Author(s)

Liliana Inés Picone¹, Cecilia Videla¹, Calypso Lisa Picaud², Fernando Oscar García³, Roberto Héctor Rizzalli¹

¹Facultad Ciencias Agrarias, Unidad Integrada Balcarce Instituto Nacional Tecnología Agropecuaria (INTA) UNMdP, Balcarce, Argentina.
²AgroParisTech, Institut des sciences et industries du vivant et de l’environnement, 16 rue Claude Bernard, Paris, France.
³International Plant Nutrition Institute (IPNI), Programa Cono Sur de Latinoamérica, Buenos Aires, Argentina.

The need to accurately estimate gaseous nitrogen losses from soils is required to have a better understanding of the processes involved as well as soil and environmental conditions, and management practices contributing to these emissions. The objective was to quantify the denitrification rate using undisturbed cores with acetylene, as related to nitrogen (N) fertilization rate in a spring wheat crop (Triticum aestivum L.) under conventional tillage. Soil denitrification losses remained low throughout most of the growing season, when water-filled pore space (WFPS) was below 60%, ranging from 0.79 to 447.3 g N₂O-N ha^-1•day^-1 in the fertilized plot and was less than 47.3 g N₂O-N ha^-1•day^-1 in the control. Denitrification rates were the highest when N fertilizer was applied after frequent and intensive rain. A good correlation was found between the logarithm of the daily denitrification rate and WFPS (r = 0.67, n = 90); however the NO₃-N concentration was not a good indicator (r = 0.21, n = 90). Cumulative N₂O-N losses by denitrification averaged 3.5 and 0.9 kg N₂O-N ha^-1 in the fertilized and unfertilized treatment, respectively, during a period of 4 months this difference was not significant. Most N₂O-N losses occurred early in the spring; therefore sampling schedules need to focus on this period.

Nitrogen, Urea-N, Losses, Water Content, Soluble Organic Carbon

Picone, L. , Videla, C. , Picaud, C. , García, F. and Rizzalli, R. (2014) Denitrification in a Soil under Wheat Crop in the Humid Pampas of Argentina. Open Journal of Soil Science, 4, 312-322. doi: 10.4236/ojss.2014.49033.