Through a New NASA Grant, Interdisciplinary Team to Measure Nitrogen Released from Agriculture Sources

(Left) a satellite-based NOx emission map from TROPOMI derived by Kang’s group, which shows detailed sources of NOx in central and southern US (image credit: Kang Sun); (right)The fast flux sensors, developed by Zondlo’s group, to make continuous flux measurements of NH3 for this project (image credit: Mark Zondlo) .

As researchers continue to understand the effects agriculture plays in climate and environment, a new research project was recently funded by the NASA Interdisciplinary Research in Earth Science (IDS) program, which includes experienced researchers from four institutions. The new project has for the first time made it possible to show the impact two nitrogen fluxes — ammonia (NH3) and nitric oxide/nitrogen dioxide (NOx) — have on agricultural productivity and air quality.

The study led by Kaiyu Guan, Director of the Agroecosystem Sustainability Center at the University of Illinois Urbana-Champaign (UIUC), will integrate satellite remote sensing, strategic field work from commercial farmland in Central Illinois, and ecosystem biochemistry modeling to quantify these nitrogen emissions from agriculture across the U.S. Midwest. The goal is to quantify the magnitude of NOX and NH3 from these fields to the atmosphere. Being able to use approaches from both in situ measurements and satellite data in biochemical modeling will help corroborate the measurements of each.

The three-year interdisciplinary project brings together atmospheric scientists Mark Zondlo from Princeton University and Kang Sun from the University at Buffalo; ecosystem scientists  Steven Hall from the University of Wisconsin-Madison and Wendy Yang from UIUC; and agroecosystem modelers Guan and Bin Peng from UIUC.

Sun’s team will examine the latest NASA satellite data to understand how to develop new methods to estimate the emissions of these two trace gasses. Zondlo will use state-of-the-art, fast flux sensors to make continuous flux measurements of NOX and NH3 and also targeted measurements on a mobile laboratory to bridge the field and satellite scales. Hall and Yang, both field-level measurement experts, will measure NOX at the field level. Guan and Peng will take these measurements and develop the final model.

“It is exciting to work with a team on a project that bridges across vastly different scales and synthesizes across measurement and modeling. This approach is critically needed to advance our understanding of the patterns of agricultural emissions.”  Zondlo commented. 

Ultimately, the goal is to provide improved guidance to farmers on future use of nitrogen fertilizer and alleviation of nitrogen emissions from agricultural practices to improve air quality in agricultural dominated landscapes.

“This is a very unique NASA IDS project,” Guan explained. “We want to take advantage of satellite-based observation, in-situ data, as well as biochemical models to holistically understand the nitrogen cycle. This information has previously been hard to gather.”

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. 

Credit: Robertson & Saad 2021 JAWRA 57(3): 406

Agroecosystems Sustainability Center Associate Director Andrew Margenot gave the keynote address at The Fertilizer Institute Research Forum on March 19 in Dallas, Texas. Margenot’s address was titled Non-point source – and non fertilizer?  – nutrient losses: the case of phosphorus. 

Margenot reviewed evidence that current nutrient loss reduction strategies do not discriminate among non-point sources of nutrient losses, which include but are not limited to agriculture. Specifically, he noted that only a small percentage of streambank phosphorus erosion is recorded, yet it likely accounts for a much more significant amount of the sediment exported through the river system in the Midwest. Therefore, much of the streambank derived-P may not have been correctly attributed.  
He also points out that both legacy and residual phosphorus – a distinction he recently proposed in Environment Science & Technology – should be considered when evaluating the source for phosphorus in the streams and rivers. Lag effects of P losses from legacy and residual P sources can decouple P losses measured today from contemporary fertilizer usage. A current ASC project on this topic is funded by Illinois NREC, and recently reviewed by Margenot at the annual Illinois NREC meeting


Five University of Illinois Urbana-Champaign professors have been named University Scholars. Top, from left to right: Merle Bowen, African American studies; Cecilia Leal, materials science and engineering; and Ying Diao, chemical and biomolecular engineering. Bottom row, left to right: Brian Ogolsky, human development and family studies; and Kaiyu Guan, natural resources and environmental studies.
Bowen photo by Della Perrone; Leal, Diao and Ogolsky by L. Brian Stauffer; and Kaiyu Guan by Chris Brown Photography, courtesy of NCSA.

CHAMPAIGN, Ill. — Five University of Illinois professors at the Urbana-Champaign campus have been named University Scholars in recognition of their excellence in teaching, scholarship and service. 

The scholars program recognizes faculty excellence and provides $15,000 to each scholar for each of three years to enhance their academic career. The money may be used for travel, equipment, research assistants, books or other purposes.

“Faculty excellence is truly the University of Illinois System’s foundation, and unquestionably the basis for the exceptional academic experience of the nearly 95,000 students who enrolled in our three universities last fall,” said Nicholas Jones, the system’s executive vice president and vice president for academic affairs. 

“The University Scholars program spotlights outstanding individuals and provides resources for them to expand their academic horizons. They so richly deserve the accolades that come with this recognition, and their accomplishments also represent the standards to which we aspire as we actively recruit educators and researchers of the highest caliber.”

The five Urbana campus recipients, as described by their nominators:

Merle Bowen
Photo by Della Perrone

Merle Bowen, a professor of African American studies, specializes in Africa and African diaspora. Her recently published book, “For Land and Liberty: Black Struggles in Rural Brazil,” received the P. Sterling Stuckey Book Prize from the Association for the Study of the Worldwide African Diaspora. 

Her current research continues her concern with Black rural communities’ struggles for land and against environmental injustice. In her pedagogy, she balances detailed lectures with in-class and supplemental activities designed to stimulate student engagement, from group analyses and short presentations to structured in-class debates. 

She has mentored students from the Abdias do Nascimento Scholars Program of the Pontifical Catholic University of Rio de Janeiro and she serves as academic director of the Civic Leadership Institute for President Obama’s Young African Leaders Initiative. 

Ying Diao
Photo by L. Brian Stauffer

Ying Diao, a professor in chemical and biomolecular engineering, has established a vibrant and imaginative research program at the interface of materials chemistry, molecular electronics and biomedical sciences. Her highly creative research draws inspiration from many disciplines to significantly advance molecular electronics technology, which promises to have a transformative impact on electronics, clean energy and healthcare. 

Diao works in the area of molecular assembly and additive manufacturing. She has published 68 articles as an independent investigator. Diao is an outstanding educator, winning the School of Chemical Sciences Teaching Award in 2017. She has also mentored 33 undergraduate students, about half of whom are female. She is the chair of the department’s graduate recruiting subcommittee and works to increase diversity through proactive recruiting efforts and forming connections with HBCUs. 

Kaiyu Guan
Photo by Chris Brown Photography, courtesy of NCSA

Kaiyu Guan, a professor of natural resources and environmental studies, has advanced sensing and modeling technologies for monitoring and assessing agricultural productivity and ecosystem services. 

Guan initiated and founded the Agroecosystem Sustainability Center to bring together multidisciplinary teams to address key challenges in measuring, modeling and quantifying the sustainability of agriculture.

His academic achievements have fostered more than 140 journal articles. Guan is committed to training undergraduate students, especially underrepresented students. 

His recent work on agricultural carbon emission has gained national attention, and he has provided scientific advice related to agricultural carbon emission reduction to the White House’s Office of Science and Technology Policy and the U.S. Senate Committee on Agriculture. 

Cecilia Leal
Photo by L. Brian Stauffer

Cecilia Leal, a professor of materials science and engineering, is a pioneer in the area of biomaterials self-assembly and lipid nanoparticles. She has established a highly visible research program in determining structures and interactions of soft materials that impart biological and therapeutic function. 

Leal is the creator and lead organizer of the highly successful Girls Learning about Materials Summer Camp for middle school girls. This camp was initially supported by her NSF CAREER award and remains completely free to participants. She developed and offered three materials science-focused workshops for incarcerated students at the Danville Correctional Center as part of the Education Justice Project at Illinois. 

She has been named twice to the List of Teachers Ranked as Excellent by their students. Through her efforts to promote diversity, equity and inclusion, she has made significant, culture-shifting changes to the materials science and engineering department  and the Grainger College of Engineering.

Brian Ogolsky
Photo by L. Brian Stauffer

Brian Ogolsky, a professor of human development and family studies, is an internationally recognized leading scholar in the field of relationship science, an award-winning teacher and director of graduate programs, and a generous contributor to faculty governance. 

Ogolsky has made major theoretical and empirical contributions to the field of relationship science, with a specific emphasis on romantic partners’ relationship functioning. His publication record includes two internationally awarded books (with a third in press), nine chapters in edited volumes and 47 peer-reviewed journal articles. 

He has been named to the List of Teachers Rated as Excellent by their Students every semester he has taught. Ogolsky excels as a mentor for students, and he has received the Faculty Mentor Award and the Provost Award for Excellence in Graduate Student Mentoring. 

He has served on the board of directors for the National Council on Family Relations and the International Association for Relationship Research. He has served on grant reviews for the National Science Foundation, Robert Wood Johnson Foundation, and the Social Sciences and Humanities Research Council of Canada.  

A study led by researchers at the Agroecosystem Sustainability Center (ASC) at the University of Illinois Urbana-Champaign quantifies the soil organic carbon (SOC) benefits from cover crops in maize-soybean rotations in Midwestern U.S. agroecosystems.

The study, published in Global Change Biology, used ecosys, an advanced process-based ecosystem model, to assess the impacts of winter cover cropping on SOC accumulation under different environmental and management conditions. By understanding how SOC benefits can be achieved and optimized, farmers and policymakers will be able to enact management practices that support fertile fields that also sequester atmospheric carbon dioxide (CO2) into the soil.

Cover crops have been found to be effective in increasing soil organic carbon by sequestering atmospheric CO2 into the soil, and thus have large potential to mitigate climate change. An accessible method of measuring SOC benefits would help farmers, government agencies, and industries implement climate-smart cover cropping practices. However, an accurate and cost-efficient method of quantifying SOC benefits is still largely unavailable.

To help address this need, ASC researchers are taking an ecosystem modeling approach. Their study revealed that growing cover crops can increase SOC by an average of 0.33 megagrams of carbon per hectare per year (which is equivalent to 0.54 tons of atmospheric carbon dioxide per acre per year) in Illinois, and that SOC benefits can be improved through increasing cover crop biomass. The ecosys model not only helps quantify SOC benefits from cover crops, but also improves the scientific understanding of environmental factors that control on SOC benefits, including soil conditions, weather, and cover crop species.

Connecting with the team’s previous work, the researchers also found that there is a trade-off between SOC benefits from cover crops and cash crop yield. Specifically, if cover crops have larger growth windows, they grow larger biomass and thus have higher SOC benefits. However, under these circumstances, there is increased risk that the yield of cash crops is reduced due to the competition with cover crops for resources and nutrients including water, nitrogen, and oxygen in the soil; the work has been confirmed by a recent empirical study involving ASC members. Different lines of work collectively stress the need for careful cover crop management to avoid potential risks.

Comprehensive mechanistic modeling could help resolve this trade-off issue by simulating cover crop growth under different conditions. In U.S. Midwestern fields, management practices such as selecting specific cover crop types and regulating their growth window are major controlling factors of their SOC benefits. Through simulation, the modeling approach could help choose optimal management practices that maximize SOC benefits without compromising crop yield.

“Our study demonstrated that the ecosys model, with rigorous validation using field experiment data, can be an effective tool to guide the adaptive management of cover crops and quantify SOC benefits from cover crops,” said Ziqi Qin, lead author on the publication and graduate student in the U of I’s Department of Natural Resources and Environmental Sciences (NRES). “This provides practical tools and insights for practitioners to better manage cover crop and for policymakers to better design agricultural policies.”

In addition to SOC benefits, the researchers also found that cover crops could benefit the soil environment in other ways. The ecosys simulations indicated that the amount of carbon stored in microbes in the soil increased when cover crops were present. This finding is consistent with previous empirical studies that have found increased soil fertility when using cover crops.

“The optimal practices to manage cover crops vary for each field,” said ASC Founding Director Kaiyu Guan, NRES Associate Professor and also the project lead on the newly published study. “Our work identified the trade-off between cover crops and cash crops, which further proves the necessity to develop management guidance and technical assistance to farmers to better take advantage of cover crops while also maintaining cash crop yield.”

Co-authors on this study include U of I researchers Wang Zhou, Bin Peng, Tongxi Hu, María B. Villamil, Evan DeLucia, Andrew J. Margenot, Zhangliang Chen, and Jonathan Coppess; Jinyun Tang from DOE Lawrence Berkeley National Lab; Zhenong Jin from the University of Minnesota; Robert Grant from the University of Alberta; and Mishra Umakant from DOE Sandia National Lab.

This research was funded by the Illinois Nutrient Research & Education Council, NSF CAREER Award, USDA NIFA Program, and Foundation for Food and Agriculture Research.

— News release by April Wendling, iSEE Communications Specialist

URBANA, Ill. – According to national USDA statistics, no-till and conservation tillage are on the rise, with more than three quarters of corn and soybean farmers opting for the practices to reduce soil erosion, maintain soil structure, and save on fuel. However, these estimates are based primarily on farmer self-reporting and are only compiled once every five years, potentially limiting accuracy. 

In a new study, University of Illinois scientists demonstrate a way to accurately map tilled land in real time by integrating ground, airborne, and satellite imagery.

“We’ve shown remote sensing can quantify regional-scale tillage information in a cost-effective manner. This field-level information can be used to support growers in their management practices, as well as to support agroecosystem modeling and provide tools to the USDA to verify their census data,” says the study’s lead author, Sheng Wang, a research assistant professor in U of I’s Department of Natural Resources and Environmental Sciences (NRES) in the College of Agricultural, Consumer and Environmental Sciences (ACES). He is also a research scientist in the Agroecosystem Sustainability Center (ASC) at U of I.

Wang and the research team took photos of the ground at participating field sites throughout Central Illinois, generating 6,719 GPS-tagged images. Then they arranged for an airplane equipped with high-powered hyperspectral sensors to fly over the region. The airborne system scanned 40,000 acres per hour and captured rich spectral signatures of the ground at a scale of about half a meter.

Wang fed the ground photos into a computer that learned to differentiate bare ground from crop residue, a hallmark feature of no-till and conservation tillage. After training on labeled ground images, the computer could interpret and predict hyperspectral images from the airborne sensor with about 82% accuracy. Using this ground-to-air upscaling as a model, the computers then developed an algorithm to scale up again, this time from the air to space, using satellite data.

Compared to upscaling directly from the ground to the satellite, which was only accurate about 22% of the time according to a separate analysis in the study, the airborne layer increased mapping accuracy to 67%.

“In remote sensing, we’re always trying to link ground-truth data with spectral signals from satellites, but that represents a big scale mismatch. The intermediate-scale hyperspectral data helps to augment ground-truth data because it can provide both high resolution and accuracy. It’s a major innovation; nobody has done this in the agricultural world. This cross-scale technology significantly advances our capability to create ground-truth information,” says Kaiyu Guan, associate professor in NRES, founding director of the ASC, and senior author on the study.

Although the method was tested in Champaign and surrounding Illinois counties, Guan says the team is working to scale the technology to the broader Midwest and the nation. Now that airborne sensors and computers have been trained to detect evidence of tillage using ground images, it should be possible to forego or minimize ground photos in the next iteration.  

The article, “Cross-scale sensing of field-level crop residue cover: Integrating field photos, airborne hyperspectral imaging, and satellite data,” is published in Remote Sensing of Environment [DOI: 10.1016/j.rse.2022.113366]. The research was supported by the U.S. Department of Energy ARPA-E SMARTFARM projects and the Foundation for Food & Agriculture Research (FFAR) Seeding Solutions Award. Partial funding was also provided by a Foundation for Food and Agriculture Research Seeding Solutions Award, the National Science Foundation, the USDA-NIFA AIFARMS project, and the C3.ai Digital Transformation Institute.

Airplane image from Alan Wilson on Flickr.

Story Source(s):
Sheng Wang
Kaiyu Guan

A study led by researchers at the Agroecosystem Sustainability Center at the University of Illinois Urbana-Champaign provides new insights for quantifying cropland carbon budgets and soil carbon credits, two important metrics for mitigating climate change.

The results, outlined in a paper published in the soil science journal Geoderma, could simplify the process for calculating soil carbon credits, which reward farmers for conserving soil carbon through crop rotation, no-tillage, cover crops, and other conservation practices that improve soil health. The project was funded by the U.S. Department of Energy’s Advanced Research Projects Agency-Energy.

Soil carbon credits calculation based on process-based models. The uncertainty in the calculated carbon credits is much smaller than the uncertainty in the initial soil carbon stock (Image by Geoderma)

Agricultural activity causes a significant amount of soil organic carbon to be released into the atmosphere as carbon dioxide, a greenhouse gas that contributes to climate change. Several conservation practices have been suggested to help sequester that carbon in the soil, but their potential to enhance the total SOC in a soil profile, known as SOC stock, needs to be assessed locally. Such assessments are key to the emerging agricultural carbon credit market.

Accurately calculating cropland carbon budgets and soil carbon credits is critical to assessing the climate change mitigation potential of agriculture as well as conservation practices. Those calculations are sensitive to local soil and climatic conditions, especially the initial SOC stock used to initialize the calculation models. However, various uncertainties exist in SOC stock datasets, and it’s unclear how that can affect cropland carbon budget and soil carbon credit calculations, according to lead author Wang Zhou, Research Scientist at the ASC and the Department of Natural Resources and Environmental Sciences at Illinois.

In this study, researchers used an advanced and well-validated agroecosystem model, known as ecosys, to assess the impact of SOC stock uncertainty on cropland carbon budget and soil carbon credit calculation in corn-soybean rotation systems in the U.S. Midwest.

They found that high-accuracy SOC concentration measurements are needed to quantify a cropland carbon budget, but the current publicly available soil dataset is sufficient to accurately calculate carbon credits with low uncertainty.

“This is a very important study that reveals counter-intuitive findings. Initial soil carbon data is very important for all the downstream carbon budget calculation. However, carbon credit measures the relative soil carbon difference between a new practice and a business-as-usual scenario. We find that the uncertainty of initial soil carbon data has limited impacts on the final calculated soil carbon credit,” said ASC Founding Director Kaiyu Guan, Blue Waters Professor in NRES and the National Center for Supercomputing Applications at Illinois and lead of the DOE-funded SMARTFARM project at iSEE, which featured several co-authors on this paper.

The results indicate that expensive in-field soil sampling may not be required when focusing only on quantifying soil carbon credits from farm conservation practices — a major benefit for the agricultural carbon credit market.

“Uncertainty in SOC concentration measurements has a large impact on cropland carbon budget calculation, indicating novel approaches such as hyperspectral remote sensing are needed to estimate topsoil SOC concentration at large scale to reduce the uncertainty from interpolation. However, uncertainty in SOC concentration only has a slight impact on soil carbon credit calculation, suggesting solely focusing on quantifying soil carbon credit from additional management practices may not require extensive in-field soil sampling — an advantage considering its high cost,” Zhou said.

“The approach in this study can be applied to other models and used to assess important uncertainties of the carbon sequestration potential of various conservative land management practices,” said Bin Peng, the other primary author of the study and Senior Research Scientist at ASC and NRES.