Research

Current Projects:

Manipulating the soil microbiome through cover crop diversification for added agroecosystem benefits

Planting diverse cover crop mixtures has a variety of agricultural and ecological benefits, but it remains difficult to reliably predict which benefits will be realized from particular combinations of cover crop species. At the same time, the soil microbiome (i.e., the complete collection of bacteria, fungi, and other microorganisms living in soil) is known to mediate crop growth and ecological processes, but its complexity makes it difficult to manage directly. We hypothesize that the soil microbiome plays a key role in realizing agro-ecological benefits from cover crop diversification, but relationships between plant diversity and soil microbial diversity are still not well understood. To address this gap we will directly measure the diversity of soil microorganisms selected for by individual cover crop species. We will then design cover crop mixtures that experimentally manipulate plant diversity in controlled ways to generate new knowledge about the relationships among crop diversity, the soil microbiome, and ecosystem functions that translate to more reliable improvements in plant production systems. The expected benefits will result in a significant step towards using crop diversification more purposefully to manage the soil microbiome, and by extension, improving yield, soil health, and agricultural sustainability.

Collaborators: Jacob Barney and Brian Strahm

Funding: USDA-NIFA

Impacts of antibiotic additions on ecosystem processes in agricultural soils

Antibiotic usage has continuously increased since their discovery, and more recently, microbial resistance to antibiotics has been a growing concern. In agroecosystems, livestock treated with antibiotics have the potential to spread antibiotics, resistant bacteria, and antibiotic resistance genes (ARGs) to soil through manure. The resulting spread of ARGs and other changes in soil microbial communities could impact human health and ecosystem functioning. We are investigating how long-term repeated additions of manure from cattle treated with antibiotics impact soil microbial communities and the prevalence of ARGS. We are also looking at how this impact is dependent on soil and environmental properties.

Collaborators: Mike Strickland, Katharine Knowlton, Jeb Barret

Funding: USDA-NIFA

Freshwater salinization and microbial ecology

Human activity including urbanization, agriculture, and deicing has been increasing total salinity and associated base cations (Ca, Mg, K, Na) in freshwaters worldwide. Although numerous consequences of freshwater salinization have already been identified, most studies focus on broad gradients of total salinity while ignoring the effects of low concentrations of different types of salts. Bacteria perform many integral functions in aquatic ecosystems and thus play a vital role in ecosystem function and health. Therefore, determining the effects of freshwater salinization on bacterial communities will help improve watershed management. Through a series of controlled laboratory experiments, we are identifying the effects of different types of salts and associated base cations on bacterial diversity, function, and persistence of fecal bacteria. We aim to improve our understanding of how increased ion concentrations are impacting bacterial ecology which can open the door to a whole new aspect of managing salts, water quality, and ecosystem function that is currently not considered.

Collaborators: Meredith Steele, Erin Hotchkiss, Leigh-Anne Krometis, and Bryan Brown

Funding:VT Institute for Critical Technology and Applied Science; VT Fralin Life Science Institute; VA Water Resources Research Center

Training future leaders to solve resource challenges at the confluence of water and Society

The Confluence Research and Extension Experience for Undergraduates program, focused on water and society, trains cohorts of summer undergraduate researchers in 2018, 2019, and 2021. We aim to provide intellectually challenging, interdisciplinary research and extension experiences for diverse undergraduates from across the US. During the summer program our undergraduate fellows will: 1) Develop a detailed and nuanced understanding of the complexity of anthropogenic influences and stakeholder needs within mixed-use watersheds; 2) Gain appreciation for the disciplinary diversity required to address critical, complex water resources issues; 3) Improve their ability to communicate scientific findings to audiences of varying backgrounds in formal and informal situations; 4) Acquire a foundation in technical, social, and collaborative skills to help them succeed in future research and professional activities; and 5) Form a professional network that can support future careers in water management (e.g., graduate degrees, agricultural/industry careers, public service, etc.). This USDA-funded REEU will catalyze interactions between students from widely varying disciplines by focusing on research questions that require innovative approaches to scientific collaboration and data visualization, as well as communication to and engagement with an array of local stakeholders. Our diverse team of experienced mentors includes environmental scientists, social scientists, engineers, and computer scientist will both guide individual student efforts as well as collectively model successful interdisciplinary collaboration.

Collaborators: Cully Hession, Leigh-Anne Krometis, and Erin Ling

Funding: USDA-NIFA