Location: Soil, Water & Air Resources Research2010 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 fertilizer and the impact of nitrogen 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 nitrogen fertilizer were compared using urea-ammonium nitrate (UAN) with and without stabilizer with ExtraStable Nitrogen (ESN), stabilized N source (SuperU®), and anhydrous ammonia. These studies were conducted in both continuous corn and corn following soybean using the same nitrogen (N) treatments and rates. Yield data and yield components were collected from each replicate treatment along with nitrous oxide emissions, plant biomass and leaf area, and remote sensing estimates of leaf nitrogen status, biomass, vigor, and leaf area, and leaf chlorophyll readings. The results in 2009 showed there was a definite effect of improved nitrogen management on yield with the stabilized nitrogen systems showing an increased yield over unstabilized materials. There was a 25 bu/A increase with SuperU compared to no stabilizer at a rate of 150 lb/A. The difference in these systems was the continued greening of the leaf material during grain-filling which translated into a longer grain-filling period and was reflected in a larger kernel weight. The nitrous oxide observations also revealed the stabilized materials had less loss to the atmosphere early in the growing season. These materials offer effective management strategies for use by producers. There are email exchanges with the project team on the progress of the project and status of the observations during the growing season.