Large scale field demonstrations to test the carbon sequestration potential of enhanced weathering in working lands
Abstract
Removing carbon dioxide (CO2) from the atmosphere in time to avoid the worst impacts of climate change will require large scale carbon (C) sequestration technologies that can be deployed on short time scales. Working lands, such as crop and rangelands, are currently a major source of greenhouse gas emissions but hold enormous potential for decreasing atmospheric CO2 through enhanced weathering (EW). While the potential for EW remains unrealized, model projections estimate that amending two-thirds of croplands with basalt dust could extract 0.5-4 Pg CO2 yr-1 by 2100. Even less is known about the potential in rangelands, which cover >30% of the terrestrial land surface. Conceptual models and field tests of EW will help constrain global estimates and inform where this strategy can be most effective. At the Working Lands Innovation Center, we have developed EW demonstration sites in both crop and rangelands that span variable plant, soil, and climate types throughout California. Here we are monitoring plant and soil conditions to verify C sequestration estimates and to quantify co-benefits for farming, ranching, and soil health. In this talk, I will discuss three approaches we are using to evaluate EW as a strategy for C sequestration in working lands. First, we developed conceptual frameworks for EW that outline mechanisms for C sequestration, rank biophysical influences, and illustrate co-benefits. Second, we deployed a large-scale field demonstration, where we are monitoring yield, weathering rates, surface alkalinity, and inorganic C. Third, we collected preliminary data from a corn field where wollastonite, gypsum and basalt were applied. Here we found that basalt amendments significantly increased yield (9.98% stover and 8.46 % grain and cob) while wollastonite amendments significantly increased yield (12% stover and 13.44% grain and cob) and soil bicarbonate. These effects were more pronounced in organic compared to conventionally managed corn, suggesting that sites with high organic matter, or where organic inputs are applied, might experience synergistic effects on C sequestration. The myriad co-benefits, low cost ($20-60/tCO2) and relative ease of deploying EW technology make this a CO2 removal strategy that demands rapid testing, development, distribution, and deployment.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2020
- Bibcode:
- 2020AGUFMB003.0001A
- Keywords:
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- 0402 Agricultural systems;
- BIOGEOSCIENCES;
- 0412 Biogeochemical kinetics and reaction modeling;
- BIOGEOSCIENCES;
- 0414 Biogeochemical cycles;
- processes;
- and modeling;
- BIOGEOSCIENCES;
- 0428 Carbon cycling;
- BIOGEOSCIENCES