A New Index Tool to Assess Risk of N2O Emissions.

Nitrogen inputs are needed to maintain the economic viability of the world’s agroecosystems and to maximize the production of food needed for the growing world population. However, nitrogen inputs also increase the potential for nitrogen losses via several pathways of the nitrogen cycle, such as increases in emissions of N₂O, which has been associated with increased potential for global warming. Delgado et al. (2006) published a new Nitrogen Index that can be used to conduct quick assessments of the risk of N losses via leaching, surface and atmospheric N pathways. We modified this new N Index to include a new risk index to assess the effects of N₂O emissions. This new risk index assesses N inputs from fertilizer, organic sources, and crop residue, and assessments of N₂O emissions risk can be conducted within five minutes. It integrates management data with data on soil physical and chemical properties, hydrologic characteristics, and weather, to assess the level of risk. It also considers off-site factors. Preliminary results suggest that the N₂O risk values calculated by the N₂O risk index correlate with measured values.  Additionally, the results also suggest that values calculated by the N₂O risk index correlate with simulated values from other computer models. This preliminary work suggests that there is potential to use this new feature to assess N₂O emissions risk. The basic algorithms used to develop this new assessment tool and the correlation values of the risk index simulations and measured values will be presented. We suggest that this new approach for assessing the risk of different management decisions on N₂O emissions can be used to assess both the direct and indirect N₂O emissions and even the carbon sequestration equivalents of the calculated N₂O emissions risk.