DMPSA application reduces N2O emissions from exogenous NH4+ and NO3- sources in irrigated maize

Sonia García-Marco1, Guillermo Guardia1, Alberto Sanz-Cobena1, Laura M Cardenas2, Elizabeth R Dixon2, Miguel Ángel Repullo2 and Antonio Vallejo1

1Chemistry and Food Technology Department, E.T.S.I. Agronómica, Alimentaria y de Biosistemas, Universidad Politécnica de Madrid, Ciudad Universitaria, 28040 Madrid, Spain [email protected]; [email protected]; [email protected]; [email protected]

2Rothamsted Research, North Wyke, Okehampton, Devon EX20 2SB, UK [email protected][email protected]

Abstract

Agriculture is a major anthropogenic source of nitrous oxide (N2O). Application of nitrogenous (N) fertilizers enhances the emission of this greenhouse gas (GHG), mainly due to the biogenic processes of nitrification and denitrification. The use of nitrification inhibitors (NIs), that delay the microbial oxidation of NH4+ to NO3-, has been reported as a successful tool for mitigating N2O losses. In this context, a field experiment using 15N labeled fertilizers was carried out in an irrigated Mediterranean maize field aiming to evaluate the effectiveness of the NI 2-(3,4-dimethyl-1H-pyrazol-1-yl) succinic acid isomeric mixture (DMPSA) on mitigating N2O emissions, and assess the processes involved in its production. The experiment, performed in 1 m2 microplots, involved the application of 15NH4NO3 or NH415NO3- (with and without DMPSA) to quantify the amount of N2O coming from exogenous NH4+, exogenous NO3- and endogenous soil N. The resulting N2O fluxes confirmed that the addition of DMPSA led to a significant (54%) abatement of this GHG. In this experiment, both nitrification and denitrification were partially inhibited by DMPSA. When NI was not applied, the largest N2O emissions were expected from NH4+ than from NO3--based fertilizers due to nitrification.