Graduating December 2025
Student Profile: Ashley Paulsen
Ph.D. Candidate, Department of Plant Pathology, Entomology and Microbiology, Graduating December 2025
When Ashley Paulsen talks about her research, it’s clear she’s passionate about finding practical, sustainable solutions to one of agriculture’s biggest challenges: nitrogen fertilizer use.
“Inorganic nitrogen fertilizer is one of the largest, most expensive, and most polluting inputs in agriculture,” Paulsen explains. “Excess nitrogen often leaches into waterways, and nitrogen from Iowa contributes significantly to algal blooms and dead zones in the Gulf of Mexico. My research focuses on how we can reduce fertilizer use without sacrificing crop yield.”
The hypoxic “dead zone” in the Gulf of Mexico, driven largely by that excess nitrogen and phosphorus carried from the Mississippi River watershed, poses a serious threat not only to marine ecosystems but also to the region’s economy. The low-oxygen water forces commercially important species, such as shrimp and fish, into migration, reduces catch sizes, and raises operating costs for fishers who must travel further or fish less efficiently. In fact, nitrogen runoff from farms has been linked to more than $2.4 billion in annual damage to Gulf fisheries and marine habitats. Additionally, the dead zone costs the U.S. seafood and tourism industries approximately $82 million per year, with ripple effects extending to processing, hospitality, recreation, and coastal communities. For students like Ashley Paulsen, who are working to reduce fertilizer use and improve crop-microbe interactions, these economic stakes underscore the real-world importance of sustainable agriculture. By helping prevent nutrient overload at the source, the work supports healthier waterways and coastal economies.
Working in the Halverson Lab at Iowa State University, Paulsen studies how bacteria that live in the soil and on corn roots can boost plant growth naturally. “Our lab has isolated a group of beneficial bacteria that can be combined to form a synthetic microbial community,” she says. “My work has focused on characterizing these bacteria, understanding their interactions, and exploring how they affect corn root development.”
To achieve this, Paulsen employs a range of cutting-edge approaches, including genome assembly, microbiome profiling, and biofilm analysis. “Over the course of my project, I even developed a new bioinformatics pipeline for microbiome profiling,” she notes proudly.
Beyond the lab, Paulsen’s time in the Department of Plant Pathology, Entomology and Microbiology (PPEM) has helped her grow as a communicator and mentor. “PPEM has helped me improve my teaching and speaking skills immensely,” she says. “It’s also deepened my passion for teaching and outreach.”
That passion extends to volunteering at science outreach events, where she inspires young students to explore the field of microbiology. “I love helping others see how exciting and important this field is,” Paulsen says. “Microbes are tiny, but their impact is enormous.”
After graduation, Paulsen plans to continue her research in crop microbiomes with the goal of becoming a faculty member in academia. “I came to Iowa State because it’s one of the top universities for studying plant–microbe interactions,” she says. “This experience has confirmed that I’m right where I belong.”
When she’s not in the lab, Paulsen enjoys unwinding with cross-stitch, knitting, and puzzles, hobbies that reflect the same patience and attention to detail that make her a meticulous scientist.