Soil Health and Human Health in smallholder agricultural landscapes

PhD Candidate, Geography

Scow Soil Microbial Ecology Lab

Geography Graduate Group

Department of Land, Air, and Water Resources

University of California, Davis

I am a biogeographer and PhD candidate in Geography in the Department of Land, Air, and Water Resources at the University of California, Davis.

My research addresses the relationships between the soil microbiome, human gut microbiome, and human health. In my doctoral dissertation work, I am investigating the associations between the composition and structure of the gut microbiome of children and the soil microbial communities found in and around  their homes in rural Kenya. I also aim to identify whether these relationships may have an influence on the child’s burden of acute and/or chronic diarrheal disease, and whether features in the larger landscape surrounding the household may be an underlying driver of these relationships.

Prior to pursuing a PhD, I earned a MSc in International Agricultural Development from UC Davis and worked in a variety of roles in research support and communications.

I am committed to pursuing integrative research spanning human health, communities, and the environment that makes a meaningful contribution to rural lives and livelihoods in the global South. 

Image of Mariah Coley in front of blue sky and mountains





PhD Geography
University of California, Davis

Associations between soil microbial communities, gut microbiome, and child health

My doctoral dissertation research addresses the relationship between the local soil microbiome and human gut microbiota for children in rural households in Kenya.

Soil-gut microbiome associations





PhD Geography
Coursework and training
University of California, Davis


Preferences for small-scale irrigation technologies among women and men smallholder farmers in Uganda

Drip irrigation and soil health for commercial tomato growers in the California Central Valley

Selected courses taken

◊ Soil science
◊ Plant and crop system modeling
◊ Critical social science of agriculture
◊ Political ecology
◊ Quantitative geography
◊ Geostatistics
◊ Spatial methods in community research



MSc International Agricultural Development
University of California, Davis


Participatory farm-system modeling for scenario analysis and decision support with smallholder farmers in Uganda

Selected courses taken

◊ Participatory research methods
◊ Data in the built environment (“R bootcamp”)
◊ Physical geography
◊ Theory and practice in int’l development
◊ Project management for int’l development
◊ Microeconomics of smallholder farm systems


Kate Scow (Major advisor)
Robert Hijmans
Heidi Ballard





Research support & other work

Author contributions

Contributing author and project coordinator for The California Nitrogen Assessment

Contributing author and project assistant for a special issue of Agricultural Systems, Agricultural research for rural prosperity: rethinking the pathways

Scientific communications

Website development: Whole Orchard Recycling

Website development: Innovations in Dry-Season Horticulture