SOIL NOx/NH3 May, 1987  California Institute of Technology releases report indicating that soil surfaces and fertilizer applications account for 20% of the ammonia (NH3) emissions in the South Coast Air Basin (Los Angeles). 1994  California Air Resources Board awards $250,000 contract to U.C. Berkeley to perform soil NOx measurements on various crops in the San Joaquin Valley. This contract was awarded without any input from the agricultural community. Summer, 1995  U.C. Berkeley conducts multiple NOx measurements on several crops in San Joaquin Valley. Report indicates peak emissions immediately following fertilizer application, but negligible emissions over time. 1995 The California Regional Particulate Matter Air Quality Study (CRPMAQS) develops two Technical Support Studies that will address soil NOx and NH3. These are TSS 14 - Development of a Methodology for Estimating Emissions of NOx and NH3 from Soils, and TSS 15 - Evaluation of Methods for Determining Ammonia Emissions from Selected Sources in the San Joaquin Valley. September, 1996  Sonoma Technology, Inc. (STI) releases draft final report for TSS 15, which indicates that ammonia emissions from the soil and fertilizer applications account for 46% of the ammonia emissions in the San Joaquin Valley. Report indicates these emissions are a leading source of ammonia, second only to dairies. Winter, 1996 Sonoma Technology conducts NH3 measurements on an alfalfa field in a limited study. Results indicate negligible emissions. January, 1999 CDFA - Fertilizer Research and Education Program awards contract to Research For Hire to develop fertilizer application calendar. This calendar will be used to help develop a more accurate seasonal emissions inventory for fertilizer emissions. April, 1999 California Air Resources Board (CARB) awards $186,000 contract to CSU-Fresno to measure ammonia emissions from fertilizer applications. Measurements will take place in late 1999 and spring/summer 2000. CSU-Monterey, CE-CERT of U.C. Riverside and NASA-Ames will be collaborating on the project. KEY ISSUES New Ozone and PM2.5 Ambient Air Quality Standards These new standards will only focus more attention on this issue as NOx is a significant contributor to ozone formation during the summer, and NOx and NH3 are significant contributors to secondary particulate (PM2.5) formation during the winter. These secondary particulates are composed primarily of nitrates and secondary organics, such as ammonium nitrate and ammonium sulfate.

DEFINITIONS CRPMAQS:  The California Regional Particulate Matter Air Quality Study. A twenty-seven million dollar study to determine the causes and solutions to the particulate matter problem in the San Joaquin Valley. NOx:  Oxides of nitrogen including NO and NO2. NH3:  Ammonia PM10:  Particulate Matter with an aerodynamic diameter smaller than or equal to a nominal ten (10) microns. PM2.5:  Particulate Matter with an aerodynamic diameter smaller than or equal to a nominal 2.5 microns.