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; Auburn, AL; and University Park, PA) 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:
Quantity water and nutrient balances of cropping systems that include bioenergy crops and new management practices. A three-year field study was conducted from 2010 to 2012 in which nitrous oxide emissions and corn grain yields were compared among six nitrogen sources, including the slow release and inhibitor-treated fertilizers. Field studies were completed in the fall of 2012 and funding expired in April 2013. Nitrogen source did not significantly impact either nitrous oxide emissions or grain yield in any year of the study. Rainfall was below normal in each year, and dry conditions appeared to have had a stronger influence than the form in which the nitrogen was applied. A manuscript outlining the results of the study has been tentatively accepted by the Agronomy Journal, pending final approval of revisions.