ASC Associate Director Wendy Yang Finds Collaboration Environment Essential to Tackling Nitrous Oxide Emissions

Wendy Yang – Professor of Plant Biology (Courtesy University of Illinois News Bureau)

What stood out about the University of Illinois Urbana-Champaign when Wendy Yang interviewed for a tenure-track faculty position in its Department of Plant Biology a decade ago was the institution’s trademark collaborative nature. A decade later, in that environment, she and her collaborators are making their mark in solving some of the globe’s most pressing climate issues.

“I realized immediately that Illinois is a unicorn institution,” she said. “I met world-class scientists in so many disciplines who don’t have egos, who work together and are collaborative with no walls between units on campus. I’ve been here for 10 years and I’m glad that first impression was accurate.”

That collaborative environment was instrumental in the establishment of two major centers headquartered at Illinois, in which Yang is a core figure — the Center for Advanced Bioenergy and Bioproducts Innovation (CABBI), now in its seventh year and its second round of funding, and the Agroecosystem Sustainability Center (ASC), now in its third year. Yang is Associate Director of ASC and Sustainability Theme leader for CABBI.

It is that against backdrop where Yang has established her research lab and is working to tackle global climate issues, such as mitigating soil nitrous oxide emissions.

“I’ve been working to understand soil nitrous oxide emissions since even before my first day as a graduate student,” noted Yang, who holds a B.A. from Harvard University and a Ph.D. from University of California-Berkeley. “What piqued my interest has been the fact that it has been a tough challenge for the scientific community for decades. Although scientists have known some of the processes that have produced nitrous oxide emissions since before the 1900s, and there have been hundreds if not thousands of studies on these processes, we still can’t predict these emissions in the field. That’s something we need a better understanding of if we are going to successfully mitigate nitrous oxide emissions from agricultural systems.” 

Yang points out that part of the dilemma is that up until now much of the research to understand drivers of soil nitrous oxide emissions has been done in a controlled environment in laboratories. The U.S. Department of Energy funding through ASC’s SYMFONI and SMARTFARM projects has not only brought the research to the field, but allowed the purchase of 20 chambers distributed throughout the field that automatically measure soil nitrous oxide emissions each hour. 

“When you go outdoors, soil conditions are very complex,” Yang said. “Thanks to this project, we’ve been able to produce unprecedented high-spatial, high-temporal resolution data sets on nitrous oxide emissions. It has been a dream project for me. No one else has been willing or able to invest that much funding in one field, but that’s what we need.”

Her team has discovered that even within the confines of a single field, the nitrous oxide emissions are varied — some places higher and some lower. That, among other things, has helped inform management practices where researchers can target the hot spots. 

The collaborative nature of ASC has meant researchers aren’t doing their work in silos, which has been important in helping make recommendations to farmers in areas such as cover cropping. While Yang’s team is looking at its effects on nitrous oxide emissions, ASC Director Kaiyu Guan, Associate Director Andrew Margenot, and DoKyoung Lee, professor of crop sciences, are also doing cover cropping work and can share their findings with Yang’s group.

“A big challenge, especially for the farmers, is increased volatility in precipitation,” she said. “Not only are we getting more intense spring rainfall, but now we’re also getting  drought  that makes it so difficult to not only manage crop productivity, but also to attain the intended sustainability outcomes of climate-smart agricultural practices.” 

Yang’s group is currently conducting a meta-analysis to evaluate trade offs in the soil carbon benefit from practices versus unintended effects on soil nitrous oxide emissions.  While cover cropping might reduce carbon emissions, it might also increase nitrous oxide emissions, which Yang notes is 300 times better at trapping heat than carbon dioxide. 

“A small increase in nitrous oxide emissions may completely offset the climate change mitigation benefits of the soil carbon gains,” Yang said. “What we have learned from our SMARTFARM research is that greater soil organic carbon availability is part of what makes these nitrous oxide hot spots hot.”

Yang shares Guan’s vision of a future where scientists can not only analyze 20 different spots within a field but scale that up to regions, countries, and even the globe.

“What excites me about Kaiyu’s work is that he is crossing that scale from meters to hundreds of kilometers,” Yang said. “We aim to discover predictive variables that can be remotely sensed and scaled from one field to across regions.” 

In that vein, Yang has taken her studies to the area of the globe that is responsible for the highest naturally produced nitrous oxide emissions — tropical rain forests. That’s because nitrous oxide naturally occurs in soils that lack oxygen. Because the rain often pushes the oxygen out of the soils, it encourages the process of nitrous oxide there. 

“One of the reasons I love studying nitrous oxide is that while there are really important questions we need to address in agricultural systems here, we are also indirectly affecting natural emissions. My work has importance everywhere,” Yang said. 

“When I first started in this field some 20 years ago, we were a bit more concerned about the industrialization of the tropical regions and how the nitrogen deposition we’ve seen in temperate industrialized countries was coming to these tropical areas. We wanted to understand how indirectly fertilizing these areas could change tropical nitrogen cycling. We weren’t considering management of tropical forests, but more so representing those changes in our models. Everything that goes into our Earth system models is crucial for predicting future climate change.”

Part of the challenge in reducing nitrous oxide emissions is reversing the cycle. Half of the increase in atmospheric nitrous oxide concentrations comes from human activity, which has resulted in both increased rains and drought. Yang notes that it directly affects the nitrous oxide emissions that occur naturally not only in rainforests, but elsewhere as well. 

“We expect that as the amount of reactive nitrogen we put into the atmosphere increases, it either rains out or it settles out and it fertilizes even our natural ecosystems,” Yang noted. “So even when humans are not having direct impacts on nitrous oxide emissions through fertilizer application, we are still indirectly fertilizing our natural ecosystems, particularly in areas near industrial activities. There have even been studies which show that near roadways, emissions coming out of the tailpipes of cars end up depositing near the roadways.” 

Image Credit: Wendy Yang

“There is currently a lot of interest in climate smart agriculture with start-up companies emerging and industry leaders pouring funds into this,” Yang added. “I think everyone wants an easy solution, for instance sprinkling microbes on the soil, that would fix our problems for us. However, I think we are realizing that there is a reason why those microbes aren’t surviving naturally or dominating naturally in agricultural soil environments. We need to broaden our focus in developing technologies to reduce the nitrous oxide emissions.”

Which is why it has been important for Yang’s group to work closely with that of Margenot, whose focus is also on soil composition, and with Guan and Jonathan Coppess, who can work closely with politicians on areas such as government subsidies to make these climate practices cost-effective for the farmer. 

Yang is excited about what future collaborations could mean in helping solve these global climate issues. She has been doing team science leadership training through the Carl R. Woese Institute for Genomic Biology. 

“We learned that when you build a team, you need to have team members who work well together, not necessarily just the best and the brightest,” she said. “Our success with CABBI shows that at the University of Illinois we know how to function at that large scale, and we know how to build teams that work well together.” 

While the collaborative nature of ASC shows its benefits in research, it also benefits from being at the heart of the study area – the Midwest – and its understanding of bringing to the table the most applicable piece to the puzzle: the farmers. 

“Through DK and Andrew’s relationships with the farmers, we have insight into the actual challenges of the farmer,” Yang said. “We understand the importance of trying to come up with solutions that are not counterproductive to the livelihoods of the farmers.

“I think one of the strengths of our ASC team is that because we have people looking at the same problem from different angles, we can see the tradeoffs, whereas other people may have blind spots because they are only looking at it from one angle,” she said. “Because at ASC we have people from many disciplines working together as a team, we can holistically address these questions.”

With the core group of ASC researchers, including Yang, transitioning from early-career to mid-career scientists, it produces a unique energy. 

“We are on the upper trajectory in our research programs,” Yang noted. “We are finding a lot of overlap in our visions for not only what we want to accomplish as scientists, but also the impact we want to have on society. One of the exciting parts for me is that when we put all that energy together and it’s all going in the same direction, there is so much we can accomplish. We all have big dreams.”

Due to its status as a long-lived greenhouse gas, controlling the emission of nitrous oxide (N2O) is recognized as a core component of climate change mitigation. This gas largely comes from nitrogen fertilizer applied to soil in agricultural regions. An international team led by the Agroecosystem Sustainability Center (ASC) at the University of Illinois Urbana-Champaign is developing an initiative to better track and understand these emissions. This is the foundation to formulate better ways to reduce soil nitrous oxide emissions and verify those reductions. ASC convened this group of international leaders in soil nitrous oxide research on Jan. 17-19 in Chicago to develop a consensus vision for this new initiative and strategize about next steps.

At the heart of the plan is an observational data network called N2Onet, which will accelerate the progress toward fully understanding the drivers of soil N2O emissions and improving model predictions of those emissions. The three-day workshop helped articulate the challenges currently hindering this progress and how this network could be designed to help overcome those challenges.

Fertilizer plays a critical role in high crop production, which in turn helps feed a growing world population. Climate-smart practices aim to maintain or even increase the productivity of agricultural lands while reducing the rate of greenhouse gas accumulation in the atmosphere. Current practices such as reduced tillage and cover cropping may increase carbon uptake and storage in agricultural systems, but could unintentionally stimulate soil N2O emissions, which would counter those climate mitigation outcomes.

Knowledge of N2O emissions is currently limited due to a lack of high spatiotemporal resolution data on emissions and their potential drivers in the environment. The most commonly used emissions measuring tool relies on a manual chamber-based approach that limits the spatial and temporal extent of sampling, likely not capturing some areas that disproportionately contribute to field-scale emissions and episodic, short-lived emission pulses that can account for over half of annual emissions. This can lead to inaccurate prediction and evaluation of how agricultural practices affect emissions. 

N2Onet strives to fill in those gaps by bringing together data that can lead to transformative research in this area, akin to what the Ameriflux Network is doing for carbon cycling. A novel aspect of the network will be the synthesis of data across spatial scales, developing new measurement protocols and sites, to simultaneously support breakthroughs in process-based understanding of emissions, greenhouse gas accounting, and modeling of emissions.

“I was excited to see convergence in ideas about what is needed in an observational network to accelerate the knowledge advances needed to effectively measure, model, and mitigate agricultural soil emissions of this potent greenhouse gas,” said Wendy Yang, ASC Associate Director and Professor of Plant Biology at Illinois. “The workshop successfully built momentum behind this initiative to bring together N2O researchers and their data from around the world, and ASC will continue to play a leading role in this effort.” 

The N2Onet organizing committee include ASC scientists Yang, Evan DeLucia, and Kaiyu Guan, and Claudia Wagner-Riddle from University of Guelph.