Resumo

COSENTINO, VANINA ROSA NOEMÍ; BRUTTI, LUCRECIA NOEMÍ; CIVEIRA, GABRIELA  e  TABOADA, MIGUEL ÁNGEL. APORTE DE LA FIJACIÓN BIOLÒGICA DE NITRÒGENO A LA EMISIÓN DE N_zO DESDE EL SUELO CON CULTIVO DE SOJA. Cienc. suelo [online]. 2015, vol.33, n.2. ISSN 1850-2067.

Nitrous oxide (N₂O) is the main greenhouse gas (GHG) emitted from agricultural soils as a by-pass product of nitrification and denitrification processes. The Intergovernmental Panel on Climate Change (IPCC) excluded from its GHG inventory guidelines in 2006 the Nitrogen Biological Fixation (NBF) as a source of N₂O emissions by crop legumes, due to the lack of solid scientific evidenceon the existence of these emissions. However, at present the actual amount of N₂O emissions by crop legumes in the field is still under investigation, with special emphasis on soybeans which are is the main commodity produced by Argentina and a main biodiesel source. The influence of NBF on N₂O emissions can be tested using non-nodulating soybean varieties. This study aims to compare and analyse N₂O emissions from nodulating and non-nodulating soybean varieties in order to clarify the actual influence of this commodity on field GHG emissions. Gas samples were collected from closed non-vented chambers. N₂O emissions ranged from -9 to +15 |ig N-N₂O m^-2 h^-1 and only in the last sampling date, values differed significantly between treatments (non-nodulating > nodulating soybean). N₂O emissions were positively related with soil N-NO₃ concentration and soil water-filled pore space (WFPS). Results show that in this field study, NBF caused only a slight impact on N₂O emissions. These results agree with the latest IPCC guidelines in 2006 for GHG inventories.

Palavras-chave : N₂O flux, non nodulating soybean, legumes.

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