2009 Annual Report 1a.Objectives (from AD-416) The fertilizer industry and the USDA-Agricultural Research Service's (USDA-ARS) GRACEnet project need scientifically sound N2O emissions data from field research plots treated with various N sources across the U.S. The USDA-ARS GRACEnet cross location project has (1) a research network in place; (2) established cross location protocols for greenhouse gas sampling; (3) the facilities and personnel; and (4) the initial instrumentation required to expand its collection of this type of data. GRACEnet objective 2 includes the collection of CO2, N2O and CH4 greenhouse gas data, in addition to soil carbon sequestration. This research project will evaluate the effects of controlled release and stabilized nitrogen sources on nitrous oxide emissions in rainfed and irrigated cropping systems at several ARS research locations compared with the commonly used urea and urea-ammonium nitrate fertilizer sources. 1b.Approach (from AD-416) Nitrogen source studies will be conducted at five ARS locations (Fort Collins, CO; Ames, IA; St. Paul, MN; Pullman, WA; and Auburn, AL) to collect greenhouse gas emissions data from corn, cotton, wheat, and potato cropping systems (varies with location). Several N fertilizer sources (a controlled release polymer-coated urea (ESN); a stabilized urea source, SuperU or UAN treated with AgrotainPlus; UAN and/or Urea as conventional sources) will be applied as a minimum to a cropping system at each location. Except for the irrigated Fort Collins site and one irrigated site at St. Paul, all sites are rainfed cropping systems, with either conventional tillage or no-tillage management practices, or both. Nitrogen rates at each location will include at least a near optimal N rate (for greenhouse gas data collection) for the crop and cropping system. The N sources will be applied using normal farming practices at each location. Nitrous oxide emissions (and possibly CO2 and CH4 emissions) from each N source treatment and a check (zero fertilizer N applied) treatment will be monitored several times each week during the growing season. Methods used for greenhouse gas measurements will follow those established for the ARS GRACEnet program. Crop yield data, needed soil water and temperature data, and other necessary data needed to interpret the greenhouse gas emissions results will be collected. A scientifically sound experimental design with a minimum of 3 replications will be used at each location. 3.Progress Report In this field study an evaluation of different forms of nitrogen (N) fertilizer and the impact of N stabilizers on corn growth and yield and the emission of nitrous oxide (N2O) has been undertaken commencing in 2008. Sixteen different treatments with combinations of preplant only or preplant with sidedress application of N fertilizer were compared using urea and ammonium nitrate (UAN) with and without stabilizer with ExtraStable Nitrogen (ESN). Results from the 2008 experiment revealed that N with stabilizer produced the highest corn yields with less total N applied. There were shifts in the N2O emission patterns with the stabilizer added to later in the growing season. Observations of leaf chlorophyll during the growing season showed that it was not possible to differentiate among treatments until near the time of reproductive development. This study has been altered for 2009 to include both a continuous corn and corn following soybean crop scenario with slight modifications in the fertilizer types being used in the study. At this point in the season the response across fertilizer treatments in the continuous corn plots is more pronounced than in the corn following soybean because of the residual effect of the soybean crop on nitrogen availability. Email was used to exchange information developed as part of the project and to evaluate progress.