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RESEARCH PRODUCT

Predicting in situ soil N2O emission using NOE algorithm and soil database

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This paper presents a new algorithm, Nitrous Oxide Emission (NOE) for simulating the emission of the greenhouse gas N2O from agricultural soils. N2O fluxes are calculated as the result of production through denitrification and nitrification and reduction through the last step of denitrification. Actual denitrification and nitrification rates are calculated from biological parameters and soil water-filled pore space, temperature and mineral nitrogen contents. New suggestions in NOE consisted in introducing (1) biological site-specific parameters of soil N2O reduction and (2) reduction of the N2O produced through nitrification to N2 through denitrification. This paper includes a database of 64 N2O fluxes measured on the field scale with corresponding environmental parameters collected from five agricultural situations in France. This database was used to test the validity of this algorithm. Site per site comparison of simulated N2O fluxes against observed data leads to mixed results. For 80% of the tested points, measured and simulated fluxes are in accordance whereas the others resulted in an important discrepancy. The origin of this discrepancy is discussed. On the other hand, mean annual fluxes measured on each site were strongly correlated to mean simulated annual fluxes. The biological site-specific parameter of soil N2O reduction introduced into NOE appeared particularly useful to discriminate the general level of N2O emissions from site to site. Furthermore, the relevance of NOE was confirmed by comparing measured and simulated N2O fluxes using some data from the US TRAGNET database. We suggest the use of NOE on a regional scale in order to predict mean annual N2O emissions.