2011 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 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.
A field experiment being conducted in a moderately textured soil in Rosemount, MN, under dryland corn production was continued for a second year. This experiment is measuring the effect of controlled release fertilizer products on nitrate leaching, grain yields, and N use efficiency with under both conventional tillage and no-till management. A second study was initiated in a similar soil type in St. Paul, MN under dryland corn production and conventional tillage to measure the effect of controlled release fertilizer products on N2O, NO, and NH3 emissions, grain yields, and N use efficiency. In both studies, polymer-coated urea and urea impregnated with urease and nitrification inhibitors were compared to conventional urea and non-fertilized control treatments. In the St. Paul study, all fertilizer sources are being compared using both uniform broadcast followed by incorporation and subsurface banding application modes. This progress contributes to meeting Objective 1 of our NP202 Project Plan which was to “Quantify the impact of agricultural practices and environmental changes on surface/atmosphere exchange of greenhouse gases (GHG) in order to develop farming systems that reduce global warming potential (GWP) and promote soil C sequestration.”