California Air Resources Board

Principal Investigator/Author: Jorge L. Mazza Rodrigues

Contractor: University of California, Davis

Sub-contractor: University of Wisconsin, Madison

Contract number: 22RD036

Project Status: Active

Relevant CARB programs: AB 32 Climate Change Scoping Plan, Nitrous Oxide Emissions from California Lands

Topic areas: Climate Change, Greenhouse Gas Emission Inventory Program, Greenhouse Gas Inventory

Research Summary:

Nitrous oxide (N₂O) is a potent greenhouse gas (GHG) which contributes to climate change. Cropland is the largest source of N₂O emissions in California, derived primarily from nitrogen fertilizers applied in the field to increase crop yield.

N₂O emissions from cropland are highly variable both spatially and temporally due to changes in soil environmental conditions such as soil nitrogen content, water content, organic carbon content, and temperature that affect soil microbial activities involved in converting soil nitrogen chemicals to N₂O. Numerous studies have been conducted in the past to characterize N₂O emissions from California cropland. However, impacts of pesticide application, such as use of fumigants in the field, on N₂O emissions have received little attention. The project will perform field and laboratory experiments to investigate N₂O emissions in fumigated cropland and develop emission estimates that integrate fumigation effects on N₂O emissions. Results of this project will address the knowledge gap on the fumigation impacts on N₂O emissions, inform CARB’s N₂O inventory, and support the California Department of Pesticide Regulation’s (CDPR) decision making on management of fumigant use in California croplands.

Keywords: nitrous oxide (N2O) emissions; pesticide;  greenhouse gas emissions; soil; soil emissions; climate change