Research

Si Gao, PhD (she/her)

I am a soil ecologist studying how the soil system serves as a natural solution to climate change. My work focuses on understanding how agricultural, forest, and rangeland management practices influence soil health and ecosystem functions. My research broadly includes soil organic matter persistence, greenhouse gas dynamics, ecosystem carbon and nutrient cycling, fire, charcoal, and the impact of cultural fire stewardship practices on the soil system.

I am currently an Assistant Professor in the Department of Environmental Studies at California State University, Sacramento. I am also a member of the Traditional Ecological Knowledge Lab at Oregon State University. Previously I worked with Dr. Thomas H. DeLuca at Oregon State University; and Dr. Rebecca Ryals, Dr. Asmeret Asefaw Berhe, and Dr. Teamrat A. Ghezzehei at the University of California, Merced.

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Research Highlights

Determining soil greenhouse gas fluxes in a field experiment established in a winter wheat field in Central California. (credit: S. Gao)

Demonstrating regenerative agricultural practices at a community garden in Missoula, Montana. (credit: S. Gao)

Quantifying greenhouse gas emissions (N2O, CH4, and CO2) and global warming potentials during dairy manure windrow composting at a Dairy Farm in Madera, California. (credit: S. Gao)

Use of locally-produced biochar, manure compost, and biochar manure co-compost in conventional agricultural cropping fields to improve soil carbon persistence in Madera, California. (credit: S. Gao)

Examining the interactions between soil organic amendments and rotational cattle grazing on a productive pasture in western Montana. (credit: S. Gao)

Evaluating the influence of biochar and cattle manure on soil nutrient transformations in a field experiment established in Ovando, Montana. (credit: S. Gao)

Quantifying pyrogenic carbon generation and ecosystem carbon flux following the 2020 Holiday Farm Fire in the Willamette National Forest in western Oregon. (credit: S. Gao)

Soil application of locally-produced biochar in small-scale organic farms in San Juan Islands, Washington. (credit: S. Gao)

A community-engaged biochar field research established at ten organic farms at the San Juan Island, Orcas Island, and Waldron Island, Washington. (credit: S. Gao)

Biochar and chicken manure interact to improve soil nutrient retention in organic farming systems. (credit: S. Gao)

Forest biomass management, biochar production using local feedstocks in Northwestern US. (credit: S. Gao)

Using organic amendments for carbon sequestration in rangeland ecosystems of western Montana. (credit: S. Gao)

Selected publications

Locally produced wood biochar reduced soil nutrient leaching in temperate organic farming systems

Manure and wood biochar interact to improve ecosystem nutrient retention in western rangelands

Dairy manure co-composting with wood biochar plays a critical role in meeting global methane goals

Pyrogenic carbon generation from fire and forest restoration treatments

Pyrogenic carbon accelerates nitrogen cycling in forest soil 'charosphere' detected by microdialysis

Pyrogenic carbon buffers excess nutrient loading in forest soils exposed to fire retardant chemicals

In the Media

"Is biochar a game-changer for sustainable farms?" on Civil Eats by Anna Guth (visit website here)
"Time for another look at biochar?" on TimberWest by Jack Petree (visit website here)
"West Coast researchers turn to biochar in fight against climate change" on ABC7 News SF Bay Area (visit website here)
"New strategies could help California meet methane goals" on ABC7 News Bay Area (visit website here)