ARB Research Seminar

This page updated March 23, 2016

Evaluating Mitigation Options of Nitrous Oxide Emissions in California Cropping Systems

Photo of Martin Burger, Ph.D.

Martin Burger, Ph.D., Project Scientist, Department of Land, Air and Water Resources, University of California, Davis

June 16, 2016
Cal EPA Headquarters, 1001 "I" Street, Sacramento, CA

Research Project


Agricultural soils are a major source of the greenhouse gas nitrous oxide (N₂O) in California, contributing 53% of the State's total N₂O emissions. Production of N₂O in soil is mainly a microbial process involving transformation of various nitrogen (N) species, which can be affected by many soil variables governing soil microbial activities. It is possible, therefore, to minimize N₂O emissions from soil through proper management practices that would shun soil conditions known or suspected to stimulate N₂O emissions.

As this seminar will demonstrate, this project examined effects of different N fertilizer types and placements, use of nitrification inhibitors (NIs), subsurface drip irrigation (SDI), and organic management on N₂O emissions from crops of tomato, corn, and lettuce. Overall, the use of NIs, SDI instead of furrow irrigation (FI), and incorporation of N fertilizer into two instead of one band most consistently reduced N₂O emissions in tomato or corn. SDI effects in lettuce were inconclusive. Organic management in tomato showed slightly higher direct N₂O emissions than conventional management, due to the FI associated with organic systems. N₂O emissions in different fertilizer sources were in order of ammonium N > mixed ammonium and nitrate N > nitrate N, indicating that nitrification contributed more N₂O than denitrification in the systems tested. The results of this study provided experimental evidence for mitigating N₂O emissions from California cropping systems. More analyses, however, would be required to assess the economic and other environmental impacts as well as the total carbon footprint of the management options.

Speaker Biography

Martin Burger, Ph.D., is currently a Project Scientist at the Department of Land, Air and Water Resources, University of California, Davis (UCD). Dr. Burger's research is focused on developing sustainable agricultural management practices that increase nitrogen use efficiency, conserve water, and minimize greenhouse gas and air pollutant emissions. His research has addressed questions of fertility, cover crop and irrigation management, and plant nitrogen use under elevated carbon dioxide. Dr. Burger has conducted numerous field studies in a variety of cropping systems, including row and orchard crops, and dairy forage production systems. Most of his study sites were in the Sacramento and San Joaquin Valleys, but he has also participated in projects in Minnesota, Brazil, and China. Martin Burger received a Ph.D. in ecology from UCD.

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