-over-year decline in the crush in March does raise some concern that the projection may be a bit too high.
“Although the magnitude of consumption and prospects for year-ending stocks will have some influence on corn and soybean prices, prospects for the size of the 2016 crops will be the main driver of prices for the next four months,” Good says. “In the near term, those expectations will be influenced by the pace of planting and early-season crop conditions. Expectations will also be influenced by the USDA’s June 30, Acreage report indicating whether planted acreage differed from intentions.”
Crop size will ultimately depend on summer weather.
“We have previously made the case for an elevated risk of yields falling below trend value this year as summer weather is influenced by the fading El Niño episode,” Good says. “Even after the recent rally, new crop prices may still understate that risk. It will not be surprising to see periods of volatile prices, similar to that just experienced, continue through the summer. Now is the time for producers to establish targets for pricing a portion of the 2016 and 2017 crops.”
Causes of childhood obesity complex, but families, media play key roles
URBANA, Ill. — Children’s genetic risks for obesity may be reduced by interventions that strengthen family communication and help children manage their emotions and feelings of satiety, according to a new review of research on the problem.
Although the causes of obesity are complex, families have significant influence on children’s dietary habits and weight, and should be involved in planning healthy living campaigns and efforts to curb food marketing that targets children, suggest the study’s authors, Barbara H. Fiese and Kelly K. Bost, both with the University of Illinois.
“The family system plays an important role in understanding childhood obesity – not as a source of blame but as part of a larger ecology that may support or derail children’s health,” wrote Fiese and Bost, who are scholars with the U. of I.’s Family Resiliency Center and its Synergistic Theory and Research on Obesity and Nutrition Group, better known as the STRONG Kids program.
While researchers have identified about 20 genes that heighten people’s risk for obesity, a recent large study with 10-year-old children found that children’s awareness of and response to feelings of fullness or hunger mediated the relation between their genetic risk for obesity and their body mass index, Fiese and Bost wrote.
Published recently in the journal Family Relations, the paper by Fiese and Bost indicated that shared family meals provide powerful opportunities to promote and model healthy eating behaviors and reduce children’s likelihood of developing eating disorders or weight problems.
“Family communication is key to the developmental processes that promote – or disrupt – healthy eating habits, physical activity and internal cues to satiety,” said Fiese, who is the center’s director as well as a professor of human development and family studies. “Families who routinely engage in positive forms of direct communication and show genuine concern about each other’s activities also have children who are less likely to be overweight or obese, or engage in unhealthy eating habits.”
In a recent study of 200 families, Fiese’s research team found that children whose family members shared meals that lasted at least 20 minutes each a minimum of four times a week weighed significantly less than peers whose family dinners were three or four minutes shorter.
Parenting styles, parent-child attachment relationships and feeding practices all have been found to be reliable indicators of children’s food consumption, eating behaviors and risks for obesity. However, experts often don’t involve parents when planning healthy-living campaigns for fear that parents will feel they are being blamed for their children’s weight problems, according to the study.
Parents who are indulgent – those who are not very demanding and are highly responsive to their children’s desires – tend to have children who eat fewer fruits and vegetables and more foods with high levels of sugar and fat, Fiese and Bost report.
“Several studies have indicated that parental responsiveness to young children’s distress, including early hunger cues, contain some of the first learning experiences of dyadic stress coping and the resulting regulation of internal states, including emotions,” said Bost, a professor of child development.
Researchers have found that using electronic media while dining increases children’s risks for obesity as well, and Fiese and Bost hypothesize that there may be several reasons for this effect. Focusing on TV shows, text messages or other media may impede the positive communication and social interaction that promote healthy dietary habits. Adults may forego opportunities to model healthy eating habits such as portion control and be less attentive to what their children are consuming, the researchers said.
Studies also have found that people who are engrossed in watching TV or using their computers tend to eat mindlessly, consuming greater amounts of unhealthy foods and ignoring feelings of fullness, Fiese and Bost report.
Another hazard associated with electronic media usage during meals is that it increases children’s exposure to food commercials and advergames – video games created as product-marketing vehicles, oftentimes to whet young viewers’ appetites for unhealthy foods such as sugary snacks, cereals or soda, Fiese and Bost wrote.
Both the Institute of Medicine and World Health Organization have identified the marketing of foods high in fat, sugar and salt as an important causal factor in childhood obesity, Fiese and Bost report.
Children between the ages of 2 and 11 view more than 10 food advertisements on TV daily, and although most 5-year-olds can name common food brands, they tend to recall more of the unhealthy products, researchers have found. Even worse, when children see an advertisement multiple times or in various forms, such as on billboards and on the Web, they perceive that food as nutritious, Fiese and Bost wrote.
Although the researchers support greater collaboration of experts with families, educating parents about the need to eat healthy and increase physical activity may not be enough, the researchers wrote: Parents also need the social tools to put concepts into action.
Toward that end, researchers at the Family Resiliency Center developed a series of educational videos called Mealtime Minutes, which address common problems such as sibling conflict, picky eaters and electronic device usage during meals. The videos are available on the center’s website, on Youtube and Vimeo.
Herbicide resistance in waterhemp continues to grow
- Populations of the broadleaf weed waterhemp have been found to be resistant to the class of herbicides known as HPPD-inhibitors.
- A University of Illinois study shows waterhemp resistant to HPPD-inhibitors were also resistant to several other classes of herbicides, making it even harder to control chemically.
- Weed management programs that do not rely exclusively on chemical methods may be the key to reducing waterhemp populations over time.
URBANA, Ill. – Twenty-five years ago, waterhemp was virtually unknown to Illinois farmers. Today, the broadleaf weed blankets corn and soybean fields across the state and the Midwest, causing yield losses from 40 to 70 percent.
As it marched through the region, waterhemp began to develop resistance to the most commonly used herbicides of the day. A relatively new type of resistance to a class of herbicides called HPPD-inhibitors was discovered in waterhemp populations in Illinois and Iowa in 2009. Now, thanks to a new University of Illinois study, we know that some of those populations are also resistant to alternative herbicides, making them even harder to kill.
“We looked at the response of a McLean County, Illinois, population to a number of HPPD-inhibitors and several herbicides of six other classes in the field and in the greenhouse,” says University of Illinois weed scientist Aaron Hager.
The researchers looked at whether it was possible to control plants with higher application rates of HPPD-inhibitors. But it turned out that, even with twice the label rate of some HPPD-inhibitors, the plants were able to recover after two weeks.
“When we did our first greenhouse work with this, no one had ever seen this kind of recovery before. When we looked at the plants seven days after spraying with HPPD-inhibitors, they were very injured. But, by 12-14 days, you could see that new, healthy tissue was emerging from the plants,” Hager recalls.
The researchers also evaluated the timing of post-emergence herbicide application.
“The idea was that perhaps a smaller plant size might be more sensitive than a larger plant,” Hager explains. “The level of injury of small, 1- to 2-inch plants was more than what we recorded on larger plants, but it was still less than an acceptable level of control. So, really, application timing is not going to be something that a farmer could use to overcome HPPD-resistance.”
When waterhemp was treated with herbicides from different classes, there was more bad news.
“We essentially confirmed that we can’t control this population with three classes of herbicides, the HPPD-inhibitors, the ALS-inhibitors, or the PSII-inhibitors. The weight of everything together points to the fact that this population is using resistance mechanisms that we haven’t seen before,” Hager says.
That said, the McLean County population is not the only waterhemp population that is resistant to multiple herbicide classes. In fact, Hager says that it’s rare to find a population that is resistant to only one class.
“What’s changed over time is the number of different classes to which it’s resistant. In 2000, we first found a population that had three-way resistance. Then we found one with four-way resistance. Those are individual plants with resistance to two, three, or four different classes of herbicides,” Hager notes.
There are some herbicides that are still effective, at least on specific populations. The McLean County population is sensitive to glyphosate, glufosinate (a GS-inhibitor), and multiple PPO-inhibitors, such as fomesafen.
Hager cautions that, with certain resistance mechanisms, the ability to predict which herbicides will be effective on any given population has been lost, and that chemical control alone is not the answer. If a farmer switches to a class of herbicides that works today, it is unlikely to work for very long before waterhemp develops resistance.
“Ultimately, we know how to win the battle,” Hager says. “If we attack waterhemp at the most vulnerable stage in its life cycle—the seed—we could beat this thing in five to seven years.”
Hager recommends that farmers let seeds germinate, then mechanically work the soil before planting the crop.
“You’ve just reduced your seedbank by millions, maybe hundreds of millions, and it didn’t cost you a dime,” Hager notes.
Farmers should repeat this strategy for multiple years until the seedbank is diminished. Another key is pulling out any stragglers before they go to seed.
“Let’s say it’s late July, and you see a few of these things popping up. Don’t let them go to seed,” Hager warns. “It’s not fun. At that time of year, it’s hot, sticky, and miserable, but the ultimate goal is to reduce the seedbank. You can’t let female plants go and make hundreds of thousands of seeds and then run a combine through at the end of the year. You’re going to reseed that whole field.”
According to Hager, no new herbicides are being developed that are likely to work on waterhemp long-term.
“We’ve got to get people off this idea that we’ve got a chemical solution for waterhemp, because in some cases, we don’t,” Hager adds.
The article, “Responses of a waterhemp (Amaranthus tuberculatus) population resistant to HPPD-inhibiting herbicides to foliar-applied herbicides,” is published in Weed Technology. Lead author, Nicholas Hausman, along with co-authors Patrick Tranel, Dean Riechers, and Hager, are from the University of Illinois. Financial support was provided by Syngenta Crop Protection.
The paper can be read at http://www.wssajournals.org/doi/full/10.1614/WT-D-15-00098.1.