4R N Management Science Consensus to Modify Nitrous Oxide Estimation in the Field to Market Fieldprint Calculator

IPNI and The Fertilizer Institute (TFI) are leading a project (with cooperation by Fertilizer Canada), to help strengthen the science underpinning the Field to Market Alliance for Sustainable Agriculture Fieldprint Calculator (FPC) and its field-scale greenhouse gas (GHG) emissions estimates. Project goals were to overview and enlist current agronomic and soil science N management knowledge, which may allow modifications of the Field to Market FPC nitrous oxide (N₂O) estimator; ultimately enabling the FPC to be more inclusive of all the 4Rs of Nutrient Stewardship (right source, rate, time and place of application). Presently, the FPC estimates N₂O emissions (direct plus indirect) associated with fertilizer and/or manure N inputs by relying on a single coefficient. That coefficient was developed by the Intergovernmental Panel on Climate Change (IPCC), but was intended only for national or country-level gross emissions estimation; not farm or field-scale emissions.

Twenty Land Grant University N management scientists as well as N₂O emission scientists from the USDA-NRCS and ARS were invited to a workshop, to collectively develop consensus-based suites of 4R-sensitive N management practices. Seven corn, soybean and wheat system 4R N management frameworks (3-tiered at Basic, Intermediate, Advanced) were developed to help guide farmers and crop advisers toward increased N use efficiency, greater crop productivity, and lower residual N balance in the soil. Outcomes of intermediate and advanced management tiers are expected to lead to reduced N₂O emissions. The project anticipates being able to provide 4R fertilizer management N₂O emission reduction modifiers to Field to Market (in Excel format), for integration into the FPC fertilizer N-related N₂O emission algorithms by early to mid-2016.

Additional project work is underway to integrate 2014 USDA modeled baseline N₂O emissions that vary with US Land Resource Region cropping system and soil texture differences. These varied baseline emissions may more fairly and accurately reflect the inherent soil moisture, temperature and environmental factors that strongly drive N₂O emissions in farmer’s fields. The project is expected to broaden the science base and approaches used in developing and adapting cropping system sustainability metrics used within the Field to Market FPC and by members of the US food industry supply chain; not just N₂O emissions, but possibly water quality and soil health metrics also.