Basalt Weathering And Carbon Sequestration In Willamette Valley Hazelnut Orchards With Restoration Site Applications

Soils hold more than three times the carbon currently stored in the atmosphere, yet soil management practices in American agriculture remain largely invisible in public conversations about climate change. This thesis examines whether basalt dust, applied through a process called enhanced rock weathering (ERW), could serve as a uniquely viable and climate positive alternative to agricultural lime in Oregon's Willamette Valley hazelnut orchards. Oregon produces 99% of the United States' hazelnuts, and maintaining hazelnut productivity depends on correcting naturally acidifying soils with lime. Lime is effective but carries a significant carbon cost, generating CO₂ both during production and upon dissolution in soil. Basalt, a silicate rock abundant in the Pacific Northwest, weathers through a different chemical process that consumes rather than releases CO₂, converting atmospheric carbon dioxide into stable bicarbonate that travels through river systems toward long-term ocean storage. Through a structured synthesis of existing research, this thesis evaluates basalt ERW across three dimensions: agricultural viability, carbon sequestration potential, and regional feasibility in the Willamette Valley context. Drawing on laboratory incubation studies, national-scale modeling, and preliminary field data from the Highbanks restoration site in Springfield, Oregon, this thesis argues that the Willamette Valley presents an unusually favorable context for ERW adoption, combining local basalt availability, a mesic climate, and perennial orchard systems with deep root networks that can accelerate silicate weathering. At the same time, this thesis identifies significant gaps. No field-scale economic comparison between lime and basalt yet exists for Oregon hazelnut systems, and rigorous carbon flux verification requires paired water chemistry and discharge data, along with sampling across multiple seasons, which has not yet been conducted in Oregon orchards. The preliminary data from Highbanks illustrate the complexity of ERW applications in the real world, including unexpected lysimeter pH results that underscore the importance of hydrologic context in interpreting field measurements. The evidence reviewed here supports serious investment in field-scale ERW research in the Willamette Valley. If confirmed, replacing lime with basalt dust could simultaneously address soil acidity, reduce agricultural CO₂ emissions, and contribute to durable long-term carbon sequestration in one of the Pacific Northwest's most agriculturally significant regions.

Grantor dc:publisher

University of Oregon

Year dc:date.issued

2026

Author dc:creator

• Penna, Grace

Advisor dc:contributor.advisor

• Silva, Lucas

• Enhanced rock weathering
• Carbon sequestration
• Willamette Valley Hazelnut orchards
• Soil pH management
• Restoration Application

Statement dc:rights

• CC BY-NC-ND 4.0

Language dc:language.iso

en_US

Handle dc:identifier.uri

https://hdl.handle.net/1794/33303

OAI record oai:identifier

https://scholarsbank.uoregon.edu/server/oai/request?verb=GetRecord&metadataPrefix=dim&identifier=oai%3Ascholarsbank.uoregon.edu%3A1794%2F33303