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 two sites in Becker, MN and one site in Rosemount, MN to collect greenhouse gas emissions data from corn and potato cropping systems. A controlled release polymer-coated urea (ESN) and/or a stabilized urea source (SuperU) and Urea as a conventional source will be applied to each cropping system at each location. Except for the irrigated site at Becker, 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 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.
All field experiments planned for this project were completed in FY 2011 and no funding has been received by the St. Paul location from this project since FY11. Over the course of this project, 8-site years of field experimentation were completed comparing the use of specialty fertilizer products as a potential method for reducing nitrous oxide (N2O) emissions and other N losses from fields used for potato and corn production in Minnesota. Overall, the results have shown that urea amended with microbial inhibitors was more consistent in reducing N losses compared with polymer-coated urea or conventional (uncoated) urea, and that the timing of rainfall events in relation to crop N demand and fertilizer application timing are important factors in regulating N2O emissions. Data from this project has resulted in 4 peer-reviewed publications and a 5th in preparation, as well as several presentations to scientific and non-scientific audiences. Results from the project were also used in a recently completed PhD dissertation as part of the University of Minnesota Land and Atmospheric Science program. This work was part of a multi-location project within ARS which included similar experiments conducted at several ARS locations throughout the U.S. This progress contributes to meeting Objective 3 of our NP212 Project Plan which is to “Enable reduced N2O emissions from fertilized cropping systems through improved understanding of controlling mechanisms, as a contributor to the ARS Greenhouse Gas Reduction through Agricultural Carbon Enhancement network (GRACEnet).”